Chinese Black, Green & Oolong Tea is NO Health Beverage. Lead, Chromium, Cadmium and Potentially Toxic Levels of Manganese + Endocrine Disrupting PFCs Are the Rule

"Pesticide pollution: Chinese tea may not be safe to drink," this is what you could read on the website of Greenpeace in 2012, already and obviously this has not changed over the last 2 years | read more

I've actually written about the problem with toxins in tea, specifically green tea from China, before and I wouldn't be too sure, whether bad news like the previously reported "-20% Reduction in Green Tea From Just 5 Cups a Day" (learn more) could not possibly be a result of heavy metals and/or other toxins, as well. This and the fact that the data I am going to talk about in the following paragraphs is based on analyses of 43 representative tea products (including 18 green, 12 Oolong, and 13 black teas) from 7 main tea production provinces in China makes today's SuppVersity article relevant for everyone who consumes green tea from China or of unkown origin - China is the cheapest, so guess, where it's from ;-)

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Apropos "Guess where it's from!", if I had to guess, I would say that 99% of the black, green and olong tea extracts in green tea, fat burner, pre-workout, anti-oxidant, and other commercially available supplements will be from China. The fact that cadmium (Cd), inorganic and thus toxic chromium (Cr) and lead (Pb) were present in samples from Zhejiang, Fujian, Yunnan, Anhui, Hunan, Guangdong and Taiwan is relevant for ~95% of the SuppVersity readers.

You think that's an old hat? Well, what about the perfluorinated compounds (PFCs) the researchers, who are by the way working for the China Ministry of Agriculture and thus certainly not interested in making Chinese tea look like a poisonous swill, detected in all samples. The concentration of these emerging and ubiquitous organic pollutants in the samples varied. In view of the already established negative health effects of which Eriksen et al. (2009), Corsinia et al. (2012) and Posta et al. 2012) write that they encompass...

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  Would all commercially available teas have to be labeled like this? A previous study which found also Aluminum & Arsenic in tea bags, would suggest just that | read more

  thyroid dysfunction, 
• preeclampsia,
• increased risk of high cholesterol
• increased risk of cancer, 
• liver dysfunction, 
• disruption of the immune system,
• disturbances of the endocrine (=hormone) system, 
• developmental delays, and
• fertility issues

...which could potentially occur with chronic exposure to comparatively low amounts of these toxins, this is certainly disconcerting.

PFCs are everywhere: Due to their toxic effects in humans and other organisms, PFCs were added to the list of banned chemicals in the Stockholm Convention on Persistent Organic Pollutants in 2009 (Ma and others 2012). Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been detected in animals and water samples from rain, river, wastewaters, and sea. They are present in plants and crops, including all twenty foodstuffs that were examined in 2004 in Great Britain by Gem et al. in 2006. PFCs are present in wheat, oats, potatoes, and maize (Stahl. 2009) and their concentration is the highest in plants / crops that grow in or close to the ground - including the peeled edible parts of carrots, potatoes, and cucumbers.

If you look at the maximal heavy metal content (individual circles in Figure 1) you will see that eventually, even the high manganese content of up to 240mg/100g could become problematic.

Figure 1: Box plots of Cd, Pb, Cr, Cu, Zn, and Mn contents in 43 tea products from south China. The central solid line within each box is the median, and the bottom and top of each box represent the 25th and 75th percentiles, respectively (Zhang. 2014); the values outside this range are plotted as individual outliers (o).

The upper tolerable intake level (UTI) of manganese is only 11mg for an adult. If you adhere to the recommended 3g per 150ml water you would thus exceed the UTI by ~30% with with the amount of tea you'd put into only 2 cups! That's bad news, even if the hot water does not extract the total amount of manganese. It is after all not unlikely that toxic effects such as the Parkinson-esque shaking (tremors), which is supposedly a direct result of the neurotoxicity of manganese (Dobson. 2004),  can occur with the chronic ingestion of subtoxic doses in the 5mg/day range, as well.

And while the combination of cadmium, lead and chromium is etching away your brain and nervous system, the PFCs, which were detected in form of PFOS in only 6 samples and in form of PFOAs in 33 samples, will launch an attack on your endocrine system. Unfortunately, there is no reliable information on whether or not chronic exposure to teas with  250ng/kg dw of this endocrine disruptor will or will not have permanent negative effects on your health.

Table 1: Contents of PFOA and PFOS according to origin (left) and type (Zhang. 2014)

What we do know, though is that Oolong teas were 15x more frequently contaminated than green tea. Apropos, if you look at the data in Table 1 you will see that the tea producers in the Anhui Province are either most generously intoxicating their produce with PFC-containing products, or plant their tea plants right next to some industrial complex. Here, more than 50% of all tested samples contained both PFOA and PFOS.

Green still the "greenest": In Germany "green" mean ecological and "clean" and at least for the 43 batchs of green, oolong and black tea this association holds for Chinese teas, as well. The results of the study at hand clearly show that black teas had - on average - higher amounts of heavy metals and PFCs in them than oolong or green teas. This doesn't change the fact, though, that the major and potentially toxic manganese offender in the study was a batch of green tea (unfortunately, Zhang et al. don't disclose the province it was from). So, don't make a mistake: Green tea is not generally a safe choice - at least if it's from China.

Bottom Line: Chinese tea is certainly not your best choice! I would not go so far as to say that you must avoid it like a plague, though. Firstly, we don't really know if the heavy metal and PFC levels in the produce from other countries are much lower. Secondly, only few of the samples may be considered "officially" hazardous to your health. And thirdly, there is insufficient data on both, the amount of heavy metals (specifically manganese) and PFCs that will leach out of the leaves, into your tea and make it from there across the gut lining into your blood stream, as well as their potential long-term consequences.

The initially mentioned "Drinking Green Tea Reduces Your Testosterone Levels" study, is yet only one out of countless "surprisingly" disappointing studies with green tea and green tea supplements the negate results of which could potentially be ascribed to the presence of heavy metals or PFCs in the green tea / green tea extracts that were consumed in the study. So, maybe, but just maybe, you want to take a brief look at the back of the next bag of green, oolong and black tea you buy to check, whether it's from China?

References:

• Dobson, Allison W., Keith M. Erikson, and Michael Aschner. "Manganese neurotoxicity." Annals of the New York Academy of Sciences 1012.1 (2004): 115-128.
• Ma, Jin, et al. "State of polybrominated diphenyl ethers in China: An overview." Chemosphere 88.7 (2012): 769-778.
• Stahl, T., et al. "Carryover of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from soil to plants." Archives of environmental contamination and toxicology 57.2 (2009): 289-298.
• Zheng, H. et al. "Analysis of Trace Metals and Perfluorinated Compounds in 43 Representative Tea Products from South China." Journal of Food Science (2014). Accepted Manuscript. doi: 10.1111/1750-3841.12470

Commercially Available Teas "Not Suitable For Human Consumption": Potentially Hazardous Amounts of Lead, Aluminum, Arsenic & Co in Every Cup

Would all commercially available teas have to be labeled like this?

I am usually not a fan of articles with titles like this one (see above) - they have what you call in Germany "Bildzeitungsniveau" (the German tabloid with news like "World about to disappear in a black hole, when CERN starts operating). It is however hard to resist the urge to use a headline like the one above, if the it fits the results of peer-reviewed scientific paper so well, as it is the case with the relatively recent paper from the University of Alberta and the Luleâ University of Technology in Sweden this SuppVersity article is (almost) all about.

The corresponding experiment, the results of which were published in the peer-reviewed open-access Journal of Toxicology in October 2013, already, addresses the increasing concern about contamination of foodstuffs and natural health products. With the emphasis being on foodstuff and health, it's only logical that tea, or more precisely all currently available off-the-shelf varieties of black, green, white, and oolong teas sold in tea bags were used for analysis in the said study.

So what did the researchers do?

Schwalfenberg, Genius (no joke, the 2n author is a real 'Genius by name') and Rodushkin conducted a three-step analysis in the course of which they analyzed the content of previously identified tea contaminants like aluminum, fluoride, mercury, lead, cadmium and arsenic (Fujimaki. 2004; Lung. 2008; Wang. 2008; Alvarez-Ayuso. 2011; Tan. 2012) in commercial tea preparations.

Table 1: There are not just bad, but also healthy minerals in tea!

Before we get to the "bad stuff", though, let's start with the positive findings of their investigation. The data in Table 1 is after all evidence enough that there are also "healthy" minerals in tea - the amount is not high enough to cover your RDA, but this does not mean that it could not be at least partly related to the undeniable health benefits researchers all around the world report for people who consume uncontaminated tea on a regular base. As a loyal SuppVersity readers you know most, if not all of them from previous articles on tea. The reason I still believe it's worth enumerating them again is that I don't want you to give up on your beloved (?) tea too easily - I mean, Coke is not an alternative and for coffee fungi and other stuff could make a similarly unhealthy "supplement" to your breakfast beverage:

• Cardiovascular benefits - When we are talking about health in general and heart health in particular, most people will think of green tea. That's pretty unfortunate, because there is ample research for all varieties of teas that they can lower blood lipids, provide "clean" and thus heart healthy energy, and exert antithrombotic and anti-hypertensive effects.
• Anticancer effects - Despite the fact that the anti-cancer effects have mostly observed in in-vitro studies, there is plenty of epidemiological evidence that tea drinkers have a lower cancer risk, than the average coke guzzler (not necessarily breast cancer, though ➫ SuppVersity Facebook News).
• Metabolic syndrome - While more recent studies clearly suggest that the active weight loss effects of tea, in general, and green tea, in particular, have been totally overblown, there is still a host of controlled trials, where adding tea (not necessarily green tea) improved the effects of a energy restricted diet. Compared to the rodent trials which are still fueling the myth of the potent thermogenic effects of (green) tea, the real world results in human beings are however downright disappointing.

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  A green tea marinade will keep your meats fresh | learn more

  Anti-infective properties - Only few people (SuppVersity readers included - of course) know that green tea can be used as a mouthwash and is currently researched as an anti-bacterial food additive by researchers all around the world. According to a paper by Steinmann et al. (2013), the anti-infective effects are mediated by the antiviral, antibacterial, and antifungal properties of Epigallocatechin gallate (EGCG). The same EGCG about which you've read only recently on the SuppVersity that it is not exactly as useful as a fat loss adjuvant, as the hype would have you believe.
• Other beneficial effects - Under "Miscellaneous Effects", Schwalfenberg et al. also list the nephropotective effects of green tea, which could come very handy if you guzzle mercury contaminated green tea, everyday (unfortunately, mercury is your least problem with tea), the anti-depressive researchers have observed in people consuming 4+ cups of tea per day and the hitherto unconfirmed hypothesis that tea drinkers are (better) protected against Alzheimer’s and neurological decline.

In view of these benefits it's only logical that the Canadian + Swedish research team chose to repeat  the dichotomous health effects of drinking tea in the title of their paper "The Benefits and Risks of Consuming Brewed Tea" (my emphasis in Schwalfenberg. 2013)

Organic is not better than regular tea

To obtain a dataset that would be as comprehensive, accurate and practically relevant as possible the authors bought 30 different organic and non-organic white, green, oolong, and black teas from the the shelves of Canadian supermarkets and analyzed (a) the "raw" tea leaves (LEAF), (b) tea that had been steeped for 3-4 minutes (3MIN), (c) tea that had been steeped for 15–17 minutes (15MIN).

Know your teas: As a SuppVersity reader you will probably know that all teas come from the same plant. It's the processing that determines if we call it "white", "green", or whatever else:

• White tea: young leaves or new growth buds, withered, uncured, baked dry 
• Green tea: steamed or dry cooking in hot pans to prevent oxidation; dried tea leaves may be separate leaves or rolled into pellets (gunpowder tea)
• Oolong tea: withering of leaves under sun and warm winds with further oxidation standard between green and black teas
• Black tea: leaves are completely oxidized, withered

Due to the processing of the leaves tea from the same camellia sinensis plant can contain different amounts of contaminants depending on whether you buy it as white, green, oolong or black tea, or shredded green tea supplement.

Still, the main determinant is and remains the soil it was grown on (see Table 4)?

All tea samples underwent the same standardized procedures before they were analyzed in their raw form (cut / shredded leaves) or as an infusion that had been prepared with only one tea bag (containing 2-3g of tea) in 250 mL of distilled water in fine bone china cups.

As you will already have expected, the scientists did not just detect the previously mentioned "good minerals" (exact values see Table 1), and a host of other beneficial trace elements, i.e.

• boron 19–115µg/L, cobalt 0.4–3.56µg/L, 
• copper 26–106µg/L, chromium 0.2–14.6µg/L, 
• iron 19–62.5µg/L, manganese 534–6351µg/L, 
• molybdenum 0.03–0.131µg/L, 
• selenium <0.1–0.34µg/L, 
• vanadium <0.01–0.151µg/L, and zinc 44.6–187µg/L,

in their samples. Schwalfenberg et al. found highly significant and, more importantly, physiologically relevant amounts of toxic elements, as well:

Table 2: Established toxicant limits in supplements (µg/day).

If you look at the value in Table 3 and compare them to the limits in Table 2, there is one thing you should keep in mind: These limits have been set by average exposure, not based on toxicity tests - that sounds very comforting, right?

"Public health warnings or industry regulation indicated" -- It sounds pretty fearmongering and I would not have used it as a subheading right beneath the introduction, if the statement "Public health warnings or industry regulation might be indicated to protect consumer safety." (Schwalfenberg. 2013) was no literal citation from the conclusion of the paper I have here right in front of me.

Table 3: Levels of mercury (Hg), lead (Pb), aluminum (Al), arsenic (As) and cadmium (Cd) in tea infusions after 3-4 or 15-17 min of brewing; all values in µg/L (Schwalfenberg. 2013)

A brief glimpse at the data in Table 3 does moreover confirm there are plenty of toxins in the average Canadian super market tea, but it does not tell you how problematic the contamination actually is. To understand that you'd have to cimpare those values to the established toxicant limits Table 2, which do - and this is and will always be ridiculous -  obviously depend on where you live *sarcastic laughter*... but enough of the unproductive sarcasm, let's see what we've got:

"All teas contained significant amounts of aluminum. Tea  leaves contained from 568 to 3287 ng/g of tea. All brewed teas steeped for 3 or 15 minutes contained detectable levels of aluminum. The range was 1131µgm/L to 8324µgm/L steeping for 3 minute and 1413µgm/L to 11449µgm/L steeping for 15 minutes. Only 2 teas had levels above acceptable limits at 3 minutes of brewing but 6 of the teas had levels greater than the upper acceptable daily limit of 7000µgm/L. Clearly letting tea steep for longer than 3 minutes is not advisable. Two of the organic green teas had levels above 10,000µgm/L brewed for 15 minutes."

In view of the fact that tea is by far not the only aluminum source you are expose to, the high levels of this toxic metal that easily accumulates in the body should be reason enough not to brew your tea - especially not organic tea - for more than 3 minutes.

Organic tea is a worse offender than regular

If you take a look at the amount of lead in the various tea samples it becomes even more obvious that "organic" tea is not necessarily better for your organs, as well. This is particularly true for the best-sellers green and black tea, both of which contain significantly more lead in the "organic" vs. "regular" variety.

Table 4: Toxicant levels according to origin; Pb: lead, Cd: cadmium, Al: aluminum, As: arsenic (Schwalfenberg. 2013)

Probably the main factor that influences the toxicant levels of teas is the place of origin, thoug. As you can see in the overview in Table 4, the highest amount of arsenic, was detected in Chinese oolong teas (organic or regular). The total arsenic levels in all teas, which ranged from 0.06µgm to 1.12µgm/L for tea that had been steeped for 3 minutes to 0.08 to 1.27µgm/L for tea that had been steeped for 15 minutes was highest in white tea - obviously also from China. And last but not least, ...

"...[a]ll tea leaves had detectable levels of cadmium. 21 teas had detectable levels after 15 minutes brewing while only 18  teas had detectable levels after 3 minutes brewing suggesting that there is further leaching of this toxicant into the water over time. [As the overview in Table 4 already suggests] the highest level was 0.067µgm/L found in standard oolong tea from China." (Schwalfenberg. 2013)

Not listed in the tables are the levels of tin, barium, antimony and thallium, which were detected in all tea samples, but at levels of which the authors state that they don't have to be "considered to be of concern" (Schwalfenberg. 2013).

Should you stop drinking tea? You know that I don't like to tell people what to do. Unless, obviously I am 100% sure that I am convinced that there is a serious health risk involved.

In the case of green, black or white tea, the evidence that this is the case is yet insufficient. Personally, I will still make sure to check the geographic origin of the tea leaves (not where it was processed and packaged!) and avoid all products with the bad 5-letter word C-H-I-N-A on the label.

Bottom line: "Not of concern" is not exactly what I would say about the overall results of the study at hand. I mean, in the end, the high levels of toxicants in some of the commercially available tea preparations - specifically those from China - could actually explain why the real-world results with commercially available teas and tea supplements often fall short of the rodent studies, which are often conducted with highly purified green tea products from companies like Sigma Aldrich.

Ah, ... one last thing to keep in mind is that 18 out of 30 tested commercial tea preparations contained mercury in amounts that were as high as 20 ng/g, but did not make it from the leave to the tea. With your digestive tract being a much more efficient nutrient and (unfortunately) toxicant extractor than hot water, tea supplements could pose an even greater risk of heavy metal exposure than tea.

References:

• Álvarez-Ayuso, E., Giménez, A., & Ballesteros, J. C. (2011). Fluoride accumulation by plants grown in acid soils amended with flue gas desulphurisation gypsum. Journal of hazardous materials, 192(3), 1659-1666.
• Hayacibara, M. F., Queiroz, C. S., Tabchoury, C. P. M., & Cury, J. A. (2004). Fluoride and aluminum in teas and tea-based beverages. Revista de Saúde Pública, 38(1), 100-105.
• Lung, S. C. C., Cheng, H. W., & Fu, C. B. (2007). Potential exposure and risk of fluoride intakes from tea drinks produced in Taiwan. Journal of Exposure Science and Environmental Epidemiology, 18(2), 158-166.
• Steinmann, J., Buer, J., Pietschmann, T., & Steinmann, E. (2013). Anti‐infective properties of epigallocatechin‐3‐gallate (EGCG), a component of green tea. British journal of pharmacology, 168(5), 1059-1073.
• Tan, Z., & Xiao, G. (2012). Leaching characteristics of fly ash from Chinese medical waste incineration. Waste Management & Research, 30(3), 285-294.
• Schwalfenberg, G., Genuis, S. J., & Rodushkin, I. (2013). The Benefits and Risks of Consuming Brewed Tea: Beware of Toxic Element Contamination. Journal of toxicology, 2013.
• Wang, X. P., Ma, Y. J., & Xu, Y. C. (2008). [Studies on contents of arsenic, selenium, mercury and bismuth in tea samples collected from different regions by atomic fluorescence spectrometry]. Guang pu xue yu guang pu fen xi= Guang pu, 28(7), 1653-1657.

Coffee Rules, Green Tea Sucks!? Study Links Green Tea to Insulin Resistance and Coffee to Insulin Sensitivity. Statist. Outlier, Long- vs. Short Term Effect or Heavy Metal Toxicity?

I can't tell if bathing in coffee is healthier than in tea, but my gut tells me that it is.

Coffee may rob your sleep (see "Sleepness Nights: Are Pre-Workouts and A Huge Cup of Coffee Messing With Your Sleep?" | more), but if you look at the currently available epidemiological data, the average coffee drinker is still a pretty healthy chap. Whether this is due or in spite of the stimulating effects of caffeine is not quite certain, but a closer look at its molecular composition reveals that the average cup of real coffee has at least as many potent antioxidants, as green tea. From a molecular perspective coffee is thus by no means inferior to the catechin-laden purported health-elixir green tea. With its glucose-6-phosphatase inhibitory (van Dam. 2006) and insulin sensitizing effects (Shearer. 2003) of its chlorogenic acid and quinide, coffee has, just like green tea, tons of animal data to support its potent anti-diabetic effect.

What's healthier tea or coffee?

If you asked one hundred people, what they'd choose, coffee or green tea, if personal preferences weren't an issue and their only criteria were "beneficial health effects", I am 100% convinced that the vast majority would go with green tea. That's actually quite natural, the media does after all hype every epidemiological study that supports the notion that green tea drinkers are the healthiest chaps on earth. Studies like the one researchers from the National Center for Global Health and Medicine in Tokyo are about to publish in the venerable scientific journal Metabolism, on the other hand, are rarely present on any of the major science news outlets.

Did you know that... An inverse association between coffee consumption and HOMA-IR has been observed in the US, Sweden, the Netherlands and multi-ethnic Asian populations, the study at hand is yet the first to confirm the existence of health benefits in a Japanese population.

This is where the SuppVersity comes into play. Your place to learn that Pham et al. observed an "unexpected", statistically significant association between green tea consumption and elevated HOMA-IR levels - in other words: The regular consumption of green tea was associated with an impaired glucose metabolism / lower baseline insulin sensitivity.

Figure 1: Relative differences to coffee / green tea "no consumers" in subjects who drink different amounts of coffee and green tea every day; p-values are given in boxes only for significant changes (Pham. 2013).

These results were obtained using data from cross-sectional epidemiological surveys that had been conducted among employees of three workplaces, two municipal offices in Kyushu and one
manufacturing company, in Kanto in 2009 and 2012. Pregnant women and subjects reporting a history of stroke or cardiovascular disease (n = 25), cancer (n = 27), diabetes (n = 52) and chronic kidney disease (n = 9), as well as those who were current usersof anti-diabetic drugs (n = 1) or under medical care for hepatitis (n = 4) were excluded to minimize the influence of confounding factors and be able to make a statement about the associations between coffee and tea consumption and glucose management in the average healthy Japanese worker.

Table 1: Characteristics of the study subjects by coffee consumption; the yellow mark indicates stat. sign. inter-group differences (Pham. 2013)

"Information about dietary intake during the preceding month was obtained using a validated brief self-administered diet history questionnaire (BDHQ). Dietary intakes for 58 food and beverage items including coffee and green tea, energy, and selected nutrients were estimated using an ad hoc computer algorithm for the BDHQ, with reference to the standard tables of food composition in Japan.

The response options for coffee or green tea consumption were never, < 1cup/week (wk), 1 cup/wk, 2-3 cups/wk, 4-6 cups/wk, 1 cup/day (d), 2-3 cups/d, or ≥4 cups/d." (Pham. 2013)

It is probably not surprising that the comparatively detailed dietary analysis revealed significant correlations between the consumptions of coffee and green tea (Spearman’s r= 0.83 and 0.77 for coffee in men and women, respectively; Spearman’s r= 0.68 and 0.64 for green tea in men and women, respectively) - with a high enough subject base you can however subtract the individual influence of the two out.

Is there any reason green tea could compromise our insulin sensitivity

I have to admit that there is little direct experimental evidence that would explain the observations th researchers made, but if you remind yourselves of the first serving of the "Supplements to Improve and Restore Insulin Sensitivity" Series (overview), you will remember that the anti-diabetes effects of green tea / green tea supplements are - if they occur at all - indirect ones.

Don't forget that caps and pills are not worth a penny without you committing to the all the lifestyle changes I outlined in episode one of the "Supplements to Improve and Restore Insulin Sensitivity" series.

Unlike the bioactive substances in coffee, which have a direct beneficial effect on skeletal muscle glucose uptake, those of the often-hailed green tea catechins are primarily side effects of improvements in lipid metabolism and reduced chronic inflammation.

Assuming that the average study participant did not have significantly elevated blood lipids and wasn't chronically inflamed either, this would explain the absence of improvements in insulin sensitivity. What it doesn't explain, though, is the fact that the insulin sensitivity decreased - irrespective of the accumulating evidence which suggests that even diabetics don't benefit from green tea supplementation (latest example from Nov, 8  Wang. 2013)

Usually this is, when you take a look at the discussion in a scientific paper, read, digest and get an idea of what could be a reasonable explanation for unexpected phenomena like this. The conclusion of the paper at hand, does yet only summarize the existing scientific evidence that the vast majority of "previous studies have shown no association between habitual green tea consumption and fasting glucose" (Pham. 2013):

• a Japanese study among 1542 men reportedmarginally-significant higher odds ratios for IR with higher habitual consumption of green tea (T Otake April 2013, personal communication of the authors of the study at hand)
• Rebello et al. reported no association between green tea consumption and HOMA-IR among a multi-ethnic Asian population
• a meta-analysis including 6 clinical trials found no evidence to support an effect of green tea catechins on HOMA-IR

As Pham et al. points out conclusive evidence for or against the benefits of green tea consumption from long-term + large-scale trials is missing. Most clinical trials including those in in the previously cited  meta analyses had relatively short-term intervention (4-24 wks) and modest sample sizes (23-88 subjects). Without further research it is thus more or less impossible if genetic, lifestyle or other confounding variables or a hitherto overlooked negative long-term effect of green tea are responsible for the results. 

Table 2: Levels of toxic trace elements in tea infusion; data compiled by Tanmoy Karak, R.M. Bhagat (2010)

Aside from biological factors, the disappointing results could also be the consequence of the quality of the tea. In Japan, the upper tolerable levels for lead (Pb) are for example 4x higher, than in Europe (20mg/kg vs. 5mg/kg). With the ever-increasing Pb concentrations in tea leaves (Jin. 2005), lead and other toxic elements (see data in Table 2) could be turning the health elixir into an increasingly toxic cocktail.

"Coffee, Tea, Cacao, Caffeinated Sodas & Breast Cancer: 5+ Cups/Day?! Study & Meta-Analysis Show, It May Take More Coffee Than Previously Thought to Ward Off Breast Cancer" | more

Treat with caution: I strongly recommend not to overestimate the results of the study at hand - neither the negative ones about green tea, nor the positive ones about coffee. A BMI-stratified analysis did after all reveal that the inverse association (not causation) between coffee consumption and HOMA-IR was really significant only in the overweight/obese, but not in normal-weight, individuals.

In view of the absence of a reasonable explanation for the pro-diabetic effects of chronic green tea consumption (it may in fact be heavy metals; see Table 2), I would not suggest you switch from green tea to coffee, if you don't like it. If you are a coffee-boy or -girl, anyway, the study at hand confirms that reductions in diabetes risk are not a good reason to give up on your beloved brown brew ;-)

References:

• Jin CW, He YF, Zhang K, Zhou GD, Shi JL, Zheng SJ. Lead contamination in tea leaves and non-edaphic factors affecting it. Chemosphere. 2005 Nov;61(5):726-32.
• Wang X, Tian J, Jiang J, Li L, Ying X, Tian H, Nie M. Effects of green tea or green tea extract on insulin sensitivity and glycaemic control in populations at risk of type 2 diabetes mellitus: a systematic review and meta-analysis of randomised controlled trials. J Hum Nutr Diet. 2013 Nov 8.
• Karak T, Bhagat RM. Trace elements in tea leaves, made tea and tea infusion: A review. Food Research International. 2010; 43(9):2234–2252.

Urban Gardening: 12x More Cadmium in Your Tomatoes Than in the Conventional Produce? Plus: Domestic vs. Foreign & Conventional vs. Organic - What's Healthier?

Image 1: Allotment gardens are the new trend among young families in Germany, 45% of the 1,000,000 allotment gardens that were previously the territory of stuffy men and their garden goblins are already in their hands - that equals a total "acreage" of 21,000hectar - let's hope none of these gardens is right next to a street.

Those of you who have listened to the "Urban Gardening" episodes Alisa Profumo did on Super Human Radio back in 2011 (click here to download Part I and Part II) may remember that it is not impossible to grow your own vegetables, herbs and more - and that not just in a large garden. In fact, "urban gardening", which has here in Germany long been regarded as antiquated and "for grandmas and grandpas only" has become fashionable again, as more and more people enjoy the comfort of "knowing what they eat". Unfortunately, a recently published German study shows that believing does not mean knowing; or do you believe that people who knew that their homegrown tomatoes have 5.7x more nickel, basil more than 5.4x more anorganic chromium and their carrots 4.2x more cadmium than their conventionally grown counterparts from the supermarket around the corner would still not unsettle their faith in the general and unquestionable superiority of home-grown produce?

From the exhaust pipe into your garden and from your garden into your mouth :-(

Just to make sure that we understand each other: This is no anti-gardening post, it is just a brief reminder of the differences between hearsay and nostalgia, on the one hand and facts and reason, on the other. In that, it is very reasonable to assume that the constant pesticide assault is a problem, it is however not reasonable to assume that veggies and herbs you grow in the toxic environment of a major city like Berlin or its rural outskirts are per se "pollutant free".

Figure 1: Main importers of vegetables, root and tubers in 2011 (ITC calculations based on UN COMTRADE statistics)

Did you know that Katz et al. have shown in 2008, that...

• the pesticide residues in domestic (US) produce (fruits and vegetable) were significantly higher for 11 pesticides while imported exposures were higher for the remaining four. 
• all five pesticides that were found in potentially hazardous (yet on a per serving base still licit level) were the higher in US than in imported produce
• the mean daily exposure estimate for one pesticide, methamidophos, was above the reference dose for domestic fruits and vegetables while slightly below the reference dose for imported fruits and vegetables

... probably not, right? If you want to avoid pesticides, all-together it is advisable to chose organically grown produce, anyway - also for it's slightly higher nutrient content (see next infobox)

This is all the more true in view of previous exploratory studies, which have already shown that horticultural crops in urban or peri-urban areas are generally exposed to a higher level of pollutants of both inorganic and organic origin than the conventional produce they are supposed to replace (Shinn. 2000; Alloway. 2004). And as Ina Säumel and her colleagues point out,

"the contamination of urban horticultural products can exceed the precautionary values, and a dietary exposure to trace metals can result in significant human health risks." (Säumel. 2012)

That said it was only logical that the researchers from the Technische Universität Berlin and their colleague from the Botanical Garden of the Khmelnitskij National University in  Khmelnitsky, Ukraine, set out to compare the positive view the public has on urban- and peri-urban gardning (according to a survey among gardeners, producing "fresh and healthy fruits and vegetables" is one if not the main motivations for gardening; cf. ) to the actual level of potentially hazardous substances in their produce.

The samples were collected from 28 randomly chosen sites within inner city neighborhoods in Berlin, Germany. As the authors point out,

"[t]hese sites represent a mixture of different local settings of horticultural plantings within Berlin’s centre  and were characterized according to the following parameters: (a) overall traffic burden (otb) within a radius of 1 km around planting sites [...] (b) traffic burden of the nearest road per day [...], (c) distance to nearest road (d; in meters); and (d) presence or absence of barriers between planting sites and next street which might reduce airborne pollution." (Säumel. 2012)

In combination with the data on the planting styles of the individual produce this allowed for a very detailed analysis of the confounding factors that influenced the the zinc, copper, lead, cadmium, chromium and nickel concentrations of the 12 different horticultural crop species (tomatoes, green beans, carrots, potatoes, kohlrabi =Brassica oleracea var. gongylodes, white cabbage, nasturtium, parsley, chard, basil, mint, thyme).

Figure 2: Trace metal content of 12 different horticultural crop species from 28 randomly chosen sites within inner city neighborhoods in Berlin, Germany; data expressed relative to conventionally produced produce from the local supermarket, the dotted black line indicates the respective 100% content of the conventional produce - everything thats above this "demarcation line" has more, everything below less of the metal (calculated based on Säumel. 2012)

If you take a look at the results you may initially be shocked - 12x more cadmium in "home-grown" tomatoes than regular produce? The currently allowed maximal level of this toxic trace metal depends on the respective legislation (I guess I don't have to rant about what those differences tell you about the arbitrariness of "allowances" & co) and is in the range of 0.1mg/kg for vegetables with 0.12mg/kg the mean content is thus already right at the red line of the official "danger zone" - the maximal detected value of 0.79mg/kg is 7.9x higher and certainly no healthy alternative to the conventional supermarket tomatoes with 0.01mg/kg (i.e. 10x below the tolerable limit) of cadmium in them.

Figure 3: Soil, overall traffic burden and the distance to the nearest road are all confounding factors that will influence how much unwanted trace metals your pesticide-free produce will contain.

As you may already guess, both the overall trace metal load as well as the high discrepancies between individual vegetables and herbs are largely dependent on their individual traffic exposure with zinc, lead, nickel and chromium showing statistical significant correlations with the overall traffic burden and lead, chromium and cadmium with the distance to the nearest road.

Plant away from roads and/or behind fences or walls + other things to protect your crops

Did you know that one of the latest meta reviews confirmed the superiority of organic vs. conventionally grown produce as far as its nutrient content is concerned? According to Hunter at al. the nutrient content of organically grown vegetables was 5.9% higher, that of legumes 5.7% (for fruits the 6.5% difference did not reach statistical significance; cf. Hunter. 2012). There is however a significant difference between screened and non-screened trials, with the former having a clear-cut bias towards an even higher difference than the latter (mean difference 8%). It is however at least questionable how valuable a classification like this is, when the "superior" mineral content of organically grown veggies, for example, is mediated among others by a statistically significant +6% higher phosphor content, the level of calcium and magnesium, however is only non-significantly higher (0.6% and 3%, respectively).

Aside from planting further away from, or next to low traffic streets, placing your plants behind fences, walls or other protective barriers can be a valid method to reduce the trace metal content of your crop. Moreover, Säumel et al. point out that regardless of the traffic burden,

"[...]the vegetables planted in urban soil beds were less likely to have lead values above the critical values than vegetables planted in pots or beds that had been supplemented with commercial garden soil. This might result from the use of compost, which increases metal solubility, but more research is needed to reveal underlying causes as we could not analyse soil trace metal contents." (Säumel. 2012)

This does not necessarily mean that planting in the local soil must be better, nor is it certain that the commercial garden soil was already contaminated, it should yet raise your awareness that even when you are planting outside of the 10m danger-zone of the next street in which 67% of the analyzed crop has lead values that exceeded the standards of the European Union, the lead, cadmium, nickel and what not could already be in the soil of your garden or be accidentally introduced by the commercial garden soil you bought and used to increase your produce (for tips on safer ways than the next best fertilizer from the garden center, listen to the initially mentioned gardening episodes of Super Human Radio).

Picking the right crop, such as kohlrabi, green beans or basil and installing extra fences using the back instead of the front yard are other means that would allow for "safer gardening" even in the inner city. When you are living right next to the highway, all that will yet probably be useless. I don't know if you have something like that wherever you are from, but the good old German "Schrebergarten" (=allotment garden), is becoming increasingly popular, over here - and, as I initially mentioned, not just among old stuffy men and their garden goblins; for me personally that would not be an option, but who knows, maybe it is for you?

Bottom line: Done right, i.e. not directly next to a high traffic street and without the use of standard commercial soils and fertilizers, yet fully aware that neither the "remarkable taste" of your tomatoes, carrots & co, nor being able to say "I produced it in your own garden" let alone "on my own balcony" will  protect you from the toxins that may be present in what your 100% pesticide free produce, gardening does still offer a safe and above all self-empowering alternative to buying all your goods at the farmers market, super market or wherever else you prefer to shop.

References:

• Alloway, BJ. Contamination of soils in domestic gardens and allotments: a brief review. Land Contamination and Reclamation. 2004; 12:179-187
• Burda GmbH, 1993. Wohnwelten und Gärten in Ostdeutschland: Alltagsästhetik, Wohnmotive, Wohnstile, Gartenwerte und Gartenstile in den neuen Bundesländern. ein Forschungsbericht der Burda-GmbH, Offenburg, und Sinus, Heidelberg, 108 p. (German).
• Hunter D, Foster M, McArthur JO, Ojha R, Petocz P, Samman S. Evaluation of the micronutrient composition of plant foods produced by organic and conventional agricultural methods. Crit Rev Food Sci Nutr. 2011 Jul;51(6):571-82.
• Katz JM, Winter CK. Comparison of pesticide exposure from consumption of domestic and imported fruits and vegetables. Food Chem Toxicol. 2009 Feb;47(2):335-8. Epub 2008 Nov 27. 
• Säumel I, Kotsyuk I, Hölscher M, Lenkereit C, Weber F, Kowarik I. How healthy is urban horticulture in high traffic areas? Trace metal concentrations in vegetable crops from plantings within inner city neighbourhoods in Berlin, Germany. Environ Pollut. 2012 Jun;165:124-32. Epub 2012 Mar 22.
• Shinn NJ, Bing-Canar J, Cailas M, Peneff N, Binns HJ. Determination of spatial continuity of soil lead levels in an urban residential neighborhood. Environmental Research. 2000; 81:1-7.

Alarmingly High Levels of Lead in Calcium Supplements: Pb Content per Serving Up to 18x Over "Acceptable Levels".

Image 1: You better pick the right source of calcium: healthy milk / dairy vs. lead poisoned pills from your local pharmacy or supermarket - you still have the choice.

This, I can assure you, is a "SuppVersity News", i.e. something you will not read on the major news portals, simply because there is too much money at stake in the 3billion $ market for calcium supplements (figure according to January 2008 edition of "Heartwire") - money a huge part of which is spent by Novartis & Co to advertise their products to consumers from all age groups, regardless of the individuals' dietary calcium intake; and that despite accumulating evidence for an association of supplemental calcium intake and heart disease (for one of the latest reviews cf. Bolland. 2011)! A very recent study published in the Journal of Biological Trace Element Research (Rehman. 2011) does yet cast another, even darker shadow onto the "healthy" white chalk tabs...

What? "Pb" is not the symbol for Calcium in the Periodic Table?

Lead, that stuff nuclear physicists value, because it effectively absorbs radioactive radiation, is one of the most toxic "heavy metals" we are exposed to. And this is by no way a recent discovery. Even in ancient times, people knew about the toxic effect vessels made of this metal had on the water they contained. Back in 1990 E.K. Silberberg summarized the contemporary knowledge about the dangers of environmental lead exposure in a paper for the Environmental Defense Fund as follows (Silberberg. 1990):

[...] epidemiological studies have suggested that central nervous system (CNS) effects in children are observed at the lowest increments of lead exposure [...] Similarly, clinical studies indicate that early exposure to lead produces functionally irreversible damage to the CNS; experimental research demonstrates that this irreversibility may involve failure to remove lead from brain, permanent effects on synaptogenesis; and chelant-induced redistribution of lead from the periphery to the CNS. [...] New data on release of bone stores of lead during physiological conditions of demineralization indicate that mobilization of bone lead adds to in utero exposure of the fetus. Furthermore, postmenopausal demineralization of bone can increase blood lead levels in women by 25%; this raises concern about the potential effects of lead in an aging population and the difficulties in comprehensive exposure assessment.

As you may have guessed, time has not affected the dangers or the irreversibility of lead toxicity, so that you would assume that the results of an investigation into the lead content of 27 "commonly used" commercially available calcium supplements should be alarming enough to receive at least some public recognition. After all, it would suffice to read the abstract to be alarmed by the fact that of the calcium supplements Sohaila Rehman and her colleagues from the Pakistan Institute of Nuclear Science Technology analyzed only one out of ten "met the criteria of acceptable Pb levels (1.5µg/daily dose) in supplements / consumer products set by the United States" (Rehman. 2011).

Figure 1: Lead levels in µg in daily dose of respective calcium supplement; solid red line = acceptable Pb level for calcium supplements, dashed red line = tolerable total daily Pb intake for children <7y, dotted red line = tolerable daily Pb intake for women in childbearing age (data adapted from Rehman. 2011).

"One out of ten", well that does not sound so bad, does it? I guess you will change your mind, when you take a closer look at figure 1 - the red line at the bottom of the graph is the "acceptable Pb level" and as you can see it is met by exactly 1 out of 13 calcium chelate products (CAC 1000 by Novartis), and none of the 3 calcium chelates the researchers tested for their lead content.

Figure 2: Lead levels in µg in daily dose of respective calcium supplement; solid red line = acceptable Pb level for calcium supplements, dashed red line = tolerable total daily Pb intake for children <7y (data adapted from Rehman. 2011).

And while the lead levels of the calcium + vitamin C and calcium + vitamin D levels in figure 2 look somewhat better, there are still several outliers with Cal-C Plus from Himont Pharma, for example, providing more than 2x the tolerable daily lead intake for a child under the age 7 y (and remember these are only the official FDA figures - and you know what that means ;-) on a per serving base.

Note: The results of the study at hand may well explain a) the different outcomes of (controlled) trials and epidemiological studies on the effects of calcium supplements on cardiovascular health and b) the beneficial effects of milk and dairy intake on heart health (Soedamah-Mutuh. 2011). After all, a very recent study that was published in the Journal of Neurotoxicology and Teratology in October 2011, shows that there is a "potential for autonomic dysregulation" that manifests in "significantly greater vascular resistance and reduced stroke volume and cardiac output" in 9-11 year old children even "at levels of Pb typical for many US children" (the exact levels were 1.01µg/dL, cf. Gump. 2011).

And as if all that was not enough, the US Food and Drug Administration (FDA) and the glorious Center for Disease Control and Prevention (CDC) would have been aware of the potential of serious chronic lead intoxication from calcium supplements, if they spent more time reading scientific journals than counting the cashflow from the BigPharma companies that finance their bureaucracy. After all, Bourgoin et al. conducted a very similar study back in the 1990s, the results of which the scientists summarize in their abstract as follows (Bourgoin. 1993):

Daily lead ingestion rates revealed that about 25% of the products exceeded the US Food and Drug Administration's "provisional" total tolerable daily intake of lead for children aged 6 years and under.

In the Rehmann study it were 16 out of 27 tested calcium supplements (59%) which exceeded this limit. So  maybe the "feds" just did not act, because 1 out of 4 is not bad enough? Well, if you look at the individual results in figure 3 (usually I redo graphs, but in this case the original looks just too damn impressive), it is immediately obvious that the averages the scientist report in their abstract, do not reflect the actual potential of lead toxicity from the 70 supplemental sources Bourgoin et al. tested.

Figure 3: Results of a 1993 large-scale analysis of the lead content of 70! commercially available calcium supplements and milk (my emphasis), the safe exception (from Bourgoin. 1993)

Obviously, some of the bone based and a whole host of the "natural sources" ("natural source of calcium carbonate" according to label claim; note that coral calcium would fall into this category, as well!) are about as toxic as the worst offenders in the Rehman study. What I find do yet find particularly interesting, is that the lead content in one serving of commercial milk, which would provide the same amount of (even more bioavailable) calcium as the supplements in the study did, would provide no more than 0.71µg/day and is thusly the one and only "natural source" of dietary calcium that does not set you up for lead toxicity!

"Pah, lead!? What doesn't  kill you just makes you stronger"

Image 2: So, calcium supplement with lead are a safe source of dietary calcium, but raw milk is not? (img CounterThink)

In view of the "longstanding" history of ignorance on behalf of the governmental agencies, it sounds almost sarcastic, when Bourgoin et al. conclude their article by citing the Center for Disease Control's (CDC) statement on lead poisoning, which according to these reputable protectors of the health of the American society *cough* is "one of the most common and preventable pediatric health problems today". Notwithstanding this early insight (this is from a 1991 document from the CDC) the officials obviously have neither taken Bourgoin et al.'s advice to control calcium supplements "more rigidly" in order to "prevent unnecessary exposure in all segments of the population, particularly young children" (Bourgoin. 1993), nor have they followed the recommendation of a more recent study by Kim et al., which  estimates the mean lead intake from calcium supplements to about 5µg/day and recommends that "measures to prevent potentials of Pb toxicity from overtaking some Ca supplements should be considered" (Kim. 2010).

And while the CDC and the FDA could incidentally have missed those papers. They should actually be aware of Proposition 65, which is the common name for California's Safe Drinking Water and Toxic Enforcement Act of 1986 (Dietary Supplement Standard 173, Metal Contaminant Acceptance Levels. NSF International. August 19, 2003). In this paper, of which W.W. Kilgore writes in retrospective that (Kilgore. 1990)

[i]t creates a list of chemicals (including a number of agricultural chemicals) known to cause cancer or reproductive toxicity; [i]t limits discharges of listed chemicals to drinking water sources; [i]t requires prior warning before exposure to listed chemicals by anyone in the course of doing business; [i]t creates a list of chemicals requiring testing for carcinogenicity or reproductive toxicity; and [i]t requires the Governor to consult with qualified experts (a 12-member "Scientific Advisory Panel" was appointed) as necessary to carry out his duties.

the proposed Acceptable Intake Level (AIL) for inorganic lead (as extrapolated from animal studies) is 0.5µg/day and thusly 1/3 of the current Californian standards and 1/50 of the FDA allowance of 25µg/day! But hey, who cares? As long as the American citizens are protected from the dangers of raw milk, everything is all right, isn't it?