Quackery or Solid Science: The Zinc Tally Test - Does it Work? How Does It Work? And How Reliable is It?

"Any idea if zinc tally test is reliable? Google spits somewhat mixed conclusions." That's what SuppVersity reader David Salda asked two days ago on the SuppVersity Facebook Page and this article is a somewhat lengthy answer to a short, but very valid question.

I know that only few of you are running a website, let alone one with daily updates, but if you do you the following incident may sound vaguely familiar: You are just trying to keep up with the comments on questions on the Facebook page of your website, when an innocent question like "Any idea if zinc tally test is reliable? Google spits somewhat mixed conclusions." someone (in this case David Salda) posted on your Facebook wall, reminds you of the written, yet never finalized and published articles that lie dormant in the depth of your website's draft folder... don't get me wrong, this is unquestionably a good thing - I mean I guess there will be more people than David, who would like to have the following two questions answered, correct?

How does the Zinc Tally Test work?

Actually the procedure is pretty straight forward. You hold a 10ml solution of zinc sulphate hydrate in a distilled water base (can be bought at the pharmacy) in your mouth for 10 seconds (don't swallow it!) and see how it tastes: (1) If you don't taste anything you are zinc deficient, (2) if there is no immediate taste, but a furry/dry mineral taste develops, your are low on zinc, (3) if a definite taste is detectable right away, you are supposedly in the lower normal range, and (4) if a strong unpleasant taste is immediately present, you got plenty of zinc already.

Is the Zinc tally test an adequate means to test whether you should Supplement W/ Zinc?

No. While it cannot be totally excluded that you can identify individuals with low zinc status on the basis of the Zinc Tally Test the scientific evidence for the accuracy of this method is clearly insufficient, highly conflicting and in large parts bugged with the usual methodological flaws you see in studies on topics most allopath would deem nuturapathic *bs*.

Take a short cut to the answer to your question: If we take into consideration the currently available literature (an ebook someone sells on his own website is no "literature"), there is little to add to the conclusion the researchers from the Southern Cross University in Lismore,  Australia fomulate in the abstract of their study: Despite being widely used, the Zinc Tally Test does is not sensitive and specific enough to assess marginal zinc status in humans. It's thus not really surprising that a 1999 study by Jenna Jameson shows that its results don't even correlate with with dietary zinc intake (Jamison. 1999)

In 2012 Gruner & Arthur conducted a systematic review of the available literature in which they included only studies which provide full reports of clinical trials comparing the tally test (ZTT) to at least one other zinc test within the same sample population. The mere number of studies which matched these more or less self-evident minimum requirements, is telling, already: "3", in words "three" studies matched the criteria of inclusion.

If your breakfast looks even close to this extraordinary beans, eggs and bacon breakfast, it's him time that you learn and apply(!) the "Three Simple Rules of Sensible Supplementation" | more

"Study I compared the ZTT with sweat zinc in patients with food intolerance, reporting moderate correlation. Study II recruited pregnant women using the ZTT and serum zinc to assess zinc status, with above 70% congruence between the two tests at the start of the trial and 100% congruence at the end. Study III also recruited pregnant women at three stages during gestation, assessing ZTT and leukocyte zinc initially, later adding dietary zinc intake and at delivery cord blood zinc. No significant correlation was found between the results of these different methods; however, statistically significant differences in the ZTT responders (tasters and nontasters) were found for pregnancy outcomes." (Gruner. 2012)

And guess what: Even these studies suffered from all sorts of methodological problems. The laboratory assays that were used in the studies lacked sensitivity to zinc status. They were poorly standardized and did often deviate from the original design of the zinc tally test as it is described on the Internet.

Zinc deficiency alters general taste acuity - but not in a linear / reliable fashion

Something else that's worth mentioning in this context is the influence of low zinc levels on taste acuity in general. While the number of respective studies is not exactly high, there is good evidence that subjects with a generally impaired ability to taste tend to have lower zinc concentration in the blood and exhibit a lower ratio of apo/holo-activities of angiotensin converting enzyme (ACE), a zinc dependent enzyme in the serum (ACE ratio), than controls (Ueda. 2006). A 2010 follow up study did yet reveal that a definitive correlation between serum zinc levels and the scores on a visual analogue scale for the severity of the symptoms of did not correlate in after supplementation - whether zinc is the the cause or as so often just a corollary factor is therefor still in the open (Takaoka. 2010)

Suggested: " Zinc: 15mg Are Plenty - After 120 Days Rodents on Diets Containing 2xRDA of Zinc Develop Metabolic Syndrome" | more

Bottom line: While it stands out of question that the zinc tally test should not be your method of choice, when it comes to testing your zinc status, the observation Ueda et al. and Takaoka et al. made with respect to the ratio of apo/holo-activities of angiotensin converting enzyme (ACE) could actually be used as a measure of your zinc status. It would provide an alternative and accurate tests to determine the adequacy of your dietary zinc intake.

That's at least what the results of a 2012 experiment by Sarakura et al. in the course of which mice were zinc depleted for 9 days would suggest (Sarakura. 2012). The ACE ratio would thus be #4 on the list of tests that are considered to reflect the zinc status human beings more or less adequately. The other three tests are plasma, urinary, and hair zinc analysis (Lowe. 2009).

References:

• Jamison, JR. Mineral Deficiency: A Dietary Dilemma? Journal of Nutrition and Environmental Medicine.1999; 9(2):149-158.
• Lowe NM, Fekete K, Decsi T. Methods of assessment of zinc status in humans: a systematic review. Am J Clin Nutr. 2009 Jun;89(6):2040S-2051S.
• Sarukura N, Takai S, Ikemoto S, Korin T, Ueda Y, Kitamura Y, Kalubi B, Yamamoto S, Takeda N. Effects of dietary zinc deprivation on zinc concentration and ratio of apo/holo-activities of angiotensin converting enzyme in serum of mice. Auris Nasus Larynx. 2012 Jun;39(3):294-7.
• Takaoka T, Sarukura N, Ueda C, Kitamura Y, Kalubi B, Toda N, Abe K, Yamamoto S, Takeda N. Effects of zinc supplementation on serum zinc concentration and ratio of apo/holo-activities of angiotensin converting enzyme in patients with taste impairment. Auris Nasus Larynx. 2010 Apr;37(2):190-4.
• Ueda C, Takaoka T, Sarukura N, Matsuda K, Kitamura Y, Toda N, Tanaka T, Yamamoto S, Takeda N. Zinc nutrition in healthy subjects and patients with taste impairment from the view point of zinc ingestion, serum zinc concentration and angiotensin converting enzyme activity. Auris Nasus Larynx. 2006 Sep;33(3):283-8.

Are You ABCDE-Deficient? Common Nutrient Deficiencies in the US. Plus: How Food Fortification & New "Daily Values" Affect the Intakes of Vitamin A-E, Calcium Iron & Co

Nutrition labels on fresh blueberries - do we really need them?

I sill remember that I was shocked, when I bought a pack of blueberries and found a nutrition label underneath the plastic cover of my expensive 150g health-investement...

That's probably 2 months ago and the reason I do remember this event now is the publication of a paper that examines the effect a change in the "daily values" (i.e. the references), the figures in the obiquitous black and white table are based on, would have on the average US citizen's nutritional intake of the vitamins A, D, E, C, B-12 and folate, and the minerals calcium and iron.

"Daily Values" (DV), fortified foods and nutrient adequacy: Before I dig deeper into the actual study results, it's probably wise to point out that fortified foods are the link between the DV's and micro-nutrient intake of the average American. If manufacturers continue to fortify foods to the same %DV for each nutrient, the extent to which potential changes in DVs would affect nutrient intake adequacy depends on the proportion of nutrient intakes derived from fortified foods and the magnitude and direction of change in the DV.

According to the data Mary M. Murphy and her colleagues from the National Institutes of Health/Office of Dietary Supplements present in their latest paper, there is still a large gap between the current DV values, which represent the RDAs (recommended daily allowances) from 1968 and have been matched to

"the highest level of intake judged to be adequate to meet the known nutrient needs of practically all healthy persons in a specific age-gender group" (Murphy. 2013)

on the one hand, and supposedly "improved" candidates that could replace them: The population weighed and the population coverage varieties of the RDA & EAR.

• RDA = the average daily dietary nutrient intake level that is sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a particular life-stage and gender group
• EAR = the average daily nutrient intake level that is estimated to meet the requirements of half of the healthy individuals in a particular life-stage and gender group

As you can see in Table 1 these new recommendations are not - as you may have expected -  significantly higher than the current daily values. If you look closely, you will in fact notice that some of them are significantly lower!

Table 1: Current DVs for select vitamins and minerals and potential DVs based on population-weighted and population-coverage RDAs and EARs. AT,a-tocopherol; DV, Daily Value; EAR, Estimated Average Requirement; RAE, retinol activity equivalent; RE, retinol equivalent (Murphy. 2013).

In the case of vitamin B12 and copper, for example, the difference between the "reformed" recommendations would amount to -50%. The population-coverage RDA for vitamin C, on the other hand, is 50% higher than the old "daily values" (DV) and still more than 10x lower than the 1,000mg of ascorbic acid, of which you may have read on the Internet that it was the bare minimum intake of vitamin C (more about vitamin C).

Figure 1: Percentage of U.S. population aged >4y with dietary intakes below the EAR based on current intakes and assuming
constant %DVs in fortified foods under the current, as well as two potential DV scenarios, i.e. the population-weighed EARs or the population-coverage RDAs become the revised DV values (Murphy. 2013)

Irrespective of the "low" RDA and the high number of fortified foods, ascorbic acid is yet still one of the those micro-nutrients the diets of more than 40% of the US are deficient in. And as the overview in Figure 1 goes to tell you, this would not change, if any of the new RDAs or EARs became the new DVs, so that the amounts of vitamin C in fortified food was adjusted.

Not an improvement by any means

In a more thorough sub-analysis, the scientists observed that the differences in the proportion of the total population with usual intakes less than the EAR would be <2% of 5 out of 8 nutrients (vitamins D, E, and B-12; folate; iron), regardless of whether the policy makers sued the population weighted EARs or the population-coverage RDAs as a basis for the revision of the DVs.

To put it plainy: This means that the micronutrient intake of more then 3 million individuals would still fall below the EAR in the total population (U.S. Census Bureau. 2005).

Even worse, if someone in the upper echolons was bribed.... ah, I mean convinced by the conclusive evidence we have that using the population-weighted EARs instead of the population coverage RDA would be the best thing to do, this would increase the risks of inadequate iron and folate intake in women of childbearing age. Both, iron and folate deficiency, can result in irreversible damage to the unborn child (Scholl. 2000; McArdle. 2013). The same is true for vitamin A (Wallingford. 1986) of which Murphy et al. write that it "was identified as a shortfall nutrient (although intakes are not currently in the category ‘‘of concern’’) for the U.S. population" (Murphy. 2013).

"The Standard American Diet Has 'Optimal' Fatty Acid Ratio to Induce Diabesity." | read more

What has to be done? I hope you don't actually want me to answer this question - do you? I mean let's be honest - if people get 17–28% of total intakes of folate, iron, and vitamins A, B-12, and C and 8–12% of calcium and vitamins D and E from fortified foods (this is what Murphey et al. found) and are still deficient, you could obviously argue that we simply have to put even more vitamins and minerals into the nutrient deficient, energy dense junk the average Westerner is shoveling his piehole everyday.

But let's be honest: Wouldn't it be better to kill two birds with one stone by educating people that the stuff they eat is making them fat and sick - no matter how much artificial vitamins the "food" industry is pumping into their highly addictive, revenue-centered high-tech designer products?

References:

• McArdle, Harry J., Lorraine Gambling, and Christine Kennedy. "Iron deficiency during pregnancy: the consequences for placental function and fetal outcome." The Proceedings of the Nutrition Society (2013): 1-7.
• Murphy, Mary M., et al. "Revising the Daily Values May Affect Food Fortification and in Turn Nutrient Intake Adequacy." The Journal of nutrition 143.12 (2013): 1999-2006.
• U.S. Census Bureau. 2005 Middle series data from annual projections of the resident population by age, sex, race, and Hispanic origin: lowest, middle, highest, and zero international migration series, 1999 to 2100 (NP-D1-A). Washington: Department of Commerce; 2000 [cited 2012 Jun 16]. Available from: http://www.census.gov/population/www/projections/natdet-D1A.htm 
• Scholl, Theresa O., and William G. Johnson. "Folic acid: influence on the outcome of pregnancy." The American journal of clinical nutrition 71.5 (2000): 1295s-1303s.
• Wallingford, J. C., and B. A. Underwood. "Vitamin A deficiency in pregnancy, lactation, and the nursing child." In: Bauernfeind JC, ed. "Vitamin A deficiency and its control." New York: Academic Press, 1986:101–52.

Loss of Trace Elements not a Concern in Well-Hydrated Athletes

If you are a hard-training athlete you need more than "trace amounts" of trace elements, don't you? No, actually not. You may be somewhat disappointed now, but the expensive trace element supplement you just ordered might turn out to be a complete waste of money - at least, this is what the results of a recently published study by Carlos González-Haro et al. (González-Haro. 2010) suggest.

Figure 1: Changes in plasma trace element levels (Zn, Mn, Se and Co) for the different relative exercise intensities studied and the 7 min recovery period.

As figure 1 (above) shows, lactate concentrations constantly increased in the course of the 7 minutes after a cycloergometer test, where, after a warm-up of 10 min at 2.0 W kg⁻¹, workload had been increased by 0.5 W kg⁻¹ every 10 min until exhaustion. The trace mineral concentration, on the other hand, remained stable over the whole study period (exercise + recovery). This observation led the scientists to conclude ...

[...] in euhydrated well-trained endurance athletes no effects on plasma levels of Zn, Se, Mn and Co were observed either during medium duration exercise, at a full range of intensities (41–92%VO_2peak), or during a seven-minute recovery period. These subjects showed no deficiency in Zn or Se and probably were not deficient in Mn or Co either (though cutoff levels are not known).

So, if you have not opened your "high quality trace element" supplement yet, make use of your 14-days conversion right ;-)