Friday, February 15, 2013

Science Round-Up Seconds: DHA, Algae Oil, Fish Protein, Insulin Sensitivity, Fat Loss & Muscle Gain. Plus: Night Shifts & BPA = Pro-Carcinogenic From Breast to Prostate

It's somewhat ironic that Nurse's are one of the three high risk groups for breast cancer, because they work night shifts to help others. Who the other two groups are? Female military personnel and flight attendants on international flights.
If you did already listen to yesterday's installment of the Science Round-Up, you should actually be able to connect the dots between both, the first and second course of today's installment of the Science Round-Up Seconds, and the studies on the effects of DHA on fatty acid metabolism, as well as the fallacies of insufficient, interrupted, or irregular sleep Carl and I have been addressing, yesterday.

If all that does not ring a bell, I suspect you missed the show and have not had a chance to listen to the podcast (as usual the Science Round-Up starts in the 2nd hour of the show), yet. In this unfortunate case, I'd suggest you do at least start downloading the file while you take the first bite of today's two course menu ;-)

More things fishy from proteins with funky names to DHA and fish protein

Pollachius virens (Photo: Tino Strauss) is king, when it comes to the n:3/n:6 ratio, but with <1% of fat you will still be hard pressed to get tons of omega-3s from eating pollock... but is more really better, let alone necessary? Learn how to make the right fish choices here.
(Lane. 2013; Vikøren. 2013) -- Actually I wanted to title this one "Some Things Fishy", but then I remembered that there is already a SuppVersity post with this title, one I am still not able to make head or fin... ah, pardon tail of, by the way, because it clearly suggest that the consumption of oxidized fish oil is not a problem. Be that as it may, these are the SuppVersity Science Round Up Seconds, so the "more" does not refer to the said SuppVersity post on oxidized fish oil, but rather to the 70x* increase in the expression of a protein called Angiopoietin-like 4, which controls the availability of fatty acids for fuel I mentioned during the podcast (*the differential response for DHA was elucidated in a separate study on isolated rat hepatic cells, the general effect was however observed in a human trial, where all tested fatty acids, not just DHA, produced 11-12x ANGPTL-4 increases).

In view of the more of less undisputed benefits of having reasonable amounts of DHA (400mg) in your diet, it would obviously be nice if we could increase our intake of this relatively scarce omega-3 fatty acid in our diet, without having to resort  to fish and fish oil caps. A recently published overview of vegetarian dietary sources of omega-3 fatty acids by Katie Lane and her colleagues does however confirm what you've heard both Carl and me say on previous episodes of the SuppVersity Science Round Up, already.

The conversion of alpha linolic acid (ALA, the short-chain version of omega-3) from nuts (walnut) and seeds (flaxseed, echium) to DHA is literally zero. 

According to he researchers' review of the literature, only the ingestion of oils that were derived from micro-algae provide some, albeit preliminary evidence to support their usefulness as dietary source of DHA. The number of studies is yet relatively limited and "further research is necessary to evaluate optimal doses" (Lane. 2013) of respective supplements and/or food additives for "functional foods" (how I hate this word)

Micro-algae oils are not fish, though, and thus you would once more be missing out on the unique synergy only real foods have to offer: The fish proteins!

If you are not one of the many new visitors who have found their way to the SuppVersity only recently, the keyword "fish protein" should actually ring a bell... exactly! That's the stuff that has previously been shown to have astonishingly pronounced effects on glucose metabolism. Effect that have initially been observed in rodent studies and are not being replicated in human trials. Trials such as the one by Vikøren and his colleagues from the University of Bergen who report in their latest paper that was February issue of the British Journal of Nutrition that the provision of 3 g/d of a cabbed fish protein supplements for the first 4 weeks and 6 g/d for the last 4 weeks of a 2 months placebo controlled intervention study effectively and significantly
  • Table 1: Amino acid composition of fish, whey and casein protein (Hall. 2003; Vikøren. 2013)
    lowered the values of fasting glucose
  • 2 h postprandial glucose and glucose-area under the curve,
  • increased the important early insulin and 
  • decreased the detrimental late insulin response to glucose ingestion 
  • reduced the amount of  LDL-cholesterol (P< 0·05) and
  • led to increases in lean (+0.8%) and decreases in fat mass  (-1.6%)
compared to the calorie-free placebo. Pretty impressive results, right? That's particularly true in view of the fact that neither the food intake nor the physical activity levels changed in the course of the 8-week intervention period.

What's that: Fish protein + fish oil? (Almost) whole fish, right!

Fish happens to be a way better source of taurine than the sperm of this Belgian Blue. There is in fact so little taurine bull sperm that it is "supplemented" with this amino acid in order to keep it fresh and stable and have it survive refrigeration. Apropos, you do remember that taurine can boost testosterone levels up to 250% - at least in rodents?
The obvious question therefore is: How does that work? The scientists don't provide a satisfactory explanation and to be honest, I have nothing more than a couple of half-assed hypotheses either. My best bet, and I am suggesting that despite the fact that a recent post of mine was entitled "Don't Judge a Protein By Its Amino Acid Content", would in fact be the amino acid content. If you take a look at table 1 it is obvious that the cod protein the scientists used in the study contained one amino acid you as a SuppVersity reader should by now be familiar with and neither whey, nor casein or any of the other standard proteins has to offer: Taurine!

Yet despite the fact that taurine has the potential to boost testosterone levels, increases insulin sensitivity and has in fact been shown to actively reduce body weight in a 2003 human study by Zhang et al. (Zhang. 2003), I am not sold on the idea that the relatively minor total quantity of taurine in the already low amount of fish protein (I mean 8g?) is the only reason for the non-negligible health benefits the scientists observed in their 10 male and 10 female participants (BMI 31-37kg/m²). Maybe it's another of those funky di-peptides you've read about in the context of the nutrient repartitioning effect of whey protein hydrolysate, only lately.

Regardless of what exactly it may be that facilitated the improvements in blood glucose management and the minor, but significant improvements in body composition, the health benefits you can derive from the consumption of cod protein make the notion of fish oil, let alone micro-algae oil supplementation appear even more retarded, when eating fish once or twice a week offers a way more natural and unquestionably more tasty solution to satisfy your DHA requirement.

Night shifts and breast, BPA and prostate cancer

There are two clockworks operating parallel in your body. The one in the brain has to be hacked by light exposure (learn more about "Sunlight a la Carte"), the one in your liver and other peripheral organs, on the other hand, can be (re-)set by specific feeding strategies, like Intermittent Fasting (learn more)
I simply assume that you have by now downloaded and listened to the podcast and are thus aware of what I said about the importance of rythmicity (if you did not really get the notion, I suggest you read up on the posts in the SuppVersity Circadian Rhythm Series to get a better grasp of the different clocks that are ticking in your body ;-) Exactly this kind of rhythmicity is continuously disturbed when you are either switching back and forth from day- to night-shifts or work the night-shift continuously and dare having a social life that's simply not compatible with sleeping all day and waking all night.

That the life of a nurse, for example takes it's toll on your health and precipitates not just the development of breast cancer (+36% after 30 years of rotating night shifts; Schernhammer. 2001), but colorectal cacers (+35% after 15 years of rotating night shifts; Schernhammer. 2003) and endometrial cancer (+47% after 20+ years and even +109% in obese women; Viswanathan. 2007), as well, has been debated ever since the early years of the 21st century.

With the recent publication of two meta-analyses the debate probably will not be over; and that despite the fact that even the less unsettling analysis by Kamdar et al. reports increases in breast cancer risk of +21% for women "with ever night-shift work exposure" (Kamdar. 2013).
"Subgroup analyses suggested that flight attendants with international or overnight work exposure and nurses working night-shifts long-term were at increased risk of breast cancer." (my emphases in Kamdar. 2013)
While the Kamdar study also included observational data, this 2nd meta-analysis, which was likewise published less than a week ago, included only case-control and cohort-studies yielding risk increases of +32% and +8%, respectively (Jia. 2013). Somethin else thatg may be worth mentioning is the fact that both, the studies the scientists ranked as "high quality" research, as well as the only existing study involving female military personnel observed even higher risk increases of +40%.

Despite methodological differences and slightly different outcomes of the two meta-analyses, both research groups do reach very similar conclusions stating that the evidence is still "weak", but does "support previous reports that night-shift work is associated with increased breast cancer risk" (Kamar. 2013) and that "large-scale epidemiological studies are needed" (Jia. 2013).

From breasts to prostates ;-)

Figure 1: Effects of 4-days of BPA injections at different dosages on systemic hormone levels (Castro. 2013)
I know the subheading sounds somewhat gross, but there are certain parallels. For one, there is the same need for large-scale epidemiological studies on the connection between BPA exposure and the development and malignancy of prostate cancer as it is the case with breast cancer and night shifts. On the other hand, BPS of which a recent study was now able to show that it messes with the aromatase and 5-alpha reductase activity in the prostate and can thus precipitate prostate cancer even in adulthood (Castro. 2013), is unquestionably relevant for the development of breast cancer, as well.

What's more, the reductions in 5α-R1 and 5α-R2 Castro et al. observed in their previously healthy, adult rodents after only 4-days of BPA injections at doses of 25, 50, 300, or 600 µg/kg per day and the concommitant increase in the expression of the third isoform of 5-α reductase (5α-R3) does not only precipitate cancerous growth, it's also a recently proposed as a biomarker of cancer malignancy. In conjunction with the quasi-reversal of hormones (see figure 1), the results of this study, which happens to be the first one to demonstrate such profound detrimental effects on mature mammals, should remind us of the fact gestation and early childhood are not the only time-points in our lives, we have to beware of endocrine disruptors.

That's it for the Seconds and in case you are missing the information about fruits and vegetables, I will serve those tomorrow as part of the as of in fact short, but way more numerous "Short News". In case you are still hungry for more, I suggest you make take a slight detour to the SuppVersity Facebook Wall before you you sally into the weekend. There are a couple of appetizers waiting for you there:
  • "Does the Usefulness of Vitamin E Supplementation Depend on Your Activity Level?" While the marathon runners in the facebook study took only 50IU, 400IU is what most supplements have to offer as a minimum. Is that too much, for you? Do athletes need more? What about the hormetic response to exercise - it it even hormetic? (learn more)
    EGCG is an "anti-folate" - You still don't have to worry, nature has made sure that those who value the synergy of whole foods, or in this case drinks, won't be harmed (read more)
  • LOW(!) doses of vitamin C & E (125mg & 50IU) don't diminish the benefits of exercise - On the contrary, in marathon runners that's enough to blunt the neutrophil damage (read more)
  • Smart Kids = Lean Adults  - General intelligence as assessed in childhood has a significant and direct effect on adult obesity risk (read more)
  • Valine, vanadium and oxygenated water - All useless for athletes. That's at least what the latest installment of the "A–Z of nutritional supplements" says (read more)
When you are done with those, it's about to start news fasting, for a couple of hours until tomorrow's morning news (for you probably today's late evening news) will be published on Facebook. Have a great "Post-Valentine's Day", everyone - I just  hope your spouses were happy with their presents ;-)

  • Castro B, Sánchez P, Torres JM, Preda O, Del Moral RG, Ortega E. Bisphenol A Exposure during Adulthood Alters Expression of Aromatase and 5α-Reductase Isozymes in Rat Prostate. PLoS One. 2013;8(2):e55905.
  • Hall WL, Millward DJ, Long SJ, Morgan LM. Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite. Br J Nutr. 2003 Feb;89(2):239-48.
  • Jia Y, Lu Y, Wu K, Lin Q, Shen W, Zhu M, Huang S, Chen J. Does night work increase the risk of breast cancer? A systematic review and meta-analysis of epidemiological studies. Cancer Epidemiol. 2013 Feb 8.
  • Kamdar BB, Tergas AI, Mateen FJ, Bhayani NH, Oh J. Night-shift work and risk of breast cancer: a systematic review and meta-analysis. Breast Cancer Res Treat. 2013 Feb 12. 
  • Lane K et al. Bioavailability and potential uses of vegetarian sources of omega-3 fatty acids: a review of the literature. Critical Reviews in Food and Science Nutrition. February 2013 [Epub ahead of print].
  • Schernhammer ES, Laden F, Speizer FE, Willett WC, Hunter DJ, Kawachi I, Colditz GA. Rotating night shifts and risk of breast cancer in women participating in the nurses' health study. J Natl Cancer Inst. 2001 Oct 17;93(20):1563-8. 
  • Schernhammer ES, Laden F, Speizer FE, Willett WC, Hunter DJ, Kawachi I, Fuchs CS, Colditz GA. Night-shift work and risk of colorectal cancer in the nurses' health study. J Natl Cancer Inst. 2003 Jun 4;95(11):825-8. 
  • Vikøren LA, Nygård OK, Lied E, Rostrup E. Gudbrandsen OA. A randomised study on the effects of fish protein supplement on glucose tolerance, lipids and body composition in overweight adults. British Journal of Nutrition. 2013; 109:648-657.
  • Viswanathan AN, Hankinson SE, Schernhammer ES. Night shift work and the risk of endometrial cancer. Cancer Res. 2007 Nov 1;67(21):10618-22.
  • Zhang M, Bi LF, Fang JH, Su XL, Da GL, Kuwamori T, Kagamimori S. Beneficial effects of taurine on serum lipids in overweight or obese non-diabetic subjects. Amino Acids. 2004 Jun;26(3):267-71. Epub 2003 Dec 15.