Monday, October 2, 2017

Nine Recent Studies on Vitamins, Fruits+Veggies, Ketogenic Dieting for Endurance Athletes, Blood Pressure, Cognitive Function, Depression & Gene-Diet-Interactions from 10/17

Looking for the very latest on nutrition science? Look no further: most of the results presented in this installment of the short news have not yet been officially published after their presentation on a conference of the Nutrition Society.
I hope you don't mind that I decided to pool the most interesting of the latest studies from the Proceedings of the Nutrition Society in a single article. With the articles on vitamin D, B-vitamins, ketogenic diets in endurance athletes, and so on and so forth all being addressed individually, you can still skip studies you may not be interested in and get the gist (read the title and the last paragraph of each bullet point) within seconds.

As it is usually the case for short-news that are based on presentations at a conference, it will take time for the full papers to be written, reviewed and published. Accordingly, I cannot tell you how many eggs the subjects in the keto-diet study ate and whether they consumed their stakes rare or well-done... so please don't ask ;-)
Looking for more ways to improve your diet? Increase your potassium (K) intake!

Potassium vs. Diet-Inducded Insulin Resis.

In the Lime Light: The Ill Effects of Low K Intakes

Bad News: Most Americans are Sign. K Deficient

Lean, Healthy ... Correlates of High Hair Potassium

Eating a High Protein Diet? Better Watch K!

Potassium Bicarbonate = Anabolic!?
  • 6 months vitamin D supplementation effectively improved 25OHD levels, but without boosting cognitive function in healthy community-dwelling older adults, randomised double-blind placebo-controlled pilot trial shows (Aspell 2017).

    A recent study from the Trinity Centre for Health Sciences at the St. James's Hospital (Aspell 2017) shows that 2,000IU of D3 supplemented daily does increase the 25OHD levels by almost 50%, but the battery of tests the scientists ran to determine if this would have downstream beneficial effects on the cognitive health of the 68.5y-old (mean) subjects, 18.3% of whom were D-ficient at baseline, did not show effects on global cognitive function.

    No clear benefit of 'D' on cognition.

    Yes, conducting a study that lasts for more than 6 months may yield these benefits, but, in general, the study at hand seems to confirm that the vitamin D ain't the messiah as which it was celebrated in the past decade.
  • Milk significantly decreases LDL in 78 healthy, pre-menopausal women with habitually low intakes of milk (<250ml) who more than doubled their intake (Yeates 2017).

    After decades of being everybody's darling, milk has recently gotten a pretty bad reputation... you as a SuppVersity reader know that milk is not rat poison as some mainstream media claimed in the past (re-read my "Mill Kills [NOT]"). Accordingly, you will not be surprised that an extra 430ml/d of full-fat milk had (a) no effect on body composition, glucose management, total cholesterol, and triglycerides, but did (b) significantly reduce the levels of LDL in the 18-45-year-old women.

    Sign reductions in LDL w/ milk

    If we assume that you are lactose tolerant and like it, go for your milk people. A 1mmol/L reduction in LDL is associated w/ a 22% reduced risk of major cardiovascular events (Baigent 2010) - even in people with LDL levels as low as 2 mmol/L! Personally, I don't like the taste of pure milk, but dairy products like quark, yogurt, and cheese (likewise a falsely vilified health food) are a staple in my diet.
  • Overrated? Increasing fruit and veggie intake, alone, doesn't improve blood pressure according to six randomized controlled fruit and vegetable intervention trials that were pooled analysis by British researchers (Elsahoryi 2017).

    People expect wonders from fruits and veggies, wonders of which a recent study from the Queen's University Belfast have now shown that they won't occur even if the participants of RCTs actually managed to increase their fruit and veggie (FV) intake, significantly.

    When pooling the slopes and standard deviations from the six largest trials, there simply isn't a significant decrease in either systolic or diastolic blood pressure per portion change in fruit and vegetable intake.

    No effect of adding F/V to (bad) diet

    Let's be clear here, this doesn't mean that fruit and veggies don't have to play an important role in healthy diets. It does, however, tell you that - in the absence of other dietary changes, weight loss, and increased physical activity - simply adding a couple of servings on top of your mad Western diet ain't going to save your heart, kidney, and other organs from the damaging effects of increased blood pressure.
  • Personalized nutrition: Riboflavin attenuates increase in blood pressure in pregnant women w/ MTHFR 677C→T gene polymorphism (O'Sullivan 2017)

    Having increased blood pressure during pregnancy is not just a temporary problem. In fact, studies show that it will also increase the risk of blood pressure disturbances later in life. Accordingly, the results of the latest study from the Ulster University, the University College Dublin, and the University College Cork are of great importance...
    ... at least for those women who harbor an MTHFR 677C→T gene polymorphism and have been shown to be at greatest risk of abnormal blood pressure levels during pregnancy (McNulty 2017), this increased risk can be mitigated by a high Riboflavin status.

    No, this doesn't mean that riboflavin supplementation will help!

    It will take RCTs to confirm or refute the hypothesis that supplemental riboflavin is going to help women with MTHFR 677C→T gene polymorphism control their blood pressure during pregnancy, and rejoice: the study is already underway.
  • New study doesn't support link between high folate + low B12 and various measures of cognitive function in adults over 50 (O'Connor 2017).

    While folate has long been considered a super-vitamin, recent studies showing a high prevalence of elevated folate and low B12 levels in older people w/ cognitive problems suggested that, at least, unbalanced high folate levels could be a serious problem for granny and grandpa.
    A recent re-analysis of data from The Irish Longitudinal Study on Aging didn't find either the Mini-Mental State Examination (MMSE) scores, or the Montreal Cognitive Assessment (MoCA), or the verbal fluency to be superior in subjects w/ normal B12:folate ratios  (see Figure) compared to peers with an abnormal cobalamine to folate ratio below 258pmol/L:45.3nmol/L.

    This doesn't mean that high folate and, even more so, low B12 ain't no problem! And still evidence that simply popping pills ain't just missing: it looks as if it didn't help.

    It is important to note that the lack of associations between a low-B12-high-folate profile in a single cohort does (a) not negate the existence of such a relationship. Furthermore, there's (b) plenty of evidence that having adequate levels of both, folate and vitamin B12 and (thus) low levels of homocysteine are of essential importance to cognitive function as we age (Wolters 2004). The bad news, however, is that meta-analyses show that simply popping pills is not the solution: "Randomized trials show no effect of folic acid, with or without other B vitamins, on cognitive function within 3 years of the start of treatment." (Wald 2010).
  • Without fortified foods and B-supplements, it's hard to cover get enough B to ward off depression, scientists from the University of Ulster write (Moore 2017).

    The scientists base this statement on a re-analysis of data from the Trinity Ulster Department of Agriculture Ageing Cohort with more than 5000 subjects that found significantly higher levels of all relevant B-vitamins with increasing fortified food intakes.
    Table 1: B-vitamin levels in subjects relying on natural food sources, only, consumers of different amounts of fortified foods and supplement users (Moore 2017).
    Since low levels of folate, vitamin B6, and riboflavin all being associated with a 47-48% increased risk of depression in the same cohort, that's bad news for people who avoid both: fortified foods and supplements.

    If you want to stay mentally healthy as you age, watch your B-vitamin intake!

    When we hear about B-vitamins and aging, we usually think about cognitive decline. That the ever-increasing rates of depression in older individuals may also be driven by a lack of B-vitamins, on the other hand, is commonly overlooked. Unfortunately, the same goes for the general lack of folate, vitamin B6, and riboflavin in the diet of older individuals - a lack that can be compensated by both: fortification and supplementation, as the data from the study at hand suggests.
  • 9 grams of milk hydrolysate are enough to significantly ameliorate the glucose response to a standardized breakfast in healthy young men (Keane 2017).

    It's not news that whey protein, in general, and its fastest absorbing incarnation, i.e. hydrolyzed whey protein, can significantly improve the glucose-response to standardized meals. What scientists and functional food designers alike didn't know, yet, is whether the effects that have been previously observed with 20g and more will also occur with significantly lower intakes of a form of milk protein that ... let's be honest, here... simply tastes like crap.
    Now, a brief glance at the glucose curves Keane and Gibney recorded in their recent RCT with 13 young, healthy, male participants, indicates that even 9 grams of hydrolyzed milk protein are enough to elicit significant improvements in post-prandial glucose levels.

    Insulin haters rejoice: The low dosage doesn't even significantly elevate insulin

    In that, the study at hand didn't just demonstrate that even low(er) amounts of the bitter milk hydrolyzate can significantly reduce glycemic excursions in response to a standardized breakfast. It did also show that 9 grams of hydrolyzed milk protein can do so without exorbitant increases in insulin (as you can see insulin will still increase, but according to Keane and Gibney only non-significantly, while 12g still produced a significant increase), of which I've previously told you that they are one out of three interrelated factors that are responsible for the reduced glycemic response (the other ones are the associated increases in GLP-1 and GIP).
  • Ketogenic diet reduces iron status in endurance athletes to an extent that may compromise their performance, US researchers demonstrate (McSwiney 2017).

    After 12 weeks on a ketogenic diet (<50g/d carbohydrates >75% energy from fat), the trained endurance athletes in a recent study from the Waterford Institute of Technology showed significantly reduced markers of iron status.
    Table 2: Differential effect on "iron" levels of endurance athletes on high-CHO vs. ketogenic diet.
    While the control diet, which delivered 65% of the energy as carbohydrates and only 20% as fat (protein intakes were identical between groups), conserved the total and corpuscular levels of the oxygen-carrying hemoglobin, the subjects who had been randomly assigned to the ketogenic diet exhibited significant reductions in all three: Hb, MCH, and MCHC.

    The significant reduction in oxygen-carrying hemoglobin could be a problem for keto-athletes, but that was not tested in the study at hand.

    As highlighted in the subheading, the study didn't include performance testing, but unlike the decrease in hematocrit* in the high-carb group, the significant reduction in total (-9.3%; p < 0.05) and corpuscular hemoglobin could significantly impair the oxygenation of skeletal muscle and thus negatively affect the exercise performance of endurance athletes [*note: many will even think that the decreasing haematocrit levels may be a health benefit as high levels are associated W/ increased mortality and heart disease (Gagnon 1994) - keep in mind, though, endurance athletes usually hover at the lower end of the Hct range, anyway, and that's likewise associated with cardiovascular problems]. 
Non-Adherence and Design Problems: Two Reasons Why Recent Diet Study May Fail to Show Benefits of High(er) Protein + Dairy Intakes in Overfat (>37%) Women | learn more
Bottom line: In as much as I want to make it easier for you to get the gist out of today's research update, I am not going to summarize the already summarized bottom lines to the individual studies again. That simply doesn't make sense. So, if you want the gist and implications, read the headlines and the last paragraph of each of the mini-write-ups.

What I can and will do for you, though, is to warn you of "luxury yogurts" of which a recent study from the Food Safety Authority of Ireland (Kemp 2017) says that they are generally no healthy food choices. With levels of sugar and/or saturated fats way beyond what the health claims on the labels mislead the average consumer to believe | Comment!
References:
  • Aspell, N., Healy, M., Mc Partlin, J., Lawlor, B., & O'Sullivan, M. (2017). Effects of vitamin D supplementation on cognitive function in healthy, community dwelling older adults: Results from a randomised double-blind placebo-controlled pilot trial. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S002966511700132X.
  • Baigent, C., Blackwell, L., Emberson, J., Holland, L. E., Reith, C., Bhala, N., ... & Collins, R. (2010). Efficacy and safety of more intensive lowering of LDL cholesterol: a meta-analysis of data from 170,000 participants in 26 randomised trials.
  • Elsahoryi, N., Patterson, C., McKinley, M., Neville, C., Baldrick, F., Mulligan, C., . . . Woodside, J. (2017). The effect of increased fruit and vegetable consumption on systolic and diastolic blood pressure in six randomized controlled fruit and vegetable intervention trials: A pooled analysis. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S002966511700129X.
  • Gagnon, D. R., Zhang, T. J., Brand, F. N., & Kannel, W. B. (1994). Hematocrit and the risk of cardiovascular disease—the Framingham study: a 34-year follow-up. American heart journal, 127(3), 674-682.
  • Keane, L., & Gibney, E. (2017). The effect of various doses of a milk protein hydrolysate on the post-prandial glycaemic response in a healthy male cohort. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S002966511700146X.
  • Kemp, B., White-Flynn, T., Lyons, O., Cronin, B., O'Donovan, C., Donovan, C., & Flynn, M. (2017). Is it yoghurt or is it a dessert? Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001422.
  • McNulty, Helene, et al. "Riboflavin, MTHFR genotype and blood pressure: a personalized approach to prevention and treatment of hypertension." Molecular aspects of medicine 53 (2017): 2-9.
  • McSwiney, F., Wardrop, B., Volek, J., & Doyle, L. (2017). Effect of a 12 week low carbohydrate ketogenic diet versus a high carbohydrate diet on blood count indicators of iron status in male endurance athletes. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001458
  • Moore, K., Hughes, C., Hoey, L., Ward, M., Porter, K., Strain, J., . . . McNulty, H. (2017). Role of fortification and supplementation in achieving optimal biomarker status of B-vitamins for better mental health in older adults. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001215
  • O'Connor, D., Laird, E., O'Halloran, A., Molloy, A., & Kenny, R. (2017). Variations in vitamin B12 and folate balance: Implications for cognitive function? Findings from The Irish Longitudinal Study on Ageing (TILDA). Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001227
  • O'Sullivan, E., Pentieva, K., Ward, M., McAuley, A., Strain, J., McNulty, B., . . . McNulty, H. (2017). Riboflavin, MTHFR 677C→T and blood pressure in pregnant and non-pregnant women. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001240.
  • Wolters, M., Ströhle, A., & Hahn, A. (2004). Cobalamin: a critical vitamin in the elderly. Preventive medicine, 39(6), 1256-1266.
  • Yeates, A., Gilmartin, N., O'Kane, S., Pourshahidi, L., Mulhern, M., & Strain, J. (2017). The effect of cow's milk consumption on cardiometabolic health in women of childbearing age. Proceedings of the Nutrition Society, 76(OCE3). doi:10.1017/S0029665117001318.