Posted on

Antioxidant and Vitamin D Supplements for Athletes: Sense or Nonsense? – Research Review

Powers S et. al. Antioxidant and Vitamin D supplements for athletes: Sense or nonsense? J Sports Sci. 2011  Aug 11. [Epub ahead of print]

The idea that dietary supplements can improve athletic performance is popular among athletes. The use of antioxidant supplements is widespread among endurance athletes because of evidence that free radicals contribute to muscle fatigue during prolonged exercise. Furthermore, interest in vitamin D supplementation is increasing in response to studies indicating that vitamin D deficiency exists in athletic populations. This review explores the rationale for supplementation with both antioxidants and vitamin D and discusses the evidence to support and deny the benefits of these dietary supplements. The issue of whether athletes should use antioxidant supplements remains highly controversial. Nonetheless, at present there is limited scientific evidence to recommend antioxidant supplements to athletes or other physically active individuals. Therefore, athletes should consult with their health care professional and/or nutritionist when considering antioxidant supplementation. The issue of whether athletes should supplement with vitamin D is also controversial. While arguments for and against vitamin D supplementation exist, additional research is required to determine whether vitamin D supplementation is beneficial to athletes. Nevertheless, based upon the growing evidence that many athletic populations … Read More

Posted on

Casein Hydrolysate and Anabolic Hormones and Growth – Research Review

I want to try something a little bit different for today’s research review.  Rather than looking at a single study in the kind of obsessive detail that only I and three readers really care about, I want to look at multiple studies but in lesser detail.  Not only will this hopefully make the article a bit more relevant and readable, it will let me address more than a single topic at once.

With the sheer volume of research appearing on a weekly basis, this will at least help me to look at data in a more timely fashion.  I’d mention that, for anyone who wants an even better look at a lot of studies, you’d be well served to consider Alan Aragon’s monthly Research Review which I reviewed in the confusingly titled Alan Aragon Research Review – Product Review.

In any case, today I want to look at two recent studies which are:

  1. Deglaire et al. Hydrolyzed dietary casein as compared with the intact protein reduces postprandial peripheral, but not whole-body, uptake of nitrogen in humans. Am J Clin Nutr. (2009) 90(4):1011-22.
  2. West et. al. Elevations in ostensibly anabolic hormones with resistance exercise enhance neither training-induced muscle hypertrophy nor
Read More
Posted on

Coffee Diabetes and Weight Control – Research Review

Title and Abstract

Greenberg JA et. al. Coffee, diabetes, and weight control. Am J Clin Nutr. (2006) 84(4):682-93.

Several prospective epidemiologic studies over the past 4 y concluded that ingestion of caffeinated and decaffeinated coffee can reduce the risk of diabetes. This finding is at odds with the results of trials in humans showing that glucose tolerance is reduced shortly after ingestion of caffeine or caffeinated coffee and suggesting that coffee consumption could increase the risk of diabetes. This review discusses epidemiologic and laboratory studies of the effects of coffee and its constituents, with a focus on diabetes risk. Weight loss may be an explanatory factor, because one prospective epidemiologic study found that consumption of coffee was followed by lower diabetes risk but only in participants who had lost weight. A second such study found that both caffeine and coffee intakes were modestly and inversely associated with weight gain. It is possible that caffeine and other constituents of coffee, such as chlorogenic acid and quinides, are involved in causing weight loss. Caffeine and caffeinated coffee have been shown to acutely increase blood pressure and thereby to pose a health threat to persons with cardiovascular disease risk. One short-term study found … Read More

Posted on

Effects of (-)-hydroxycitrate on Net Fat Synthesis as De Novo Lipogenesis

Kovacs EM and MS Westerterp-Plantenga Effects of (-)-hydroxycitrate on net fat synthesis as de novo lipogenesis. Physiol Behav. (2006) May 23; [Epub ahead of print]

(-)-Hydroxycitrate (HCA) might promote weight maintenance by limiting the capacity for de novo lipogenesis (DNL). It was investigated whether HCA may reduce DNL in humans during a persistent excess of energy intake as carbohydrate. In a double-blind, placebo-controlled, randomized and cross-over design, 10 sedentary lean male subjects (mean+/-S.D., age: 24+/-5 years, BMI: 21.8+/-2.1 kg/m(2)) performed a glycogen depletion exercise test followed by a 3-day high-fat diet (F/CHO/P, 60/25/15% energy; 100% of energy expenditure (EE)) and a 7-day high-CHO diet (F/CHO/P, <5/>85/10% energy; 130-175% of EE; overfeeding). During overfeeding, they ingested 3×500 mg/day HCA or placebo (PLA). Each intervention ended with a 60-h stay in the respiration chamber (days 9 and 10). Body weight increased during overfeeding (mean+/-S.E., HCA: 2.9+/-0.2 kg, PLA: 2.8+/-0.2 kg). Respiratory quotient (RQ) was >1.00 in all subjects indicating that DNL was present. On day 9, 24-h EE was lower with HCA compared to PLA (P<0.05). On day 10, resting metabolic rate and RQ during night were lower (P<0.01 and P<0.05, respectively). Non-protein RQ, fat balance and net fat synthesis as DNL … Read More