Six Nutrition Facts from the Lab
Six Nutrition Facts from the Lab
1) Caffeine Is a ‘Double Whammy’ Supplement
Caffeine is a multifaceted chemical that promotes athletic performance and enhances weight loss. A study on caffeine by Spanish researchers showed that a moderately high dose of caffeine (4.5 milligrams per kilogram of bodyweight, or about 380 milligrams for the average male bodybuilder) increased post-exercise metabolism by 11 percent compared to a placebo (fake caffeine). The exercise consisted of 60 minutes of cycling on a stationary bike at 75 percent of maximum effort. The increase in metabolism was attributed to an elevated breathing volume. Caffeine is an excellent supplement for bodybuilders: it increases energy levels for training, enhances strength and power, and speeds fat use during and after exercise. Athletes playing NCAA sports are prohibited from taking high doses of caffeine during competition, but the restrictions have been lifted in Olympic sports. (International Journal of Sports Nutrition and Exercise Metabolism, 25:46-53, 2015)
2) Carbs Do Not Add to the Effects of Branched-Chain Amino Acids and Weight Training on Muscle Genes
Nutrient timing is an important development in sports nutrition. Key nutrients, such as leucine and citrulline, enhance the effects of weight training on muscle protein synthesis. Some researchers have suggested that co-consumption of carbohydrates would provide an additional anabolic effect. Richard Kreider from Texas A&M University, and colleagues, found that the combination of leucine or branched-chain amino acids and weight training enhanced markers of muscle-building chemicals such as IGF-1 in the activity of genes affecting muscle protein synthesis. However, also consuming carbohydrates during exercise had no additional effect. (Amino Acids, published online March 5, 2015)
3) The Downside of Beta-Alanine Supplements
Many athletes take beta-alanine supplements to improve endurance. An Australian study using competitive cyclists showed that it induced tingling and numbness, which could have negative effects on performance and have long-term health consequences. Cycling is sometimes linked to nerve problems in the sex organs and in the hands, wrists, elbows and shoulders, stemming from maintaining prolonged static positions. Alanine is an amino acid that helps supply energy during exercise. It is converted to blood sugar in the liver by a process called the glucose alanine cycle. While it is not used to synthesize muscle tissue or enzymes, it influences exercise capacity— particularly endurance performance. Alanine supplements might boost performance, but they have side effects. (European Journal Sports Science, published online January 30, 2015)
4) Leucine Plus Whey Protein Promotes Muscle Protein Synthesis After Intense Endurance Exercise
The amino acid leucine and whey protein consumed following weight training trigger increases in muscle protein synthesis that promote muscle mass and strength. Endurance training does not cause increases in muscle mass, but it does cause tissue damage that must be repaired during recovery. David Rowlands from Massey University in New Zealand, and colleagues, in a very sophisticated study, found that consuming five grams of leucine and 25 grams of whey protein after 100 minutes of intense cycling promoted muscle protein synthesis, which would help speed recovery and promote adaptation to exercise and improved fitness. Supplements containing leucine and protein consumed after exercise are good for bodybuilders and endurance athletes. (Medicine Science Sports Exercise, 47: 547-555, 2015)
5) Whey Protein, Leucine and Vitamin D Supplement Preserves Muscle Mass in Dieting Older Adults
The incidence of obesity has increased alarmingly in older adults. Excess fat increases the risk of metabolic diseases, heart attack, stroke and arthritis. Unfortunately, people lose muscle mass when they try to lose weight, which leads to decreased strength, impaired mobility and premature death. A major public health challenge is how to help older people attain a healthy weight without losing muscle mass. A 13-week study of 80 obese older adults by Dutch scientists found that people fed a supplement containing whey protein, leucine and vitamin D maintained muscle mass during weight loss, compared to a control group. Both groups participated in a weight-training program. Loss of muscle mass with aging, called sarcopenia, is a significant health problem that might be reduced through the consumption of protein and amino acids supplements. (American Journal of Clinical Nutrition, 101: 279-286, 2015)
6) Green Tea Has No Long-Term Effects on Body Composition
Green tea extract is an extremely popular supplement that curbs appetite, increases metabolic rate and boosts energy levels in athletes and people trying to lose weight. This supplement appears to have few side effects other than elevated heart rate and small increases in blood pressure. However, a 12-week study in 60 young adult men and women showed that it had no effect on fat absorption, resting energy expenditure and body composition. The active ingredients in green tea include caffeine and epigallocatechin. Other studies have found that green tea has short-term effects on suppressing appetite and increasing metabolic rate (i.e., caloric expenditure). We can infer from this study that the effects of the supplement do not last. (The Journal of Nutrition, published online March 4, 2015)