Protein Supplements: A Story Beyond Swedish Meatballs
Jay Cutler?s incredible physique is a product of superior genetics, long-term training, optimal nutrition and a committed attitude. Clearly, these factors cannot be replaced by the use of sports supplements. However, scientific study has identified a number of products that offer true benefits to performance (e.g., creatine) or the achievement of nutritional goals (e.g., meal replacement products). Even where a sports supplement does not produce a true physiological effect, an athlete might attain some performance benefit because of a psychological boost, or placebo effect. The placebo effect describes a favorable outcome arising simply from an individual?s belief he/she has received a beneficial treatment.
The placebo effect was clearly demonstrated in one of the earliest studies of anabolic-androgenic steroids. Male athletes who had been involved in heavy weightlifting for the previous two years volunteered for a weight training experiment using anabolic steroids (Dianabol). They were told they would receive 10 milligrams per day of Dianabol, when in fact they received a placebo— an inactive substance provided in a form identical to the genuine drug. Strength data were collected over the last seven weeks of the pre-treatment training period and over all four weeks of the treatment (placebo) period. Even though the subjects were experienced weightlifters, they continued to gain somewhat impressive amounts of strength during the pre-treatment training period. However, strength gains while subjects were taking the placebo were substantially greater than during seven-week pre-treatment period. The group improved an average of 11 kilograms during the seven-week pre-treatment period, but improved 45 kilograms during the four-week placebo period! Thus, “Placebol” is a very effective ergogenic aid!
Historically, bodybuilders and other strength-power athletes have always consumed a lot of protein supplements. A survey of supplement use in high school athletes in 1984 found that 22 percent consumed protein drinks, nine percent consumed amino acid supplements and 17 percent consumed either weight-gain or weight-loss products (which contain high-levels of protein). Supplements that work through a placebo effect, but have no intrinsic effects, eventually fall by the wayside and are abandoned by the majority. Protein supplements are used because they apparently work. And even though there have been numerous attempts to discourage it, the popularity has not waned.
However, it’s important to emphasize the point that these supplements should be used as an adjunct to an otherwise balanced nutritional plan, not as a substitute for one. With that said, this article examines some science behind different protein supplements.
Table 1. Protein Supplement Types
Protein powders (containing protein varying in purity from 34% to almost 100%)
Meal replacement powders (containing protein, carbohydrates, vitamins, minerals and sometimes, other nutrients or fats)
Weight gain powders (containing protein, carbohydrates and sometimes fats, vitamins, minerals and other nutrients)
Bars (some bars contain 25 grams or more of protein and are advertised as a dietary protein source)
Ready-to-drink liquids (may or may not contain carbohydrates and other nutrients)
Pills (tablets, capsules or wafers containing protein and sometimes, other nutrients)
Protein hydrolysates (in powder, beverage, bar, or pill forms)
Amino acids (in combinations of 18 or more that approximate protein, or mixtures of a few amino acids, or individually— these may be stand-alone products or added to other protein-containing supplements)
Data from Bucci and Unlu 2000. 1For more information on protein hydrolysates, see my article in Muscular Development, Apr., 2003.
Milk proteins are commercially available as 1) whole milk proteins; 2) caseinates; and 3) whey proteins. Milk protein is approximately 80 percent caseinate and 20 percent whey protein. Milk protein isolates are produced from skim milk by two basic methods: 1) ultrafiltration, diafiltration (to concentrate protein) and drying, or 2) low or high pasteurization, precipitation, washing and drying. Milk protein concentrates and isolates contain more than 90 percent protein and are commonly used in foods and dietary supplements.
Several Romanian studies involving a milk powder containing approximately 90 percent protein and mineral salts have shown the ergogenic effects of this supplement. In one of these studies, nine male and eight female top Olympic athletes were given 1.2-1.5 grams of milk protein per kilogram of body mass per day during a period of six months. The milk protein was consumed in addition to 2.2-2.5 grams protein per kilogram of body mass per day in their diets.
A control group with the same number of athletes and from the same sports was fed the same diet, but without the addition of extra milk protein.
The results indicated that the extra milk protein significantly improved physiological condition and led to better sports performance, even when compared to the controls. However, it’s possible that these studies were confounded by interacting effects from exogenous anabolic agent use (e.g., anabolic steroids) and/or by variable training/peaking preparations due to the timing of competitions held during the data collection.
Whey proteins are extracted from liquid whey produced as a byproduct of cheese or casein manufacturing. Whey protein concentrates (about 80 percent protein) are produced from liquid whey by clarification, ultrafiltration, diafiltration, and drying. Whey protein isolates (more than 90 percent protein) are produced from liquid whey by a variety of techniques. Whey proteins in particular have been singled out as the ultimate form of protein based on essential amino acid composition, branched-chain amino acid (BCAA) content, sulfur amino acid content, taste acceptance, ease of mixing, stability in liquids and rapidity of digestion.
Dr. L.C. Lands and co-workers compared effects of whey protein concentrate and casein on muscular performance, body composition and lymphocyte glutathione concentration. (Glutathione is a peptide that contains one amino acid residue each of glutamic acid, cysteine and glycine). Glutathione occurs widely in plant and animal tissues, and plays a major role in protecting skeletal muscle and other body tissues from oxidative damage.
In this study, 20 healthy young adults (10 men, 10 women) were studied pre-supplementation and three months post-supplementation with either whey protein (20 grams per day) or casein placebo. Exercise performance was assessed by whole leg isokinetic cycle testing, measuring peak power and 30-s work capacity. Further, lymphocyte glutathione was used as a marker of tissue glutathione. There were no baseline differences. Follow-up data on 18 subjects (nine whey protein, nine placebo) were analyzed. Both peak power and 30-s work capacity increased significantly in the whey protein group. Lymphocyte glutathione also increased significantly in the whey protein group, with no change in the placebo group.
However, the exact mechanism(s) by which whey protein improved muscular performance is unclear. According to authors of this study, the most obvious mechanism would be an increase in intracellular glutathione levels, leading to a decrease in oxidant-induced muscular dysfunction. In addition, subjects on whey protein had a decrease in their percentage of body fat while maintaining their weight.
Recently, Drs. Ewan Hu and Michael Zembel published an excellent literature review on whey protein in the respected Journal of Nutritional Biochemistry. They concluded that whey protein supplementation may enhance lean body mass in conjunction with appropriate training. Also, bioactive compounds isolated from whey may also improve immune function and gastrointestinal health. Thus, it appears whey protein is the ultimate source of protein for athletes. However, more research is needed before firm conclusions can be drawn.
Soy protein has been a subject of extensive industrial research to produce a virtually pure protein isolate in commercial quantities. Soy protein is produced from soybeans via water extraction, followed by precipitation, washing and drying procedures to yield either a soy protein concentrate (about 70 percent protein) or soy protein isolates (about 90 percent protein).
Some extraction procedures use ethanol/water mixtures that remove isoflavones. Isoflavones have been studied in postmenopausal osteoporosis and generally found to have a positive effect in maintaining bone density and reducing fractures. However, since they are relatively new agents, the long-term benefits or consequences, as well as their impact on fracture reduction, need more clarification.
In the past, low protein purity of soy-derived protein sources led to consumer dissatisfaction due to gastrointestinal disturbances, poor taste and poor mixability. Although these objections have been successfully eliminated, the image of poor tolerance of soy protein remains in the minds of many consumers. However, the significantly lower cost of soy protein isolates compared to egg, whey and some milk proteins has made soy protein supplements more attractive.
The most consistently demonstrated beneficial effect of soy has been on lipids. Federal Drug Administration (FDA) approval for consumer labeling of soy foods has been given in the U.S., stating that “included in the daily diet, they may reduce the risk of heart disease.” This is based primarily on the lipid benefits. A meta-analysis of 38 published controlled human clinical trials of an average of 47 grams daily of soy protein consumption (primarily in subjects with hyperlipidemia), noted significant reduction in total and LDL cholesterol (“bad cholesterol”) and triglycerides, with the hypocholesterolemic effect significantly related to pre-treatment cholesterol levels.
Further, soy protein contains a higher percentage (35 percent) of five “critical cluster” amino acids, including glutamine, arginine and the BCAA than other proteins, such as whey, casein, egg and beef (Figure 1). In theory, these are the amino acids preferred for fortification of proteins by the dietary supplement industry, and they have hypothetical benefits for exercising individuals.
Amount of “Critical Cluster” Amino Acids in Various Protein Sources
These amino acids are hypothesized to be of primary importance among amino acids for muscle metabolism. Solae?refers to isolated soy protein. Soy protein isolates are less expensive than whey, milk and egg proteins, and possess favorable organoleptic properties, such as mixability, taste, texture and ease of flavoring. In addition, recent data have confirmed that soy protein is complete for humans, and has similar biological value in humans (as illustrated by Protein Digestibility-Corrected Amino Acid Score (PDCAAS)), to milk, beef and egg proteins.
Four double blind, placebo-controlled studies on elite Romanian athletes all administered 1.5 grams per kilogram of body mass per day additional protein from isolated soy protein for eight to 16 weeks during stressful training periods. In general, lean body mass was preserved or increased, muscular strength was maintained or increased and urinary mucoproteins were decreased in soy protein-supplemented subjects, while adverse effects were noticed in placebo subjects. Again, it’s possible these studies were confounded by interacting effects from exogenous anabolic agent use and/or by variable training/peaking preparations due to the timing of competitions held during the data collection. Moreover, it should be noted that these studies have not been published in major peer-reviewed journals. To my knowledge, only one study on soy protein supplementation and exercise has been so published.
Dr. V. Stroescu and colleagues evaluated the metabolic and hormonal response in elite female gymnasts undergoing strenuous training and supplementation with isolated soy protein. Fourteen top female gymnasts (Romanian Olympic Team) took part in this study to examine their hormonal metabolic profile and to investigate any possible changes resulting from a four-month program of strenuous training and daily supplementation with soy protein at a level of one gram per kilogram of body mass.
According to the authors, the results of their study suggest lower metabolic-hormonal stress in elite female gymnasts undergoing strenuous training while receiving daily supplementation with isolated soy protein. Although more research is needed, soy protein isolate is an under-recognized means of providing high-quality protein for exercising individuals and perhaps may possess other benefits due to isoflavone content and actions.
However, some sports nutritionists feel soy protein is not a good protein source for male athletes. Theoretically, exposure to high levels of soy phytoestrogens could alter the hypothalamic-pituitary-gonadal axis in men. Thus, three dietary intervention studies have reported the effects of soy or soy phytoestrogen consumption on reproductive hormones in men. Dr. R.C. Habito and co-workers performed a randomized crossover study of 42 men with a mean age of 45.7 years who consumed 150 grams of lean meat or 290 grams of tofu daily for four weeks. Blood concentrations of estradiol, testosterone and dihydrotestosterone did not differ between the two diets. The mean testosterone-estradiol ratio was 10 percent lower, sex hormone-binding globulin was nine percent higher and the free androgen index was seven percent lower after tofu consumption.
However, this slight reduction in androgenic activity was not confirmed by Dr. C. Nagata and colleagues, who reported a parallel-arm study of 34 men with a mean age of 32.4 years, half of whom consumed an average of 343 milliliters of soymilk daily for two months. Blood concentrations of estradiol, total and free testosterone and sex hormone-binding globulin did not differ between the groups. These results are generally consistent with those of Dr. J.H. Mitchell and co-workers, who found no changes in blood concentrations of estradiol, testosterone, follicle-stimulating hormone or luteinizing hormone in men consuming a tablet containing 40 milligrams per day of soy isoflavones. In summary, there may be small effects of soy consumption on steroid hormones.
Carbohydrate-Protein Supplements and Glycogen Resynthesis
Athletes who must train or compete in exhaustive events on successive days should replace muscle and liver glycogen stores as rapidly as possible. Thus, an athlete recovering from an exhaustive endurance event should ingest sufficient carbohydrate as soon after exercise as is practical. It was also postulated that adding protein to the carbohydrate ingested during the recovery period would enhance muscle glycogen resynthesis above that achieved with carbohydrate only. Indeed, a recent study by Dr. John Ivy and colleagues has clearly demonstrated that a carbohydrate-protein supplement is more effective for replenishing muscle glycogen after exercise than a carbohydrate supplement alone.
Meal Replacement Products
A number of studies have evaluated long-term weight maintenance using meal replacement products, either self-managed, with active dietary counseling, or with behavioral programs compared with traditional caloric-restricted diet plans. All the studies resulted in maintenance of significant weight loss after two to five years of follow-up. Interestingly, meal replacements were also found to improve food patterns, including nutrient distribution, intake of macronutrients, and maintenance of fruit and vegetable intake.
Anyone who is consistently bitching that “protein supplements are nothing but a waste of money” is a pseudoscience quack.