Protein tops the list of nutrients for all fitness buffs. In fact nowhere does "of primary importance" carry more weight than in the gym.
Some athletes, particularly strength athletes, may consume several times the DRI of protein in an effort to increase muscle mass and improve performance. Is this justified? DRIs are designed to prevent protein malnutrition, but do they necessarily represent optimal levels of protein intake for either physical performance or disease prevention?
In the March 2006 issue of the American Journal of Clinical Nutrition, Robert Wolfe of the University of Texas Medical Branch in Galveston argues that maintenance of muscle mass, strength and metabolic function should be important considerations when determining dietary recommendations. Muscle serves as an important reservoir of amino acids critical for meeting the demands for protein synthesis that accompany both acute and chronic diseases, demands for immune response proteins and wound repair proteins. Also, muscle mass tends to increase bone density, via the stress placed upon the bones from more forceful muscle contraction. Wolfe suggests nitrogen balance may be adequate for determining protein needs to prevent malnutrition but inadequate for maximizing muscle mass, strength and metabolic function.
The April 2006 issue of the International Journal of Sport Nutrition and Exercise Metabolism discussed just how difficult it is to determine the "optimum" range of human protein requirements. Amino acid absorption rate, rate of urea synthesis and excretion and rate of protein synthesis all must be considered in addition to nitrogen balance. The authors conclude that much study needs to be done, but, "In the face of the rising tide of obesity in the Western world, where energy consumption overrides expenditure, a more prudent and practical approach, which may provide favorable outcomes, is a 25 percent protein energy diet, which would provide 118g protein on a 8000kJ/d diet [1914 calories/day] at 1.5 g/kg/d for an 80-kg individual."
It seems all dietary roads today lead to weight control.
Protein and satiety
Arguably the most powerful force driving our recent protein awareness is concern over weight control and the meteoric rise in the popularity of low carb diets. As dieting trends fluctuate between low fat and low carbohydrate extremes, and we stew over separating the "good" fats and carbohydrates from the "bad," protein has gained a reputation as not only the muscle-building macronutrient, but also the slimming one.
Why? Protein helps us to feel full. "The scientific literature indicates that protein can elicit a stronger satiety effect over the short-term compared to carbohydrate or fat," says Brent Flickinger, senior research manager-nutritional science at Archer Daniels Midland Co. (www.admworld.com), Decatur, Ill. "Increasing satiety of foods is one tactic for addressing the issue of body weight, which has drawn the interest of both the academic community and food industry."
If protein is so satisfying, then why haven't low carb diets been more effective at halting the obesity epidemic? After all, they are by default high in protein. Maybe the emphasis was placed too much on the evils of carbohydrates and not enough on the virtues of protein.
An appetite-suppressing gut hormone called peptide YY is released in abundance when we eat protein foods, suggests "Critical role for peptide YY in protein-mediated satiation and body-weight regulation," an article in the September 2006 issue of Cell Metabolism. Though touted by some as justification for low-carb diets, the study more aptly supports what most nutritionists have always suggested: The higher-protein intake characteristic of low-carbohydrate diets is satisfying in the beginning, so dieters eat fewer calories. But later, when the natural desire carbohydrate builds up, gorging on foods rich in saturated fats to divert hunger is both ineffective and dangerous.
A better approach may be the hunger satisfaction strategy: Increase protein intake from a variety of sources, so that shunning the excess calories from both refined fats and carbohydrates is easier. It's an approach on which many manufactures are banking.
"The more we can offer simplicity while taking the sacrifice out of dieting, the easier it is for women to pursue their shape-management goals," says Mark Baynes, senior vice president of marketing at the, Morning Foods Division of Kellogg Co. (www.kelloggs.com), Battle Creek, Mich. He was referencing the new Special K line of protein-enhanced products that include snack bars, meal bars, and Special K2O protein water. The new protein water features 5g of whey protein isolate per bottle.
A readily absorbed milk protein, whey is the water-soluble byproduct of making cheese, as in curds and whey. One of the proteins highest in biological value, whey is rich in essential amino acids and a favorite among bodybuilders, as well as weight-conscious adults. Whey protein isolate (90 percent pure protein) is pleasant tasting and free of fat and lactose, making it suitable for almost any application.
The low calorie Special K protein bars feature a mixture of whey, nuts and soy proteins. The concept is simple: A nutrient-dense high protein snack will help the busy dieter stave off hunger and stick with a sensible diet.
Expanding soy markets
The humble soybean, a staple in Asian cultures, is a protein source with endless possibilities that go beyond traditional products such tofu, tempeh and soy sauce.
First, the oil can be removed. Soy oil is a good source of essential fatty acids including the valuable omega-3s. What's left is defatted soy flour, a high-protein flour that can be used for breads or to make textured vegetable protein.
Soy concentrates, about 70 percent protein, and soy isolates, around 90 percent protein, result from successive removal of carbohydrates. How these stages are accomplished determines the particular characteristics of the soy product, leaving the food manufacturers with a plethora of choices.
"Prolisse soy protein isolate is separated from the other components in soybeans through a patented, water-based filtration process developed by Cargill," says Deborah Schultz, market development manager at Cargill Health & Food Technologies (www.cargillhft.com), Minneapolis. "This differs from the traditional process, which utilizes acid to precipitate the protein. Cargill's process helps to maintain the natural integrity of the protein." And consumer demand is increasing along with research into the benefits of soy.
"Growing amounts of research continue to link soy and soy protein with health benefits," offers Tom Woodward, vice president of sales and marketing for Devansoy (www.devansoy.com), Carroll, Iowa, which provides organic soy proteins, powders and flours.
"In addition to the FDA health claim of 1999 linking soy protein with cardiovascular health, multiple other potential benefits have been identified. Research has indicated soy could help to prevent certain types of cancer, such as breast cancer and prostate cancer. Further studies have shown soy could help to reduce the effects of osteoporosis, especially in women, and could even help to regulate the enzymes that affect blood sugar levels in diabetics," he says.
We no longer think of protein as only meat, fish and chicken or the milk we serve the kids with dinner. It's now the booster for snacks, cereals, smoothies, bars, even water. It's what you eat between meals to stave off hunger. Satiety is now becoming the gold standard, along with nutrient density, in diet foods, and satiety has a tie to protein. The promise of these foods is that you can satisfy hunger and maintain energy without eating more calories than you need; you can do it comfortably and tastefully, and so avoid packing on the unwanted pounds; you can even add some muscle.
The number of potential protein sources is growing to match the demand for healthy protein choices, giving manufacturers increased freedom to be creative. But here's a note of caution from a balance nut. We've recently emerged from two successive eras, where extreme low fat and extreme low carb philosophies grabbed a lot of unwarranted attention. Protein is important, "of primary importance," but in excess it has a down side, just like any nutrient, something of which we should maintain awareness.