Protein provides amino acids for cell and tissue development throughout the body for growth and repair of cells. The body requires protein as a source of essential amino acids not produced by the body. One to three servings of protein per day in the diet meet the body's protein needs for healthy adults. Athletes and bodybuilders use high protein for muscle development, and high-protein diets may support weight loss. You can use protein powders to make shakes with milk or juice and add them to breads and other baking products to increase protein content.
Protein Powder Sources
The most common sources of protein for powder supplements include milk and soy. Milk contains both whey and casein proteins. Whey, a complete protein in cow's milk, is the liquid removed during cheese making and contains all the essential amino acids. According to a 2003 study by Ohio State University researchers K. D. Kent, W. J. Harper and J. A. Bomser published in "Toxicology in Vitro," casein absorbs more slowly than whey, but does not contain cysteine. According to MedlinePlus, soy is the only plant protein to contain all the essential amino acids.
Protein Absorption
Protein breaks down in the digestive tract by enzyme action to make the amino acids available to repair the body's cells and to make new cells. Protein powders as nutritional supplements are not regulated by the Food and Drug Administration for safety and effectiveness. Protein powders may be hydrolysates, broken down into two or three amino acids for rapid protein absorption. According to a review of protein research by Anssi H. Manninen published in "Nutrition & Metabolism" in 2009, intact whey protein absorbs as well if not better than whey protein hydrolysates; intact casein protein absorbs slowly and in the short term, hydrolyzed casein protein may increase absorption of amino acids.
Protein Powder and Weight Loss
According to a study performed by Christopher M. Lockwood and colleagues at the University of Oklahoma and published in "Nutrition & Metabolism" in 2008, protein powder supplement with low carbohydrate and low-fat improved metabolism resulted in greater weight loss and cholesterol profile than exercise alone. The increased carbohydrate to protein ratio of subjects drinking protein shakes increased from a typical 3:1 suggested for healthy adults to approximately 1:1 and resulted in a voluntary reduction in calorie intake. The authors indicate additional research is needed to determine the mechanism of action.
Health Benefits
Protein powders may provide additional health benefits based on the source of protein. According to the Ohio State University study, whey contains cysteine, the amino acid necessary for the body to make the antioxidant glutathione. This study showed whey protein increases glutathione levels in prostate cells with the potential for reducing the risk of prostate cancer. According to MedlinePlus, research on the health benefits of soy provides strong evidence of moderate cholesterol lowering capability.
Side Effects
Allergic reactions to milk and soy result in a range of symptoms from mild to severe and may require immediate medical attention. Symptoms of allergic reaction include rash, difficulty breathing, swelling of the tongue or throat and sudden drops in blood pressure. Protein powder supplements may cause nausea, bloating and constipation. According to MedlinePlus, high protein intakes may strain the kidneys.
Interference with Mineral Absorption
Essential minerals needed for biochemical reactions for growth and cellular repair may be incompatible with protein supplements. According to MedlinePlus, soy may interfere with the absorption of calcium, zinc and selenium and increase the absorption of manganese. Casein interferes with zinc absorption, though other proteins increase zinc absorption. Use protein powder supplements according to package directions and as directed by your healthcare provider.
References
- "Toxicology in Vitro"; Effect of Whey Protein Isolate on Intracellular Glutathione and Oxidant-induced Cell Death in Human Prostate Epithelial Cells; K. D. Kent, et al; February 2003
- MedlinePlus: Soy
- "Nutrition & Metabolism"; Protein Hydrolysates in Sports Nutrition; AH Manninen; September 28, 2009
- "Nutrition & Metabolism"; Minimal Nutrition Intervention With High-protein; CM Lockwood et al; April 21, 2008
- MedlinePlus: Protein in Diet
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