Dietary Animal Plant Protein.Pdf Subida Exitosa

New Perspectives on Dietary Protein and Bone Health

Dietary Animal and Plant Protein and Human Bone Health: A Whole Foods Approach1,2
Linda K. Massey3
Food Science and Human Nutrition, Washington State University Spokane, Spokane, WA 99210
ABSTRACT Urinary calcium excretion is strongly related to net renal acid excretion. The catabolism of dietary protein generates ammonium ion and sulfatesfrom sulfur-containing amino acids. Bone citrate and carbonate are mobilized to neutralize these acids, so urinary calcium increases when dietary protein increases. Common plant proteins such as soy, corn, wheat and rice have similar total S per g of protein as eggs, milk and muscle from meat, poultry and fish. Therefore increasing intake of purified proteins from either animal or plant sourcessimilarly increases urinary calcium. The effects of a protein on urinary calcium and bone metabolism are modified by other nutrients found in that protein food source. For example, the high amount of calcium in milk compensates for urinary calcium losses generated by milk protein. Similarly, the high potassium levels of plant protein foods, such as legumes and grains, will decrease urinary calcium.The hypocalciuric effect of the high phosphate associated with the amino acids of meat at least partially offsets the hypercalciuric effect of the protein. Other food and dietary constituents such as vitamin D, isoflavones in soy, caffeine and added salt also have effects on bone health. Many of these other components are considered in the potential renal acid load of a food or diet, which predictsits effect on urinary acid and thus calcium. “Excess” dietary protein from either animal or plant proteins may be detrimental to bone health, but its effect will be modified by other nutrients in the food and total diet. J. Nutr. 133: 862S– 865S, 2003. KEY WORDS:
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animalAn increase in protein consumption increases urinary calcium excretion over the entire range of protein intakes, from marginal to excess (1). Each 10-g increase in dietary protein increases urinary calcium by 16 mg, and doubling protein increases urinary calcium by 50%. Osteoporotic fracture rates increase as cultures become “Westernized.” Many lifestyle changes occur during culturaldevelopment, typically a decrease in physical activity and change in diet. Dietary change usually includes an increase in animal foods at the expense of plant foods. Because increases in dietary animal protein are associated with increases in urinary calcium excretion, the increase in osteoporotic fractures has frequently been attributed to the increase in dietary animal protein. Frassetto et al. (2) foundthe cross-cultural relationship between hip fracture rates and dietary protein was positively related to animal protein intake and inversely related to vegetable protein intake. Even when non-Caucasian populations were removed from the data set, these relationships were still seen. When they plotted the relationship between the ratio of vegetable to animal protein vs. hip
1 Presented as part ofa working group program “New Perspectives on Dietary Protein and Bone Health” given at the 24th Annual Meeting of the American Society for Bone and Mineral Research, San Antonio, TX, September 20, 2002. This program was sponsored by the American Society for Bone and Mineral Research and was supported by a grant from the National Dairy Council®. Guest editors for this program were Lisa A. Spence,National Dairy Council, Rosemont, IL and Connie M. Weaver, Purdue University, West Lafayette, IN. 2 Supported by the National Dairy Council, Chicago, IL. 3 To whom correspondence should be addressed. E-mail: massey@wsu.edu

fracture rate, the ratio was exponentially inversely related. However, 19 of the 33 countries had a vegetable:animal protein source ratio between 0.3 and 1.0 typical of U.S....