Plant Foods Have A Complete Amino Acid Composition
The Statement for Health Professionals from the Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association on Dietary Protein and Weight Reduction contains often quoted, but incorrect, information of the adequacy of amino acids found in plant foods.1 This report states, “Although plant proteins form a large part of the human diet, most are deficient in 1 or more essential amino acids and are therefore regarded as incomplete proteins.”
William Rose and his colleagues completed research by the spring of 1952 that determined the human requirements for the eight essential amino acids.2 They set as the “minimum amino acid requirement” the largest amount required by any single subject, and then doubled these values to make the “recommended amino acid requirement,” which was also considered a “definitely safe intake.” By calculating the amount of each essential amino acid provided by unprocessed complex carbohydrates (starches and vegetables),3 and comparing these values with those determined by Rose,1 the results show that any single one, or combination, of these plant foods provide amino acid intakes in excess of the recommended requirements. Therefore, a careful look at the founding scientific research and some simple math proves it is impossible to design an amino acid deficient diet based upon amounts of unprocessed starches and vegetables sufficient to meet the calorie needs of humans. Furthermore, mixing foods to make a complementary amino acid composition is unnecessary.4
The reason it is important to correct this misinformation is because many people are afraid to follow healthful pure vegetarian diets – they worry about “incomplete proteins” from plant sources. A vegetarian diet based around any single one, or combination, of these unprocessed starches (rice, corn, potatoes, beans, etc.) with the addition of vegetables and fruits supplies all the protein, amino acids, essential fats, minerals, and vitamins (with the exception of vitamin B12) necessary for excellent health. To wrongly suggest people need to eat animal protein for nutrients will encourage them to add foods that are known to contribute to the cause of heart disease, diabetes, obesity, and many forms of cancer, to name just a few common problems.5
St. Jeor S, Howard B, Prewitt E. Dietary protein and weight reduction. A statement for health professionals from the Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association. Circulation 2001;104:1869-74.
1. Rose W. The amino acid requirement of adult man. Nutr Abst Rev 1957;27:63l-47
2. J Pennington. Bowes & Church’s Food Values of Portions Commonly Used. 17th Ed.
3. Lippincott. Philadelphia- New York. 1998.
4. M. Irwin, Hegsted D. A conspectus of research on protein requirements of man. J Nutr 1971;101:385-428.
5. Weisburger J. Eat to live, not live to eat. Nutrition 2000; 16:767-73.
John McDougall, MD
The McDougall Program
Santa Rosa, CA 95402