By Lee Kurisko, MD
A prevalent concern regarding the elimination or reduction of animal products from the diet is about protein adequacy. “Where do you get your protein?” is a question that vegans hear over and over again. The answer is simple. They get it from the plants that they eat. More than enough protein can be obtained from whole grains, legumes, nuts, seeds, fruits and vegetables. The US government’s RDA (recommended daily allowance) is 0.8 gm/kg of bodyweight per day. This is fair less than the average muscle-building gym rat would ever believe is adequate, as they consume meat, eggs, or dairy with every meal and frequent protein supplements just to be sure that they get enough. The RDA is designed to cover a full two standard deviations above the mean (average) person’s need. This means that this value meets the need of 98% of the population. Most people need much less than 0.8 gm/kg per day. The RDA works out to be about 46 grams of protein daily for women and 56 grams for men. Such an amount is easily met eating nothing but plants.
In his book, “Fasting and Eating for Health”, Dr. Joel Fuhrman gives the example of a typical day of plant-based eating. With a caloric intake of 2095 calories, 73.12 grams of protein are consumed in his sample with nothing but plants. It would be the very rare individual for which this would not be enough. It is certainly possible that athletes may need more, but because they are active, they will be eating more food in general thereby getting more calories.
The typical objection to this claim is that plant protein is lower quality, with a less than optimal make up of constituent amino acids. In Dr. Fuhrman’s example, he also gives the breakdown of the amino acid intake, and it is sufficient across the board.
The amino acids in animal products are not optimal for good health. For example, meat is heavy in methionine. This amino acid is readily metabolized to homocysteine, which has been implicated in heart disease, osteoporosis, cancer and dementia. It is also heavy in lysine which interferes with the mTOR metabolic pathway hastening aging. It is well established that caloric restriction can prolong life expectancies for laboratory animals. It has been speculated that it is not the calorie restriction per se causing the effect, but the incidental decrease in lysine that lengthens life.
A number of mechanisms have been established with animal protein interfering with health. As one example, the ingestion of animal products raises IGF-1 (insulin like growth factor one), which is an established cancer promoter.
In summary, plant-based diets can provide plenty of protein, and with an even more healthy composition than meat-based diets.
Lee Kurisko MD is Chief Medical Officer with Medibid and radiologist with Consulting Radiologists Ltd. based in the Twin Cities. He is Medical Director of Diagnostic Imaging at St. Francis Regional Medical Center in Shakopee, Minnesota. He is trained in Family Medicine, Radiology, Neuroradiology and Nutritional and Metabolic Medicine.
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