1) Amino acids, as the name implies are acids; the sulfur-containing amino acids are the strongest acids of all, they breakdown into powerful sulfuric acid. Excess acid, as discussed above, is a primary cause of bone loss leading to osteoporosis and kidney stone formation.29
2) Methionine is metabolized into homocysteine animal foods are the major source of the amino acid, homocysteine, in people the more meat in the diet, the higher a persons blood level of homocysteine. A diet high in fruits and vegetables lowers the levels of this amino acid. Epidemiological and clinical studies have proven homocysteine to be an independent risk factor for heart attacks, strokes, closure of the arteries to the legs (peripheral vascular disease), blood clots in the legs (venous thrombosis), thinking problems (cognitive impairment), and even worse mental troubles, like dementia, Alzheimer's disease, and depression.30
3) Sulfur feeds cancerous tumors. Cancer cell metabolism is dependent upon methionine being in the diet; whereas, normal cells can grow on a methionine-free diet (feeding off of other sulfur-containing amino acids). This methionine-dependency has been demonstrated for breast, lung, colon, kidney, melanoma, and brain cancers.31,32 Increasing methionine in the diet of animals promotes the growth of cancer.33
There is also evidence of cancer promoting effects of methionine mediated through a powerful growth stimulating hormone, called insulin-like growth factor - 1 (IGF-1).34 Meat and dairy products raise IGF-1 levels and promote the growth of cancers of the breast, colon, prostate, and lung.35
4) Sulfur from sulfur-containing amino acids is known to be toxic to the tissues of the intestine, and to have deleterious effects on the human colon, even at low levels.36 The consequence of a diet of high-methionine (animal) foods may be a life-threatening inflammatory bowel disease, called ulcerative colitis.37-38
5) Sulfur restriction prolongs life.39 Almost seventy years ago, restricting food consumption was found to prolong the life of animals by changing the fundamental rate at which aging occurs.40 Restriction of methionine in the diet has also been shown to prolong the life of experimental animals. By no coincidence, a diet based on plant foods is inherently low in both calories and methionine thus the easiest and most effective means to a long and healthy life.
6) Possibly a stronger motivation to keep protein, and especially methionine-rich animal protein, out of your diet is foul smelling odors halitosis, body odor, and noxious flatus akin to the smell of rotten eggs are direct results of the sulfur (animal protein) you eat.41,42
