One of the most compelling studies in the past decade has investigated the relationship between a Methionine restricted diet and cancer. Researchers from Harvard Medical School and the University of California, Davis, determined that reducing methionine in the body could increase the effectiveness of DNA-damaging therapies by preventing the growth of cancer cells. The study also found that methionine-restricted diets significantly reduced the size of tumors in a laboratory dish model.
The role of methionine in metabolism is unclear. Fortunately, methionine is a key amino acid required for protein, RNA, and cellular proliferation. It also acts as an anabolic stimulant. Studies of cancer patients have shown that a methionine-restricted diet mimics the effects of caloric restriction. This may be why so many people with cancer are able to benefit from this strategy.
Methionine can be consumed orally but the human body can’t make it in large quantities. This is why doctors prescribe a low-methionine therapeutic diet for individuals with certain genetic defects in the methionine cycle. A person with CBS deficiency lacks the enzyme cystathionine beta synthase (CBS), which is essential commit homocysteine to the transulfuration pathway. A person with CBS has an abnormal methionine pool and must follow a strict low-protein diet for at least a year.
Methionine is a common nutrient in animal diets. Methionine is a vital component of animal proteins, so methionine restriction in the diet may protect the health of livestock. Methionine is also found in animal feed, where the methionine is used for animal food. However, the dietary intake of methionine in the US is only 10% of the recommended daily intake. The highest average daily amount of methionine is found in men aged between 19 and 30 years of age.