Becoming vegan after a cancer diagnosis is not a good idea. A new study reveals the importance of animal proteins in treating cancer patients.

Becoming vegan after a cancer diagnosis is not a good idea. A study published in Clinical Nutrition highlighted the importance of animal proteins in treating cancer patients. Meat, milk, fish, and egg proteins would play an important role in active cancer treatment, with significantly better results in the patients treated. This effect appears to be due to the positive impact of animal proteins on muscle anabolism, higher than plant proteins, due to the optimal composition of amino acids that promote muscle health.

Ensuring the coverage of nutritional requirements, including protein, which is higher in cancer patients, is crucial to prevent and minimize adverse health effects, such as muscle loss often observed in the presence of cancer. Optimal nutrition during cancer treatment can significantly relieve symptoms, improve health and quality of life, and increase the likelihood of successful treatment and, thus, survival.

Reducing or eliminating meat and animal-source foods is often wrongly recommended to “cure” and heal cancer. Still, this conversion does not bring benefits, and it is also harmful to health. While reducing alcohol consumption has brought obvious results, vegan or vegetarian diets have aroused concern due to the importance of animal proteins for skeletal muscle health, which weakens the ability to support muscle mass following a cancer diagnosis.

The loss of muscle mass is one of the distinguishing features in the case of cancer and malnutrition that brings a lower tolerance to treatment and a decrease in the probability of survival. Given the importance of muscle health in the oncological context, the study analyzes the potential impact of animal protein sources (beef, pork, chicken, fish, eggs, milk, cheese) and plants (vegetables, legumes, cereals and soybeans) on muscle anabolism in cancer, to suggest an optimal ratio intake.

An insufficient intake of high-quality proteins, such as animal proteins, worsens the inflammatory anorexia that occurs in the case of cancer and the adverse effects of therapies, aggravating catabolism and muscle loss. Plant proteins are less efficient due to the oxidation of the amino acids, lower muscle protein synthesis and lower leucine content than animal proteins.

The presence of anti-nutritional factors of plant proteins, such as trypsin inhibitors, tannins and phytates, also adversely affects the digestibility and availability of amino acids. In addition, plant proteins resist proteolysis in the gastrointestinal tract, decreasing its digestibility, particularly worrying those with gastrointestinal cancer. This increases the number of undigested proteins in the colon, which alter microbial metabolism, generating harmful metabolites that can adversely affect muscle health.

In addition, compared to animal-source foods, a higher volume of plant proteins is needed to obtain an adequate intake of amino acids, which is far from positive in the case of cancer, where adequate protein intake from a lower volume of food is essential, that only the higher quality of animal proteins can provide.

Thus increasing the intake of high-quality proteins such as animal proteins (1.2-2 g/kg/day total) has a protective effect, constitutes optimal nutritional care and can be safely included in the diet. Therefore, based on the study’s results, it is recommended that animal proteins should make up at least 65% of the diet of cancer patients, a percentage considered an optimal starting point to support muscle anabolism for people undergoing active cancer treatment. The authors conclude that current dietary guidelines should be updated, considering these findings for future nutritional recommendations.