Parkinson’s patients often suffer from constipation, which is first and foremost a problem brought about by the disease itself, i.e. slowing down of gastrointestinal peristalsis along with slowing down of limb movement. Of course, long-term medication can also bring certain side effects and aggravate the symptoms of constipation. For example, Methyldopa, which is a compound preparation of levodopa and benserazide, is the most commonly used and effective drug in the treatment of Parkinson’s. It has to rely on transporter proteins, i.e., “carriers”, in the intestinal tract before it can enter the blood circulation and reach the brain to exert its medicinal power. Meat and milk contain large amounts of protein, and their breakdown products, amino acids, quickly take up all the transport “carriers”. The drug has to wait until the “carriers” are free before it can cross the intestinal wall and enter the bloodstream. Therefore, it is best to take methyldopa or benzoin (benzoin is the same as methyldopa) 60 minutes before ingesting meat or milk, so that they are absorbed into the bloodstream preferentially and are not affected by the food. It also avoids drugs and food affecting each other and aggravating constipation. Meat, poultry, fish, milk and eggs are all high-protein foods, which have to be converted into amino acids and absorbed into the blood, of which milk especially interferes with the absorption of methyldopa. Cow’s milk can be replaced by soy milk, and try to choose soy milk with added vitamin D and calcium. Plant proteins (soy products, nuts) can also meet part of the body’s need for protein, which contains a much higher proportion of carbohydrates than proteins, which facilitates absorption, so patients are encouraged to consume more soy products to supplement the protein deficit.