Many people like to eat fruits and fruits are rich in nutrients such as vitamins, minerals and cellulose. Eating fruits in moderation is beneficial to the body, but some people have diarrhea after eating too many fruits, especially in infants and children. Why is this?

In traditional Chinese medicine, many fruits are classified as cold food: "watermelon, cold in nature", "apple, cool in nature", "banana, cold in nature", "pear, cool in nature", "orange, cool in nature" …Many people also think fruit is cold because they get diarrhea after eating it. Are cold fruits the cause of diarrhea?

People with weak constitution or weak spleen and stomach will indeed have diarrhea if they eat too much cold food. Eating too many cold fruits and frozen fruits in the refrigerator, it is not unfounded for people with poor stomach to eat these cold foods and have diarrhea.

Diarrhea after eating fruit, the problem may also appear in "fructose intolerance"!

Many foreigners also have diarrhea after eating fruit, although they have never heard that fruit is a cold food. This is different from "eating cold drinks will cause diarrhea". It cannot be attributed to the result of psychological effects influenced by culture. So what is the substance that makes some people have diarrhea when they eat fruits? All fruits are rich in fructose, could it be caused by this particular ingredient? It is unbelievable to say that this was first confirmed experimentally by Swedish medical scientists as late as 1978.

Fructose is a kind of simple sugar. The simple sugar in food can be directly absorbed into the blood by the small intestine without being digested. The actual situation is not so simple. The fructose that reaches the small intestine does not run into the blood by itself like water, but needs a transport tool (carrier) to transport it in. The carrier specifically used to carry fructose is a protein called GLU5 on the epithelial cells of the small intestine. The number of carriers is limited. If too much fructose is eaten and GLU5 is too busy, what will happen?

The unabsorbed fructose remains in the intestinal tract, making the osmotic pressure of the intestinal juice higher than that of the plasma, and the water in the plasma is lost into the intestinal tract, and the intestinal tract has more water than usual. When the fructose reaches the colon, it becomes food for the bacteria living there and produces short-chain fatty acids and a large amount of gas after fermentation, which stimulates intestinal peristalsis. The excess water in the intestinal tract cannot be fully absorbed, leading to diarrhea.

Under normal circumstances, many people will not experience diarrhea if they eat too much fruit. However, some people lack fructose carriers in their bodies, or the efficiency of fructose carriers to transport fructose is relatively poor. They can absorb less fructose at one time than normal people. If they eat too much fruit, they are prone to abdominal pain and diarrhea. This condition is called fructose malabsorption, also known as dietary fructose intolerance. About half of the population has varying degrees of dietary fructose intolerance.

In addition, there is a kind of hereditary fructose intolerance, which is very rare. It is due to the lack of enzymes in the liver that break down fructose, and the fructose absorbed into the body cannot be broken down, which will lead to hypoglycemia and liver disease.

It is not that patients with dietary fructose intolerance cannot eat any fruit. Some fruits will cause diarrhea after eating, and some will not. What is going on?

It turns out that there is another carrier called GLU2 in the small intestine, which can transport both glucose and fructose. Its transport efficiency of fructose is very low, but glucose can greatly improve its transport efficiency. So glucose can help the absorption of fructose. Whether a fruit can cause fructose intolerance is not only related to the content of fructose, but also related to the ratio of fructose and glucose.

1. Fruits with higher glucose content than fructose, such as bananas, oranges, grapefruits, pineapples, kiwis, and strawberries, are not likely to cause fructose intolerance.

2. Fruits with higher fructose content than glucose, such as apples, pears, watermelons, cantaloupe, dates, carambola, mangoes, cherries, lychees, papayas, and grapes, can easily lead to fructose intolerance.

Contrary to glucose, sugar alcohols can reduce the activity of fructose carriers, which is not conducive to the absorption of fructose. So those fruits that contain sugar alcohols, such as peaches, plums, and apricots, may cause fructose intolerance even though the glucose content is higher than fructose.

It can be seen that the reason why fruits are considered "cold" and cause diarrhea should be fructose intolerance. There is truth behind some of the traditional sayings. But not all. Some of the traditional sayings passed down by word of mouth are summaries of experience, while others are rumors. For example, bananas are considered "cold in nature", can "moisten the intestines" and "lax the bowels", and patients with diarrhea should not eat them. There is no scientific basis for this. The glucose content of bananas is much higher than that of fructose, and it does not contain sugar alcohols, so it will not cause fructose intolerance.

However, people with fructose intolerance should strictly control their fructose intake in daily life, control or not eat foods containing fructose, sucrose and sorbitol.