The functions of the intestines, and the three key nutrients to include in your gut-friendly breakfast

In the ideal intestines, the good bacteria are dominant.

Research has shown that there are 100 trillion bacteria living inside the intestines, weighing about 1.5 kg. These bacteria can be classified into good bacteria that have positive effects on the intestines, bad bacteria that are harmful to the intestines, and opportunistic bacteria that are neither good nor bad. The ratio of these three types is typically 2:1:7. However, if the opportunistic bacteria, which have the largest population of the three, team up with the bad bacteria, the intestinal environment will deteriorate quickly.

To prevent this, it’s important to maintain the good bacteria’s dominance at all times. As long as the good ones are dominant, the intestinal activity is smooth, and there’s no need to worry about constipation.

If the intestinal environment deteriorates, the entire physical condition is negatively affected.

If the balance of the intestinal microbiota is lost, the bad bacteria start producing harmful substances. And if the intestines are damaged by such substances, the risk of colorectal cancer and other intestinal disease increases.

Also, as those harmful substances are absorbed through the intestinal wall, enter the bloodstream, and travel throughout the body, you might suffer rough skin, lethargy, and compromised immunity, which will make you more susceptible to colds and various other negative symptoms. In addition, as the blood becomes thicker due to those harmful substances, it becomes more difficult for the nutrients in the bloodstream to be absorbed by the cells. When this occurs, those nutrients turn into fat and build up, and will eventually develop into obesity.

Fermented foods

The lactic acid bacteria contained in yogurt and other fermented foods perform the crucial function of increasing the population of good bacteria in the intestines, and improving and maintaining the intestinal environment. As lactic acid bacteria are unable to settle down inside the intestines for extended periods, it is essential to continuously consume fermented foods.

Fermented foods: yogurt, cheese, kimchi, miso, amazake (traditional Japanese sweet drink made from fermented rice), etc.

Dietary fiber

There are two types of dietary fiber. One is insoluble dietary fiber, which is known to absorb a lot of water and swell up, increase fecal mass, and promote peristalsis. The other is water-soluble dietary fiber, which becomes gelatinous when it absorbs water, increases the fecal water content, and aids excretion. Water-soluble dietary fiber is also a source of food for the good bacteria living in the intestines, and helps improve intestinal health.

Compared to the post-war era, the daily intake of dietary fiber in Japan has been declining. Meanwhile, there is an opposite trend in the U.S. where their dietary fiber intake has been rising, with fewer cancer patients being reported, possibly reflecting this positive trend.

Foods containing water-soluble dietary fiber: Kiwi fruit, apple, okra, spinach, etc.
Foods containing insoluble dietary fiber: Sweet potato, mushrooms, wakame (a species of edible seaweed), glutinous rice, etc.

Oligosaccharides

Oligosaccharides are a type of carbohydrate, which can reach the large intestines and become a source of food for the lactic acid bacteria living there, and also help increase the number of good bacteria in the intestines. However, as they are basically a type of sugar, you must be careful not to eat too much.

Foods containing oligosaccharides: Kinako (roasted soybean flour), common bean, burdock, adzuki bean, onion, honey, banana, garlic, etc.

Supervision: Dr. Hiroyuki Kobayashi, Professor, Department of Hospital Administration, Department of General Medicine, Juntendo University Hospital