Fighting Foreign Invaders With Good Nutrition

The immune system’s immense power to combat disease holds great promise for better health as nutritional science learns more about the relationship between the body’s own defenses and the food we eat.

An adequate nutrient intake is important for proper immune function. Major components of the immune system-the skin, intestinal cells, and white blood cells-require continual nutrient support to function. Early humans were plagued by famine, infections, and death. Today, because of better nutrition, many of us avoid that cycle.


The skin forms an almost continuous barrier surrounding the body. Invading microbes have difficulty penetrating the skin. However, if the skin is split by lesions, bacteria can easily penetrate this barrier. Skin health is hampered by deficiencies of such nutrients as essential fatty acids, vitamin A, niacin, and zinc. Vitamin A deficiency also decreases gland secretions in the skin-necessary secretions that contain enzymes capable of killing bacteria. Bacterial eye infections in disadvantaged countries are also often caused by vitamin A deficiency.

Intestinal Cells

The cells of intestines form an important barrier to invading microbes black latte recenze. Not only are the cells closely packed together, but also specialized cells that produce immune bodies are scattered throughout the intestinal tract. These immune bodies bind to the invading microbes, preventing them from entering the bloodstream. When both protein and vitamin A are deficient, the specialized cells produce fewer immune bodies.

For a person in a deficient nutritional state, the intestinal cells break down so that microbes more easily enter the body and cause infections. Two common results of undernutrition are diarrhea and bacterial infections of the bloodstream. To protect the health of the intestinal tract, an adequate nutrient intake is necessary-especially of protein, vitamin A, vitamin B6, vitamin B12, vitamin C, zinc, and other nutrients needed for intestinal cell synthesis and maintenance.

White Blood Cells

Once a microbe enters the bloodstream, white blood cells move in to attack it. A variety of white blood cells participate in this response. These agents are notably less active in elderly years, partly because the thymus gland, which processes immune cells, shrinks after sexual maturity. One class of white blood cells matures in the thymus gland. As a group, together with specialized proteins, these cells make various immune bodies to bind, engulf, and digest microorganisms. In the process, they create a template (memory) that allows future recognition of the microbe. Recognition allows more rapid attacks in the future.

Nutrient intake affects these white blood cells and protein factors. Some white blood cells live only a few days. Their constant resynthesis requires a steady nutrient input. The immune system needs iron to produce an important killing factor that white blood cells use; we need copper for the synthesis of a specific type of white blood cell; and we need adequate amounts of vitamin C, protein, vitamin B6, folate, and vitamin B12 for general cell synthesis and, later, cell activity. Zinc and vitamin A are also needed for the overall growth and development of the immune cells.

Undernourished People

One proof that nutrition is important to immune status is the body’s response to invading microbes; microbes normally present in the body usually cause disease only in severely undernourished people. A good example is measles. Many undernourished children who contract it die. However, most people who experienced measles survived. (You may also have been vaccinated against measles.) Thus the presence of a virus or microbe in the body does not guarantee its triumph over the immune system. But if a person’s health is already compromised through undernutrition, the chances of a destructive microbe winning are greater.

An infection that occurs primarily in undernourished people is called an opportunistic infection. Opportunistic infections also are characteristic of acquired immunodeficiency syndrome (AIDS), a disease where one class of white blood cells becomes severely depleted. A type of pneumonia that rarely occurs in people with normal immune function is often able to take hold in people with AIDS.

Immune function decreases with age. The effects are very similar to the changes that occur with undernutrition. This means that elderly people need to be doubly sure that they meet their nutrient needs so that their immune systems will provide an effective defense against disease.

A Note of Caution

Although many studies show that good nutritional status is associated with good immune status, other studies also show that an overabundance of certain nutrients can actually harm the immune system. Too much polyunsaturated fatty acids and vitamin E have been implicated in a decreased immune response in mice. Taking too much zinc (300 milligrams per day for 6 weeks) also appears to decrease immune function. This decrease may be partially caused by zinc interfering with copper absorption. The copper deficiency contributes to decreased synthesis of a specific class of white blood cells, as I mentioned before.

The message here is that eating a balanced diet will help maintain the health of all components of the immune system. Our bodies need this system to continuously defend us from harmful microbes in the environment. However, consuming more nutrients than needed is not going to boost the immune system to higher abilities. In fact, it can harm certain aspects of immune function. In fact, it can harm certain aspects of immune function

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