Vitamin C and foods like citrus fruits, chicken soup, and tea with honey are popular examples. Yet the design of our immune system is complex and influenced by an ideal balance of many factors, not just diet, and especially not by any one specific food or nutrient. However, a balanced diet consisting of a range of vitamins and minerals, combined with healthy lifestyle factors like adequate sleep and exercise and low stress, most effectively primes the body to fight infection and disease.
What is immune response?
The immune system protects the body from possibly harmful substances by recognizing and responding to antigens. Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Non-living substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens. Your body's cells have proteins that are antigens. These include a group of antigens called HLA antigens. Your immune system learns to see these antigens as normal and usually does not react against them.
Factors that supress our immune system?
- Older age: As we age, our internal organs may become less efficient; immune-related organs like the thymus or bone marrow produce less immune cells needed to fight off infections. Aging is sometimes associated with micronutrient deficiencies, which may worsen a declining immune function.
- Environmental toxins (smoke and other particles contributing to air pollution, excessive alcohol): These substances can impair or suppress the normal activity of immune cells.
- Excess weight: Obesity is associated with low-grade chronic inflammation. Fat tissue produces adipocytokines that can promote inflammatory processes.
- Poor diet: Malnutrition or a diet lacking in one or more nutrients can impair the production and activity of immune cells and antibodies.
- Chronic diseases: Autoimmune and immunodeficiency disorders attack and potentially disable immune cells.
- Chronic mental stress: Stress releases hormones like cortisol that suppresses inflammation (inflammation is initially needed to activate immune cells) and the action of white blood cells.
- Lack of sleep and rest: Sleep is a time of restoration for the body, during which a type of cytokine is released that fights infection; too little sleep lowers the amount of these cytokines and other immune cells.
How to boost up immune system through food?
- Probiotic foods include kefir, yogurt with live active cultures, fermented vegetables, tempeh, kombucha tea, kimchi, and miso.
- Prebiotic foods include garlic, onions, leeks, asparagus, artichokes, dandelion greens, bananas, and seaweed. However, a more general rule is to eat a variety of fruits, vegetables, beans, and whole grains for dietary prebiotics.
- Echinacea: Cell studies have shown that echinacea can destroy influenza viruses, but limited research in humans has been inconclusive in determining echinacea’s active components. Taking echinacea after catching a cold has not been shown to shorten its duration, but taking it while healthy may offer a small chance of protection from catching a cold.
- Garlic: The active ingredient in garlic, allicin sativum, is proposed to have antiviral and antimicrobial effects on the common cold, but high-quality clinical trials comparing garlic supplements to placebo are lacking. A Cochrane review identified only one trial of reasonable quality following 146 participants. Those taking the garlic supplement for 3 months had fewer occurrences of the common cold than those taking a placebo, but after contracting the cold virus, both groups had a similar duration of illness.
- Tea catechins: Cell studies have shown that tea catechins such as those found in green tea can prevent flu and some cold viruses from replicating and can increase immune activity. Human trials are still limited. Two randomized controlled trials found that green tea capsules produced less cold/flu symptoms or incidence of flu than a placebo; however, both studies were funded or had author affiliations with tea industries.