The study highlights foods that strengthen your body’s defenses

In a recent review in the journal Food Science & Nutrition, a team of researchers summarized the current medical knowledge regarding the role of certain common foods in strengthening the immune system. The comprehensive article covered the benefits of consuming fruits, vegetables, spices, animal products and other foods to maintain a healthy immune system.

Study: Common foods to boost human immunity: A review. Image Credit: Danijela Maksimovic / Shutterstock

Background

The human immune system protects the body from pathogenic invasions. Humans are born with innate immunity (with cells such as macrophages and neutrophils). Some immunity (such as some types of white blood cells or lymphocyte cells) is acquired by exposure to pathogens. However, scientists have known for a long time that a healthy diet is key to maintaining and improving immunity. A dysfunctional immune system can lead to problems such as bronchial asthma, cystic fibrosis, and fibromyalgia.

Immune cells need a lot of energy to function, and micronutrients and micronutrients maintain an immune response. Although the immunological function of specific nutrients such as vitamins, minerals, and fibers has been reviewed in previous research, the immune benefits of specific food items have not been explored. In this review, the research team attempted to address this gap, documenting commonly available foods that can boost immunity and increase resistance to disease.

Immune System and Nutrition

In humans, the immune response comes mainly from active immunity, in which antibodies are produced within the body. In addition to immune cells, other components include physical barriers such as the skin, physiological barriers such as saliva and stomach acid, and complement proteins.

Antibodies or immunoglobulins, produced due to exposure to pathogens, are classified as immunoglobulins A (IgA), D (IgD), E (IgE), G (IgG), and M (IgM). T and B lymphocytes, such as suppressor T cells, killer T cells, and helper T cells, are critical for recognizing, attacking, and eliminating pathogens. Infections of organs such as the spleen filter and abnormal cells in the blood, and glands can trap germs and other foreign materials.

Healthy lifestyle choices such as eating a nutritious diet, following a regular sleep schedule, minimizing stress, and avoiding unhealthy habits such as smoking can strengthen immunity and reduce the likelihood of suffering from certain conditions.

Along with plant and animal foods, water plays a vital role in boosting immunity. When you stay hydrated the mucous membranes are kept moist, cells are oxygenated and various systems work. Toxins are transported to the kidneys and then to the urinary tract before they are expelled from the body, but they may build up in the body and cause illness due to dehydration. Drinking sufficient quantities of water can also prevent urinary tract infections by stopping the formation of kidney stones.

Inadequate nutrient consumption can weaken the development of the immune system and make the body more vulnerable to allergies, infections and chronic inflammation. This highlights the importance of adequate nutrition for the optimal functioning of the immune system.

The researchers conducted a literature search of major scientific databases such as PubMed, Web of Science, and Scopus to identify studies that focused on the immunomodulatory properties of common foods. These included peer-reviewed literature such as research papers, meta-analyses, and systematic reviews.

Immunity-boosting foods and nutrients

Citrus fruits such as oranges and lemons are rich in vitamin C, which promotes the formation of lymphocytes, strengthens the body’s epithelial barriers, and acts as an antioxidant by reacting with free radicals, which can damage the immune system. Other beneficial compounds found in citrus fruits include selenium, dietary fiber, folic acid, and flavonoids, which are antioxidant and anti-inflammatory agents.

Papayas contain folic acid, retinol, riboflavin, thiamine, niacin, potassium, iron, fiber and calcium. Carotenoids such as beta-carotene can be converted to vitamin A and strengthen the immune response, while retinoic acid promotes the growth of lymphocytes at sites of infection and inflammation in the stomach.

Similarly, kiwis also contain vitamin C, K, potassium, carotenoids, fibers and antioxidants; they are anti-inflammatory foods that can reduce the risk of developing the flu. Pomegranate has antiviral properties and can suppress germs like Listeria, Clostridium, and Salmonella, and promote healthy bacteria like Lactobacillus and Bifidobacterium.

Indian gooseberries have a powerful antioxidant called ellagic acid, while almonds are rich in vitamin E. Broccoli is rich in fiber and several antioxidants, as well as vitamins A, C, and E, phytochemicals such as polyphenols, minerals, and vitamins. Ginger, in addition to being a promising immunomodulator, improves digestion and improves appetite, which may be beneficial to the immune system. Garlic, turmeric, onion, mushrooms and tea are also beneficial foods to include in regular diets for a healthier immune system.

Role of animal sourced foods (AFF)

An important characteristic of ASF is that they contain high quality digestible proteins, essential amino acids, and micronutrients. Prolactin, a hormone found in milk, promotes lymphocyte and thymocyte movement; milk also contains immunoglobulins and whey proteins, which stimulate the synthesis of antibodies.

The composition of yogurt is similar to milk, but calcium can be absorbed more efficiently from yogurt than milk. In addition to proteins, vitamins, and minerals, eggs contain choline, which breaks down an amino acid called homocysteine, which is linked to cardiovascular disease. Eggs are an affordable source of protein for those who do not have access to pulses and dairy.

While medicine is key to healing from health conditions, maintaining a nutritious diet provides the first line of defense against infection and illness. Incorporating whole foods and beneficial fruits, vegetables, dairy and eggs can reduce the risk of developing various conditions and reduce their severity if they do occur.