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Best Vitamins for Boosting Immune System

Your immune system suffers when you’re surrounded by sniffles and coughs or feeling frazzled by all of life’s demands. Exercising and eating well are great immune system enhancers, but take time and discipline to implement. With countless meetings, errands and infected door handles, how do you boost your immune system quickly and effectively?

Whether you’re scrambling to get out the door or skipping your workout for an early morning meeting, immune boosting supplements offer a quick and easy boost. Several vitamins play key roles in boosting immune system function. Make sure your supplements for boosting immune system function contain the following vitamins.

Vitamin A

According to research by Harvard Medical School, vitamin A has an “unexpected and crucial effect on the immune system.” Specifically, vitamin A metabolizes into retinoic acid as well as other chemicals that are natural immune system boosters. Retinoic acid performs several roles in the immune system.

First, retinoic acid enhances the immune system’s cytotoxicity, which is its ability to kill antigens. Antigens are anything—from viruses to cancer cells—that can potentially make you sick.

Retinoic acid makes your immune system better able to kill these antigens by increasing the activity of dendritic cells and enhancing the production of T cells. Dendritic cells capture antigens and produce chemicals called cytokines to stimulate your immune system. T cells respond to this chemical activation by performing a number of functions. One of these functions is to destroy antigens.

While retinoic acid makes T cells and dendritic better at what they do, another vitamin A metabolite, retro-retinoids, actually increases the number of B cells your body produces. B cells differ from T cells in that they produce antibodies to fight infection rather than directly attacking antigens.

By metabolizing into retinoic acid and retro-retinoids, vitamin A has a powerful effect on the immune system. Vitamin A influences T cells, B cells and even little-known, but powerful, dendritic cells, making vitamin A one of the essential vitamins for boosting immune system function.

Vitamin D

Like vitamin A, vitamin D metabolizes into several compounds to boost immune system function. In the form of these metabolites, vitamin D plays a crucial role in the formation of suppressor T cells.

Suppressor T cells prevent the immune system from overreacting. When you get sick, your immune system goes into action. Dendritic cells secrete chemicals that act as a call to arms. Cytotoxic T cells respond by directly attacking antigens in a way that amounts to hand-to-hand combat. Like a soldier overtaken by adrenaline, these cytotoxic T cells may not know when to stop attacking. Yet if they continue their assault, you could develop a disorder in which your immune system begins attacking your own body’s cells.1 Using chemicals called lymphokines, suppressor T cells halt cytotoxic T cells before they destroy your own body’s cells and cause an autoimmune disease.

Multiple sclerosis (MS) is one such autoimmune disease. Many researchers, including those at the University of Wisconsin, hypothesize that vitamin D deficiency plays a crucial role in the development of MS. They say that this hypothesis would explain why MS occurs in locations away from the equator, but is nearly nonexistent in equatorial areas, where sun exposure stimulates vitamin D production. Recent studies suggest that vitamin D’s role in activating suppressor T cells may explain this phenomenon.2

With its role in activating suppressor T cells that regulate your immune system, Vitamin D is a natural immune booster that aids in the prevention of autoimmune disorders.

Vitamin C

Researchers in Switzerland report that vitamin C is one of the vitamins that play “important roles in immune function” and reduce the “risks, severity, and duration of infectious diseases.”3

Vitamin C is a natural immune booster several ways. First, it improves natural killer (NK) cell activity, which is essential in a natural remedy for cold sore outbreaks. NK cells help defend your body against viruses and are essential for preventing cold sore outbreaks. NK cells release special proteins that restrict viral infections while your body is producing the cytotoxic T cells it needs to heal itself.6

Vitamin C also contributes to the increased production of lymphocytes. Lymphocytes are white blood cells produced in the bone marrow that go on to become either T cells or B cells.

Vitamin C also improves the chemotaxis quality of immune system cells. Chemotaxis refers to the cells’ ability to move in response to chemical stimulus. Essentially, the success of your immune system depends on the abilities of its cells, such as B cells and T cells, to move toward infections.

Your body uses vitamin C to fight infections in a surprising number of ways and may be a natural remedy for cold sore outbreaks. From improving NK cell activity to increasing white blood cells to helping cells find their way through your bloodstream, Vitamin C is a natural immune booster.

Vitamin E

Researchers in Japan say that vitamin E is a “potent antioxidant” and is an “important nutrient” for immune system support. Much of vitamin E’s significance lies in its impact on T cells as they mature in the thymus.4

White blood cells are produced in the bone marrow. A subset of these white blood cells travels to the thymus where they are “educated” to become T cells. Within the thymus, each T cell learns a specific job. Helper T cells support other cells of the immune system. Cytoxic T cells destroy infected cells during an immune response. Memory T cells are responsible for long-term immunity such as against chicken pox. Suppressor T cells keep the immune system in check, preventing allergies and autoimmune disorders. As we age past puberty, our thymus significantly reduces its output of T cells.5

The researchers in Japan found that vitamin E supplementation “markedly improved” this “decreased cellular immunity with aging” and is a natural immune booster. They found that supplementing with vitamin E actually improved the process by which T cells matured to their specialized roles.4

While good nutrition and exercise are important immunity boosters, taking vitamins for boosting immune system function is part of a comprehensive healthy lifestyle, especially when they include vitamins that are natural cures for cold sores. Studies have shown that the above vitamins are especially important for immune system health and are in the best immune supplements.


1 Mora JR, Iwata M, von Andrian UH. Vitamin effect on the immune system: vitamins A and D take centre stage. Retrieved January 19, 2012 from


2 Hayes CE, Cantorna MT, Deluca HF. Vitamin D and Multiple Sclerosis. Retrieved January 19, 2012 from


3 Wintergerst ES, Maggini S, Hornig DH. Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Retrieved January 19, 2012 from


4 Moriguchi S, Muranga M. Vitamin E and immunity. Retrieved January 20, 2012 from


5 Clermont College Biology Course. Immune System. Retrieved January 20, 2012 from


6 Science Daily. Science Reference. Natural killer cell. Retrieved January 25, 2012 from



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