With the cold and flu season upon us, good nutrition is vital to boosting
your immune system. Immunity involves a complex network of specialized cells and
organs that evolved to defend the body against attacks by foreign invaders such
as bacteria, viruses, fungi and other parasites. The two basic kinds or types of
immunity are termed innate and acquired. Innate immunity, also known as genetic
or species immunity, represents a wide range of immune protective factors that a
person is born with. In contrast, acquired immunity becomes part of the host
defenses by means other than heredity. Within this category,
immune protection can be acquired naturally or artificially. Natural
acquired immunity is developed through recovery from a specific infectious
disease, while artificial acquired immunity occurs when the host receives a
vaccine or antitoxin. This category can be further subdivided by using the terms
active (the host actively produces antibodies in response to a solution of
antigens such as those in a vaccine) and passive (the host passively accepts
preformed antibodies present in products such as an antitoxin). When our immune
system malfunctions, the consequences can range from microbial infections to
Many nutritional supplement ingredients are readily available and can help
improve immune system health. Some of the more popular and scientifically
substantiated ingredients include:
- Echinacea has been shown to stimulate the immune system by increasing the
activity of certain immune cells and by promoting the release of cytokines
(cellular communication and regulatory molecules) from these immune cells.#
- Elderberry contains flavonoid derivatives called
anthocyanidins that appear to have immunomodulatory effects. These compounds in
elderberry extract have been found to bind to viruses and block their ability to
invade host cells.# In this way, elderberry is thought to reduce the severity of
viral flu symptoms.
- Scientific studies on
ingredients such as zinc, Korean ginseng, Vitamin C, beta-glucans and
arabinogalactans all enhance and improve the effectiveness of the immune system
by increasing the protective activity of certain immune cells. Macrophages,
neutrophils, NK (natural killer) cells and T-cells (T-lymphocytes) are
responsible for attacking and neutralizing foreign, disease-causing microbes.
Without the proper functioning of these immune cells, infectious diseases such
as colds and the flu usually occur more frequently, are more severe, and have a
- Another promising avenue for natural immune support is
vitamin D3. Studies now indicate that vitamin D, once only recognized for
supporting bone health, may be a key nutritional component in enhancing immune
The following overviews of some recent studies tout the immune system
benefits of vitamin D:
- A recent study showed that vitamin D signals the immune system to fight
infections. Scientists discovered that T cells—white blood cells that are
like soldiers who search out and destroy the targeted invaders—require
vitamin D to function. The study author explains, “When a T cell is exposed
to a foreign pathogen, it extends a signaling device or ‘antenna’ known as a
vitamin D receptor, with which it searches for vitamin D. This means the T
cell must have vitamin D or activation of the cell will cease. If the T
cells cannot find enough vitamin D in the blood, they won’t even begin to
mobilize.” From this study, researchers realize how crucial vitamin D is for
activating the immune system. The finding could have significant
implications in the fight against global epidemics. Nearly half of the
world’s population has sub-optimal levels of vitamin D, a problem that’s
getting worse as people spend more time indoors.
- Researchers theorized that the flu season occurs in winter months
because of the lack of direct sunlight, and subsequent lower levels of
protective vitamin D produced in the body. Their research indicates that
influenza epidemics, and possibly even the common cold, are brought on by
seasonal deficiencies in antimicrobial peptides, resulting from winter-time
deficiencies in vitamin D.
- In a study of Japanese schoolchildren, vitamin D supplements taken during the
winter and early spring helped prevent seasonal flu. The study found that
children receiving 1,200 IU of vitamin D daily were 58 percent less likely to
catch influenza A.
- People with higher blood levels of vitamin D had a 50 percent reduction
in the risk of developing acute respiratory tract infections than those with
lower blood levels. Additionally, of those with high vitamin D blood levels
who did develop infections, there was a marked reduction in the number of
days they were ill. Researchers concluded, “Maintenance of a [sufficient]
25-hydroxyvitamin D serum concentration should significantly reduce the
incidence of acute viral respiratory tract infections and the burden of
illness caused thereby, at least during the fall and winter in temperate
1. Echinacea. Pharmacist’s Letter/Prescriber’s Letter Natural Medicines Comprehensive Database. 8th ed. Stockton, CA: Therapeutic Research Faculty; 2010. p. 605.
2. Elderberry. Pharmacist’s Letter/Prescriber’s Letter Natural Medicines Comprehensive Database. 8th ed. Stockton, CA: Therapeutic Research Faculty; 2010. p. 615.
3. Von Essen MR, et al. Vitamin D controls T cell antigen receptor signaling and activation of human T cells. Nature Immunology. 2010; 11(4):344-349.
4. Cannell JJ, Vieth R, Umhau JC, et al. Epidemic influenza and vitamin D. Epidemiology and Infection. 2006; 134:1129-1140.
5. Urashima M, et al. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. American Journal of Clinical Nutrition. 2010; 91(5):1255-60.
6.Sabetta JR, DePetrillo P, Cipriani RJ. Serum 25-Hydroxyvitamin D and the Incidence of Acute Viral Respiratory Tract Infections in Healthy Adults. PLoS One. 2010; 5(6):e11088.