Vitamin D3 for Cold and Flu Prevention

We will soon be heading back into the cold and flu season in Canada, which usually begins around November and ends in April. While limiting exposure to the viruses  associated with these respiratory tract infections is indeed important, making sure that your immune system is in top shape to quickly and effectively clear any infectious microbes it encounters is the best way to prevent a full-blown illness. If you tend to get sick frequently during the winter months, now is a good time to make sure that your immune system is working at its best. Vitamin D3 is one of your key tools for helping you fight off these microbes.

Vitamin D exists in our body in an inactive form, and it only transforms into its active, vitamin D3 form if our skin is exposed to sunlight. Needless to say, this is difficult to do in the winter, and most Canadians are deficient in vitamin D3 unless they supplement with the active form throughout the fall and winter months. Vitamin D3 has been shown to activate the innate immune response and leads to the production of antimicrobial peptides (called cathelicidin and defensins) which help fight off viruses and secondary bacterial infections. Adequate vitamin D3 levels have been associated with a decreased risk of influenza and other respiratory tract infections. One study even showed that this decreased risk is passed on from pregnant mothers to their children for their first year of life.

One way to check if you have enough vitamin D is through a blood test, serum 25(OH)D. While levels above 50nmol/l are generally considered sufficient, many experts in the field believe that levels of 100nmol/l or higher are more optimal. Studies so far have shown that those who were most deficient prior to vitamin D3 supplementation gained the most anti-viral protective effects. Darker skinned individuals, who tend to produce less active vitamin D3 when exposed to the sun, are especially prone to being deficient during the winter months.

Although vitamin D3 status plays a powerful role in immunity, it is far from the only variable affecting our defenses against colds and flus. Naturopathic doctors have many other preventative treatments available, and can individualize your treatment protocol based on your health status, unique susceptibilities, current medications, diet, and lifestyle.

References:

Am J Clin Nutr May 2010 vol. 91 no. 5:1255-1260.

Epidemiology. 2012 Jan;23(1):64-71.

Int J Infect Dis. 2010 Dec;14(12):e1099-105. Epub 2010 Oct 29.

J Clin Virol. 2011 Mar;50(3):194-200. Epub 2011 Jan 15.