Dr. Jack Rutherford
Move over vitamin C. It’s vitamin D that seems to provide the strongest defense against the common cold, according to a recent study. Researchers at the University of Colorado studied 19,000 people about their health habits and took blood samples to determine the frequency of respiratory problems.
They found that people with the lowest levels of vitamin D reported 40 percent more respiratory conditions, including frequent colds, than those who had normal vitamin D levels. Asthmatics who were vitamin D-deficient were five times more likely to have had a recent respiratory infection. Those with chronic obstructive pulmonary disease who were also low on vitamin D had twice the number of respiratory infections.
Modern folklore has it that vitamin C wards off colds, yet there is little science that backs that up. Meanwhile, the evidence in support of vitamin D as a super infection fighter is growing. In addition to the University of Colorado study, several other investigations have linked low blood vitamin D levels to a higher risk of respiratory infections, including a Finnish study that found that people with low vitamin D levels took twice the number of sick days because of colds and other related problems.
Medical experts suggest that vitamin D protects against infection by regulating a protein that kills microscopic bacteria, fungi and viruses and also prevents the immune system from releasing too many inflammatory “cytokines” and “chemokines” into infected lung tissues.
People can stock up on vitamin D simply by spending more time outdoors, soaking in the sun’s rays. Most people should spend 10 to 15 minutes a day outdoors, at least a few times weekly. Besides that, oily fish, egg yolks and fortified cereals are good sources of vitamin D. And there are always vitamin D supplements.
It is important to keep in mind that are our immune system’s need for vitamin D increases as we age. Therefore, while the recommended adequate intake for vitamin D for people under age 50 years is 5 micrograms a day, for people over 50, the AI is 10 micrograms a day. Individuals who are dark-skinned, housebound or live in tall buildings, air polluted areas, use sunscreens or wear layers of clothing may need more vitamin D.
