For decades, parents gave children cod liver oil during the winter months. They had no scientific studies to support their belief that there was something in that nasty oil that was good for you. But new research published in BMJ Open shows that an ingredient in cod liver oil, vitamin D3, helps prevent cold and flu symptoms.
Swedish researchers recruited 140 patients who had immune deficiencies. All of the subjects experienced at least 42 days of respiratory tract infections during the previous year. They were given either 4,000 IUs of vitamin D3 daily or a look-alike placebo. They kept diaries of their symptoms and use of antibiotics was carefully charted. The study lasted for a full year.
The patients who were taking vitamin D3 daily were significantly lower on a respiratory tract infection score than those taking placebo. They were also much less likely to require antibiotics. The placebo group averaged 33 days on antibiotics compared to 16 days for the vitamin D3 group. They also had fewer ear infections, sinus infections and overall sick days. People on vitamin D were much less likely to develop Strep throat as well.
Similar results were found in Japan as well when researchers conducted a study comparing vitamin D3 supplements with placebo in schoolchildren. They found that children getting vitamin D3 were about half as likely to come down with the flu compared to the kids taking placebos. Children susceptible to asthma were less likely to experience an attack if they were in the group getting vitamin D3 supplementation.
Vitamin D deficiency is common during the winter months, when we’re not getting outside as much. It acts as an immune system modulator, preventing excessive inflammation and increasing white blood cell activity in the lining of the respiratory tract, which protects the lungs from infection.