February 12, 2018
458 Vitamin D, Colds and Flu [12 Feb 2018]
This has been an unusually bad year for influenza and severe colds, collectively called upper respiratory infections or URIs. Many observational studies have found that low levels of vitamin D are associated with increased risk for URIs. But the few random controlled studies testing to see if supplementing with D could lower the risk had conflicting results.
A meta-analysis published in February 2017 in the British Medical Journal combined the data from 25 randomized controlled trials to look at the effect of vitamin D supplementation on incidence of acute respiratory tract infection. It concluded that vitamin D supplementation was safe and offered some protection against acute respiratory tract infections, but only with frequent dosing (daily or weekly – not monthly or longer).
A study in Toronto published in JAMA in 2017 compared 2000 IU and 400 IU vitamin D (daily as oral drops) in 700 children over one respiratory season. Infections averaged slightly more than 1 per child with no significant difference between the two groups. Incidence of influenza infections was reduced 50% in the high dose group but there were too few (10% of infections) to be conclusive.
Last month a recent study of infants from China reported that high dose vitamin D reduced the risk of URIs and also improved symptoms. A random controlled clinical trial published in January 2018 in Pediatr Infect Dis J studied 400 healthy infants between 3 and 12 months of age. Half were given 400 IU and half 1200 IU vitamin D daily as oral drops. The infants were monitored for symptoms of fever, cough and wheezing for four months.
Over the four months 121 cases of influenza A infection occurred – 78 in the low dose group and 43 in the high dose group. As well as having fewer occurrences, the duration of the symptoms (fever, coughing and wheezing) were all significantly shorter in the high dose group. The authors concluded “High-dose vitamin D (1200 IU) is suitable for the prevention of seasonal influenza as evidenced by rapid relief from symptoms, rapid decrease in viral loads, and disease recovery. In addition, high-dose vitamin D is probably safe for infants.”
The Vitamin D Council recommends vitamin D supplementation of 5,000-10,000 IU per day for adults and 1,000 – 2,000 for infants. Vitamin D supplementation is especially important during the winter season when URIs are most common and of course when we cannot obtain vitamin D from the sun.
For more information on this or other natural health topics, stop in and talk to Stan; for medical advice consult your licensed health practitioner.