Last Wednesday I posted a piece about poor vitamin D levels being linked to asthma severity. New evidence has just emerged (1) which has found that vitamin D3 supplementation during the winter may reduce the incidence of flu (influenza A) in children, especially those suffering with asthma.
This was the first rigorously designed clinical trial to evaluate the relationship between vitamin D and diagnosed seasonal influenza (flu). The trial was conducted in schoolchildren, aged between 6 and 15, and lasted from December 2008 until March 2009. Children were given either 1200iu per day of vitamin D3 or an inactive placebo supplement. Diagnosis of flu was carried out by a doctor and it was found that children receiving the vitamin D were less likely to contract flu when compared to children taking the placebo. Specifically, the vitamin D group was 58 percent less likely to catch influenza A(1).
Interestingly children with a previous diagnosis of asthma who were taking the vitamin D had fewer asthma attacks than those taking the placebo (1). The authors of the study hope to confirm these findings in a trial targeting children with asthma. It has previously been found that individuals with asthma who have low levels of vitamin D in their blood are at about five times the risk for colds and flu. A large-scale trial into the usefulness of vitamin D for improved lung function will be really interesting and important since many individuals suffer from asthma.
It is always best to check with a doctor before starting a new supplement regimen but this data adds to the volumes of research now available for the benefits of vitamin D to health. As previously mentioned there is no current agreement over how much daily vitamin D needs to be taken in order to achieve optimal blood levels. I would suggest most adult (age 18 and over) individuals in the UK would require a supplement of around 2000iu vitamin D daily. Higher doses (up to 5000iu daily) may well be useful but I would not recommend such a regimen unless under the supervision of a medical doctor who can monitor blood levels regularly. For children under the age of 18 lower doses would be necessary, perhaps in the region of about 1000iu per day as used in the study described above – however, before giving children a supplement it is always best to speak to a medical doctor. When looking for vitamin D supplements two forms are generally available. Cholecalciferol, known as vitamin D3, and ergocalciferol or vitamin D2. Cholecalciferol, D3, is generally taken to be the more potent, easily absorbed and preferred form of vitamin D.
(1)Urashima M et al. 2010. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010 Mar 10. [Epub ahead of print]
Written by Ani Kowal
Related posts:
- Can Omega 3 fatty acids in late pregnancy reduce the risk of asthma development in children?
- Could boosting vitamin D levels help asthma sufferers?
- Can dietary change help asthmatics to breathe easier? Part II
- The Vatican seems to be stocking up on black elderberry extract in a bid to prevent flu
- Probiotics for the prevention of eczema in children
