Post by Emily White
For as long as I can remember the words ‘slip, slop, slap’ have been gospel. Whenever you step out into the sun it is hard not to think about skin cancer and thereby the importance of covering up. However scientists are now suggesting that we have taken this a bit too far with a lot of people suffering from a Vitamin D deficiency- without even knowing!
Vitamin D is synthesised in the skin following exposure to sunlight. It can also be obtained in small amounts from the diet. Vitamin D is crucial for many, many functions within the body. It has an important role in bone health, immunity and mood. Interestingly studies have shown that people with depression often have low levels of Vitamin D (1). We can produce ample amounts of vitamin D from the sun even from only short bouts of exposure (around 15 minutes). However with the increasing awareness of the negative effects of the sun many people are covering up too much and simply failing to get this level of exposure, which is obviously worsened in the winter months! The aim of the game is to get sufficient amount of sun exposure but without burning. This will obviously vary from person to person depending on your skin tone but usually around 15-20 minutes will suffice.
In winter it can be especially hard to get sufficient vitamin D from the sun and therefore supplemental Vitamin D can be a good option. However to put it bluntly there is a lot of crap on the market and it can be confusing when deciding what to go with. When you look at a supplemental vitamin D product you will usually either see in the ingredients list Vitamin D2 or Vitamin D3, so which is best?
Vitamin D2 is a vegetable derived form of Vitamin D, whereas D3 is animal derived. A meta-analysis looked at mortality rates for people who supplemented their diets with D2 as apposed to D3. The individuals who used the D3 form found a relative risk reduction of 6% whereas the ones who used the D2 form had a 2% relative risk increase (2). Some studies have also suggested that Vitamin D3 supplementation has also been shown to maintain serum vitamin D levels in the long run, which can be important in the winter months when sunlight exposure is greatly depleted (3, 4, 5). Due to this evidence it is probably best to stick with vitamin D3 as a supplement. Cod liver oil can often be a great source of vitamin D3 however if you are after an exact recommendation it is always good to consult with a qualified nutritionist or naturopath!
Obviously the best way to get Vitamin D is from sun exposure so even sitting out in the sun for 15 minutes during your lunch break can work wonders for your health and everyday performance but if you think that you may not be getting enough, it is definitely important to consider taking a supplement.
1. Wilkins CH, Sheline YI, Roe CM, Birge SJ, Morris JC. Vitamin D Deficiency Is Associated With Low Mood and Worse Cognitive Performance in Older Adults. The American Journal of Geriatric Psychiatry. 2006;14(12):1032-40.
2. Bjelakovic G, Gluud LL, Nikolova D, Whitfield K, Wetterslev J, Simonetti RG, et al. Vitamin D supplementation for prevention of mortality in adults. Cochrane Database Syst Rev. 2011(7):CD007470.
3. Holick MF. Vitamin D Deficiency. New England Journal of Medicine. 2007;357(3):266-81.
4. Heaney RP, Recker RR, Grote J, Horst RL, Armas LA. Vitamin D(3) is more potent than vitamin D(2) in humans. J Clin Endocrinol Metab. 2011;96(3):E447-52.
5. Logan VF, Gray AR, Peddie MC, Harper MJ, Houghton LA. Long-term vitamin D3 supplementation is more effective than vitamin D2 in maintaining serum 25-hydroxyvitamin D status over the winter months. Br J Nutr. 2013;109(6):1082-8.