Vitamin D behaves more like a hormone than a vitamin, targeting the kidneys, intestines, brain, pancreas, skin, bones, reproductive organs and some cancer cells. Hormones are chemicals in your body that tell cells what to do.
What happens if you don’t have enough Vitamin D?
Ongoing research is investigating the link between a deficiency in vitamin D and a number of health conditions –
cardiovascular health (hypertension, type 2 diabetes, obesity), mental health (autism, cognition, and depression), immune health (asthma, multiple sclerosis, rheumatoid arthritis) and pregnancy disorders (preeclampsia).
There are also investigations into Vitamin D’s role in cancer prevention as it affects cell differentiation and proliferation.
We already know Vitamin D is needed to absorb calcium from your food so that it can be deposited into your bones, preventing a disease called Rickets
Where do we get our Vitamin D?
The best source of vitamin D comes from the sun’s action (UVB rays) on your skin which converts an inactive compound in your body (dehydrocholesterol) to active D3 (cholecalciferol).
15 minutes of good daily sunshine on white bare skin should give you plenty of Vitamin D (sunscreens with a factor of 8 or more stop this process).
Dark-skinned people need 3 hours of exposure to obtain an equivalent amount of D3 to a white-skinned person after 30 minutes of sunlight.
In Ireland, it is a long Autumn, Winter and Spring and sometimes we get a not so sunny Summer! Over these darker months we rely on food for vitamin D but some of us do not eat these food and this is why supplementing Vitamin D from October to May is a good health strategy.
How much Vitamin D do I need to remain healthy?
Looking at the Irish guidelines (1999) and more recent (2011) American/Canadian guidelines, you need between 10ug and 25ug / day of Vitamin D as an adult.
Since 2007, Irish infants get supplemental 5ug/day until aged 1 as Rickets re-emerged in our society.
The ideal scenario is to get your vitamin D levels tested (blood test) and in cases where you are deficient (<20ng/mL) or insufficient (20-40ng/mL), you may be supplemented at higher levels and re-tested before adopting the recommended daily allowance.
Visit your GP for testing.
Foods sources of Vitamin D?
Vit D expressed as ug per 100g food
(info source The Composition of Foods, McCance & Widdowson’s)
Canned red salmon 12ug to 17ug
Salmon grilled/steamed 7 to 8ug
Fortified breakfast cereal 3 to 8ug (check label)
Canned sardines 5 to 8ug
Tuna, canned in brine 4ug
Fortified margarines 7 to 8ug
Butter up to 2ug
Egg, chicken 1 – 1.5ug (medium egg is 65g)
Milks and yoghurts Tr – 0.1ug per 100ml
Cheese/poultry/game 0.1 – 0.3ug
You will not be eating 100g of butter or margarine per day but could enjoy 100g of fish.
Supplementing Vitamin D
Vitamin D is being sold as an easy to use spray that you spray under the tongue every day or as a chewable tablet. Ask your local pharmacy to source the spray – it contains the natural birch tree sweetener xylitol and is very easy to take.
Conclusion: If you don’t and are unlikely to eat fresh or tinned oily fish, you really need to supplement Vitamin D through our sunless, Irish months. I recommend oily fish 2 to 3 times a week and frequently recommend tinned fish to clients as an easy-pack lunch. (advice changes if pregnant) Of course if you have the cash, a Winter sun holiday is another solution. Vitamin D is fat-soluble and is stored in your fat cells. A sun holiday will top up your storage.
Supplements: Cod Liver oils are frequently taken as a source of Vitamin D (210ug per 100g) however I advise caution with the oils from a fish’s liver given evidence of toxicity in the past.