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Does Vitamin D Really Come From The Sun?
June 28, 2011 No comments
Many sun-worshippers use the excuse “I’m just topping up on Vitamin D” to justify baking under the sun’s rays all day. You may wonder if there is any truth in that. Do we really get vitamin D from the sun and, if so, how much sun exposure is good for us?
Where does Vitamin D come from?Firstly, it’s important to understand that while the sun is a crucial factor in providing us with vitamin D, the sun itself doesn’t actually transfer vitamin D to our skin through its rays. It is, in fact, our own bodies that synthesise vitamin D in the skin from exposure to sunlight and other artificial sources of Ultraviolet B (UVB) light. In effect, the sun brings out the good in us; and you thought it was the beach-side ice-creams that played their part...
The Different DsVitamin D is a fat-soluble vitamin that comes in three commonly known forms:
- Vitamin D2 (ergocalciferol). Having trouble pronouncing this? Try: urgh-oh-kal-siff-er-role! D2 is synthesised in food via exposure to ultraviolet light and is not naturally found in the body. It is much less efficient at raising Vitamin D blood levels than D3.
- Vitamin D3 (cholecalciferol). How about this one? Try: cauli-kal-siff-er-roll! D3 is naturally made in the skin after UVB exposure. Additionally it can also be found naturally in certain foods and is the preferred source.
- synthetic version of the active form of vitamin D (calcitriol) . Vitamin D needs to be converted into its active form for the body to be able to utilise it. After exposure to UVB light, the D3 form is converted into calcidiol (this is what is measured in vitamin D blood tests) in the liver and then to calcitriol (the active form) in the cells, such as those of the kidneys and other organs.
Why do we need Vitamin D?Calcitriol – the active version of the vitamin – is not only important in the metabolism of calcium, but it is responsible for gene activation, regulation of cell growth, cell suicide (apoptosis) and immune system regulation. It is also involved in the release of neurotransmitters like “the-happy-hormone” serotonin that strongly impacts our mental state. So in a nutshell, active vitamin D is hugely important for the immune system, and our happiness to boot. In recent years sufficient Vitamin D levels have become a concern due to our lack of sun exposure
Moreover, in recent years sufficient Vitamin D levels have become a concern due to our lack of sun exposure. This is due to:
- Increased use of sunscreens for skin cancer prevention - up to 95% of UVB rays are blocked by sunscreen.
- Reduced time in the sun - our long working hours and our increasing reliance on technology keep us indoors more than ever.
Vitamin D deficiencyRickets in children have long been associated with vitamin D deficiency, as has Seasonal Affective Disorder (SAD), However, current research shows that vitamin D deficiency is a significant factor in many additional ailments, such as:
- Infections like influenza and tuberculosis
- Autoimmune Conditions, such as Multiple Sclerosis, Diabetes (I & II), Rheumatoid Arthritis
- Lower Digestive Complaints, such as Irritable Bowel Syndrome, Ulcerative Colitis, Crohn’s Disease, Coeliac Disease
- Cardiovascular Disease
- Cancer - breast, colorectal, lung, pancreatic, ovarian, prostate
Get enough vitamin D without the risk of sunburnNo matter how you look at it, the sun always seems to come out on top as the best source of Vitamin D, but when it is not possible to soak it up, or when it poses too many risks in itself, there are food sources and D3 dietary supplements that can provide adequate amounts of Vitamin D. Summer: We recommend getting 10-15 minutes of sun exposure from 10am - 2pm without sunscreen to get the important UVB rays. However, since this time of day also has the fastest burn time, we suggest keeping out of the sun from 12pm-1pm and covering the skin before even the slightest signs of redness are noticed. Exposure of the torso, arms and legs provides maximal vitamin D production. The face and hands produce very little. Winter: Winter sun does not have significant levels of UVB rays, unless you are near the equator, so we recommend looking to these food sources for vitamin D:
- Fish liver oils - cod
- Fish - mackerel, halibut, salmon, sardines and tuna
- Dairy products - butter and milk
- Sprouted seeds - sunflower seeds
- Healthy children under 1 year of age – 1,000 IU
- Healthy children over 1 year of age – 1,000 IU per every 11kg of body weight
- Healthy adults and adolescents – at least 5,000 IU
- Pregnant and lactating mothers - at least 6,000 IU
Posted in: Dietary Supplements