If I asked you what was the most important vitamin for fighting colds what would your answer be? Many people think it’s Vitamin C. It is certainly important in helping to mop up free radicals which cause damage through a process known as oxidative stress, but it’s not the most important. Vitamin D3 has been shown to boost immune function thereby helping you fight the invaders before they get a foot hold. To put it another way, Vitamin C helps you fight the effects of the chemicals released by inflammation, vitamin D3 helps to stop it in the first place.
Vitamin D3 is synthesized in the skin when exposed to sunlight. Vitamin D2 is found in plants. Vitamin D has long been known to support the absorption of calcium and formation of bone. A deficiency leads to softening of the bones and Ricketts (bandy legs). This disease is on the increase again, due to people covering up for cultural reasons and lack of sunlight in higher latitudes, especially for those of darker skin.
More recently Vitamin D3′s role in immune function regulation has been studied extensively and new research is confirming it’s importance as a vital supplement. Poor immune function obviously can leave you more susceptible to infections such as the common cold and flu. It can also reduce your ability to recognise and destroy cancerous cells, and can lead to the development of auto-immune disorders where your immune system actually attacks your own body. This process has been implicated in some inflammatory arthritis, multiple scerosis, systemic lupus. A correlation has been found between low levels of Vitamin D3 and all of these disease processes. In addition macular degeneration (blindness), hayfever, chronic rhinitis have all shown signs of being affected by low vitamin D3 levels.
This depends on your location, skin colour, diet and sun exposure. In the UK 90% of the population are below recommended levels. 75% of young adults are deemed deficient. 20-40% of young adults 19-24 years old, care home residents and children of British Asians have been found to have only a third of recommended levels. The amount needed varies according to who you read, the Endocrine Societies Clinical Practice Guidelines state from 400 iu to 800 iu as a daily requirement. With an optimum of 1000 iu to 1500 iu. In cases of deficiency 2000iu to 10000iu. You can read the guideline here. One thing is clear, if you are wrapped up for several months of the year in low sunlight you won’t be getting as much as in the summer.
Is this why you are more likely to have “bugs” in the winter? Is it also why cancers such as colo-rectal cancer are more common at higher lattitudes? There is also a possible link between latitude and multiple sclerosis and diabetes. Also have a look at this site which has a good deal more on the topic.
Natural food sources are oily fish, such as salmon and sardines and eggs. It is also in fortified cereals, spreads and powdered milk. The NHS site states that most people should have enough, but latest clinical guidelines dispute this. Supplementation should be 1000iu for babies and children (be aware that baby formula milk commonly contains vitamin D, so adjust accordingly). 1500-2000iu for adults 18+ years of age.
Generally because vitamin D deficiency is so widespread in the UK routine measurement is deemed unnecessary. A more cost-effective approach is routine supplementation with sensible sun exposure in the spring summer and autumn. High risk groups should be screened, these include people at high risk of inflammatory bowel disease, cystic fibrosis, gastric bypass patients and patients taking medication that effects vitamin D metabolism (anti-seizure meds, glucocorticoids, AIDS meds).
Historically there have been concerns as very high levels can be toxic and cause too high a level of calcium and phosphate in the blood leading to bone conditions. However it is now well established that toxicity is extremely rare. Doses of up to 10,000iu a day have been used for up to 5 months with no adverse effects, suggesting that only long-term over supplementation is an issue. However it is important to stick to the guidelines.
If you live in northern latitudes, are inside alot and use sunscreen extensively you won’t get enough from the sun. Especially with our weather!
There are many products on the market, I would recommend a natural food source variety and not a synthetic one. A quick search online should provide a wealth of information to help you choose.