Vitamin D and chronic pain
I associate vitamin D deficiency mostly with its effects on bone health: Inadequate vitamin D can lead to weak and brittle bones. There's also been a lot of new research lately showing that D deficiency may also be linked to cancer, diabetes, depression, and other serious diseases. (See also "Vitamin D Deficiency Called Major Health Risk" from WashingtonPost.com.)
Now, a new study has found that people with chronic pain frequently have low vitamin D levels. Vitamin D deficiency also appears to make people less responsive to pain medication. (Hopefully, researchers will now confirm that supplementing with vitamin D can lead to better pain management for many people.)
Vitamin D Deficiency is on the Rise
On average, the American diet provides about 250IU of vitamin D a day (mostly from fortified foods), which is just over half the recommended daily amount of 400IU. Your skin also manufactures vitamin D when exposed to ultraviolet light. But with the increased use of sunscreen, you may not be getting enough exposure to cover your vitamin D requirements.
Vitamin D deficiency is becoming so common that experts are calling for an increase in the recommended allowance. If you do not get a lot of natural sunlight on your skin, be sure to get enough vitamin D in your diet. Fish (such as salmon, herring, and mackerel) are naturally high in vitamin D. Cereals and dairy products are often fortified with vitamin D. (Here's a list of foods highest in vitamin D, generated with ND's Nutrient Search Tool.
I am afraid that the amounts of Vitamin d that are in foods are not adequate to maintain a healthy level of vitamin d.
Most people (certainly in the UK) drop down to about 40nmol/l from November through to March. For maximum calcium uptake from foods or supplement you need at least 80nmol/L (see The Vitamin D requirement in health and disease
Robert P. Heaney) and to achieve optimal muscle strength and to ensure all the systems in your body can operate without restriction from limited vitamin D availability, (see Circulating Vitamin D3 and 25-hydroxyvitamin D in Humans: An Important Tool to Define Adequate Nutritional Vitamin D Status
Bruce W. Hollis) 100nmol/L are required.
"The urgent need to recommend an intake of vitamin D that is effective" informs us that 400iu/d vitamin D3 raises nmol/L status by 7-12nmol/l
It's basic maths to work out how much vit d you require to raise your winter low from 40nmol/L to 80nmol/l and the same maths will enable you to work out how much more will be required to keep your status over 100nmol/l until you can go in the sun again in April.
But it is misleading to imply that EFFECTIVE amounts of Vitamin d can be found in foods. To raise from 40 to 100nmol/l is bound to take something like 2000iu/d vitamin D3 and it is simply unrealistic to suggest that 2000iu can be obtained from food sources.