Winter to most of us means that we don't spend much time outdoors, and even on days when the sun does make an appearance, it's normally while we are at work.. meaning little or no exposure to vitamin D.
Sun exposure is the main source of the vitamin for most of us, but in the Northern Hemisphere it's been proven that for 6 months of the year it's impossible to synthesise adequate levels and this has widespread implications for our health. Vitamin D deficiency is now thought to be the most prevalent nutritional diseases of the 21st century!
Too little sun has been linked to increased risk of Osteoporosis, Type 1 Diabetes and Autoimmune disorders (including Multiple Sclerosis, Arthritis and IBD) as well as certain types of cancers (breast, colon, prostate and pancreatic), asthma in children and cognitive impairment in older adults.
If your exposure to sunlight is limited: The body converts Vitamin D to its active form through sunlight. If you live in the northern hemisphere, work indoors or wear clothing that covers your skin from head to toe (possibly for religious reasons) you are more likely to become deficient.
You have dark skin: Melanin the pigment found in higher amounts in dark skin, reduces the ability to synthesise vitamin D in response to sunlight.
You follow a strict vegetarian diet: Most natural food sources of vitamin D are animal-based, including fish and fish oils, egg yolks, cheese, fortified milk and cereals. (read this article for specific vitamin D levels in food). If you're vegetarian, you could be missing out.
Your digestive tract cannot adequately absorb vitamin D. Certain medical problems, including Crohn's disease, cystic fibrosis and celiac disease can affect your intestine's ability to absorb vitamin D from the food you eat (webmed.com)
You are obese. Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of vitamin D.
So how much to we need
Life Stage Recommended Daily Amount
Birth to 12 months 400 IU
Children 1–13 years 600 IU
Teens 14–18 years 600 IU
Adults 19–70 years 600 IU
Adults 71 years and older 800 IU
Pregnant and breastfeeding women 600 IU
- If, like me you're already missing the sun, it may be worth considering a nutritional supplement.
- If you take a multivitamin, check to see that it supplies at least the recommended daily amount.
- Try taking a walk during lunch time - even a 10 minute dose will help to up your levels.
Harris, S; Vitamin D and African Americans; The Journal of Nutrition, 2006
Office of Nutritional Supplements, Dietary supplements fact sheet: Vitamin D;