Researchers in the United Kingdon, funded by Cancer Research UK, suggest that people with very fair skin may be unable to spend enough time in the sun to make the amount of vitamin D the body needs - while also avoiding sunburn.
The study, published in Cancer Causes and Control, also suggested that melanoma patients may need vitamin D supplements as well.
However sunlight and supplements are not the only factors that can determine the level of vitamin D in a person's body. Inherited differences in the way the body processes vitamin D into the active form can also affect blood vitamin D levels.
The study defined the optimal amount of vitamin D required by the body as at least 60 nmol/L. (At present there is no universally agreed standard definition of an optimal level of vitamin D.)
Researchers measured the vitamin D level in the bloodstream of approximately 1,200 people and determined that roughly 730 people had an insufficient level. Those with fair-skin had significantly lower levels.
Researchers chose 60 nmol/L as the optimal vitamin D level in part because there is evidence that levels lower than this may be linked to greater risk of heart disease and poorer survival from breast cancer.
Blood vitamin D levels below 25 nmol/L are considered deficient and are associated with poor bone health. A level of 25 to 75 nmol/L is considered insufficient and 76 to 250 nmol is sufficient. However, some experts contend that higher levels, 90-100 nmol/l, may be desirable for optimal health effects. A blood level higher than 250 nmol/L may lead to vitamin D toxicity.
In Canada, adults are advised to take a daily supplement of 1000 IU vitamin D in the fall and winter months. Adults over 50, individuals who are dark skinned and those who don't expose their skin the sun in the summer months should take vitamin D year round. Some people may need a higher dose to maintain a sufficient blood level.
The safe upper daily limit for vitamin D is 4000 IU.
If you are considered about your vitamin D level, speak to your doctor about having your blood tested.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.