With summer upon us, vitamin D, otherwise known as the sunshine vitamin, is once again in the headlines.
With all of this publicity, most health-conscious people are probably now aware of vitamin D’s key functions. Not only does this fat-soluble vitamin regulate the absorption of calcium and phosphorus for maximum bone strength, it is also essential to proper functioning of the immune system.
It seems, however, that this knowledge isn’t translating into dietary and lifestyle changes. A growing number of researchers believe that North Americans are woefully lacking in this key vitamin. One study published in The Archives of Internal Medicine even suggested that as many as 75% of Americans are vitamin D deficient.
As controversy continues to swirl around deficiencies and what appropriate levels should be, vitamin D’s recommended daily dose (RDA) was recently raised from 400 IU to 600 IU for people aged 1 to 70. Many doctors and nutritionists believe that this number is far too low, but increasing the RDA does lend credence to current vitamin D research which shows that vitamin D’s role may go beyond protecting bones and boosting the immune system. Vitamin D deficiency is increasingly being linked to a variety of disorders. Studies are currently examining the link between Vitamin D and the following conditions:
- Increased Infections (especially in winter)
- Sore achy muscles
- Prostate cancer
- Breast Cancer
- Colon Cancer
- Cardiovascular Disease
- Neuromuscular Problems
- Multiple Sclerosis (MS)
- Sleep Apnea
Testing Vitamin D Levels
So how do we know if our vitamin D levels are low? While visual musculoskeletal deformities like rickets are an obvious indicator, there are few other visual clues. Less recognized symptoms can include:
- Brain fog
- Bone pain
- Muscle weakness, aches, and cramps
- Frequent bone fractures
- Unexplained fatigue
- Excessive cavities, weak brittle teeth
A simple blood test called the 25-hydroxy vitamin D, or 25(OH)D test, measures the level of vitamin D in the blood. In Canada, vitamin D recommendations vary from province to province, but a reading of less than 37.5 nmol/L is generally the standard used to recognize vitamin D deficiency for adults. Both Health Canada and Osteoporosis Canada recommend the use of vitamin D supplements to achieve and maintain acceptable levels. To determine how much vitamin D you need, talk to your doctor about arranging a blood test. Factors such as your age, sex, lifestyle, time of year, health, and where you live can affect your requirements.
Causes of Vitamin D Deficiency
- Lack of sun exposure. The body creates vitamin D when skin is exposed to the sun. If you limit exposure by covering, up or spending too much time inside, you are missing an opportunity to load up on this essential vitamin.
- Age. As we grow older our kidneys lose their ability to readily convert vitamin D to its active form. Older people also tend to be more sedentary and spend more time inside, limiting their exposure to the sun.
- Skin tone. Darker skinned individuals require significantly more sun exposure to produce the same amount of vitamin D as lighter skinned individuals. The pigment in darker skin acts as a barrier, not unlike sunblock. It inhibits the skin’s ability to convert the sun’s rays to Vitamin D.
- Health conditions. Underlying health conditions like Crohn’s or celiac disease can inhibit absorption of vitamin D.
- Some drugs, including steroids, can interfere with vitamin D metabolism and affect calcium absorption.
- If left unchecked, a diet lacking foods containing vitamin D or proper supplementation will lead to deficiencies.
Preventing Vitamin D Deficiency
The number of foods rich in Vitamin D is limited. Cod liver oil is an excellent source and for years was the gold standard for the prevention of rickets in children. Just 1 tsp has between 400 and 1,000 IU/Vitamin D. Other natural sources include: salmon, sardines, mackerel, tuna, shiitake mushrooms, and egg yolks. Fortified sources like milk, yogurt, orange juice, and some cheeses have been credited with helping fill the void left by our lack of sun exposure.
In northern climates like Canada, attaining optimum vitamin D levels can be a challenge. It can be difficult to get enough sun exposure to maintain or increase vitamin D levels, and food sources alone are often inadequate. Taking vitamin D supplements can help.
There are two forms of Vitamin D: D2, which is made by plants, and D3, which is the vitamin D created by our bodies when exposed to sunlight. Vitamin D3 is the more active of the two and is more easily metabolized, making it the preferred form for supplementation. Vitamin D supplements should always be taken with a meal containing fat. Studies have shown an average of 32% more vitamin D absorption from supplements taken with fat-containing meals than from those taken on an empty stomach.
And, as with any nutritional concern, always work with your doctor to find the optimal solution for your personal health.