Though calcium and vitamin D serve different purposes, they’re the Batman and Robin of vitamins. Calcium can’t be properly absorbed by the body without vitamin D. When Health Canada upped the daily recommended intake for vitamin D last December, it meant more than just good news for your calcium intake. Vitamin has been in spotlight recently for research that suggests it can help protect against various cancers. We separated the fact from fiction and rounded up a few easy ways to ensure you’re meeting the new daily requirements.
Why we need the dynamic duo
Calcium’s known for helping to promote and maintain bone strength and density, but a small portion of our calcium intake also goes into the bloodstream. That calcium helps muscle and heart contraction, and can also help maintain healthy weight and blood pressure, nerve impulses and blood clotting.
None of that matters without vitamin D, though. In addition to helping our body absorb calcium, the sunshine vitamin (so called because our body naturally produces it with sunlight exposure) regulates the immune system and can help maintain a healthy weight and reduce the risk of arthritis in women.
Vitamin D and cancer
Some studies have suggested that higher intakes of vitamin D are linked to reduced risk of colorectal, prostate and breast cancer. Many epidemiological studies have shown lower rates of cancer among people living in southern latitudes who are exposed to stronger sunlight.
But 2007 was a promising year for vitamin D-related cancer research. A four-year clinical trial published in the American Journal of Clinical Nutrition found a 60 to 77 per cent reduction in cancer rates among the 1,200 postmenopausal women studied. The women took a daily dose of 1,100 IU of vitamin D “ almost twice the recommended daily intake.
The same year, University of California researchers suggested in the American Journal of Preventive Medicine that a 2,000 IU supplement alongside 10 to 15 minutes in the sun daily could reduce a person’s risk of colorectal cancer by two-thirds. They also said breast cancer rates were 50 per cent lower in people who had high vitamin D intakes.
The Canadian Cancer Society issued a recommendation in 2007 that Canadians should consider taking 1,000 IU daily in fall and winter based on the growing body of evidence about the link between Vitamin D and reducing risk for colorectal, breast and prostate cancers.
But the research isn’t all conclusive. Another study published in the Journal of the National Cancer Institute found that high levels of vitamin D in men does not amount to a lower risk of developing prostate cancer. In some cases, it may be associated with more aggressive forms of the disease.
There’s a cornerstone study in process that began in 2009. This one aims to determine whether vitamin D and fish oil can lower the risk of developing cancer or heart disease, or having a stroke. The five-year study will track 20,000 people with no history of heart attacks, stroke or a major cancer.
How to up your daily intake
Supplements are an easy option, but are not always necessary (especially since they’re often expensive). In the case of calcium and vitamin D, you can often get all you need from your diet and sun exposure. Despite Health Canada’s revised daily vitamin D recommendation, they said in the same statement that they believe most are currently meeting their needs for vitamin D.
Most dairy products are a good source of calcium, as well as leafy greens and green vegetables like spinach and broccoli.
Few foods naturally contain vitamin D, but luckily many of the foods rich in calcium also have vitamin D added to help with absorption. Milk, orange juice and margarine are often good sources of vitamin D.
Fish are the real winners in naturally providing vitamin D. The best sources are salmon (bonus: omega 3 fatty acids, too!) and bluefin tuna.
The easiest way to ensure you’re getting enough vitamin D is through exposed sunlight. And exposed means sans sunscreen or sun protection. Fifteen minutes should be sufficient in full sunlight, but if you’re fair, that can be long enough to get a nasty sunburn. It’s a tricky tradeoff. More sun protection means longer sun exposure is required to get the full effect.