It’s that time of year again. The days are getting shorter, the temperatures are dipping lower and before we know it, it’ll be winter. But, in the vitamin world, specifically the vitamin D world, winter is already here. This vitamin is often called the sunshine vitamin because in summer, your body makes vitamin D when it’s exposed to sunlight. But, around mid-October, the angle of the sun changes so that no matter how sunny our days are, your body is unable to make vitamin D through sun’s rays. And, this vitamin D winter lasts until spring, making diet and/or supplements very important.
There’s a lot of research going on with vitamin D that points to its many positive benefits. Best known for its role as a partner with calcium in keeping your bones strong and lowering risk of osteoporosis, there are many more areas that D may help. Studies suggest a role for vitamin D in lowering cancer risk and other studies link low levels of vitamin D to chronic diseases including heart disease and type 2 diabetes. There is some evidence that it plays a role in keeping your immune system healthy and may be associated with autoimmune disorders like rheumatoid arthritis and multiple sclerosis.
How much do you need?
For adults, the Recommended Dietary Allowance for vitamin D is 600 IU (15 mcg) per day up to age 70 and 800 IU (20 mcg) per day over 70.
Many experts feel it should be higher. For example, Osteoporosis Canada recommends daily supplements of 400 to 1000 IU for adults under age 50 without osteoporosis or conditions affecting vitamin D absorption. For adults over 50, supplements of between 800 and 2000 IU are recommended.
The safe upper limit for adults is 4000 IU (100 mcg) per day.
Now, when it comes to food, it can be very challenging to get enough through diet alone.
The only natural sources of vitamin D come from fatty fish such as salmon, mackerel and sardines with smaller amounts in eggs and beef. Most of our dietary D comes from fortified foods such as cow’s milk, margarine, fortified soy or rice beverages, some yogurts and fortified orange juice. One cup of fluid milk or fortified beverage has about 100 IU, 3 ounces (85 g) of salmon had about 400 IU, 1 egg has about 45 and 2 tsp margarine has 55.
For most people, especially at this time of year, it’s wise to supplement your diet with vitamin D. My advice is to look at your own intake from both food and supplements and discuss with your health care provider what would be best in terms of supplements to meet your own needs.