Vitamin D — And Why It’s Important

You’ve probably heard that vitamin D is called the sunshine vitamin. That’s because we produce the vitamin when our skin is directly exposed to the sun. During the fall/winter months from October to March however, those of us living in the northern latitudes may not get enough sunlight to produce vitamin D. Working indoors, clothing and the use of sunscreens can also limit the amount of vitamin D that we make.

Vitamin D — And Why It's Important

Vitamin D helps protect older adults from osteoporosis because it improves our body’s absorption of calcium, which is important for maintaining strong bones. Emerging research suggests that vitamin D may also play a role in protecting against cancer, heart disease, autoimmune diseases, influenza, fractures and falls, type 2 diabetes and even depression.

Research also shows that adults with higher levels of vitamin D tend to have more lean muscle mass, and that vitamin D supplements may improve muscle strength and physical fitness in older adults.

Recommended Daily Dose of Vitamin D

The amount of vitamin D you need increases with age since our bodies become less efficient at producing the vitamin from sunlight. Men and women ages 60-70 should get 600 IUs (15 mcg) of vitamin D per day, while those over 70 should take in 800 IUs (20 mcg).

The Best Foods for Vitamin D

Only a few foods naturally contain vitamin D. Some of the best sources are:

  • fatty fish (such as salmon, mackerel, tuna and sardines)
  • egg yolks
  • shiitake mushrooms
  • cod liver oil
  • cow’s milk
  • yogurt
  • goat’s milk
  • fortified plant based beverages (such as soy, rice or almond beverages)
  • some breakfast cereals
  • margarine
  • various brands of orange juice

Check the nutrition labels to see whether the food contains vitamin D. Some foods may be fortified with vitamin D. If you’re lactose intolerant, choose the non-dairy foods from this list.

Symptoms of Vitamin D Insufficiency

You can become deficient in vitamin D if you’re not eating enough from food, spend a lot of time indoors, wear sunscreen with a SPF (Sun Protection Factor) of 30 or more, or if you have limited exposure to sunlight. The skin becomes less efficient at making vitamin D as we age, making older adults, particularly those over the age of 65, at risk for developing a deficiency.

Those with dark skin, kidney disease, liver disease, Crohn’s disease or celiac disease may have also be at risk for vitamin D deficiency.

Some symptoms and side effects of vitamin D deficiency are: body swaying, falls and bone fractures, bone pain and muscle weakness (these may also be signs of osteomalacia, a softening and thinning of the bones). The best way to know whether you’re low or deficient in vitamin D is to have a blood test to measure your level of 25-hydroxyvitamin D.

Vitamin D Supplements

You may be wondering if you should get vitamin D from sunshine, food or supplements. That depends on many factors, including your diet, climate, vitamin D blood levels, the amount of time you spend outdoors and your risks for developing skin cancer.

There are two types of vitamin D supplements:

  • Vitamin D2 (ergocalciferol)
  • Vitamin D3 (cholecalciferol)

The vitamin D3 form is more effective at increasing vitamin D levels in your blood. It’s sold over the counter as pills or chewable tablets. During the winter months, it may be advisable to take a vitamin D supplement. (In Canada, adults over the age of 50 are advised to take a vitamin D supplement of 400 IU every day.)

Vitamin D is a fat-soluble vitamin, meaning it’s best absorbed with fat. So, the best time to take vitamin D supplements is with a meal or beverage that contains some fat. If you take a vitamin D supplement, be sure that you don’t exceed a daily total of 4000 IU from both food and supplements. Too much vitamin D can damage your kidneys and cause hypercalcemia, which may lead to nausea, vomiting, constipation and weakness.

Editor’s note: Vitamin D supplements may interact with certain medications. Always check with a dietitian, doctor, pharmacist or health care professional before taking any supplements.

About the Writer

Sue Mah

As a dietitian and chef’s daughter, Sue loves good food. She is President of Nutrition Solutions, focusing on nutrition for health/wellness. With generations of grandparents playing mahjong in their 90s, Sue is a cheerleader for healthy active aging.

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