Winter is here, the days are shorter and you’re barely seeing the light of day. Does the lack of sunlight have you asking, “Should I take vitamin D supplements?” Or maybe you’re taking them already. CBC Radio asked me this very question on the heels of a recent review in the British Medical Journal stating that most people probably don’t need a vitamin D supplement. What gives?
The authors of the BMJ review state that “a healthy diet and short bursts of sunlight are effective for MOST people when it comes to Vitamin D.”
So who needs a vitamin D supplement and who doesn’t? And do you need more vitamin D in the winter when you’re getting less sun exposure? Here are the answers you’re looking for.
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A big shout out to Kate Comeau and others at Dietitians of Canada for helping provide some of the research and stats to help me prepare for coast-to-coast interviews on vitamin D!
What Does Vitamin D Do?
Vitamin D helps your body absorb calcium and phosphorus for strong bones and teeth. It can also prevent rickets in children and osteomalacia or osteoporosis in adults. Vitamin D keeps your immune system working well to help protect against infection.
Why Is There So Much Hype About Vitamin D?
Vitamin D is such a hot topic and has been for the past 5 years or more. People were so excited about vitamin D being the new “miracle” nutrient based on some early research findings.
Hundreds of research papers came out reporting the links between lower vitamin D levels in the blood and lower risk of health issues such as heart disease, cancer, diabetes, weight gain, multiple sclerosis, mood disorders and death from all causes.
So what’s the issue? Just because two things are linked doesn’t mean there’s a cause and effect relationship.
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The bad news is the media overemphasizes the results of nutrition studies and downplays and “buts” or cautionary notes from the researchers. The result? Plenty of headlines about vitamin D being a cure-all, causing people to stock up on huge bottles of vitamin D… whether they needed it or not.
Fast forward a few years. Now that the results of randomized controlled trials are just beginning to be published, we are learning more about whether there could be a cause-and-effect relationship between vitamin D and some of these health issues. So far, the results aren’t as magical as people had hoped.
Some studies suggest blood levels of vitamin D are low as a marker of disease instead of it being the cause of health issues. That’s what happens when we put the cart before the horse. If something is low during a certain disease state, mega-dosing on that nutrient won’t necessarily fix the issue. That seems logical, right?
When it comes to nutrition, people get so excited about a potential cure or magic bullet that they proceed full steam ahead with taking supplements, even when there isn’t strong enough evidence to back that up. I guess “proceed with caution” isn’t such a sexy message… and doesn’t make a great headline, either.
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Are Canadians Getting Enough Vitamin D?
Many Canadians aren’t getting enough vitamin D from food, with analysis from the 2004 Canadian Community Health Survey indicating the prevalence of inadequate vitamin D intake from food and supplements is between 54 and 84%.
Despite that, blood levels of vitamin D in research studies suggest that only about 8% of Canadians are at risk of vitamin D deficiency (with serum hydroxy vitamin D levels <30 nmol). Blood tests are the best way to measure vitamin D status because this takes into account not only vitamin D from food and supplements, but also what our body produces from sun exposure.
How Much Sun Do I Need for Vitamin D?
What’s recommended is 15 minutes of sunlight a day on your face and hands in order to produce enough vitamin D. The issue is, there are many factors that will impact how effective this is. Fctors like time of year, time of day, weather (if it’s overcast, for example), where you live (northern latitudes will get less of those UVB rays), skin pigmentation and more.
Does Sunscreen Prevent You From Getting Vitamin D?
Being exposed to ultraviolet B (UVB) radiation in sunlight provides the mechanism for more than 90% of the vitamin D production in most people.
Although in theory sunscreen blocks some of the production of vitamin D, most people don’t reapply as often as advised (every hour) or use enough for it to be 100% effective in blocking out all UVB rays.
That’s why trying to get more vitamin D isn’t a good reason to stop using sunscreen. You will likely still be exposed to some UVB rays and produce some vitamin D.
Please do continue using sunscreen to prevent skin cancer. Added bonus: look younger longer!
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Which Foods are High in Vitamin D?
Most adults ages 19-70 need 600 IU of vitamin D a day; preferably from food (and supplements if needed). If you’re 71 or older, you need 800 IU of vitamin D every day.
Excellent sources of vitamin D include oily fish such as salmon and Arctic char, egg yolks, milk and fortified milk alternatives such as almond milk and soy milk, and fortified milk products such as yogurt.
How much of these foods would you need to eat to get your 600 IU of vitamin D?
- 2 cups of milk or fortified milk alternative
- 2 eggs
- 3/4 cup vitamin D fortified yogurt
- 2 1/2 ounces of oily fish such as salmon or Arctic char
Realistically, most people will eat more than 2 1/2 ounces of salmon. Let’s say you have a 6 ounce serving of salmon at dinner (about the size and thickness of your hand) and you’re getting 1000 IU of vitamin D. That’s almost the amount for 2 days!
The great news about vitamin D is it’s fat soluble, so your body literally saves it up for a rainy day… or other times you need it. Your diet will vary day to day, so the main thing is to incorporate vitamin D-rich sources when you can.
For more foods that contain vitamin D, check out this list from Dietitians of Canada.
Should I Take Vitamin D Supplements?
There are various groups of people who might need a vitamin D supplement. Do you or someone you know fall into one of these categories?
Age Groups at Risk of Low Vitamin D
- Babies who are breastfed or given a combination of breast milk and formula should be given a supplement of 400 IU of vitamin D a day until the age of 2.
- Adults ages 50 and older: Health Canada recommends you take a supplement of 400 IU of vitamin D each day in addition to eating foods that are rich in vitamin D.
Special Diets at Risk of Low Vitamin D
- Anyone who avoids fish, milk or fortified milk alternatives and egg yolks
Diseases That Affect Vitamin D Absorption
- Crohn’s Disease
- Celiac Disease
- Cystic Fibrosis
- Liver Disease
If you have one of these conditions, speak to your physician about vitamin D supplements.
Diseases That Require More Vitamin D
If you have one of these conditions, speak to your physician about vitamin D supplements.
- People with darker skin tones
- Higher latitudes
- Shift workers
- People who work indoors
- People who stay inside most of the time
How Much Vitamin D Should I Take?
If you’re not sure how much vitamin D you’re getting from food, download a free app such as Eatracker and track your food and drinks for a few days. That should give you a good idea of how much vitamin D you’re getting each day on average.
Not getting enough vitamin D? Meet with a registered dietitian for personalized tips and strategies to get more vitamin D-rich foods and drinks into your day.
If you have a chronic disease associated with lower vitamin D levels, speak to your doctor about whether you should take a vitamin D supplement and how much to take.
To find out your vitamin D levels, visit your doctor and request a serum 25 hydroxy vitamin D test. If you have low blood levels of vitamin D, you may need a supplement to top yourself up.
The Canadian Cancer Society recommends that Canadians speak to their physicians about taking a supplement of 1000 IU of vitamin D in the fall and winter months. Some people may need to continue taking a supplement year round.
How Much Vitamin D Is Too Much?
With any nutrient, getting enough is important… but getting too much isn’t a good thing. More is not better!
The upper limit for vitamin D is 4000 IU a day from food and supplements. This would be really tough to get to with food, so really it’s overdoing it on supplements that we worry about.
So what does your body do with the extra vitamin D if you’re taking too much from supplements?
Vitamin D is fat soluble, which means your body stores it rather than peeing out the extra as with water soluble vitamins such as vitamin C.
The extra vitamin D could cause your body to absorb more calcium which can build up in your blood vessels, heart and kidneys. These are not areas that you want hardening up with calcification!
Are you taking a vitamin D supplement? Why or why not? Share in the comments!