Rethink on how much vitamin D you need every day

Foods high in vitamin D

Did you know the average adult needs 400-600 international units (IU) or 10-15 micrograms of vitamin D every day?

You probably didn’t, and even if you did, how are you going to know whether you’re achieving that?

Confusing? Yes, and even more so when you’re told that your body makes vitamin D from cholesterol when your skin in exposed to sunlight.

Cholesterol and sunlight – two no-go areas for many of us.

But let’s assume you’ve got these things worked out. You’re eating enough oily fish and enjoying a burst of occasional sunshine, and perhaps you’re even popping a daily vitamin D pill. Perfect. Your bones should be just fine.

Now scientists are looking at something new – could vitamin D also bring other health benefits and, if so, how much is required?

It was believed that low levels of vitamin D increased the likelihood of heart attacks and stroke. Did that automatically mean higher levels reduced the chances of those heart issues?

Added to this was research that suggested vitamin D may also contribute to other health benefits, such as resistance to some cancers, diabetes, hypertension and multiple sclerosis.

But before you go slamming down handfuls of vitamin D or adding extra portions of oily fish to your diet, those studies remain questionable and have evoked mixed results.

Now, researchers at Intermountain Health, a US not-for-profit healthcare system with 385 clinics and 33 hospitals, are conducting studies to determine how much vitamin D is enough not only to improve bones but to also improve other health conditions.

Early clinical trials suggest that the current recommendation for vitamin D allowance is too low to achieve optimal health benefits for people with certain cardiac problems.

The study’s author, Dr Heidi May, says that further studies hope to confirm that sufficient quantities of vitamin D can reduce the risk of adverse cardiovascular events.

“Clinicians should then be more proactive in testing and treating low vitamin D levels,” she said.

“Currently, we are following participants (632 people) until there have been enough events that have occurred so we can compare if treating low vitamin D reduces cardiovascular outcomes compared to not actively treating low vitamin D.”

Findings are expected mid-2024.

How much you need as you age

Currently, the recommended dietary allowance for vitamin D is 400-600 IU for adults under 70 years of age, and 800 IU, or around 20mcg, for adults over 70.

As you age, your body is no longer as efficient at synthesising, absorbing and digesting vitamin D as it was when you were younger, says Robin Foroutan, an integrative dietitian at the Morrison Center in New York City. These issues can lead to an increased risk for osteoporosis (bone disease), among other potential health issues.

Also, body size and sex change the intake recommendations with body size deemed most influential. Dr Foroutan says that while men generally weigh more than women, the relative amount of body fat an individual has may be more pertinent, since vitamin D is stored in body fat.

Vitamin D supplements can help those with low levels. If you suspect your levels are low, the best option is to seek medical advice. A simple blood test via your GP will provide the answer, and your doctor will then recommend supplements if required.

While you can’t get too much vitamin D through sun exposure, high supplement doses over time can cause vitamin D toxicity. So always check with your health professional.

Do you have a regular blood test for vitamin D? Are you often low? Do you take regular supplements? Share your experience in the comments section below.

Also read: Can vitamin D supplements reduce your risk of chronic inflammation?

Disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.

Written by Steve Perkin

Steve Perkin had a long and distinguished career as a journalist, covering sport and general news and writing daily columns for The Age and the Herald Sun. He's written three books and is a regular YourLifeChoices contributor.


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  1. “Vitamin” D is produced by our bodies so it’s actually a hormone, not a vitamin. Vitamins are only available in supplements and food whereas hormones are produced by the body. In the case of “Vitamin” D ,it’s a hormone the kidneys produce that controls blood calcium, concentration and impacts the immune system. It is also known as calcitriol, ergocalciferol, calcidiol and cholecalciferol.

  2. Vitamin D supplements only produce expensive urine as D isn’t a vitamin but a hormone which, unlike vitamins, only the body can produce. 10 minutes of sunlight on our arms and face 3 or 4 times per week is cheaper and more effective, even on overcast days. If you can see your way around, there’s sunlight!

  3. Of course the important thing you get from actual sun exposure is nitric oxide. That’s what helps your arteries. So I think the risk of skin damage is more than compensated by that huge plus.

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