Vitamins 201: should you supplement vitamin D?
This is part 1 of a 2-part series on vitamin D. Stay tuned for next week’s post on vitamin D and immunity.
You may recall I touched on vitamin D in a previous post. Here, we’ll take a deeper dive.
Image by @drugwatcher on Unsplash
What is vitamin D?
Vitamin D, first identified as a vitamin early in the 20th century, is now recognized as a prohormone.
What’s a prohormone?
A prohormone is a precursor of a hormone. Prohormones can travel the blood stream as a hormone in an inactivated form, ready to be activated later in the cell. The body naturally produces prohormones as a way to regulate hormone expression.
Why is it important?
Your body needs vitamin D for building and maintaining healthy bones.
Your body can only absorb calcium, the primary component of bone, when vitamin D is present.
Vitamin D’s anti-inflammatory, antioxidant and neuroprotective properties support immune health, muscle function and brain cell activity.
How’re we doing?
About 1 billion people worldwide have vitamin D deficiency, while 50% of the population has vitamin D insufficiency.
Approximately 35% of adults in the United States have vitamin D deficiency.
Sun shining through tree leaves
How does our body get vitamin D?
Vitamin D isn't naturally found in many foods, but you can get it from fortified foods, and fatty fish such as salmon, mackerel and sardines.
This is a benefit of fatty fish. It’s not a recommendation to consume more of it. The recommendation I’ve heard from nutrition researchers, for those who want to consume fish, is 2-3 servings per week.
Your body also makes vitamin D when direct sunlight converts a chemical in your skin into an active form of the nutrient (calciferol).
There are 2 primary causes of vitamin D deficiency
Not getting enough vitamin D in your diet and/or through sunlight
Your body isn’t properly absorbing or using vitamin D
How easy is it to get enough vitamin D from the sun?
Not very.
The amount of vitamin D your skin makes depends on many factors, including the time of day, season, latitude and your skin pigmentation.
Depending on where you live and your lifestyle, vitamin D production might decrease or be completely absent during the winter months.
Sunscreen, while important for skin cancer prevention, can also decrease vitamin D production.
If you spend a significant portion of your day at home or in an office, you may not be getting enough sun exposure to maintain your vitamin D levels.
Other lifestyle factors
BMI of 30 or higher
Individuals with a body mass index (BMI) of 30 or more have lower serum D levels than individuals without obesity.
Obesity does not affect the skin’s capacity to synthesize vitamin D. However, greater amounts of subcutaneous fat sequester more of the vitamin. People with obesity might need greater intakes of vitamin D to achieve D levels similar to those of people with normal weight.
Now we know what it is, where it comes from, and that most people aren’t getting enough of it, the next question is…
Should you supplement?
Talk to your doctor.
My approach
I want to know my vitamin D level is within range. This is an easy thing to test as part of annual bloodwork.
Doctors I follow are recommending ongoing supplementation for most people to keep levels steady.
While a few of the packaged foods I buy are fortified, I don’t go out of my way to get vitamin D from food. It’s not the most important thing to me when I choose a product.
I spend time outdoors intentionally. I take a vegan 2,000 IU supplement a few days a week.
If your level is consistently within range without supplementation, that’s a great outcome too.
How much do we need?
Vitamin D RDAs, source: nih.gov
Have you had your vitamin D level tested? Was it within reference range? Let me know!
Thanks for reading!
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