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What is Vitamin D? Getting Under the Microscope

by Liza Semenova

Let’s dive in! What is vitamin D? 

Vitamin D is a nutrient, more specifically a fat-soluble vitamin, that’s not found in many foods naturally.

So, where does it come from?

Throw your shades on because one way to get some of your vitamin D is from the sun. Your body produces this nutrient in the form of the hormone vitamin D3, when your skin is directly exposed to the UVB light (meaning not through a window). 

Most foods that do have vitamin D, are fortified with it. Food sources include: 

  • Natural sources include fatty fish like salmon, tuna or mackerel
  • Beef liver, cheese, and egg yolks have small amounts are natural sources of vitamin D3
  • Almost all the milk in the U.S. is fortified with vitamin D, including dairy and non-dairy like soy, almond and oat

What are the benefits of vitamin D and is there an optimal form?

SmartyPants formulas use vitamin D3 (cholecalciferol) because it’s what your body prefers and can easily use. Vitamin D2 (ergocalciferol) is another source commonly found in fortified foods and supplements but it’s less bioavailable than D3.

Vitamin D3 supports normal immune function, but that’s not all. It also helps with the absorption of calcium and phosphorus helping you (or your growing kid) build and maintain strong bones and teeth! Talk about a join-t force.

How much should I take daily?

The recommended amount of vitamin D depends on a few factors, like gender and age. Below are the Dietary Reference Intakes as established by the Health and Medicine Division of the National Academy of Sciences.

Chart of Vitamin D Recommended IntakeWhat are the signs of a vitamin D deficiency?

Deficiency can happen for a few reasons. It may be because you’re not consuming enough or absorbing enough from food, a lack of exposure to sunlight, or your kidneys aren’t able to convert the nutrient into its active form.

It’s rare, but for kids, deficiency causes rickets, a disorder in which their bones become soft and bend. In adults, a significant lack of vitamin D leads to osteomalacia, resulting in bone pain and muscle weaknesses.

There’s a difference between vitamin deficiency and suboptimal, or less than the desired amount of a vitamin. Suboptimal intake is actually very common. Why? As we mentioned, food sources of vitamin D are rare. Having a darker skin tone also places you at a higher risk for deficiency because melanin actually reduces your skin’s ability to make the nutrient.

On the other hand, does too much have side effects?

Too much vitamin D can cause nausea, weight loss, poor appetite, constipation, and weakness. Since a higher amount of vitamin D also raises blood levels of calcium, excessive amounts can lead to confusion, disorientation, heart arrhythmias, and damage to the heart, blood vessels, and kidneys.

The good news is, toxicity is pretty rare and would require extremely high and prolonged intake. You’re more likely to experience suboptimal levels than toxicity. 

What SmartyPants products have vitamin D?

Some of our best sellers include our Women's Formula, PhD Women's Formula, Men's Formula, PhD Men's Formula, Kid's Formula, Teen Girl and Teen Guy Formula.

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Liza Semenova