Under the Microscope: What is Vitamin D?

by Joann Row

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.

Ok, so if most foods don’t have vitamin D, where does Vitamin D come from?

Throw your shades on because one way to get some of your vitamin D is from the sun. Your body produces vitamin D 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 of vitamin D include: 

  • Fatty fish like salmon, tuna or mackerel are natural sources of vitamin D3
  • 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 is the best form of vitamin D, and what are the benefits of vitamin D?

SmartyPants formulas with vitamin D 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.

Vitamin D sounds pretty great, but how you must be wondering, how much vitamin D 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?

Vitamin D 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 vitamin D into its active form.

It’s rare, but for kids, vitamin D 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 vitamin D. Suboptimal vitamin D 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 vitamin D.

On the other hand, does too much vitamin D 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 vitamin D intake. You’re more likely to experience suboptimal levels of vitamin D than toxicity. 

What SmartyPants products have Vitamin D?

Some of our best sellers with vitamin D 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.

Show Comments

Looks Like You Need a Pick Me Up

Our delicious all-in-one vitamin supplements are packed with the nutrients you need to live the good life.

Shop smartypants vitamins

Joann Row