D-coding Vitamin D: The Top 5 Myths You Need to Know

As a registered dietitian who works with Canadian families, I am often asked about the nutritional supplements each family member should take. My answer varies depending on many factors, but what is always standard – across the board – is my recommendation for Canadians to take vitamin D3.  

As with most things in the nutrition world, this does not come without questions, queries and even some push back. There’s no shortage of misinformation out there about nutrition – vitamin D included. So, I’m here to bust some of the top vitamin D myths out there and share my expert recommendation on supplementation for the whole family.  

Why is Vitamin D so Important? 

Also known as the “sunshine vitamin,” this essential nutrient helps your body use the minerals that are parts of bones and teeth, including calcium and phosphorus. Vitamin D deficiency is also noted as a risk factor in several health conditions and is associated with decreased immune function.  

How Much Vitamin D Do We Need?  

This depends on age. Babies ages 0–12 months require 400 International Units (IU) per day, children and adults who are 1–70 years old require 600 IU per day, and adults over the age of 70 require 800 IU per day. Based on these recommendations, and what we know about vitamin D status in regard to health, I recommend that breastfed babies ages 0–12 months receive a daily 400 IU supplement, children and adolescents take 600 IU per day, and adults take 1000–2000 IU per day or more – depending on the amount specified by a physician or dietitian – if they are deficient.  

Myth #1: You get enough vitamin D from the sun.  

Vitamin D is made by the body after exposure to the sun. The sun’s rays hit cholesterol in the skin cells, providing the energy for vitamin D synthesis to occur. However, sunscreen blocks those vitamin D–producing UV rays, so do long sleeves and pants. This means, if you live in a cool climate (like we do) or are really careful about sunscreen (which you should be), you do not get enough sun exposure to produce the optimal amount of vitamin D. This is why supplementation is so important!  

Myth #2: You should rely on food first to get vitamin D.  

It’s true that foods such as milk, fish, and eggs provide some vitamin D, but likely not as much as necessary. For example, a 7-year-old would need to consume six cups of cow’s milk per day to meet their vitamin D requirements. As a registered dietitian, I would never recommend this amount of milk per day for anyone. Vitamin D supplements are the answer!   

Myth #3: You only need to supplement if you’re deficient in vitamin D. 

It’s true that you absolutely need to take a vitamin D supplement if you are deficient, but it’s a myth that you should only take a supplement to correct a deficiency. What happens if you discontinue supplementing after your vitamin D status returns to normal? It will likely dip down again over time. This is why I recommend that Canadians maintain vitamin D supplementation throughout the year.  

Myth #4: Vitamin D must be paired with vitamin K2.  

One of the biggest vitamin D myths that I encounter these days is that it must be paired with vitamin K2 for proper absorption in the body. While these two vitamins can be paired because they’re both fat soluble and both contribute to bone health, let me be clear: they work just as well separately, and neither is required for better absorption of the other. However, if you do have vitamin K deficiency or require extra support in terms of bone health, a combination supplement might be right for you.  

Myth #5: Once your baby turns one, they no longer need a vitamin D supplement. 

Ironically, a child’s vitamin D requirements jump from 400 IU (between 0–12 months) to 600 IU per day after the age of one! This is why it’s imperative that you continue to offer your child a supplement of at least 400 IU per day (if not the full 600 IU per day) throughout childhood and into adolescence.