Spotlight Nutrient: Vitamin D
Vitamin D is known as the “sunshine vitamin.” But what do we do during winter when the sun barely shines? How do we know if we have enough? And why do we need it anyway?
Well, we need vitamin D for strong bones and a stronger immune system. It’s also important for muscles (including our heart), our brain, and has anti-cancer activity (1). During the summer months, we get some from the sun shining on our bare skin. So, getting enough can be tough during the winter. Many doctors, like Dr. Mercola, believe in a little unprotected sun daily. He says a deficiency is downright dangerous. “Vitamin D deficiency has been linked to cancer, diabetes, osteoporosis, rheumatoid arthritis, inflammatory bowel disease, multiple sclerosis and autism.”
Here’s what you need to know:
- Recommendations are very conservative (super low). The Institute of Medicine recommends only 600 IU daily as the RDA (recommended dietary allowance) (2). Other experts say we need more (3).
- Doctors don’t normally check vitamin D levels! You can (and should) ask your doctor to check your levels. They should be at least 30 ng/mL, but really should probably be higher.
- Most foods don’t contain enough. Here are a few: fatty fish (salmon, tuna, sardines), cod liver oil (gross, we know, but it’s a great source!), beef liver, and egg yolks.
- Supplementation may be necessary.
- Make sure to find a vitamin D3 supplement (not D2). If your doctor has prescribed weekly doses, then it’s probably vitamin D2. You want to take D3 on a daily basis instead of D2 on a weekly basis. It’s more effective at reaching and maintaining healthy levels (4). Before starting a supplement, make sure to talk to your physician because vitamin D does have a toxicity level.
Here’s a helpful guide for recommended intake:
|Recommended daily for adults|
|Food and Nutrition Board (Institute of Medicine)||600 IU
800 IU (seniors)
|Endocrine Society||1,500-2,000 IU|
|Vitamin D Council||5,000 IU|
Vitamin D helps keep your immune system strong through the winter, and you’re likely not going to get enough from food. Talk to your doctor or Registered Dietitians about this information to make sure you’re at your best this winter!
- Council TVD.
- Del Valle HB, Yaktine AL, Taylor CL, Ross AC. Dietary reference intakes for calcium and vitamin D: National Academies Press; 2011.
- Holick MF. Vitamin D and health: evolution, biologic functions, and recommended dietary intakes for vitamin D. Clinical Reviews in Bone and Mineral Metabolism. 2009;7(1):2-19.
- Logan VF, Gray AR, Peddie MC, Harper MJ, Houghton LA. Long-term supplementation is more effective than D2 nutrition. 2013;109(6):1082-8.