If you’re following a healthy diet you probably don’t need a whole lot of vitamins since you get plenty in the food you eat. But the one vitamin you won’t find in food is vitamin D. In fact, only oily fish like salmon and cod have any appreciable levels of vitamin D. We typically rely on the sun (not food) for  vitamin D and few people get enough sun exposure to achieve healthy levels of this important vitamin.

Most people know the function of vitamin D in keeping your bones healthy, but few are aware of how far-reaching vitamin D’s effects are. Vitamin D receptors are found throughout the body and affect nearly every part of healthy functioning. Studies show that vitamin D deficiency is associated with all of the following:

  • Muscle weakness
  • Higher risk of falls and fractures
  • Heart disease and stroke
  • Diabetes
  • High cholesterol
  • Colon, breast, and prostate cancers
  • Multiple sclerosis
  • Rheumatoid arthritis
  • High blood pressure

Despite its myriad benefits, few people get enough vitamin D to see them. Even if you get plenty of sun compared to your peers, it is doubtful that you are getting enough to keep your vitamin D stores replete. Remember that our ancestors were out in the sun all day, every day, while we rarely get out for more than a few hours per week. Studies suggest that up to 95% of adults are vitamin D deficient, and even in San Diego these numbers aren’t too far off. I’d say that about three-fourths of my patients on average are deficient in vitamin D without supplementation.

Over the counter vitamin D supplement doses range from a low of 400 to a high of 5,000 units (U) per pill. About 1,000 U daily is usually sufficient to achieve and maintain healthy blood levels of vitamin D, although more may be necessary in some cases. Vitamin D is fat-soluble, so taking it with food helps absorption.

A blood test for vitamin D is cheap and covered by most insurance plans. The optimal range is about 50–60 ng/mL, which is in the midpoint of the normal range. Luckily, vitamin D toxicity is rare and usually associated with exceptionally high doses approaching 10,000 U daily. Taking 1,000–2,000 U daily, or about 5,000– 10,000 U per week on average, is likely to be a safe and effective dose.