References used for all of the nutrient pages can be found at the bottom of the Nutrition Facts page. Click here.

What is Vitamin D?


  • Vitamin D (also known as calciferol) is actually a hormone and differs from other nutrients in that we can make it by using cholesterol in our skin and sunshine (if not wearing sunscreen)

  • After vitamin D is made in the skin or consumed in a meal it needs to be activated by both the liver and the kidneys

  • The plant form of vitamin D found in fungus and yeast is called vitamin D 2 or ergocalciferol

  • The animal form of vitamin D is called vitamin D3 or cholecalciferol

  • Once vitamin D is processed in the liver it is called 25-hydroxy vitamin D or calcidiol

  • After it is processed in the kidneys it is fully activated and called 1,25 dihydroxy vitamin D or calcitriol


How Much Do I Need?


  •  RDA for Men and Women 18-70 is 15 mcg/d (600 IU)

  •  RDA for Men and Women >70 is 20 mcg/d (800 IU)

  •  RDA is set assuming that no vitamin D is synthesized by the sun

  •  Upper Safe Limit is 100 mcg (4,000 IU)


Why Do I Need Vitamin D?


  • Vitamin D is best known for its role in bone health

  • Vitamin D helps the body absorb calcium and it acts as a hormone by regulating levels of calcium and phosphorus in the blood

  • There are receptors for vitamin D all over the body and currently there is research investigating the role of vitamin D in many important areas such as immunity, cancer, diabetes, osteoarthritis, muscle strength and others


Do I Get Enough Vitamin D from the Sun?


  • How much sun you need each day depends on a lot of variables including how much skin is exposed, the color of your skin, your age and the UV index (a measure of how strong the UV rays are)

  • There are of course concerns about skin cancer if you are out in the sun without sunscreen so ideally you will just be exposed long enough to get the benefit of vitamin D without burning

  • For adequate exposure 50-75% of skin should be exposed between 10:30 am and 3 pm when the UV index is 3 or higher

  • You can find out what the UV index is in your area by clicking  here and entering your zip code

  • If you live in an area north of the line running between Los Angeles and Atlanta the UV rays are not strong enough to produce vitamin D from November to March

  • The chart below is from a lecture given by Dr. Matt Lederman- it gives some guidance on amount of time needed in the sun to produce adequate vitamin D based on skin types:


Skin Type

UVI (0-2)

UVI (3-5)

UVI (6-7)

UVI (8-10)

UVI (11+)

Always Burn, Never Tan

None

10-15 min

5-10 min

2-8 min

1-5 min

Easily Burn, Rarely Tan

None

15-20 min

10-15 min

5-8 min

2-8 min

Sometimes Burn, Slowly Tan

None

20-30 min

15-20 min

10-15 min

5-10 min

Rarely Burn, Rapidly Tan

None

30-40 min

20-30 min

15-20 min

10-15 min

Never Burn, Always Dark

None

40-60 min

30-40 min

20-30 min

​15-20 min

Double exposure time if you are 50 or older


Plant-Based Food Sources


  • ​Sunshine is the ideal way to get vitamin D but if you are unable to get outside, are concerned about skin cancer or live north of Los Angeles and Atlanta then fortified plant-based foods, UV exposed mushrooms or supplements are your best option


Food

Vitamin D Content 

Vanilla soy milk, 1 cup

2.9 mcg (116 IU)

Vanilla almond milk, 1 cup

2.4 mcg (96 IU)

Portobello mushrooms exposed to UV light, 1 cup sliced and grilled

13.1 mcg (524 IU)

Total cereal, 3/4 cup

2.5 mcg (100 IU)

Kellogg's raisin bran, 1 cup

2.3 mcg (92 IU)

Fortified orange juice, 1 cup

2.5 mcg (100 IU)



Deficiency Symptoms


  • Impaired bone mineralization leading to rickets

  • Osteomalacia and osteoporosis

  • Deficiency may also contribute to increased rates of death, muscle pain, cancer, diabetes, high blood pressure, autoimmune conditions and depression



Toxicity Symptoms


  • Excessive calcification of bone and soft tissues

  • Kidney stones

  • Hypercalcemia

  • Headache

  • Weakness

  • Nausea, vomiting

  • Constipation


How to Assess Status


  • The best measure of vitamin D status is serum 25-hydroxy vitamin D3 (calcidiol)

  • The Institute of Medicine defines a normal range for calcidiol to be 20-70 ng/ml

  • Discuss supplementation with your physician if your levels are below normal


Notes


  • The RDA for vitamin D used to be given in a measurement called international units (IU) and you will likely still see this term on supplement labels

  • The measurement used now is micrograms (mcg) of cholecalciferol

  • One IU = 0.025 mcg cholecalciferol

  • To convert mcg to IU just divide mcg by 0.025, (15 mcg / 0.025 = 600 IU)

  • To convert IU to mcg just multiply IU by 0.025, (600 IU x 0.025 = 15 IU)

  • Food labels usually list the amount of vitamin D in a serving as a percentage of daily value (DV)

  • The DV for vitamin D is 400 IU so if the label says that it contains 10% of the DV per serving than each serving contains 40 IU


Links


For more information on vitamin D, please check out these videos from Dr. Michael Greger:


Vitamin D (the Sunshine Vitamin)

Kristen Zaier, ​​Plant-Based RD