​​Vegan RD for the Animals

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:
  

​

Double exposure time if you are 50 or older

Vegan 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 vegan foods, UV exposed mushrooms or supplements are your best option

​

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:

• Recommendation change

• Evolutionary argument for optimal vitamin D level
  

• Vitamin D is the new vitamin E
  

• ​Vitamin D and mortality
  

• Vitamin D supplements may be necessary
  

• Difficulty of arriving at vitamin D recommendations
  

• How the Institute of Medicine arrived at their recommendations
  

• Resolving the vitamin D debate
  

• Take vitamin D supplements with meals
  

Vitamin D (the Sunshine Vitamin)​