3 Things Everyone Should Know About Vitamin D

sunshine, grassy field

1. Vitamin D is inextricably linked to your overall health.

“Low vitamin D status is linked to a number of different conditions. These include certain cancers, muscle weakness and types I and II diabetes—possibly even schizophrenia and multiple sclerosis,” says Professor James Fleet, of Purdue University.

Vitamin D isn’t just about strong bones

It plays a role in cardiovascular disease, estrogen excess, brain cell growth and the inflammatory immune response.

Vitamin D Benefits

Vitamin D can affect the risk of breast, colon and ovarian cancers, possibly due to its role in the cell life cycle or its ability to block excess estrogen.

Various studies have found lower incidence of childhood asthma and Type I diabetes in children that live closer to the equator. These children have higher levels of sun-synthesized vitamin D.

A Framingham Heart Study found that low vitamin D in those over 59 years old contributed to two times the risk of experiencing a cardiological event (heart attack, heart failure or stroke) in the following 5 years of life.

Our immune cells contain receptors for vitamin D. Vitamin D seems to prevents prolonged or excessive inflammatory response which is linked to many autoimmune disorders: multiple sclerosis, rheumatoid arthritis, irritable bowel disorders, hypertension and psoriasis.

2. Vitamin D isn’t actually a vitamin.

What we know as vitamin D is really a precursor to a steroid hormone: it is also known as provitamin D.

The conversion of vitamin D happens first in the liver and then in the kidneys before it becomes the compound that is biologically active: calcitriol.

Vitamin D’s major role is the metabolism and maintenance of calcium. Calcium levels rise with added vitamin D supplementation and rising calcium may shut off vitamin D.

Increased calcium can cause mental confusion, heart rhythm problems and kidney stones. Calcitriol works with the parathyroid hormone to maintain calcium levels.

When vitamin D levels are low, the parathyroid becomes overactive. Hyperparathyroidism results in drops in phosphorous. Without phosphorous, calcium and other compounds cannot mineralize in bone. Therefore, vitamin D is also responsible for maintaining phosphorous levels in the blood.

Since vitamin D affects the ability of calcium to bind to proteins, it is believed that it is also linked to vitamin K (which has a lot to do with these proteins as well.)

Iron deficiency may slow vitamin D absorption and potassium may help conserve calcium in the body, thereby influencing vitamin D.

3. Milk is NOT your best source of Vitamin D

The dairy industry would have us think that milk is our best source of vitamin D. In fact, pasteurized milk is linked to both calcium and vitamin D deficiency disorders.

The best source of vitamin D is sunlight. Ultraviolet rays convert vitamin D into the form that our bodies use, and unlike food and supplement sources, it is very difficult to get too much vitamin D this way.

Your skin is able to regulate this vitamin D conversion according to heat and other factors, store pre-vitamin D for future use and destroy amounts above and beyond what is safe.

As little as 5 minutes of natural sunlight can cause vitamin D production in the body and 20 minutes produces 20,000 international units (IU).

It’s very difficult for those who live in northern latitudes to produce adequate vitamin D during winter months.

Tanning beds that emit 2-6% UVB radiation may help but research needs to be done on this.

Few foods naturally contain bioavailable sources of vitamin D. Fish is one of the best sources. A decade or so ago, the USDA listed the vitamin D content of dietary foods, but little research had been done at that time and analysis methods are still lacking.

FoodFood AmountVitamin D
IU (International Units) /
% Recommended Daily Value
Cod Liver Oil1 Tablespoon1,360/340
Salmon3.5 Ounces400/100
Mackerel3.5 Ounces345/86
Sardines1.75 Ounces250/63
Tuna3 Ounces200/50
Egg120/5
Beef Liver3.5 Ounces15/4

Milk does not naturally contain vitamin D, raw or otherwise. Synthetic vitamin D is added to cow’s milk, soy milk and rice milk but there are problems with products enriched with vitamin D.

Synthetic vitamin D is only half as effective as natural and can block natural vitamin D’s effects. It can be toxic and affect calcium levels.

The precursor to vitamin D is found in both plant and animal products but animal-derived products contain the building block that we need to create calcitriol—the compound we make best use of.

Vitamin-D-fortified foods and dietary supplements mostly contain ergocalciferol (D2) rather than cholecalciferol (D3). D2 is created by irradiating yeast and other molds, D3 by irradiating animal oils and cholesterol.

D3 from animal cholesterol is closest to what sunlight produces in humans and is converted 500 times faster than D2. It’s estimated that D3 is 4 times more effective in humans than D2 and “vitamin D2 should no longer be regarded as a nutrient appropriate for supplementation or fortification of foods.”

No clinical trials have shown D2 to be effective at preventing bone fractures, for instance, while every trial of D3 does.

Some supplement manufacturers are switching over to D3 but a supplement that provides the actual food source of the vitamin, along with all of the other enzymes and compounds that naturally help us to utilize it, are more effective than the isolated vitamin alone.


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  1. Jonathan Martin says:

    <p>Good stuff on vitamin D. I did not know about the difference between D2 and D3. That’s interesting, I’m going to look into it more. Thanks for sharing!</p>

  2. Cathi says:

    <p>When I get sick or feel like I’ve got something coming on, I know I should increase my D3 but, I’m not sure how much more. I don’t want to over do it. Good article. I’m passing this along. Love the new website too.</p>

  3. To says:

    <p>I just found out that im deficent in vit d dr perscribed vit perscription I have high blood pressure and type 2 diabeties and take meds for both now I wonder once the vit will help and I get off the meds</p>

  4. Janet Murchison says:

    <p>I would like Dr. Josh to comment to the 4 reader comments above. His great article opened similar questions also with myself.</p>

  5. Sam says:

    <p>How much D3 does one need to take daily? Started taking one tablet per day this week.</p><p>Also, how does one get off Synthroid (88 mgs/da) and move to something more natural. Looked at Kelp, but it does not appear that I could take enough on a daily basis to accommodate my needs? Any ideas?</p><p>Thanks!</p>

  6. Dr. Axe says:

    <p>Typically 5,000 IU’s of Vitamin D3 is an appropriate amount to supplement with for starters. However, if you are having severe health symptoms and they continue to persist I recommend getting your Vitamin D levels tested. You can order a Vitamin D testing kit for just $65 on http://www.vitamindcouncil.org.<br/>In regards to taking Synthroid and a kelp supplement I recommend you always work with your physician when getting off any kind of medication. I would supplement with Kelp to increase the amount of organic iodine that is available.</p>

  7. Donna says:

    <p>Can you still get enough vitamin D, within 15 minutes, in the winter?</p>

  8. Dr. Axe says:

    <p>It is more difficult to get enough Vitamin D from the sun alone in the wintertime if you live in more northern regions, especially since the majority of your skin is covered. That’s where the supplementation with Cod Liver Oil comes in.</p>

  9. Laura says:

    <p>I have been working towards your overall eating lifestyle for awhile, however cannot seem to get past the most important part. Every time I take cod liver oil I get indigestion and burp it all day long. </p><p>Thought I heard of something you could take with it to help that but can’t remember what it was.</p>

  10. Nancy says:

    <p>Dr. Mercola says that there are healthy tanning beds that are a good way to get vitamin D. Do you know there are any in the Franklin/Brentwood TN area?</p>

  11. frannie says:

    <p>I have hypothyroidism (Hashimoto’s autoimmune) and am seeking relief from ten-year-long hip/back pain. I have never had my D3 levels checked. Is there a link between thyroid hormone levels and vitamin D deficiency?</p>

  12. frannie says:

    <p>Oh I forgot to mention I have labral tears, a herniated disc, fai and retroverted hips, but only today did a doc mention that D deficiency might be the true cause of my pain (some people have labral tears that are asymptomatic… pain free)</p>

  13. Joyce Meisenholder says:

    I have just had the thyroid T123 test done. I was told that my labs just before that “might be adjusting themselves” and now that I have had the test, they say that the test “is consistent with a low grade Grave’s disease”. I am to have labs done again in 2 weeks. What natural product is best to take to eliminate the Graves’s disease and get my thyroid back in balance?

    • Dr. Axe says:

      It’s hard to say with Graves disease. It could be caused by heavy metal poisoning, it could be caused by a loss of curve in your neck or disc degeneration, or you may be lacking a nutrient like Iodine.

      But one thing you can do that will help immediately is start following a diet loaded with Real Foods like: Vegetables, Fruits, Beans, Nuts, and Organic Meats.

  14. Shane says:

    Nice blog! Very interesting and informative topic. I’ll look forward for more info. Thanks for the share!

  15. Rachel says:

    I have estrogen domiance & dr’s really don’t know how to treat it, I’ve now been diagnoised with vitamin d deficiancy is there a connection between the two?

  1. Jonathan Martin says:

    <p>Good stuff on vitamin D. I did not know about the difference between D2 and D3. That’s interesting, I’m going to look into it more. Thanks for sharing!</p>

  2. Cathi says:

    <p>When I get sick or feel like I’ve got something coming on, I know I should increase my D3 but, I’m not sure how much more. I don’t want to over do it. Good article. I’m passing this along. Love the new website too.</p>

  3. To says:

    <p>I just found out that im deficent in vit d dr perscribed vit perscription I have high blood pressure and type 2 diabeties and take meds for both now I wonder once the vit will help and I get off the meds</p>

  4. Janet Murchison says:

    <p>I would like Dr. Josh to comment to the 4 reader comments above. His great article opened similar questions also with myself.</p>

  5. Sam says:

    <p>How much D3 does one need to take daily? Started taking one tablet per day this week.</p><p>Also, how does one get off Synthroid (88 mgs/da) and move to something more natural. Looked at Kelp, but it does not appear that I could take enough on a daily basis to accommodate my needs? Any ideas?</p><p>Thanks!</p>

  6. Dr. Axe says:

    <p>Typically 5,000 IU’s of Vitamin D3 is an appropriate amount to supplement with for starters. However, if you are having severe health symptoms and they continue to persist I recommend getting your Vitamin D levels tested. You can order a Vitamin D testing kit for just $65 on http://www.vitamindcouncil.org.<br/>In regards to taking Synthroid and a kelp supplement I recommend you always work with your physician when getting off any kind of medication. I would supplement with Kelp to increase the amount of organic iodine that is available.</p>

  7. Donna says:

    <p>Can you still get enough vitamin D, within 15 minutes, in the winter?</p>

  8. Dr. Axe says:

    <p>It is more difficult to get enough Vitamin D from the sun alone in the wintertime if you live in more northern regions, especially since the majority of your skin is covered. That’s where the supplementation with Cod Liver Oil comes in.</p>

  9. Laura says:

    <p>I have been working towards your overall eating lifestyle for awhile, however cannot seem to get past the most important part. Every time I take cod liver oil I get indigestion and burp it all day long. </p><p>Thought I heard of something you could take with it to help that but can’t remember what it was.</p>

  10. Nancy says:

    <p>Dr. Mercola says that there are healthy tanning beds that are a good way to get vitamin D. Do you know there are any in the Franklin/Brentwood TN area?</p>

  11. frannie says:

    <p>I have hypothyroidism (Hashimoto’s autoimmune) and am seeking relief from ten-year-long hip/back pain. I have never had my D3 levels checked. Is there a link between thyroid hormone levels and vitamin D deficiency?</p>

  12. frannie says:

    <p>Oh I forgot to mention I have labral tears, a herniated disc, fai and retroverted hips, but only today did a doc mention that D deficiency might be the true cause of my pain (some people have labral tears that are asymptomatic… pain free)</p>

  13. Joyce Meisenholder says:

    I have just had the thyroid T123 test done. I was told that my labs just before that “might be adjusting themselves” and now that I have had the test, they say that the test “is consistent with a low grade Grave’s disease”. I am to have labs done again in 2 weeks. What natural product is best to take to eliminate the Graves’s disease and get my thyroid back in balance?

    • Dr. Axe says:

      It’s hard to say with Graves disease. It could be caused by heavy metal poisoning, it could be caused by a loss of curve in your neck or disc degeneration, or you may be lacking a nutrient like Iodine.

      But one thing you can do that will help immediately is start following a diet loaded with Real Foods like: Vegetables, Fruits, Beans, Nuts, and Organic Meats.

  14. Shane says:

    Nice blog! Very interesting and informative topic. I’ll look forward for more info. Thanks for the share!

  15. Rachel says:

    I have estrogen domiance & dr’s really don’t know how to treat it, I’ve now been diagnoised with vitamin d deficiancy is there a connection between the two?