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Vitamin D: Important to have, but hard to get

Updated: May 29, 2020

This micro-nutrient deserves its own article, and you’ll soon see why. It is one of the most important nutrients that every cell in our body needs, but unfortunately it is very hard to get. Almost half of Americans are deficient in Vitamin D. Therefore I recommend everyone take Vitamin D supplement, and this is why:


There are different forms of Vitamin D. Vitamin D2 is called ergocalciferol, and it is found in the skin and plant products. Vitamin D3 is called cholecalciferol, and is found in animal products. But this isn’t even the form the body uses. The liver changes D3 to 25-D3, and this is the storage form of the vitamin. When vitamin D is needed, the liver releases it to the blood, and then the kidney and other cells convert that to 1, 25-D3 which is called calcitriol. Calcitriol is like a hormone, it can go into the cells and make changes and help cells find balance.


I think of vitamin D as the hormone that helps every cell find balance. It’s most famous for its role in the bones: regulating how calcium is used, and regulates bone growth and bone remodeling. But it also helps all cells in the body. It helps cells know when to grow, but not grow too much, and when there is too  much growth it tells some cells to die. It helps immune cells know what and when to attack. It helps muscle cells know when to contract, but not too much. It helps glands know when to secrete hormones, but not too much. It helps the brain know what chemicals to release and how much. And we are learning more and more about the effects of vitamin D on regulating cells and systems in the body. So as you can imagine, when there isn’t enough vitamin D, these cells and systems can get out of balance, not work right, and can lead to dysfunction and disease.

Acute deficiency

If the human body gets very little vitamin D, the first thing it effects is calcium. Low calcium levels cause the bones to soften. In kids this is called rickets. In adults it causes osteoporosis. With severely low levels, the calcium can get so low that seizures happen.

Chronic deficiency

If the body doesn’t get enough vitamin D for a long time, the cells don’t work as well. It can increase the body’s risk of getting certain diseases, such as high blood pressure and autoimmune disorders (such as multiple sclerosis and rheumatoid arthritis).  New research is emerging about vitamin D’s role in preventing disease, right now there is evidence for a connection with 200 conditions.

Now going back to my very first article: chronic disease typically have 2 hits. One is usually a genetic predisposition, and the 2nd is usually environmental. For some people who have a genetic predisposition, low vitamin D could possible be the 2nd hit that causes disease. Not only can vitamin D help prevent disease, it can also be used to help improve disease. It is true: you are what you eat, and food can be medicine!

All cells: Vitamin D helps with cell regulation of growth and death. When cells do not have regulation of growth and death, then cancer can occur. Therefore vitamin D can help decrease risk of cancer. Vitamin D and cancer

Bone: As mentioned above, vitamin D is important for calcium and bones.

Immune system: Vitamin D is used in immune cells to help regulate when an immune cell “attacks” and when it doesn’t. Low vitamin D can increase infection and autoimmune disease because the cells don’t know when to attack and when not to. Vitamin D and Autoimmune disorders

Pancreas: Vitamin D is used to help regulate release and response to insulin, so low levels can increase risk of type II diabetes. Vitamin D and diabetes

Cardiac: Heart and blood vessel muscles use vitamin D to know how much to contract. Low levels of vitamin D can cause an imbalance in blood vessel contraction causing high blood pressure and increased risk of heart attacks. Vitamin D and Heart

Muscle: Just with heart and blood vessel muscles, skeletal muscles use vitamin D

Brain: We are starting to learn that the brain uses vitamin D to balance the chemicals used to signal. Vitamin D increases levels of chemicals such as dopamine and serotonin that helps to improve mood. This maybe a contributing factor for seasonal affective disorder, the increase in depressive and anxiety symptoms in the winter when less sun is exposed. Vitamin D and depression

Research has also demonstrated that vitamin D helps older people with brain function. Vitamin D has a variety of brain protection roles, including helping to rid the brain of beta-amyloid, an abnormal protein that is believed to be a major cause of Alzheimer’s disease. An international study showed that seniors with very low levels of vitamin D are at twice the risk of Alzeimer’s disease. (

Weight regulation: Vitamin D is important to the effectiveness of leptin, the appetite hormone that tells you when you are full. When vitamin D is low, it is harder to feel full. When vitamin D levels are replenished and back to normal levels, leptin’s actions are restored, thus creating feelings of satiety and aiding in weight loss.

It is estimated that 43% of Americans do not have an adequate blood level of Vitamin D. As you can see, that may be contributing to America’s high rate of obesity, depression, heart disease, cancer, diabetes, autoimmune diseases, etc.


I warned you getting vitamin D naturally is difficult, and you are about to find out why.  There are basically 4 sources: the sun, animal fat, fortified foods, and some plants. But it is more complicated than that!

It is difficult to get from the sun: light skinned people would have to spend 2 hours a week outside in the sun with majority of skin exposed without sunscreen. The average American spends 93% of their time indoors, and sun through windows doesn’t increase vitamin D as well. Darker skin people would have to spend even more time since their pigment reflects the sun’s rays. It also depends where you live: the further away from the equator the less sun rays get to the earth’s surface. Interestingly, years ago it was noted autoimmune diseases (such as multiple sclerosis) and cancer rates were highest in places further away from the equator. We now know sunlight and vitamin D was the reason! But direct sun exposure causes skin cancer (especially with less ozone layer to filter out harmful rays), so we need to wear sunscreen or clothing to prevent direct sun. But only direct sun increases vitamin D.  Therefore direct sunlight is not the best way to get vitamin D because the benefit of too much direct sun exposure to get vitamin D is not worth the skin cancer risk.

It is also hard to get in food. Vitamin D is a fat soluble vitamin, so it is found in fat. Fat from aquatic animals and egg yolks contain vitamin D. But how the animal was raised makes a difference. Fresh caught salmon contains 3-4 times as much vitamin D as farmed salmon. Free range chickens who get enough sun may have good amount of vitamin D, but chicken that is in a livestock building without access to sun will not have vitamin D. Fortified food is another source. Some of our food and processed food is fortified: dairy and cereals have some vitamin D. But without being in fat, it may not be absorbed very well.

There are some plant based sources, such as mushrooms and algae. But most of these are in the D2 form which is hard for the body to turn into the D3 form, so it isn’t as good at helping active form levels.

For this reason I advise everyone to take at least 400-600 units of vitamin D per day. And depending on your diet and sun exposure, even more maybe needed. The goal blood level of 25, D3 is 30-50 ng/ml. Research shows that consuming 1,000 IU daily would help 50% of people reach a vitamin D blood level of 33 ng/ml. Consuming 2,000 IU daily would help nearly everyone reach a blood level of 33 ng/ml.

Since it is a fat soluble vitamin, it can be stored in our liver, and at high amounts for a long time can be toxic. But it is very rare, it would take daily intake ranging from 40,000–100,000 IU for several months to be toxic. Also it is impossible to get too much vitamin D from sunlight, so not to worry when you’re on a beach vacation (but you should be wearing sunscreen anyways;)


As you can see it is very hard to get enough vitamin D naturally from sun and food. Therefore I recommend everyone take a supplement. But as usual, it is deeper than that. You have to make sure it is Vitamin D3, cholecalciferol. That is the form that is best at raising body’s levels of the active form of vitamin D.


Infants who are fed less than 34 ounces of fortified formula (exclusively breastfeeding, or feeding small amounts of formula), need to be supplemented with at least 400 units of vitamin D. AAP Prevention of Vitamin D deficiency

Besides infant formula, there isn’t a reliable way for children to get the right amount of vitamin D. Basically anyone not drinking 1 liter of fortified infant formula needs to take at least 400 units of vitamin D3 per day! I personally have me and my family take 1000-2000 units per day. And I recommend people with conditions such as asthma and psoriasis, to take at least 2000 units per day.


I also recommend people be informed consumers. Supplements are not as regulated as medications, so just because it says something on the label, may not mean that is what or how much is in it. Research the company and make sure they are reputable. One company our practice recommends is Metagenics. The products are backed by science and verified by 3 independent organizations.


I hope I demonstrated that vitamin D is important and hard to get. Low levels of vitamin D in the standard American diet maybe one of the factors contributing to the increase in chronic disease in America. So take 400-2000 units of vitamin D3 supplement everyday!

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