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The Diseases of Low Vitamin D and How to Avoid Them

Do you supplement with 2000-5000 International Units (IU) of vitamin D each day? Or, do you use your lunch hour to lie in the sun in just a loincloth? If not, you’re likely low in vitamin D.

More than half of the world’s population is deficient in vitamin D, and as many as four out of five in the United States may be below optimal levels.

Low blood levels of vitamin D increase risk factors for diabetes, arthritis, dementia, and bone loss. You could also be increasing your risk of viral infections, like the flu.

Fortunately, the most common micronutrient deficiency in the world is easily preventable. High-quality supplements are inexpensive, and if you live in the right latitude, you can get a healthy dose from moderate mid-day sun exposure.

After reading this article, you’ll understand why vitamin D is one of my Foundational Five, the best supplements for foundational health.

In all my many years of practice of medicine, I’ve never seen one vitamin, even vitamin C, have such a profound effect on human health.

Dr. Soram Khalsa, board-certified internist and medical director of the East-West Medical Research Institute

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What is Vitamin D?

Vitamin D is actually a prohormone, not a vitamin. It influences the expression of more than 200 genes and acts as a precursor to hormones such as DHEA and cortisol.

The active form is called 25-hydroxy vitamin D, or 25(OH)D.

You consume vitamin D in two forms: ergocalciferol (D2) and cholecalciferol (D3). However, even if you consume fortified foods like orange juice or milk, you’ll fall woefully short of optimal cholecalciferol intake.

Ergocalciferol comes from plants. Humans cannot convert it to cholecalciferol very well.

Cholecalciferol comes from animals and is superior to ergocalciferol at improving vitamin D status. The best food sources include fatty fish, beef liver, and cod liver oil.

Of course, food and supplementation aren’t the only ways to raise 25(OH)D. Since the time of Adam and Eve, humans relied on sun exposure.

In ancient Egypt, Greece, Rome, Babylon, and Persia, sunlight (heliotherapy) prevented and treated various medical conditions.

Juzeniene A, et al.

When the sun reaches your skin, the UVB rays stimulate the production of 25(OH)D. Of course, sunblock prevents this production.

To benefit from the sun’s rays, you need to live close to the equator and expose most of your skin to the mid-day sun for 20-30 minutes. That would give you about 10,000 IU, or 200 times the amount in a glass of fortified milk.

Some practitioners believe exposing your private parts to the sun is the best way to get vitamin D to levels to rise. I have no personal experience, but if you have the right place to try nude sunbathing, go for it.

A lack of sun exposure limits the amount of vitamin D in your body, but other factors reduce its production, as well.

For example, melanin blocks UV rays, and UV rays stimulate vitamin D production. As a result, those with darker skin produce less vitamin D than those with lighter skin when exposed to the same amount of UV light.

Liver and kidney dysfunctions compromise the conversion of cholecalciferol to active vitamin D. Also, certain medications like statins and plant compounds interfere with absorption.

Cholesterol and vitamin D are absorbed in similar ways. Medications and plant compounds that interfere with cholesterol uptake also interfere with vitamin D absorption.

Effects of Low Vitamin D

Since vitamin D affects almost every body system, it’s no surprise that low levels can lead to catastrophic consequences.

The Flu

The role of vitamin D in supporting your immune system cannot be understated.

A British doctor named R. Edgar Hope-Simpson first connected low 25(OH)D to the flu. He observed that in both hemispheres, cases of the flu rise in late fall and early winter, which is the same time when levels drop from their summertime high. His observations were correct.

In one study, supplementing with 2000 IU of cholecalciferol has been shown to lessen the occurrence of cold and flu symptoms.

In another study published in 2010, children in Japan took 1200 IU of cholecalciferol or a placebo from December 2008 through March 2009. At the end of the study, 18.6% of the placebo group and 10.8% of the vitamin D group got the flu.

That’s a 42% reduction, using an amount that still isn’t enough to reach optimal levels in most people.

Interestingly, the CDC found that flu shot was only effective in 23% of people who got it based on 2014 data.

Read More: Are You Going to Get a Flu Shot?

Insulin Resistance and Diabetes

Excessive carbohydrate consumption causes insulin resistance and diabetes. Low vitamin D makes it harder for your body to handle carbs, making it more likely you’ll develop carbohydrate intolerance.

Research shows low vitamin D increases the risk of developing metabolic syndrome by 52%.

Raising levels in those with insulin resistance has been shown to reduce symptoms of insulin resistance.

Not surprisingly, obese people tend to have the lowest levels, and since insulin resistance and obesity are often tied together, optimizing vitamin D may help improve body composition.

Of course, it won’t do it alone. You still need to follow a well-designed nutrition and exercise program.

Read also: The Ultimate Guide to Keto.

Heart Disease

Vitamin D reduces the buildup of cholesterol in macrophages, white blood cells that attempt to repair damaged heart tissue. Without sufficient D, the macrophages turn into foam cells, laying down fatty deposits and causing atherosclerosis.

Interestingly, some statins increase vitamin D levels, which could be one way statins improve patient outcomes. I’m not saying statins are appropriate for everyone, by the way.

Osteoporosis, and Bone Fractures

Calcium has been the poster child for bone health for decades. Yet, without sufficient magnesium and vitamins K and D, taking tons of calcium is pointless. In fact, excessive calcium supplementation without magnesium, D, and K could lead to significant health problems.

Vitamin D mediates calcium absorption. And don’t forget, high-protein diets also support better bone health.

Pregnancy and Cognitive Function

A 2020 study published in The Journal of Nutrition showed that mothers with higher vitamin D levels during pregnancy had children with higher IQs when measured at 4-6 years old.

Other Effects Of Low Levels

The following is part of a growing list of complications connected to low vitamin D.

  • Atopic dermatitis
  • Cancer

This is like the Holy Grail of cancer medicine; vitamin D produced a drop in cancer rates greater than that for quitting smoking, or indeed any other countermeasure in existence.

Dennis Mangan, clinical laboratory scientist

Vitamin D is a precursor to adrenal steroid hormones, including DHEA, androstenedione, and cortisol.

  • Decreased strength
  • Increased body fat
  • Low birth weight of newborn babies
  • Multiple sclerosis
  • Psoriasis
  • Rheumatoid arthritis
  • Schizophrenia
  • Type I diabetes

Read also: How Vitamin D Affects Testosterone Levels.

What Are Optimal Vitamin D Levels?

The table below shows the risk ranges typically referenced by doctors and lab testing companies.

Risk Category ng/mL nmol/l
Deficient <20 <50
Insufficient 20-29  50-72
Adequate >30 >73

Unfortunately, these levels should have been thrown out with tube TVs. The term “Adequate” should probably be replaced with “Survivable,” and definitely shouldn’t be mistaken for “Sufficient.”

The Vitamin D Council recommends the following ranges based on the most current research.

Risk Category ng/mL nmol/l
Deficient <40 <100
Sufficient 40-80  100-200
High Normal 80-100 200-250
Undesirable 100-150 250-375
Toxic >150 >375

Remember, the average person’s blood level is only 16-25 ng/mL

If your doctor won’t order a lab test for you, find another doctor, or just order a vitamin D test yourself.

How to Choose a High-Quality Supplement

As I mentioned above, you’ll find two forms of vitamin D in dietary supplements:

  1. Vitamin D2 (ergocalciferol)
  2. Vitamin D3 (cholecalciferol)

D2 comes from plants, so vegan supplements contain this form. However, it’s incredibly ineffective.

Supplementing with D2 to raise your blood vitamin D levels would be like using an eyedropper to get rehydrated after a trek across the desert. Don’t waste your time and money, even if it’s “vegan.”

To become 25(OH)D, you must convert D2 to D3. The human body doesn’t make that conversion well.

Not all cholecalciferol is the same. Pure cholecalciferol is incredibly small. It’s so tiny that raw material suppliers usually dilute it to make it easier to work with.

Most of the time, they dilute cholecalciferol with lactose, BHT, BHA, sodium benzoate, or sorbic acid.

Here’s where it can get misleading. Since the raw material the supplement company orders is cholecalciferol, and the lactose is only included to dilute the nutrient, the lactose does not need to be disclosed on the finished product label.

When you buy cheap vitamin D, it’s probably diluted with lactose or one of the other questionable materials mentioned above. If you have lactose intolerance, you could end up scratching your head, wondering why you have constant diarrhea even though you don’t consume milk.

To maintain optimal levels, the Vitamin D Council recommends:

  • Children: 1000 IU per 25 pounds of body weight
  • Adults: 5000 IU including pregnant and breastfeeding women
  • Upper limit (for us Northerners): 10,000 IU per day

Frequently Asked Questions

What are the best sources?

The best sources are exposure to sunlight (without sunblock) and dietary supplements. You also get some from cod liver oil, fatty fish, beef liver, and fortified foods, though your vitamin D intake won’t be enough even if you eat these regularly.

How much vitamin D should you get? 

Your daily need varies based on your sun exposure and skin type. However, most people need much more than the 400IU-800IU, which is common in fortified foods.

The Vitamin D Council suggests about 5000 IU per day for most people.

Are vitamin D supplements vegan?

Most vitamin D comes from the skin of fish or sheep’s wool, so it is animal-sourced. However, it’s possible to get it from plants called lichens, so more companies will likely offer this type to satisfy the vegan market’s needs.


If you scrolled right to the bottom of this article looking for the summary, here are the key points you need to know:

  • You are very likely low in vitamin D, and it can compromise your health in a myriad of ways, from body composition to cardiovascular health and cancer, and fighting off the flu to reducing fracture risk.
  • Your doctor should be more than willing to test your levels, and if he or she won’t, find a different doctor or order your own lab testing.
  • If you were hoping to find a good food source of cholecalciferol, there isn’t one.
  • To optimize your levels, move near the equator and lay out in the sun for a half hour each day in your loincloth, or for better results, bare naked. Or, start supplementing with a high-quality supplement.

Read also: The Foundational Five: The Best Health Supplements for (Almost) Every Body.

View References

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