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Vitamin D Supplements Are Useless… Or Not

Updated: Sep 7, 2023

Updated Sept. 7, 2023

A recently released study called VITAL initially seemed to put the final “nail in the coffin” regarding the use of supplemental vitamin D. As the accompanying editorial stated, the study showed that vitamin D did not reduce risk of bone fractures, and therefore the authors recommended stopping routine measurement of vitamin D levels.

So, what’s the real story on vitamin D?

In general, there seem to be two schools of thought regarding vitamin and mineral supplementation. The first held by most traditional doctors is that most supplements are useless, poorly regulated, and only result in very expensive urine where most are metabolized and excreted from the body. The second, held by most integrative medicine physicians, is that due to reasons such as reduced nutrient content in our food, poor quality diets of most Americans, and specific genetic abnormalities, there is a need for a specific and broad use of supplemental vitamins and minerals to replace those essential (meaning your body is unable to manufacture them) compounds.

So, which one is it? And specific to vitamin D what is the evidence of benefits?

Vitamin D2 vs. D3

First, be aware that there are two forms of Vitamin D—D2 and D3. Here's a closer look at the different forms and how they might fit into your dietary and wellness needs.

Vitamin D2 (Ergocalciferol)

Vitamin D2 is a form of vitamin D that comes from plant sources, particularly fungi and yeast exposed to ultraviolet (UV) light. It's a suitable option for vegetarians and vegans and is often found in fortified foods like orange juice, cereals, and plant-based milk.


  • Suitable for vegetarians and vegans.

  • Available in many fortified foods.


  • Often considered less effective at raising vitamin D levels in the blood compared to D3.

Vitamin D3 (Cholecalciferol)

Vitamin D3 is the most common form of vitamin D used in supplements and is derived mainly from animal sources, such as fish liver oil, egg yolks, and lanolin from sheep's wool. It is the same form of vitamin D that your body produces when exposed to sunlight.


  • More potent and effective at raising vitamin D levels in the blood.

  • Closer to the natural form produced by the body.


  • Not suitable for strict vegetarians and vegans without specific sourcing (see below for vegan D3 options).

Vegan Vitamin D3

In response to the growing demand for plant-based options, some manufacturers have created vegan D3 supplements derived from lichen. This form of D3 offers a plant-based alternative that retains the efficacy of animal-derived D3.


  • Suitable for vegetarians and vegans.

  • Potentially more effective than D2.


  • Might be more expensive and harder to find than other options.

When it comes to selecting the appropriate vitamin D supplement, it's essential to consider your individual dietary preferences and needs. For those following a strict vegetarian or vegan diet, Vitamin D2 or vegan D3 can be excellent options. If you have no dietary restrictions, Vitamin D3 from animal sources may offer the most benefits.

Remember, supplements are only one part of a comprehensive health strategy. Balanced nutrition, regular sun exposure (when appropriate), and an overall healthy lifestyle are equally important in maintaining optimal vitamin D levels.

Effects of Vitamin D on the Body

Vitamin D is a complex vitamin with multiple effects on our bodies. As with any supplement, it is essential to understand both the potential benefits and risks, especially for specific populations such as the elderly, pregnant women, or those with certain medical conditions.

First, let’s list some of the benefits of Vitamin D supplementation:

  1. Bone Health: Vitamin D regulates the absorption of calcium and phosphorus from the gut and maintains adequate serum levels necessary for bone mineralization. This promotes bone growth and prevents conditions like osteoporosis and rickets. It's particularly beneficial for postmenopausal women, the elderly, and those at higher risk for bone-related disorders.

  2. Immune System Support: One of the vital roles of Vitamin D in the body is its ability to modulate the immune system. This modulation isn't just about amplifying the immune response but ensuring that it operates in a balanced way. By doing so, Vitamin D enhances the body's ability to fend off pathogens, thereby potentially reducing susceptibility to infections.

  3. Reduction of Inflammation: Vitamin D plays a role in reducing inflammation within the body, which is essential in the management and prevention of chronic inflammatory conditions.

  4. Mood and Mental Health: Some studies suggest that vitamin D can improve mood and reduce symptoms of depression and anxiety. There is emerging research that the brain and immune system communicate continuously, with each influencing the other's function. For instance, chronic inflammation, a sign of an overactive immune system, has been linked to conditions like depression and cognitive decline. With Vitamin D playing a role in immune regulation, ensuring optimal levels might contribute to better mental health and cognitive function.

  5. Cellular Health and Cancer Prevention: Vitamin D modifies the encoding of proteins that regulate cell proliferation, differentiation, and apoptosis (cell death). These regulatory effects have significant implications for the prevention and treatment of cancer by ensuring that cells grow, differentiate, and die in a controlled manner.

  6. Chronic Disease Prevention: Beyond its role in cancer prevention, vitamin D may prevent other chronic diseases, such as cardiovascular disease.

  7. Regulation of Glucose Metabolism: By regulating glucose metabolism, vitamin D plays a role in maintaining healthy blood sugar levels. This regulation may have implications for diabetes management and prevention.

  8. Pregnancy Support: Adequate vitamin D levels are vital for a healthy pregnancy, aiding in fetal development and possibly reducing the risk of complications like pre-eclampsia.

All of these seem to be pretty important, so how do we determine if we have enough Vitamin D? As is said, in life nothing is easy!

Vitamin D levels measure 25, hydroxyvitamin D. Vitamin D can be ingested from multiple sources of foods and dietary supplements. It can also be produced by exposure to ultraviolet radiation in your skin. It is known as calciferol which is then converted to 25 hydroxy vitamin D in the liver. It undergoes a special conversion in our kidneys to 1, 25 hydroxyvitamin D, also known as calcitriol. This is the biologically active form of the vitamin.

Measuring vitamin D levels involves a simple blood test. It actually measures the level of 25 hydroxyvitamin D since the active form of 1, 25 hydroxyvitamin D fluctuates rapidly due to day to day metabolic demands. The measurement is usually expressed as nanograms per milliliter (ng/ml) but can also be shown as nanomoles per liter (nmol/l) just to increase confusion. Here are the values considered to be normal from the NIH Fact Sheet:

There is an ongoing debate regarding what is considered normal and what are considered optimal levels for your metabolism. According to the American Endocrine Society, levels below 20 ng/ml are considered deficient. Some recommend levels of 50 to 70 ng/mL as the ‘optimal range’.

In a study conducted by the Mayo Clinic, there was one adverse effect seen due to supplementation. This was in a person that was taking 50,000 units per day for three months. That is an extraordinary dose since most supplements are in the 1,000-5,000 units per day range (or 25-125 mcg). A study of breast cancer patients showed an 87% reduction of risk in those with levels greater than 60 versus less than 20 ng/ml.

So back to the headline study, the one that showed no benefit of supplementation of vitamin D for fractures. An excellent analysis done by Dr. Peter Attia’s team, which points out several deficiencies in the study, is here.

Combine this with the large volume of published studies showing patients with adequate vitamin D levels versus suboptimal:

  • Reduction in cancer deaths here

  • Reductions in mortality from Covid here

  • Reduction in rates of depression here

  • Reductions in rates of dementia here

  • Improvement in symptoms from rheumatoid arthritis here

  • Impact on insulin sensitivity here

While the literature will continue to define specific patients who will benefit from Vitamin D supplementation, I tend to follow what is called the precautionary principle. The precautionary principle is a useful strategy for decision-making when physicians and patients lack evidence relating to the potential outcomes associated with various choices. According to a version of the principle, one should take reasonable measures to avoid threats that are serious and plausible.

For example, it’s important to consider some of the well-known risks of Vitamin D Supplementation:

Risks of Vitamin D Supplementation

1. Toxicity: Taking vitamin D in excessively high doses can lead to toxicity, causing nausea, vomiting, weakness, and serious issues like kidney damage. This is a particular concern for those who may already have high levels of vitamin D in their system.

2. Interaction with Other Medications: Vitamin D may interact with certain medications, including some that affect heart rhythm or blood pressure. If you're taking medication, it's essential to consult your healthcare provider before starting supplementation.

3. Potential Overabsorption of Calcium: While vitamin D helps with calcium absorption, too much can lead to hypercalcemia, a condition characterized by high levels of calcium in the blood. This can result in kidney stones and cardiovascular issues.

4. Not Suitable for Certain Medical Conditions: Individuals with conditions like sarcoidosis, tuberculosis, or lymphoma may be more susceptible to vitamin D toxicity and should exercise caution with supplementation.

There are also considerations for specific populations:

  • The Elderly: As people age, the skin's ability to synthesize vitamin D decreases. Supplementation may be beneficial but should be carefully monitored to avoid toxicity.

  • Pregnant Women: While vital for a healthy pregnancy, vitamin D supplementation should be approached with care and always under the guidance of a healthcare provider.

  • People with Chronic Kidney or Liver Disease: These individuals may not convert vitamin D to its active form effectively and may require specific forms of the supplement.

With these considerations in mind, my opinion is that the use of Vitamin D supplementation is consistent with minimizing risk and maximizing benefit when the information is conflicting.

My recommendation: get your Vitamin D Level checked and supplement if under 30 ng/ml.

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