It’s no secret that vitamin D is a mighty nutrient that influences various aspects of health. Adequate vitamin D levels have been associated with protection against respiratory infections, cognitive decline, bone disease, depression, autoimmune disease, and even COVID-19.

With all the health benefits vitamin D provides, research shows that over 40% of the U.S. population is deficient, with significantly higher rates seen in Black (82%) and Hispanic (69%) populations. In fact, it is estimated that as many as 1 billion people worldwide may be classified as having insufficient vitamin D levels.

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Why are so many people low in this critical nutrient? It’s simply not easy to obtain in the amounts required to support optimal health. A person can acquire vitamin D through food sources such as eggs, fortified orange juice and milk, some types of mushrooms, and fatty fish. However, some people may not like these foods, some may have allergies, and some may not have access to them at all. Even for those who consume this limited list of foods, most don’t eat them in large enough quantities to meet their vitamin D needs regularly.

The human body can also manufacture vitamin D when the skin is exposed to adequate amounts of sunshine. But due to seasonal changes in sunlight, geographical locations where sun rays are not intense, or avoidance of sun exposure with sunscreen, clothes covering, or long days in the office, many people are not meeting their needs through sunshine exposure either.

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Therefore, it’s no shock that The Council for Responsible Nutrition (CRN) recently found that four in five Americans use supplements and that vitamin D use in particular has increased significantly over the past year. Navigating the supplement industry can be overwhelming and unclear for those who decide that a vitamin D supplement would support their health. It’s critical to learn how to navigate the industry and find the right vitamin D supplement for you.


Determine How Much You Need

The National Institute of Health (NIH) recommends an average daily intake of 600 IU per day for adults up to age 70 and 800 IU per day for adults over 70. However, one must ask, due to the significant variability in individual lifestyle, sun exposure, age, and food intake, is this amount right for everyone?

In the blood, vitamin D is measured in the form of 25-hydroxyvitamin D and is often reported as either nanomoles per liter (nmol/L) or nanograms per milliliter (ng/mL). Research suggests that a circulating level of 25-hydroxyvitamin D greater than 30 ng/mL is required to maintain a healthy level of vitamin D. Other studies indicate levels of 40-60 ng/mL may provide additional benefits, such as cancer prevention.

Furthermore, evidence suggests that higher vitamin D intakes beyond current recommendations are needed to bring most individuals into the desired range, which are associated with better health outcomes. The Endocrine Society confirms these suggestions stating that adults may require 1500 – 2000 IU per day to raise the blood levels of 25-hydroxyvitamin D above 30 ng/mL.

The best way to know how much vitamin D is right for you is to, first, determine your current levels. If you live in a sunny place, spend adequate time outside, and regularly consume foods high in vitamin D, you may need a smaller dose supplement to reach optimal levels.

If you live in a place (or live a lifestyle) that does not allow for time in the sun and eat a diet devoid of vitamin D-rich foods, then a higher dose supplement may be right for you.

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Moreover, the NIH has identified groups more likely to be at risk for vitamin D deficiency. These groups include infants consuming breast milk, older adults, people with darker skin pigmentation, people with obesity, people who seldom go outside, and people with malabsorption conditions. Knowing your vitamin D status could make all the difference if you fall into any of these categories.

To determine your current vitamin D status, you can work with your healthcare provider or take a simple at-home vitamin D test. Once your results are in, a vitamin D calculator can help you determine your individual needs to optimize your vitamin D status. When choosing a supplement, be sure the product provides the vitamin D amount that’s right for you.


Decide What Form is Right For You

Vitamin D often comes in two forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D3 is made in the skin under the influence of UV light. D3 is the form we consume from other animal products such as oily fish, egg yolk, and butter and is also the form we make on our own with sunlight exposure.

Vitamin D2, on the other hand, is derived from plants. It can be found in mushrooms grown in UV light, yeasts and is often used in fortified foods and dietary supplements since it is cheap to produce.

Dietary supplements can contain either vitamin D2 or D3. Vitamin D2 in supplements is manufactured using UV irradiation of ergocholesterol found in yeast and is therefore appropriate if you would prefer a plant-based product. Vitamin D3 in supplements is produced with irradiation of 7-dehydrocholesterol from lanolin, a fatty substance secreted by the skin glands of sheep to condition their wool. Fish oil is another source of vitamin D3 found in supplements.

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Both D2 and D3 have been found to increase blood levels of vitamin D. But there is evidence indicating that vitamin D3 is better. Several studies, including one systematic review, concluded that vitamin D3 raises serum vitamin D concentrations and maintains levels longer than vitamin D2. Therefore, if either option is available to you, vitamin D3 may be the better option for supplementation.


Decide What Route is Best For You

Vitamin D supplementation can commonly be administered via pill, liquid, buccal (between the gum and cheek), or sublingual (under the tongue). Since vitamin D is a fat soluble vitamin, when taken in pill or liquid form, it must go through two steps in order to be absorbed through the aqueous lining of the digestive tract. Therefore, based on the overall health of the person (particularly the gut health), the bioavailability of vitamin D can differ greatly.

If the gut is an issue, some consider buccal or sublingual supplements to be better. Sublingual and buccal medications can be absorbed through the sublingual blood vessels, bypassing the gut. Studies have shown that sublingual vitamin D supplementation is an effective method for those who have malabsorptive issues and persistently low vitamin D levels despite oral supplementation. But is it more effective for those who are clinically healthy?

According to some research vitamin D supplementation through capsule and sublingual spray have been found to be effective and equivalent in healthy subjects. However, other studies have reported a rather large difference in effect.

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One study compared buccal spray to an oral soft gelatin capsule over a period of 30 days. Interestingly, they found nearly two times the increase in serum vitamin D levels in healthy subjects, and nearly three times the increase in serum vitamin D levels in those with malabsorption syndrome in the buccal spray group compared to the gelatin capsule group. These results suggest that the buccal spray formulation had a significantly higher mean increase in both subject groups, healthy subjects and those with intestinal malabsorption syndrome.

Without a clear and definitive answer to what route is most effective, considering compliance may be a good place to start. Since all routes have been found to increase serum levels, start with the route you are most willing to take regularly. If you hate the taste of the sublingual and buccal supplements and can more easily tolerate the gel capsules, start with the gel capsules.

Test your vitamin D levels after a few months of supplementation and if your levels are not where you want them, then maybe try a different dose or route. If you don’t mind the sublingual or buccal administration, you can start there since some research suggests it’s more effective. Again, test after a few months to ensure the route and dose is right for you.


Find a Supplement that You Trust

Once you have determined the amount and type of vitamin D that are right for you, it’s time to narrow down the many supplement companies to find one you trust. Since the U.S. Food and Drug Administration (FDA) does not have the authority to review dietary supplements for safety and effectiveness before they hit store shelves, consumers must do their due diligence to ensure they purchase a safe and effective supplement.

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Independent organizations cumulatively referred to as Third-Party Testing companies are working to provide accountability in the supplement industry. Well-known by athletes working to reduce the risk of consuming illegal supplements, third-party certified products can benefit anyone. A third-party certification includes an audit of the manufacturing process, an evaluation of the product’s quality, and an evaluation of the labeling to ensure it is accurate and compliant with regulation.

The U.S. Anti-Doping Agency (USADA) currently recognizes NSF certified for Sport as the third-party testing program best suited for athletes to reduce risk from supplements. Still, there are several other quality third-party testing companies you can look for. Some other common ones include and USP. When buying a supplement that is third-party tested, you can rest assured that the quality of the product meets the minimum standards, and that the label accurately reflects what is in the bottle.


Understand the Risks

When it comes to vitamin D, more does not mean better. Vitamin D is a fat-soluble vitamin. This means two important things for consumers. First, it’s best when taken with high-fat food, such as avocado.

Second, it can be stored in our body’s fat cells and can potentially become harmful if levels get too high. For this reason, be sure not to exceed the safe upper intake level of 4000 IU per day for adults. It is also recommended you measure your vitamin D status annually and make intake adjustments to optimize vitamin D blood levels over time.

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Additionally, adding any dietary supplement poses a risk if you have certain medical conditions or take other prescribed medications or nutritional supplements. Vitamin D may interact with prescription medications such as Orlistat, cholesterol-lowering statins, steroids, and thiazide diuretics. Be sure to tell your doctor, pharmacist, or other trusted healthcare provider about any dietary supplements, prescription medications, or over-the-counter medicines you take before beginning a new supplement routine.

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These statements have not been evaluated by the Food and Drug Administration. This test is not intended to diagnose, treat, cure, prevent or mitigate any disease. This site does not offer medical advice, and nothing contained herein is intended to establish a doctor/patient relationship. OmegaQuant, LLC is regulated under the Clinical Laboratory improvement Amendments of 1988 (CLIA) and is qualified to perform high complexity clinical testing. The performance characteristics of this test were determined by OmegaQuant, LLC. It has not been cleared or approved by the U.S. Food and Drug Administration.

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