Best Vitamin D Supplements of 2021: Benefits, Side Effects, Foods List and COVID-19

What Is Vitamin D?

Vitamin D is a fat-soluble vitamin, meaning that it dissolves in fats and oils and can be stored in your body for a long time.

Vitamin D is important to the body in many ways. It helps the body absorb calcium from food and supplements. Muscles need it to move, for example, nerves need it to carry messages between the brain and every body part, and the immune system needs vitamin D to fight off invading bacteria and viruses. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Vitamin D is found in cells throughout the body.

best vitamin D supplement malaysia

Benefits of Vitamin D

Here are some potential benefits of vitamin D:
  • Reduced risk of osteoporosis, falls, and fractures. Higher doses of vitamin D can help prevent osteoporosis, falls, and fractures in older adults (Trusted Source).
  • Better strength. Vitamin D can increase physical strength in both upper and lower limbs (Trusted Source).
  • Cancer prevention. Vitamin D may help prevent cancer. One study noted that 1,100 IU per day — alongside calcium — reduced cancer risk by 60% (Trusted Source, Trusted Source).
  • Depression management. Studies show that vitamin D may ease symptoms in people with clinical depression (Trusted Source).
  • Reduced risk of type 1 diabetes. One study in infants linked 2,000 IU of vitamin D per day to a 78% reduced risk of type 1 diabetes (Trusted Source).
  • Improved mortality. Some studies suggest that vitamin D reduces people’s risk of dying during the study periods, indicating that it may help you live longer (Trusted Source, Trusted Source).
However, many of these results are preliminary. According to a recent review, more evidence is necessary to confirm many of these benefits (Trusted Source).

Best Vitamin D Supplements 2021

We have done our research and shortlisted the best for you. The list is based on recommendations by third party organizations, online reviews and popularity on search results and forums.

Here are the best vitamin D supplements that you can buy today.

1. Now Foods Vitamin D3 & K2 (120 Veg Caps)

Around $10.51 > Check Price on Amazon

More than 3,000 customer reviews and a 4.7 out of 5 overall rating on Amazon. As compared to the Sports Research Vitamin K2 and D3, the dose of the vitamin D3 and K2 are lower.
  • 1,000 IU / 45 mcg (D3 / K2) per veg capsule
  • Also has 3 mg of vitamin C per veg capsule
  • Supports Bone Health
  • Plus Cardiovascular Support
  • Non-GMO
  • Family Owned Since 1968
  • GMP Quality Assured

Editor's Note: Most of the Top 10 Vitamin D supplements as listed on the Amazon Best Sellers have dosages that exceed the maximum recommended dose (In USA and UK) of Vitamin D of 4,000 IU. Most of the brands also come in multiple dosages. Do check the label before you purchase.

2. Vitamin D by Nature’s Bounty for Immune Support

Price: $17.10 > Check Price on Amazon

More than 14,000 customer reviews and a 4.8 out of 5 overall rating on Amazon. #3 in Vitamin D Supplements of Amazon Best Sellers.
  • Immune support: 350-count, 2,000 IU Vitamin D3 Softgels for immune health. Vitamin D by Nature’s Bounty may assist the immune system by helping to regulate T and B-lymphocytes. Vitamin D3 is a more potent form of Vitamin D.
  • Strong, healthy bones: In addition to immune support, getting a sufficient amount of Vitamin D is critical to building and maintaining strong bones in adults. It is essential for calcium absorption to help support healthy bones. Nature’s Bounty Vitamin D3 Softgels supplement the Vitamin D your body needs for overall health.
  • Year-round support: Vitamin D3 supplements by Nature’s Bounty contain the same form of Vitamin D that is naturally formed in the body through exposure to sunshine. Nature’s Bounty Vitamin D3 helps replicate the benefits of natural sunshine all year long.
  • Purity is our priority: Nature’s Bounty is committed to safety and purity in all our supplements. Our rapid release Vitamin D3 Softgels are non-GMO, gluten- and sugar-free, and contain no artificial colors, or sweeteners.
  • From the trusted wellness experts: Nature’s Bounty Vitamin D supplements are a product of 50 years of dedication to quality, consistency and scientific research to make vitamins and nutritional supplements of unrivaled excellence.
Vitamin D by Nature's Bounty also come in various other dosages:
Most customers that purchased Vitamin D supplements on Amazon also bought this item: 

What is the difference between Vitamin D and D3?

There are two main dietary forms (NIH):
  • Vitamin D3 (cholecalciferol). Found in some animal foods, like fatty fish and egg yolks.
  • Vitamin D2 (ergocalciferol). Found in some plants, mushrooms, and yeasts.

Of the two, D3 (cholecalciferol) seems to be almost twice as effective at increasing blood levels of vitamin D as D2 (ergocalciferol) (NIHNIH).


Vitamin D Deficiency

Vitamin D deficiency is one of the most common nutrient deficiencies.

Some people are at a greater risk than others. In the United States, 41.6% of the total population is deficient, although minorities fare worse — 82.1% and 69.2% of blacks and Hispanics are deficient, respectively (Trusted Source).

Additionally, older adults are at a much greater risk of being deficient (Trusted Source).

Those who have certain diseases are also very likely to be deficient. One study showed that 96% of people who had experienced heart attacks were low in vitamin D (Trusted Source).

Overall, vitamin D deficiency is a silent epidemic. The symptoms are usually subtle and may take years or decades to surface.

The most well-known symptom of vitamin D deficiency is rickets, a bone disease common in children in developing countries.

Rickets has been mostly eliminated from Western countries because of the fortification of some foods with vitamin D (Trusted Source).

Deficiency is also linked to osteoporosis, reduced mineral density, and increased risk of falls and fractures in older adults.

What’s more, studies indicate that people with low vitamin D levels have a much greater risk of heart disease, diabetes (types 1 and 2), cancer, dementia, and autoimmune diseases like multiple sclerosis (Trusted Source).

Finally, vitamin D deficiency is linked to a reduced life expectancy (Trusted Source, Trusted Source, Trusted Source).

That said, it’s unclear whether deficiency contributes to these diseases or whether people with low levels are just more likely to get them.

Too Much Vitamin D Side Effects

Below are the 6 main side effects of too much vitamin D.

1. Elevated blood levels

Achieving adequate levels of vitamin D in your blood may help boost your immunity and protect you from diseases like osteoporosis and cancer.

However, there isn’t agreement on an optimal range for adequate levels.

Although a vitamin D level of 30 ng/ml (75 nmol/l) is typically considered adequate, the Vitamin D Council recommends maintaining levels of 40–80 ng/ml (100–200 nmol/l) and states that anything over 100 ng/ml (250 nmol/l) may be harmful (Trusted Source).

While an increasing number of people are supplementing with vitamin D, it’s rare to find someone with very high blood levels of this vitamin.

One recent study looked at data from more than 20,000 people over a 10-year period. It found that only 37 people had levels above 100 ng/ml (250 nmol/l). Only one person had true toxicity, at 364 ng/ml (899 nmol/l) (Trusted Source).

In one case study, a woman had a level of 476 ng/ml (1,171 nmol/l) after taking a supplement that gave her 186,900 IU of vitamin D3 per day for two months.

This was a whopping 47 times the generally recommended safe upper limit of 4,000 IU per day.

The woman was admitted to the hospital after she experienced fatigue, forgetfulness, nausea, vomiting, slurred speech, and other symptoms.

Although only extremely large doses can cause toxicity so rapidly, even strong supporters of these supplements recommend an upper limit of 10,000 IU per day (Trusted Source).

2. Elevated blood calcium levels

Vitamin D helps your body absorb calcium from the food you eat. In fact, this is one of its most important roles.

However, if vitamin D intake is excessive, blood calcium may reach levels that can cause unpleasant and potentially dangerous symptoms.

Symptoms of hypercalcemia, or high blood calcium levels, include:
  • digestive distress, such as vomiting, nausea, and
  • stomach pain
  • fatigue, dizziness, and confusion
  • excessive thirst
  • frequent urination
The normal range of blood calcium is 8.5–10.2 mg/dl (2.1–2.5 mmol/l).

In one case study, an older man with dementia who received 50,000 IU of vitamin D daily for 6 months was repeatedly hospitalized with symptoms related to high calcium levels (Trusted Source).

In another, two men took improperly labeled vitamin D supplements, leading to blood calcium levels of 13.2–15 mg/dl (3.3–3.7 mmol/l). What’s more, it took a year for their levels to normalize after they stopped taking the supplements (Trusted Source).

3. Nausea, vomiting, and poor appetite

Many side effects of too much vitamin D are related to excessive calcium in the blood.

These include nausea, vomiting, and poor appetite.

However, these symptoms don’t occur in everyone with elevated calcium levels.

One study followed 10 people who had developed excessive calcium levels after they had taken high-dose vitamin D to correct deficiency.

Four of them experienced nausea and vomiting, and three of them had a loss of appetite (Trusted Source).

Similar responses to vitamin D megadoses have been reported in other studies. One woman experienced nausea and weight loss after taking a supplement that was found to contain 78 times more vitamin D than stated on the label (Trusted Source, Trusted Source).

Importantly, these symptoms occurred in response to extremely high doses of vitamin D3, which led to calcium levels greater than 12 mg/dl (3.0 mmol/l).

4. Stomach pain, constipation, or diarrhea

Stomach pain, constipation, and diarrhea are common digestive complaints that are often related to food intolerances or irritable bowel syndrome.

However, they can also be a sign of elevated calcium levels caused by vitamin D intoxication (Trusted Source).

These symptoms may occur in those receiving high doses of vitamin D to correct deficiency. As with other symptoms, response appears to be individualized even when vitamin D blood levels are similarly elevated.

In one case study, a boy developed stomach pain and constipation after taking improperly labeled vitamin D supplements, whereas his brother experienced elevated blood levels without any other symptoms (Trusted Source).

In another case study, an 18-month-old child who was given 50,000 IU of vitamin D3 for 3 months experienced diarrhea, stomach pain, and other symptoms. These symptoms resolved after the child stopped taking the supplements (Trusted Source).

5. Bone loss

Because vitamin D plays an important role in calcium absorption and bone metabolism, getting enough is crucial for maintaining strong bones.

However, too much vitamin D can be detrimental to bone health.

Although many symptoms of excessive vitamin D are attributed to high blood calcium levels, some researchers suggest that megadoses may lead to low levels of vitamin K2 in the blood (Trusted Source).

One of vitamin K2’s most important functions is to keep calcium in the bones and out of the blood. It’s believed that very high vitamin D levels may reduce vitamin K2 activity (Trusted Source, Trusted Source).

To protect against bone loss, avoid taking excessive vitamin D supplements and take a vitamin K2 supplement. You can also eat foods rich in vitamin K2, such as grass-fed dairy and meat.

6. Kidney failure

Excessive vitamin D intake frequently results in kidney injury.

In one case study, a man was hospitalized for kidney failure, elevated blood calcium levels, and other symptoms that occurred after he received vitamin D injections prescribed by his doctor (Trusted Source).

Indeed, most studies have reported moderate-to-severe kidney injury in people who develop vitamin D toxicity (Trusted Source, Trusted Source, Trusted Source, Trusted Source, Trusted Source, Trusted Source).

In one study in 62 people who received excessively high-dose vitamin D injections, each person experienced kidney failure — whether they had healthy kidneys or existing kidney disease (Trusted Source). Kidney failure is treated with oral or intravenous hydration and medication.

Vitamin D Foods List

Here is the vitamin D3 content of a few of the best food sources (NIH):
FoodAmount% RDI
Cod liver oil, 1 tablespoon (15 ml)1,360 IU / 34 mcg227%
Salmon, cooked, 3 ounces (85 grams)447 IU / 11 mcg75%
Tuna, canned in water, 3 ounces (85 grams)154 IU / 4 mcg26%
Beef liver, cooked, 3 ounces (85 grams)42 IU / 1 mcg7%
1 large whole egg (D is found in yolk)41 IU / 1 mcg7%
1 sardine, canned in oil, drained23 IU / 0.6 mcg4%
Although fatty fish like salmon, mackerel, swordfish, trout, tuna, and sardines are decent sources, you would have to eat them almost every day to get enough.

The only excellent dietary source of vitamin D is fish liver oil — such as cod liver oil — which contains upwards of two times the Reference Daily Intake (RDI) in a single tablespoon (15 ml).

Keep in mind that dairy products and cereals are often fortified with vitamin D (NIH).

Some rare mushrooms also harbor vitamin D, and egg yolks contain small amounts.

Vitamin D and COVID-19

In recent weeks and months, there's been an upshot of studies demonstrating the benefits of vitamin D against COVID-19. The evidence is so compelling, more than 100 doctors, scientists and leading authorities have signed an open letter calling for increased use of vitamin D in the fight against COVID-19.

Based on several publications and studies, vitamin D seems to be the “most promising” supplement for COVID-19 protection. Vitamin D deficiency is known to enhance a process known as the “cytokine storm” (NIH).

Trusted Source).

There are many vitamin D studies underway. You can review the status of these trials on clinicaltrials.gov. As of January 2021, 73 studies have been launched to investigate the benefits of vitamin D against COVID-19.

Two studies in France (C Annweiler, Nov 2020G Annweiler, Nov 2020), one in India (A Rastogi, Nov 2020) and one in Spain (M Castillo, Oct 2020) showed that Vitamin D supplementation seems to decrease the mortality rate, the severity of the disease, and the inflammatory markers' levels among the COVID-19 infected patients, leading to a better prognosis and increased survival.

The largest observational study to date, looked at data for 191,779 American patients who were tested for SARS-CoV-2 between March and June 2020 and had had their vitamin D tested sometime in the preceding 12 months.

Of those with a vitamin D level below 20 ng/ml (deficiency), 12.5% tested positive for SARS-CoV-2, compared to 8.1% of those who had a vitamin D level between 30 and 34 ng/ml (adequacy) and 5.9% of those who had an optimal vitamin D level of 55 ng/ml or higher.

Data from 14 observational studies — suggest that vitamin D blood levels are negatively correlated with the incidence and/or severity of COVID-19; meaning if your vitamin D level is high, your risk for COVID-19 is low and vice versa.

A study published in November 2020 from Singapore (CW Tan, Nutrition 2020), found that those who were started on a daily oral dose of vitamin D3 (1,000 IU), magnesium (150 mg) and vitamin B12 (500 mcg) within the first day of hospitalisation and continued up to 14 days were significantly less likely to require oxygen therapy and further intensive care.

Another study, published in JAMA (JAMA Netw Open - Sep 2020) found that persons who are likely to have deficient vitamin D levels at the time of COVID-19 testing were at substantially higher risk of testing positive for COVID-19 than were persons who were likely to have sufficient levels.

The same team above, has also published a preprint article: A study at the University of Chicago of over 4,000 patients that found that untreated vitamin D deficiency was associated with an increased risk for COVID-19 infection.

study of 20 European countries found a link between low levels of vitamin D and higher percentages of COVID-19 cases and mortality. 

Separately, more than 80% of 200 people hospitalized for COVID-19 in Spain were found to be deficient in vitamin D, according to a study published in October in the Journal of Clinical Endocrinology & Metabolism.

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