Last updated: August 27, 2021

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Have you ever wondered if you should add a vitamin D supplement to your diet? In this article, we've gathered the latest and most important information about this essential molecule, so that you can learn everything you need to know about it. Keep reading to get answers to all of your questions, and to see which product might be most suitable for you.

Vitamin D promotes calcium absorption, making it a critical part of maintaining healthy bones. It also plays a crucial role in cellular metabolism, muscle function and defending your body from infection. These days, many people suffer from a deficiency in vitamin D, in part due to less frequent exposure to sunlight.

Key Facts

  • Vitamin D regulates calcium absorption and the growth of a healthy skeleton. Most of the vitamin D that our body is able to synthesise comes from natural exposure to the sun.
  • Of course we also have access to vitamin D from certain foods (like fish) and supplements.
  • Vitamin D deficiency can cause growth issues in children (also known as rickets). In adults, it can result in osteoporosis and raise the incidence of metabolic, neurological or cardiac diseases.

Our Selection: The Best Vitamin D Supplements on the Market

There are dozens of different vitamin D supplements available. It can take days of research before you feel ready to settle on one, so we designed this next section to make the process easier for you. We picked out the the very best vitamin D supplements in several categories. We hope you'll find something that's just right for you.

Buyer's Guide: Everything You Should Know About Vitamin D

Vitamin D facilitates proper calcium absorption and supports healthy bones. It also serves an important role in maintaining your cardiac, neurological and metabolic health. Studies have shown that up to 50% of the global population may be deficient in vitamin D, due to a lack of sun exposre and nutrient-poor diets.

Also known as the “sunshine vitamin”, vitamin D is crucial to a healthy body.(Source: Puhha: 54194400/

What exactly is vitamin D?

The word “vitamin” refers to a group of molecules that are essential, in small quantities, for proper bodily functions. Vitamins are often obtained directly through the foods in our diet, and they regulate the function of various hormones and enzymes.

Vitamin D, in particular, is a compound with a cholesterol-derived structure. A handful of different kinds of vitamin D have been identified; they're numbered from 1 to 5. The human body can utilise vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), so any supplement containing “vitamin D” will include one of these two molecules.

The primary difference between the two is that vitamin D2 comes from foods of plant origin, while vitamin D3 is derived from foods of animal origin. Because our skin can synthesize cholecalciferol (D3) following sun exposure, some scientists consider the molecule a hormone rather than an essential vitamin.

What does vitamin D do for the body?

Vitamin D does more than just support bone health. In recent years, scientists have discovered that vitamin D is also crucial for regulating a number of other body processes. This molecule is key to keeping our heart, brain and defenses in tip-top shape.

The following table outlines some of vitamin D's primary functions:

System Function
Skeletal Calcium absorption in the intestines. Formation of new bone and replacement of damaged bone.
Muscular Heightened strength during muscular contraction.
Cardiovascular Arterial dilation and lower blood pressure.
Renal Regulation of the renal function. Control of calcium and phosphorus levels.
Reproductive Formation of sex hormones (estrogen and testosterone).
Immune Activation of the defense system. Regulation of autoimmunity.
Nervous Neural protection. Mood stabilisation.

Scientists still don't know all of the functions of vitamin D. Still, a number of studies link vitamin D deficiency with a negative impact on various organs. This vitamin is therefore essential to human health.

How does the body absorb vitamin D?

As we mentioned earlier, vitamin D enters the body either through the food you consume or through synthesis following exposure to sunlight. The inactive vitamin D molecule needs to go through a series of reactions before the body can use it. The active form of vitamin D is a hormone known as calcitriol.

The two organs that take part in the activation process are the liver and kidney. Always consult your doctor prior to taking a vitamin D supplement if you suffer from any condition that impacts the function of those organs.

Your body may be unable to activate vitamin D molecules. In such cases, vitamin D2 or D3 supplementation needs to be supervised by a healthcare professional.

Sun exposure is certainly the most efficient way to achieve an optimal daily intake of vitamin D. However, not everyone get's outside as much as they want to or should. Alternatively, you can eat foods rich in vitamin D or add a supplement to your diet, in order to ensure that your vitamin D levels are normal.

Were you aware that vitamin D is a fat-soluble vitamin that is stored in the body's fatty tissues?

How does sunlight impact vitamin D levels?

Whenever type-B ultraviolet light hits your skin, a chemical reaction takes place that transforms cholesterol into vitamin D3. Although it varies according to several factors, experts normally recommend that you get at least ten to fifteen minutes of sunlight each day.

Synthesis is impacted by age and skin complexion; the older you are and the more pigmentation you have, the less cholecalciferol you will produce. Other factors may affect your vitamin D intake, such as the use of sunscreen, as well as weather conditions and time of year.

That's why the amount sunlight exposure required for each individual can vary. We suggest that you do some research to calculate what the ideal exposure time for you will be.

If you can't spend enough time in the sun, then a supplement may be necessary to achieve your ideal cholecalciferol intake.

What is the recommended dose of vitamin D?

The concentration of active vitamin D in the blood is measured in micrograms (μg) or nanograms (ng). Health professionals advise maintaining those levels above 30 ng. The amount of vitamin D2 or D3 required to reach a suitable calcitriol concentration is measured in International Units (IU):

Population group Recommended daily dose
Infants, 0-6 months 400 IU
Babies, 6-12 months old 400 IU
Children, 1-3 years old 600 IU
Children, 4-8 years old 600 IU
Teens, 9-18 years old 600 IU
Adults up to 70 years old 1,000 IU
Seniors over 70 years old 1,000 IU

As you can see in the table, the suggested daily dose of vitamin D goes up with age. The growth phase during adolescence also calls for vitamin D to support the development of strong bones. Those over 70, meanwhile, need higher doses of vitamin D to maintain a healthy immune system, as well as healthy muscles and bones.

Which foods contain vitamin D?

Food generally provides the body with smaller quantities of vitamin D than direct exposure to the sun. Nonetheless, some food groups offer significant amounts of this vitamin. As mentioned previously, cholecalciferol (D3) is present in foods of animal origin, while ergocalciferol (D2) is found in foods of plant origin.

The foods most rich in vitamin D come from animals. Oily fish, egg yolk and liver (chicken or veal) have an especially high cholecalciferol content. Vegetables, meanwhile, tend to have relatively small quantities of vitamin D, so vegans usually need to seek out alternative sources, such as artificially enriched foods.

Food Type of vitamin D Approximate concentration (IU)
Cod liver oil (1 tbsp.) D3 500
Salmon (75 g) D3 350
Tuna D3 150
Sardines ( 75g) D3 145
Fortified vegetable drink (250 ml) D2 (vegan) 100
Egg yolk (unit) D3 45
Fortified margarine (1 tbsp.) D2/D3 30

Vegans and vegetarians should note that ergocalciferol isn't absorbed by the body as well as vitamin D of animal origin. Luckily, supplements and fortified foods are widely available and can provide sufficient amounts of this molecule. For example, some mushroom species that are cultivated possess up to 200 IU of vitamin D per 100 g.

Vitamin D regulates hormone production, including that of insulin.(Source: Baibakova: 61624754/

Who is impacted by vitamin D deficiency?

Vitamin D deficiencies affect a significant part of the global population. Some studies estimate the figure to be 30% of the population, while others estimate that up to 80% of people are deficient in calcitriol. Sedentary lifestyles and limited sun exposure are the culprits behind this unfortunate phenomenon.

The following groups are most at risk of vitamin D deficiency:

  • Adults over the age of 55: The skin's ability to synthesise cholecalciferol decreases with age.
  • Office workers and students: These groups often spend most of their time inside and don't get sufficient exposure to sunlight.
  • People with darker skin: Higher amounts of melanin in the skin hinder vitamin D production.
  • Vegans and vegetarians: Ergosterol is more difficult to absorb and use than vitamin D from animal origins.
  • People who often use sunscreen: Sunscreen blocks UVB rays, thereby preventing the formation of vitamin D.
  • People with chronic intestinal diseases: Such diseases may limit the absorption of vitamin D in the digestive tract.

How does vitamin D deficiency manifest itself?

It has long been known that hypovitaminosis D can result in changes to bone metabolism. A lack of vitamin D results in difficulty with the absorption of calcium and phosphorus. This impacts the function of the parathyroid gland and the development of new bones.

Students and office workers who spend most of their time inside are at higher risk of vitamin D deficiency.(Source: Gstockstudio: 53684166/

Recent studies suggest that vitamin D deficiency is connceted to a more extensive symptomatology. Subjective feelings of drowsiness and fatigue can be early signs for some, while daily headaches that can't be explained by other illnesses are also linked to a lack of calcitriol.

The list below outlines some symptoms that may be connected to low vitamin D levels:

  • Onset osteoporosis, osteomalacia and rickets in children
  • Bone pain (particularly in the lower back)
  • Frequent infections
  • Achy muscles
  • Depression
  • Fatigue accompanied by headaches
  • Dementia
  • Wounds slow to heal
  • Hair loss or baldness
  • Potential increase in cancer risks
  • Heightened severity of autoimmune diseases

Who should take vitamin D supplements?

There is some debate among experts regarding who should take vitamin D supplements. Because so many people are believed to have deficiencies, some suggest that the entire population should take vitamin D supplements, while others believe that supplements should only be taken by the following groups:

  • People over the age of 55
  • Those with darker skin, particularly if they spend a lot of time inside
  • Vegans and vegetarians
  • Pregnant women (under medical supervision) and postmenopausal women
  • Office workers, students and others with limited exposure to sunlight
  • Anyone who has had bariatric surgery
  • Teens who spend significant time indoors
  • People with cardiovascular problems (heart failure, hypertension)
  • People with obesity
  • People with a diet poor in vitamin D
  • People with kidney failure
Dr. Miguel Sanchez VieraDirector of the Institute of Integral Dermatology
"The groups that truly need vitamin D are precisely those that most protect themselves from the sun, such as babies, seniors and pregnant women."

What can vitamin D supplements do for me?

Studies have indicated a link between decreased mortality from various causes and proper vitamin D levels. Much research has shown a lower incidence of osteoporosis, osteomalacia and rickets, with the appearance of other benefits connected to the activity of calcitriol at the neuronal, muscular and cardiovascular levels:

  • Improved strength and endurance
  • Lower occurrence of infections (flu and colds)
  • Lower incidence of fatigue
  • Subjective feeling of well-being
  • Boost in mood; relief from depression
  • Better control of autoimmune diseases (such as lupus)
  • Heightened memory and concentration
  • Improved control of blood pressure
  • Lower BMI, abdominal perimeter and LDL cholesterol ("bad" cholesterol)
  • Slower progression of degenerative diseases (such as aged-related macular degeneration)

Can I take too much vitamin D?

Vitamin D is a fat-soluble molecule, so it's stored in the body's fat tissues and is hard to remove. Taking excessive amounts can therefore result in intoxication. This is different from water-soluble vitamins like vitamin C, which is excreted with urine.

You should not exceed 4,000 daily IU of vitamin D unless directed by a doctor. If you do, some consequences that might occur include vomiting, weakness, renal colic and arterial calcifications. That said, sun exposure only provides the necessary amount of the vitamin and has not been associated with cholecalciferol poisoning.

Ken CederFormer Co-Director, Hippocrates Health Institute
“Light is the basic component from which all life originates, evolves and is energised. Light and health are inseparable.”

What are the different kinds of vitamin D supplements?

As we mentioned aboce, over-the-counter vitamin D supplements will contain either vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol). These vitamins are processed by the liver and kidneys, leading to the active form of vitamin D (calcitriol). An heightened risk of intoxication is linked to calcitriol, so it's only available by prescription.

  • Vitamin D3 (cholecalciferol): This molecule comes from animal products and requires sun exposure to be synthesised in the skin. Because it is the most bioavailable form, it's recommended for most looking to take a vitamin D supplement. However, it is not suitable for vegans and vegetarians.
  • Vitamin D2 (ergocalciferol): Found in mushrooms and plant-based foods, this compound is suitable for vegans and vegetarians. However, it is more difficult for the body to absorb and store than vitamin D3. This kind of supplement is recommended for individuals on strict vegetarian diets.

Why take vitamin D supplements rather than calcium?

In recent years, experts recommended that older people include calcium supplements in their diet, especially menopausal women at risk of bone damage. But excessive calcium intake has recently been associated with a paradoxical rise in fractures.

Excessive calcium supplementation can result in other undesirable side effects, such as kidney stones and arterial calcifications.  Vitamin D helps build strong bones, but its connection to these unpleasant occurrences is not as evident. A good diet can easily give us with the calcium our body needs.

Shopping Criteria

Shopping for the right vitamin D supplement can be very overwhelming, so we've put together the most relevant factors to make it easier for you. Be sure to take into account the following characteristics so that you won't be disappointed later on.


Unfortunately, vitamin D supplements do cause allergic reactions in some users. Be sure to check the ingredients of any supplements you're considering. You may find trace amounts of allergens present.

Pharmacological Interactions

Vitamin D may have unwanted interactions with some medications, enhancing or limiting their effectiveness.

We advise you to speak with your doctor prior to using vitamin D supplements if you're taking any of these treatments:

  • Medication for chronic renal failure
  • Hypolipidemic agents (cholesterol-lowering medications)
  • Anticonvulsants
  • Medication for psoriasis
  • Corticoids
  • Digoxin (antiarrhythmic treatment)
  • Antihypertensive treatment
  • Antibiotics
  • Certain diuretics
  • Laxatives

Vegan and Vegetarian Nutrition

Pay special attention to potential vitamin D supplements if you follow a vegan or vegetarian diet. Vitamin D3 comes from animal sources and is therefore not suitable for vegans. D2, or ergocalciferol, supplements are the only products that are 100% from vegetable origins.

You may see some supplements advertised as “vegan vitamin D3.” It's very difficult to verify such claims, so we strongly suggest that you stick to ergocalciferol in order to be sure you aren't consuming any animal products.

Vitamin D can be taken in capsule form. (Source: Puhhhar: 47895081/

Ingestion Method

Make sure you're comfortable with the method of ingestion when you pick out your preferred supplement, since you'll need to take it on a regular basis.

Here are the various kinds of vitamin D supplements:

  • Tablets: These tablets are usually coated with an excipient that adds a pleasant taste and makes them easier to swallow.
  • Softgels: They are easier to ingest and offer faster absorption. The coating is gelatin (or a vegan alternative).
  • Oral spray: This is made for those who have trouble swallowing tablets. It can be sprayed directly into the mouth, but some people use it on food.
  • Drops: This is another good form for anyone who has difficulty swallowing pills. The use of a dropper allows for precise dosage.

Value for Your Money

You can find packages that provide enough vitamin D to last a whole year. If you need long-term supplementation, we suggest you invest in a large supply from the start. You will save a lot in the long run.


Vitamin D, also known as the “sunshine vitamin,” gives the body strength and vitality. However, the increasingly sedentary lifestyle that many have these days means deficiencies are too common. You should consider supplementing with vitamin D2 or D3 if you want to maintain strong bones, an active immune system and a sharp mind.

We hope this article has helped you gain a better understanding of this important nutrient. Be sure to use this information to select the right supplement for you, so that you can reap all the best benefits of vitamin D. Careful supplementation will contribute to your enjoyment of a full, active and happy life.

If you liked our vitamin D guide, please feel free to leave a comment with your thoughts and be sure to share this article with your friends on your social media!

(Source of featured image: Songpracone: 53649602/

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