23 Reasons Vitamin D is The 'Remedy for Everything but Death' (Research Review 2023)

By Dr Frank Yap, MD - June 03, 2023

What is Vitamin D

Vitamin D or known as “calciferol” is a fat-soluble vitamin that can be found naturally in certain types of food. Sunlight is also a natural source of Vitamin D. Our skin produces Vitamin D when exposed to the sun’s ultraviolet B (UVB) rays.

They are also sold in the form of dietary supplements.

The Global Vitamin D Market size was worth US$ 1.1 billion in 2022 (R), and it is estimated to reach a valuation of US$ 1.7 billion by the end of 2028, expanding at an annual compound rate of 7.0% between 2023 and 2028.

Related: Best Vitamin D Supplement

a. How the Body Processes Vitamin D – Vitamin D activation

Vitamin D needs to undergo two conversion steps to become active (Source).

First, it is converted to calcidiol, or 25(OH)D, in your liver. This is the storage form of the vitamin.

Second, it is converted to calcitriol, or 1,25(OH)2D, mostly in your kidneys. This is the active, steroid-hormone form of vitamin D.

b. What Does Vitamin D Do In Your Body?

Calcitriol interacts with the vitamin D receptor (VDR), which is found in almost every single cell in your body (Source, Source).

When the active form of vitamin D binds to this receptor, it turns genes on or off, leading to changes in your cells. This is similar to how most other steroid hormones work (Source, Source).

But scientists have recently discovered that it also plays roles in other areas of health, such as immune function and protection against cancer (Source).

c. How Long is Vitamin D Stored in the Body?

Vitamin D undergoes two hydroxylations in the body for activation. Calcitriol (1,25-dihydroxyvitamin D3), the active form of Vitamin D, has a half-life of about 15 h, while calcidiol (25-hydroxyvitamin D3) has a half-life of about 15 days. (Source)

Benefits of Vitamin D

Vitamin D is important to the body in many ways. It plays a significant role in optimizing health. Scientists are still discovering the many ways in which your body uses vitamin D for regulation and modulation.

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.

Many of vitamin D health benefits have been thoroughly confirmed in the biomedical literature. In fact, since 1964, there have been more than 100,000 search results on PubMed database (National Library of Medicine).

We have compiled and organised salient research in this article, on well over 20 health conditions (including COVID-19) that may be benefited from the use of vitamin D.

Vitamin D Benefits for Immune System

i. Vitamin D and Autoimmune Diseases

Vitamin D’s involvement in inflammation and both acquired and innate immune responses may explain why it appears to beneficial for preventing autoimmune diseases (BMJ 2022). Vitamin D receptors are present in nearly all cells of the human immune system, including monocytes/macrophages, T cells, B cells, natural killer cells and dendritic cells.

Because immune cells in autoimmune diseases like psoriasis respond to Vitamin D’s ameliorative effects, supplementing Vitamin D-deficient people with autoimmune disease may have benefits beyond bone and calcium homeostasis. (Source)

ii. Vitamin D and Infections

Vitamin D has multiple actions on the immune system, including enhancing the production of antimicrobial peptides by immune cells, reducing damaging proinflammatory cytokines and promoting the expression of anti-inflammatory cytokines.

Vitamin D deficiency affects the body’s susceptibility to infection and has been associated with influenza, hepatitis C, human immunodeficiency virus (HIV) and other viral diseases [Source].

According to Dr. Roger Seheult, Vitamin D..

- Stimulates “the innate immune response, which provides frontline protection against infectious agents”

- Increases expression of antimicrobial peptides in your monocytes and neutrophils

- Enhances expression of an antimicrobial peptide called human cathelicidin, “which is of specific importance in host defenses against respiratory tract pathogens”

iii. Vitamin D and Mortality

Vitamin D deficiency is linked to a reduced life expectancy:

The role of vitamin D for cardiovascular disease and overall mortality (Source)
Low 25-hydroxyvitamin D is associated with increased mortality in female nursing home residents (Source).

Some studies suggest that vitamin D reduces people’s risk of dying during the study periods, indicating that it may help you live longer:

Vitamin D and mortality: meta-analysis of individual participant data from a large consortium of cohort studies from Europe and the United States (BMJ 2014)
Vitamin D supplementation and total mortality: a meta-analysis of randomized controlled trials (Source).

iv. Vitamin D and Cancer

A Harvard research study, published in the JAMA Network Open medical journal (2020), overturns the initial findings of a study of 25,000 people published in 2018.

Initially researchers believed there was no benefit from taking vitamin D, as they detected no reduced incidence of cancer diagnoses overall. But they were puzzled because cancer deaths went down among those taking the supplements.

A secondary analysis, published last night, found this anomaly can be explained by the fact that vitamin D seems to stop metastatic cancers - those aggressive types which spread to other parts of the body.

Researcher Dr Paulette Chandler, a primary care physician and epidemiologist at Harvard's Brigham And Women's Hospital in Boston, said: 'Vitamin D is a supplement that's readily available, cheap and has been used and studied for decades.'

'Our findings, especially the strong risk reduction seen in individuals with normal weight, provide new information about the relationship between vitamin D and advanced cancer.'

Another systematic review (Kuznia 2023) of 14 RCTs (randomized controlled trials), concluded that vitamin D3 did not reduce cancer mortality in the main meta-analysis of all RCTs because the observed risk reduction by 6 % was not statistically significant. However, a subgroup analysis revealed that vitamin D3 administered daily, in contrast to bolus supplementation, reduced cancer mortality by 12 %.

Like Harvard's, most research on vitamin D and cancer shows a link between people who get enough of the vitamin and lower rates of the disease, less aggressive cancers and lower risks of dying from the disease.

Many experts now recommend 800 to 1,000 IU a day, a goal that's nearly impossible to attain without taking a supplement. Although protection is far from proven, evidence suggests that vitamin D may help reduce the risk of prostate cancer, colon cancer, and other malignancies.

Although the role of vitamin D in cancer prevention remains an area of research interest and debate, avoiding deficient levels is recommended. (American Cancer Society 2020)

Vitamin D Benefits for Skin

i. Vitamin D for Dry or Itchy Skin

Severe dryness of the skin or Ichty can be an indicator of Vitamin D deficiency. Getting enough Vitamin D can improve symptoms of skin disorders that cause dry, itchy skin.

ii. Vitamin D and Psoriasis

Oral Vitamin D supplementation is an important supplementary therapeutic choice for psoriatic patients. Vitamin D supplementation may also be crucial in preventing psoriasis-related comorbidities, hypertension and metabolic syndromes.

iii. Vitamin D and Vitiligo

According to one study, high-dose Vitamin D therapy may be both safe and beneficial in the treatment of vitiligo. Sixteen vitiligo patients with low Vitamin D status were given 35,000 IU per day for six months, along with a dairy and calcium-rich food limitation and minimum hydration of 2.5 L per day. And the outcome, fourteen of them had repigmentation ranging from 25 to 75%.

It’s still uncertain if high-dose supplementation provides any benefits for long-term patients with vitiligo.

iv. Vitamin D and Atopic Dermatitis

Vitamin D may play a role in improving the symptoms of Atopic Dermatitis. The findings of this study imply that Vitamin D supplementation may help reduce the severity of atopic dermatitis and can be considered as safe and manageable treatment option. However, this conclusion still needs larger-scale studies over a longer duration of treatment.

v. Vitamin D Benefits For Acne

Acne is a common and complex skin disorder that can be stressful for many patients due to its chronicity. Although acne is caused by a number of factors, but chronic inflammation is an important mechanism.

According to a study, Vitamin D has an immune regulatory function in sebocytes, implying that Vitamin D may have anti-inflammatory properties in acne patients.

Vitamin D Benefits For Women

If a woman is Vitamin D deficient during pregnancy, it may impact the bone health of her baby. Pregnant women who had a Vitamin D deficiency were more prone to preterm labor, premature birth or developing infections. They are also more likely to develop life-threatening high blood pressure (preeclampsia) and are also more likely to require a Cesarean section.

i. Does Vitamin D Help Balance Hormones?

Yes. This is because Vitamin D is a hormone that communicates with other hormones. Thus, having sufficient Vitamin D2 and D3 can help ease and prevent hormonal fluctuations.

ii. Does Vitamin D Raise Estrogen Levels?

Yes, the Vitamin D levels in a woman’s body has a positive correlation with a woman’s estrogen levels. Those with higher levels of Vitamin D in their bodies tend to have higher levels of estrogen.

In fact, a deficiency in Vitamin D can lead to lower estrogen levels. This may lead to depression, hot flashes and mood swings.

Vitamin D Benefits for Men

Vitamin D is essential for muscle development as it is involved in the development of skeletal muscle. Vitamin D also plays an essential role in men’s sexual function and testosterone levels. Healthy levels of vitamin D may also benefit sexual health by mitigating the risk of cardiovascular disease.

i. Is Vitamin D Good For Testosterone?

Yes, Vitamin D may boost testosterone levels and also improve sperm quality.

Vitamin D Benefits for Brain Health

i. Is Vitamin D Good For Depression?

It’s believed that vitamin D regulates more than 200 different genes by binding to vitamin D receptors that are responsible for driving a number of biological processes.

Studies have shown that vitamin D deficiency is linked to even mild depression, and evidence suggests vitamin D deficiency may be a significant driver of the rise we see in both mood and mental disorders such as psychotic and obsessive-compulsive disorders.

This study suggests that adolescents with low levels of vitamin D had improved depressive symptoms ater vitamin D supplementation.

ii. How Much Vitamin D Should I Take For Depression ?

To know if you need high or low dosage, you’ll need to get a blood test. A result of 30 nmol/L (nanomoles per liter) or under is too low, and anything over 125 nmol/L is too high. Aim for 50 nmol/L or slightly above, according to the National Institutes of Health Office of Dietary Supplements (ODS).

iii. Benefits of Vitamin D for Anxiety

Significantly lower levels of calcidiol were found in men and women with depression as well as in age matched patients with anxiety disorders. (Source)

A study found that taking Vitamin D supplements improved both depression and anxiety in women with type 2 diabetes.

The link between anxiety and Vitamin D still inconsistent, therefore further research is needed to fully understand the connection.

Vitamin D Benefits for Weight Loss

i. Does Vitamin D Affect Metabolism?

Vitamin D is involved in the regulation of metabolic processes and development. This includes nerve conduction, normal mineralization of bone, muscle contraction, and general cellular function throughout the body. Vitamin D supplementation can increase physical strength in both upper and lower limbs (Trusted Source).

ii. Does Vitamin D Help Lose Belly Fat?

Yes, Vitamin D can help trigger weight loss primarily in the belly. This is because Vitamin D and Calcium may work synergistically to reduce the production of cortisol, which is a stress hormone that causes you to store belly fat.

iii. Vitamin D and Diabetes

Vitamin D reduces the 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).

Vitamin D Benefits for the Digestive System

An analysis of five studies examined the link between vitamin D blood levels and colorectal cancer (Trusted Source).

Scientists found that people with the highest blood levels of vitamin D (over 33 ng/ml or 82.4 nmol/l) had a 50% lower risk of colorectal cancer than people with the lowest levels of vitamin D (less than 12 ng/ml or 30 nmol/l).

Vitamin D Benefits for the Heart

Studies have highlighted the importance of vitamin D for the prevention and treatment of heart disease, showing it plays a vital role in protecting and repairing damage to your endothelium. The findings also suggest vitamin D3:

- Helps trigger production of nitric oxide — a molecule known to play an important signaling role in controlling blood flow and preventing blood clot formation in your blood vessels

- Significantly reduces oxidative stress in your vascular system, which is important to help prevent the development and/or progression of cardiovascular disease

According to vitamin D researcher Dr. Michael Holick, author of “The Vitamin D Solution: A Three-Step Strategy to Cure Our Most Common Health Problem,” vitamin D deficiency — defined as a level below 20 ng/mL — can raise your risk of heart attack by 50%.

i. Research

An analysis of seventeen studies with over 300,000 people looked at the link between vitamin D intake and heart disease. Scientists found that taking 1,000 IU (25 mcg) of vitamin D daily reduced heart disease risk by 10% (Trusted Source).

Vitamin D has also been shown to have an anticoagulant effect. A decrease in 25-hydroxyvitamin D [25(OH)D] concentration has also been associated with an increased risk of venous thromboembolism (PubMed).

A Norwegian study published in the Journal of Clinical Endocrinology and Metabolism found “a normal intake of vitamin D” significantly reduces your risk of death if you have cardiovascular disease."

About 4,000 patients diagnosed with stable angina pectoris (chest pain caused by coronary heart disease) were followed for 12 years. The average age at the outset of the study was 62. Overall, those with vitamin D blood levels between 16.8 and 40 ng/mL (42 to 100 nmol/L) had the lowest mortality risk.

Vitamin D Benefits for Sleep

Several studies have found a link between lack of sleep, sleep disorders and vitamin D deficiency.

In 2012, Dr. Stasha Gominak, featured in the interview below, published a study in which she and her colleague used a two-year uncontrolled trial to evaluate the effect vitamin D supplementation had on neurological complaints and abnormal sleep patterns.

They engaged 1,500 people, in whom they maintained a narrow range of 25(OH)D levels between 60 nanograms per milliliter (ng/mL) and 80 ng/mL. These patients showed improvement in their sleep patterns and neurological symptoms.

Later studies by other teams of researchers found similar results. One paper published in 2014 suggested that recent reports of vitamin D deficiency may increase symptoms of airway muscle myopathy, chronic rhinitis and/or adenotonsillar hypertrophy, which may lead to obstructive sleep apnea.

One study in 2015 showed low levels of serum 25(OH)D in older men decrease sleep duration and efficiency, and a systematic review published in 2018 found vitamin D deficiency was linked to a higher risk of sleep disorders.

Also in 2018, a team of researchers evaluated vitamin D receptor genetic polymorphic variations and the impact serum concentration had on the susceptibility for obstructive sleep apnea syndrome. They found that one polymorphism explained 14.5% of the variability in serum concentration and was associated with excessive daytime sleepiness.

Finally, in late 2020, a paper published in Current Pharmaceutical Design sought to explore the role vitamin D plays in sleep regulation and the impact deficiency may have on sleep disorders. In a review of clinical trials and correlation studies they found vitamin D receptors and enzymes control activation expressed in the brain areas involved in sleep regulation. The team wrote:

“Furthermore, vitamin D can affect sleep indirectly through non-specific pain disorders, correlated with alterations in sleep quality, such as restless legs syndrome and obstructive sleep apnea syndrome.”

Vitamin D Benefits for Bone Health

Vitamin D is primarily known for helping to regulate calcium and phosphate, minerals that are key to developing and maintaining healthy bones, teeth and muscles. It does partly this by promoting the absorption of calcium and phosphorus from your gut (Source).

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

Vitamin D reduces the risk of osteoporosis, falls, and fractures. Higher doses of vitamin D can help prevent osteoporosis, falls, and fractures in older adults (Source).

Vitamin D Benefits for COVID-19

As of March 2023, there are more than 100 published clinical studies that are related to vitamin D.

Check out the evidence tracker on vitamin D and COVID-19 from c19vitamind.com (constantly updated), with more than 100 published studies by more than 900 scientists.

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Vitamin D 101: What You Need to Know

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