Vitamin D, commonly referred to as the “sunshine vitamin,” is produced naturally by your skin in response to sunlight and can also be found in foods like salmon, sardines, eggs, milk yogurt and orange juice with fortification. Vitamin D plays an essential role in maintaining strong bones and immune systems.

As studies revealed that adequate vitamin D could lower risk for certain diseases, the importance of receiving enough has grown substantially. Here’s why.

1. Bone Health

Vitamin D is widely recognized for helping the body absorb calcium, which is essential to bone health and helps lower risk of osteoporosis (which causes broken bones). Osteoporosis is a serious public health concern and costs about $95 billion each year in lost wages and medical expenses; an estimated 2 million osteoporotic fractures occur annually in the US.

Most of our vitamin D comes from sunlight exposure. How our skin synthesizes vitamin D depends on multiple factors including time of day, cloud cover, smog levels and skin pigmentation (melanin). People with darker skin produce less vitamin D from sun exposure compared to those with lighter skin tones, and sunscreen significantly inhibits our bodies ability to make vitamin D.

Studies on vitamin D supplementation and its effect on bone health are inconclusive. While several studies indicate a sufficient intake can increase bone density, others do not show a protective effect against fractures; one double-blind, placebo-controlled randomized trial of 35,243 older adults concluded that supplementing with vitamin D did not decrease hip or spine fracture risk.

This finding was unexpected given the evidence compiled to date regarding other supplements’ positive impacts on bone health in older individuals. These results and others indicate that current guidelines may need to be adjusted.

The National Academy of Medicine and National Institutes of Health recommend that healthy adults consume between 1,000 to 4,000 IU of vitamin D daily; this dose should not cause adverse side effects in most healthy adults. Furthermore, getting sufficient amounts may also assist with muscle function which is crucial to falling prevention and overall quality of life. It is believed this effect occurs due to vitamin D’s immunoregulatory properties as well as modulation of pro-inflammatory cytokines; further research should investigate this relationship as well as optimal levels for improving bone and muscle health.

2. Immune System

Vitamin D plays an essential role in our bodies, most notably by controlling calcium levels in our blood. Calcium helps form bones and muscles while improving immunity by strengthening immune response against germs. Our bodies make vitamin D from direct sunlight exposure or from foods or supplements we ingest; during winter it’s especially important that we prioritize getting enough sunshine Vitamin D!

Studies have demonstrated the beneficial properties of vitamin D to modulate both adaptive and innate immune systems, serving as an effective anti-inflammatory and possibly even protecting against autoimmune disease.

Vitamin D’s immunoregulatory properties are achieved through binding with both its vitamin D receptor (VDR) and its main metabolite, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3). Formation of 1,25(OH)2D3 can reduce B-lymphocyte proliferation while stimulating expression of anti-inflammatory cytokine IL-10 within the immune system, thus inhibiting T-lymphocyte proliferation as well as inflammation responses caused by oxidative stress [92,93].

Vitamin D helps the lungs maintain innate immunity by decreasing inflammation and strengthening host defenses against pathogens. It does this by upregulating cathelicidin, an effective antimicrobial agent against bacteria and viruses; and by upregulating CD107a to decrease neutrophil extracellular trap permeability through upregulating CD107a while also decreasing granzyme A/B release; improving airway clearance by restricting pathogen entry/spread within the lung tissue.

Recent studies have also demonstrated the protective benefits of vitamin D against respiratory infections, particularly COVID-19, by inhibiting the renin-angiotensin system, increasing ACE2 activity, and modulating both adaptive and innate immune responses. More randomized controlled trials must be conducted to assess its efficacy against COVID-19.

3. Heart Health

Vitamin D is an integral component of cardiovascular wellness. Although research on heart health and Vitamin D remains limited, some studies indicate that higher levels of this essential nutrient may lower heart disease risk while keeping cholesterol at bay. Unfortunately, high doses (more than 20 mcg daily with calcium supplements) of Vitamin D could actually raise your blood pressure significantly.

Vitamin D is essential to our overall health as we age, whether from sunlight, food sources, or supplements. Your body naturally makes vitamin D in its skin when exposed to ultraviolet B rays from sunlight; then goes through two chemical reactions in your liver and kidney to become biologically active – first with 25-hydroxyvitamin D [25(OH)D], or calcidiol and then with 1,25(OH)2D or calcitriol being the final form.

From late March/early April until September in the UK, your vitamin D needs should be fulfilled through diet and exposure to sunlight; between October and March it’s advised to take supplements in order to make sure you’re receiving enough.

If you’re taking Vitamin D supplements, aim for no more than 20 mcg daily – anything higher may lead to symptoms like nausea, vomiting, weakness, confusion and excessive urination/thirst. Extremely high concentrations can even be detrimental, potentially leading to heart failure and kidney damage.

4. Mental Health

Vitamin D, known as the sunshin vitamin, helps us build strong bones. It supports cell division and immune function and plays an integral part in brain health and healthy brain functioning – but did you know it can also boost moods and help with depression management?

Recent research by researchers demonstrated that those with higher levels of Vitamin D tended to experience lower rates of depression. It’s thought this might be because Vitamin D helps regulate serotonin, an essential neurotransmitter for mood regulation, as well as increase dopamine production in the brain which in turn causes feelings of pleasure, reduce stress levels and boost cognitive functions.

People with darker skin have an increased risk of Vitamin D deficiency as their bodies have an easier time absorbing its benefits from sunlight, particularly during winter when sun exposure drops significantly. Studies have indicated that individuals with low Vitamin D levels have a greater chance of depression and mood disorders, so it’s essential to ensure you receive sufficient amounts of this sunshine vitamin.

As it’s easy to increase our Vitamin D levels through diet (fortified foods and fatty fish like salmon), sunlight or supplements, getting at least 20 minutes of sunshine daily will naturally boost levels; supplementation may be useful during winter months when we tend to see our levels decline more significantly.

Vitamin D could aid depression sufferers by correcting an imbalance between calcium and glutamate neurotransmitters – two essential brain chemicals involved with mood regulation – which contribute to seasonal affective disorder (SAD). Such imbalance can exacerbate depression symptoms when exposed to reduced sunlight during winter months.

However, randomized clinical trials comparing the effects of Vitamin D supplementation with depression have provided mixed results, so further research and smaller subgroup analyses may be required in order to understand its role among this specific population of individuals with depression.