Vitamin D is a major player in maintaining a healthy body. The body produces Vitamin D when exposed to sunlight, that is why it is known as the “sunshine vitamin”. The fact is, it is not a vitamin at all, but a hormone that plays a major role in the immune system, inflammation, cell growth, and neuromuscular functions.

Enjoy sunshine


Sources of Vitamin D

In general, to obtain the benefits of Vitamin D it is recommended that daily intake be at least 400 IU a day. Since deficiency is common, many experts recommend doses at 2000 IU and higher. 

It is important to get 20 minutes of mid-day sun exposure a few times a week. However, a number of factors influence how much Vitamin D sunlight exposure is producing. Sunscreen use, which is recommended for skin cancer prevention, hinders the body’s ability to produce Vitamin D, as does air pollution, which can block the sun’s Ultraviolet (UV) light. Skin pigmentation is also a factor. Melanin, associated with darker skin tones, makes it more difficult for UV light to reach the cells that produce Vitamin D. Finally, more temperate climates provide less direct sun exposure, and thus less Vitamin D production. This is not as much of an issue in Central Texas, but timing is important. Vitamin D production in the skin is not efficient in the early mornings and late afternoons when the sun is low over the horizon with an angle of less than 45 degrees.

Aside from sun, you can also get extra Vitamin D through a limited number of foods. Fatty fish like salmon, tuna, mackerel, and sardines are a good source. Other options include milk, orange juice, yogurt, and cereals that are fortified with Vitamin D.


Bone Strength

The calcium that benefits the bones would not be able to do its job without Vitamin D. The D helps with mineralization of bone by promoting absorption of calcium in the gastrointestinal tract. The two together help improve bone density and prevent osteoporosis. There are multiple studies linking Vitamin D to reduced risk of hip and vertebral fractures in those over age 65.

Muscle Strength

In addition to building bone strength, Vitamin D also can influence strength in certain muscle groups. In one study, Vitamin D levels were associated with quadricep strength and stair climbing power in overweight older adults. The benefit was also noted in younger athletes where a meta-analysis of eight studies showed that supplementation with Vitamin D positively affected lower limb muscle strength in this group.

Oral Health

Vitamin D deficiency has been associated with several oral health issues including defective tooth mineralization and tooth loss, enamel defects, periodontal disease, gingivitis, and certain oral cancers. It is felt that Vitamin D is beneficial due to its anti-inflammatory activity and its ability to stimulate production of anti-microbial peptides that help fight gum disease and infection.

Medical shield protectionSupports the Immune System and Fights Inflammation

Medical shield protecting from virus

One of the most important functions of this vitamin is it role in maintaining and strengthening the immune system. It stimulates memory B cells and T-cells promoting a more robust response to various illnesses caused by viruses, bacteria, and fungus.

There appears to be a link to Covid-19 and Vitamin D. A study out of the University of Chicago Medical school published in JAMA showed that those who are deficient in Vitamin D may be at increased risk of contracting Covid-19. Other studies have linked low Vitamin D levels to more symptomatic Covid infection and worse outcomes for those who are hospitalized with the infection. This is felt, in part, to be due to the fact that Vitamin D increases anti-inflammatory cytokines which works to offset the harmful cytokine “storm” seen in the more severely ill Covid patients.

Can Act as a Mood Booster

For many years, psychiatrists have noted a link between poor response to anti-depressant medication and Vitamin D deficiency. In support of this observation, a 2017 review article in Neuropsychology found a significant relationship between depression and Vitamin D deficiency. Though it is not certain if low Vitamin D levels are a cause or effect of depression, there is nonetheless an important link. One thought is that low levels of Vitamin D may impact serotonin in the brain, a neurotransmitter that helps regulate our mood. Studies have also linked Seasonal Affective Disorder (SAD), which is a depressed mood occurring mainly during colder and less sunny months, to low Vitamin D. So having adequate vitamin D and exposure to sun can help boost your mood!

Can Help Prevent Diabetes

Researchers at UC San Diego found that Vitamin D deficiency may put people at risk of developing pre-diabetes and Type II diabetes. Study results showed that the risk of developing pre-diabetes or diabetes was 5 times greater for those with Vitamin D levels of less than 30 nanograms per milliliter. Other studies have found that cells in the pancreas that are responsible for producing blood sugar lowering insulin are dependent upon Vitamin D to optimally function. As a result, not getting enough of the “sunshine vitamin” can lead to lower insulin levels and thus higher blood sugar levels in the body.

Heart diseaseHelps With Blood Pressure and Lower Heart Disease Risk

There have been several studies that demonstrate an association between low Vitamin D and high blood pressure. One study showed that for every 10 nanogram per milliliter increase in Vitamin D, there was a 12% lower risk of developing high blood pressure. Other studies show that lower Vitamin D levels can cause an increase in blood pressure. 

There also appears to be a link between Vitamin D and stroke and heart disease. This is felt to be related to inflammation associated with lower levels of Vitamin D. Though there are multiple risk factors for developing high blood pressure and heart disease, the amount of Vitamin D that is maintained in our systems does seem to be a contributing factor.

May Help Reduce the Risk of Certain Cancers

Vitamin D may help prevent development of certain type of cancers. Most of this research is out of the National Cancer Institute and is linked to colon, breast, prostate, and pancreatic cancer.

Experimental evidence in animal studies shows that Vitamin D has been linked to several activities that might slow the development of cancer cells, including decreasing cancer cell growth, stimulating cancer cell death, reducing tumor blood vessel formation, and promoting growth of normal cells.

Weight Loss

Can Help with Weight Loss

Though more research is needed, it appears that getting more Vitamin D can help reduce body fat. Research out of Milan, Italy revealed that Vitamin D intake in overweight individuals who were deficient in the vitamin produced weight loss. Research also reveals that those low in Vitamin D are at greater risk of becoming overweight. Remember, increasing Vitamin D levels alone is not enough to achieve effective weight loss, you also need a healthy diet and exercise.

May Improve Cognitive Health and Brain Function

Vitamin D plays an important role in brain health and function. It has a neuroprotective effect on the brain. In other words, it helps protect areas of the brain essential for cognition. As mentioned earlier, this is partly due to the anti-inflammatory effect of Vitamin D but is also due to its ability to help with formation of neurotransmitter in the brain, nerve growth, and repair of damaged nerves. 

There is also found to be a link between attention deficit disorder and low Vitamin D as well as overall performance on mental exams. One study showed that people with lower Vitamin D levels had slower ability to process information.

In Summary

Vitamin D plays an important role in maintaining our health in many ways. Again, if daily sunshine requirements cannot be met, to obtain the benefits of Vitamin D it is generally recommended that daily supplemental intake be at least 400 IU a day. Since deficiency is common, many experts recommend doses at 2000 IU and higher.

Vitamin D


Benskin,Linda. (2021). The Influence of Vitamin D on COVID-19 Outcomes Chapter 4 of Covid-19 and Nutraceuticals: A Guidebook. Both Publishers and New Century Health Publishers, LLC.

Busko,M. Lack of Vitamin D Linked to CVD Biomarkers, Inflammation. Medscape. 2014 Feb 27.

Kunutsor SK et al. Vitamin D and the Risk of Future Hypertension. Eur J Epidemiology. 


Meltzer DO et al. Association of Vitamin D Status and Other Clinical Characteristics With COVID-19 Test Results. JAMA Netw Open. 2020;3(9): e2019722.

Park SK et al. Plasma 25-Hydroxyvitamin D Concentration and Risk of Type 2 Diabetes and Pre-Diabetes: A 12-year Cohort Study. April 19, 2018. 

Vigna L et al. Abstract T8:PO.110 European Congress on Obesity; May 6-9 2015