Once believed to be crucial for bone health only, vitamin D has proven to be one of the most vital nutrients for avoiding countless diseases and health conditions. The problem is that many of us have far too little vitamin D in our blood for optimal protection.

For decades, health professionals have told mothers to give their neonates vitamin D drops until they stop breastfeeding them. Why? Because vitamin D is essential for building and maintaining strong bones. This early intervention makes perfect sense. The problem, however, is that healthy bones are just one of countless health benefits linked to vitamin D. We need the nutrient in adequate amounts throughout life, not just during a brief time window in infancy.

Supports numerous body functions

A growing pile of evidence delivers clear-cut proof of D as being vital not only for bones but for a long list of other things such as muscle function, immune function, dental health, kidney function, and cellular growth, repair, and metabolism, just to mention a few. Virtually all cells in the body are equipped with so-called vitamin D receptors. This gives a rather clear indication of the importance of this vitamin. We need it to stay healthy but, unfortunately, a growing number of scientists point to the widespread vitamin D deficiency problems.

The sun is not always enough

We humans synthesize vitamin D in our skin when we expose ourselves to sunlight. Those of us living at northern latitudes are limited by the fact, from October to April, the sun sits too low in the sky to enable vitamin D synthesis. As a result, most of us lack vitamin D in the winter. This is a problem, as the cold months happen to be the time of year when our immune system is heavily challenged by circulating colds, flus, and infections. The only other way to get the vitamin is by eating some of the foods that contain it (e.g., fish, egg yolks, and beef liver) or by taking a supplement, and there is good reason to believe that this is required by many people worldwide.

Widespread deficiency

A study published in the Journal of Clinical Endocrinology and Metabolism showed that a jaw-dropping 59 per cent of the general population in the modern world is vitamin D-deficient, with a large proportion having extremely low levels of vitamin D. A 2022 review study published in Frontiers in Nutrition, where researchers looked at data from nearly eight million people from 81 countries, also points to the widespread global problems with vitamin D deficiency and insufficiency. There are many factors that contribute to the deficiency problem. For instance, sun awareness campaigns have made many people worry about sun exposure to the extent where it has a negative effect on their vitamin D synthesis, simply because they don’t get the needed amount of sun exposure. In addition, dark-skinned people do not synthesize the nutrient as effectively as people with lighter skin do. There is also the fact that many women of religious belief wear garments that cover up their skin entirely.

A rundown on vitamin D’s health benefits:

Here are some of the things which science has said about vitamin D in recent years:

It keeps your muscles healthy

In a study of young women aged 16-22, it was shown that nearly 60% had too little vitamin D and that they had more fat in their muscles, compared with women who had normal vitamin D levels.

It prevents the flu

Japanese scientists successfully demonstrated that schoolchildren who received a daily vitamin D supplement were nearly 60% less likely to catch the flu than those who did not get extra vitamin D.

It prevents depression

Low levels of vitamin D could explain why some people develop symptoms of depression, according to a team of researchers from Aarhus University Hospital in Denmark. After reviewing over 250 studies of vitamin D deficiency and its impact on human health, the research team concluded that there is a link. Apparently, patients with schizophrenia and manic depression are often born during the time of year where an expecting mother’s vitamin D levels are low, typically in the spring and winter.

It protects your heart

British researchers from the University of Warwick found by systematically analyzing several studies that middle-aged and elderly people with high levels of vitamin D were 43 per cent less likely to develop heart disease, compared with those with low levels. Their research is based on nearly 100,000 men and women of different ethnic backgrounds and ages.

American scientists from the Washington University School of Medicine have even discovered that it is particularly dangerous for diabetics to have too little vitamin D as it impairs their ability to clear cholesterol from their blood vessels.

May lower the risk of cancer

There even seems to be a link between vitamin D status and the risk of cancer. In a study published in the American Journal of Clinical Nutrition, German researchers from the German Cancer Research Center point to a relation between vitamin D status and mortality risk. By following a large group of 50-74-year-old men for nearly 10 years and pitching their vitamin D levels against their mortality rate, the scientists found a strong inverse relation between death risk and vitamin status.

71% increased mortality risk

Individuals who had vitamin deficiency were 71% more likely to die of any cause, compared with those who had sufficient levels of the vitamin. The risk of dying of cardiovascular disease specifically was increased by 39% among those who were vitamin D deficient, while cancer mortality was 42% higher in this group. Finally, there was a 150% increase in respiratory disease mortality among those who were vitamin D-deficient. All figures are significant.

Adding to the proof

The German study adds to the growing pile of studies linking low vitamin D levels to increased mortality. In 2012, a study published in the American Journal of Cardiology pointed out that people with low vitamin D levels were 164% more likely to dye of hypertension, coronary artery disease, or diabetes than those who had plenty of vitamin D in their blood. Both the German study and the American study from 2012 defined vitamin D deficiency as vitamin D levels lower than 30 nmol/L.

Did you know that…

  • Health authorities used to recommend 5 micrograms (200 international units) of vitamin D per day. Now, experts suggest between 5 and 10 times as much for normal healthy people
  • Vitamin D toxicity is rare but has occurred with doses of about 50,000 international units per day (1,250 micrograms)
  • Virtually all tissues in the body are saturated with so-called vitamin D receptors (docking stations), suggesting the universal need for this nutrient
  • Vitamin D is absorbed more easily in the digestion when dissolved in some sort of lipid like e.g., olive oil.

How much do we need?

Using an advanced computer simulation technique, American and Norwegian scientists found that people living in a sunny climate (in this case Florida) are able to get enough sunshine all year round to cover their basic need for vitamin D. In contrast, those living in areas with limited amounts of sunshine (in this case Boston) are not able to get enough vitamin D from sunlight in the winter period. Their research is published in the Journal of the American Academy of Dermatology