Vitamin D Deficiency: Symptoms and Risks

Vitamin D is a nutrient similar to steroids, and is necessary for the processing of calcium in the body. As a result, deficiency symptoms generally involve weaker bones, and rickets in children. There has also been some interest in vitamin D as a method of reducing risk of both cancer and cardiovascular disease, but evidence is quite varied so far. The main source of vitamin D is via exposure to UVA rays from the sun, as well as D fortified dairy products.

Who Is At Risk?

People who do not get enough sunshine are at risk of becoming deficient. If you live in a high latitude, with less direct sun and colder temperatures, you may be lacking in sufficient amounts of D. Obviously, too much sun is bad as well, but if you can get about 15 minutes of exposure each day, this should suffice for vitamin D levels. Also, people with darker skin do not seem to absorb it as well, and there are large deficiencies in even sunny countries like India among darker skinned individuals.

The US FDA recommended intake of vitamin D is currently 600 IU per day, which has been estimated upwards partially as a result of recent research into its beneficial effects.

General Deficiency Symptoms

The two main diseases of vitamin D deficiency are osteomalacia in adults, and rickets in children. Osteomalacia is a general softening and weakening of the bones. Rickets is a disease found in children that involves deformities of the bones and stunted growth. Rickets was fairly common in Western countries until fortified dairy products began being produced in the early 20th Century. Now it is mostly confined to low income countries.

In addition to the two above mentioned diseases, there has been a lot of interest lately about vitamin D’s alleged cancer fighting effects, discovered through multiple studies. The picture, however, is not quite clear.


Multiple studies have suggested a possible link between low vitamin D levels and overall cancer mortality, especially involving colon cancer and breast cancer.  One of the largest studies followed 4 million cancer patients in 13 different countries, and found the incidence and mortality higher amongst those in higher latitude (and thus, lower levels of sun exposure). Another metastudy found a decreased risk of colon cancer by 50% in those with higher levels of D.

But other studies have been conflicting. A 2007 study by the US National Cancer Institute found no difference in cancer mortality in those with high levels of D, but it did find a decrease in colorectal cancer by 72%. And one study from 2006 showed a 43% decreased risk of pancreatic cancer, while another showed an increase in male smokers among those with higher levels of D.

Other Effects

There are at least some studies suggesting multiple other problems with deficiency. One of the possible vitamin D deficiency symptoms in men, for instance could be low sperm levels. There is also some potential indication of a link between vitamin D and diabetes, but in both these cases there is not enough evidence to draw firm conclusions.


So as it stands now, the evidence of a connection between vitamin D and cancer is not completely absent, but it isn’t clear either. The symptoms of vitamin D deficiency include mainly softening of the bones (osteomalacia) in adults, and rickets in children, although rickets is very rare these days in most Western countries. Taking a supplement of 600 IU per day may be a good idea if you don’t get enough sunlight, but whether this will decrease your cancer risk or not remains to be seen.