Vitamin D Deficiency
Vitamin D has powerful effects on just about every system throughout the body. Vitamin D actually functions like a hormone despite its classification as a fat soluble vitamin. Every single cell in your body has a receptor for it and it is a switch for about 2000 genes in your body.
Normally your body makes vitamin D when skin is exposed to sunlight. Through a complex series of reactions, your body converts cholesterol on your skin to the usable form of vitamin D through reactions in the liver and kidneys. Unfortunately, if you live in a northern climate you will not get enough sunlight in the winter to meet all your vitamin D needs.
You can also find Vitamin D in foods such as fatty fish though it’s very difficult to get enough from diet alone.
The US government recommended daily intake is usually around 400-800 IU. This is to prevent disease, such as Ricketts. If you want optimal health you will need to supplement with much more than that.
Vitamin D deficiency has been in the news lately and is probably the most common vitamin deficiency of our modern times. A study in 2011 concluded that 41.6% of adults in the US are deficient. The darker your skin the higher the deficiency: 69.2% for Hispanics and 82.1% in African-Americans.
Risk factors for vitamin D deficiency
The darker your skin the more risk you have a deficiency. This has to do with where your ancestors lived. Obviously having light skin was an advantage in northern climates where you need to absorb all the sun you can get for vitamin D conversion. The closer you are to the equator the less of a factor sun exposure becomes.
Being elderly is a risk factor because your body just becomes less efficient at the conversion process. Supplementation at this point becomes more important than ever. Eating fortified food helps as well. Being overweight or obese is also a risk factor because the vitamin D that is produced in the skin get distributed into the fat. So like elderly people, the whole process is just less efficient. It is one theory behind why obese people have so many chronic diseases.
Depression can many times be linked to a Vitamin D deficiency. For some reason, older adults seem to be more affected by this.
In one analysis, 65% of the observational studies found a relationship between low vitamin D blood levels and depression. However, no link was found in controlled trials which carry more scientific weight. Researchers who analyzed the controlled trials noted that the dosages of vitamin D used were often very low. This is similar to Vitamin C studies which failed due to researchers using low dosages when high dosages are what medical professionals who actually use the vitamins to treat patients would typically use.
Bottom Line: Depression is associated with low vitamin D levels and some studies have found that supplementing improves mood