Vitamin D is necessary for our survival. Thankfully, the body can manufacture its own vitamin D with some help from the sun, of course. When we expose our skin to the sun, the UV light that touches our skin ignites a cascade of reactions that allow the body to make vitamin D. The downside of the body’s ability to manufacture vitamin D is that most people live in places that get very little sunshine for several months out of the year. In particular, winter months not only see less daylight but people also spend very little time outdoors.
A limited number of food sources naturally contain vitamin D like animal liver. Because of this some foods, such as dairy products, are fortified with vitamin D to widen the dietary options. Relying on food is not enough, especially if you know you’re not getting that much exposure to the sun. To understand why vitamin D is crucial for good health, let’s take a look at what it does:
- Strengthens bones
- Enhances the absorbability of other important nutrients (e.g., calcium and phosphorus), which aid in maintain strong bones
- Protects the cardiovascular system
- Improves brain activity
- Boosts immune function
- Prevents cancer
With a list such as this, it’s no wonder why sun exposure makes us feel good. Unfortunately, many people are deficient in vitamin D for various reasons:
- Sunscreen use – yes, blocking harmful UV light protects against skin cancer; however, it also blocks your body’s ability to synthesize vitamin D. Thirty minutes a day of sunlight at least two times a week is adequate for building up vitamin D levels. (Be sure to use sunscreen for the remainder of the day.)
- Diet – a processed food diet filled with unhealthy carbs won’t provide you with anything but calories
- Age – older adults have low levels of vitamin D because the body’s ability to make it declines with age
- Skin tone – melanin, a substance that gives skin its pigment, is a natural sunscreen; this is mainly why African Americans with darker skin tones will have low vitamin D levels
- Location – where you live can influence your ability to make vitamin D: people who live in northern latitudes can’t produce adequate amounts of vitamin D for most of the year because of limited daylight during winter months. Vitamin D can be stored during summer months for use during the winter. However, because many factors affect vitamin D absorbability, most people exhaust their vitamin D reserves if they rely on sun exposure alone.
Vitamin D does many good things for the body, but many factors limit its production too. Low vitamin D levels are particularly dangerous because it increases the likelihood of heart disease and cancer. It’s also been shown to increase the development of breast and prostate cancers and metastasis (the spread of cancer). The low vitamin D–cancer association stems from a host of mechanisms—one being the vitamin’s inability to activate natural killer (NK) cells, which are immune cells. NK cells block microbial and cancer cells by stifling their growth and spread throughout the body. Healthy vitamin D levels promote cancer cell death by increasing NK cell activity.
Vitamin D is crucial for good health on a number of levels. It’s likely, however, that you’re not getting enough vitamin D by relying on diet and sun exposure. While foods such as cereals and milk are fortified with vitamin D, other dietary sources are quite limited (e.g., eggs, mackerel, salmon, tuna). Food, however, is not enough: which is why I recommend vitamin D supplements to my patients. As a matter of fact, I don’t absorb vitamin D as well and take it as a supplement to maintain my vitamin D levels at a healthy range. Before you start taking vitamin D supplements, visit you doctor and ask to have your levels checked. If you’re deficient, speak with you doctor about a high-quality grade brand of vitamin D. Because most people have desk jobs or work indoors, it’s important not to eat your lunch at your desk or in the office kitchen, whenever possible. Go outside, enjoy your lunch, and soak up some sun. It’s the key to strong bones, a robust immune system, and heart health.