Until several years ago, you probably hadn’t heard much about vitamin D, unless you saw it listed on the back of your milk carton. Today there’s much more talk about it because it’s become clear that it’s important for much more than preventing rickets and that we need much more than was previously suggested.
Despite it’s name, vitamin D is actually a hormone that is naturally synthesized by UVB rays and cholesterol in our skin. It is then carried through the blood and makes its way to the liver then kidney where it undergoes additional biochemical steps to convert it to it’s final, active form. The image below from a recent review paper in Nature Reviews Cancer illustrates the process:
Vitamin D has been given so much attention in the last several years because it’s involved in so many functions in the body:
- It works with calcium and omega-3 fatty acids to make brain chemicals such as the stress fighting adrenaline and norepinephrine;
- It helps to increase the absorption of calcium and phosphorus in the intestines and is required to build and maintain healthy bones with both minerals;
- It keeps the immune system strong;
- It regulates the parathyroid gland;
- And deficiencies have been linked to certain cancers, such as colon, prostate, breast and ovarian cancers, heart disease, diabetes, multiple sclerosis, depression, fibromyalgia, PMS, and the flu;
So how do you know if you’re deficient in vitamin D and what should you do about it?
1. Have your levels checked by your doctor - Optimal levels fall into the range of 40-65 ng/ml. If you’re low, Dr. Mark Hyman recommends between 5,000 and 10,000 IU to reach your optimal levels (get checked after again after three months), and then 2,000-4,000 IU for maintenance. And those of us living in Northern latitudes, indoors most of the time, or with darker skin may need to adjust these amounts.
In fact, the government’s recent recommendations for 600 IU of vitamin D3 is believed by many to be enough to prevent rickets, but not nearly enough to protect us against the diseases mentioned above.
2. Increase your dietary sources of vitamin D - Here are some foods to include:
- cod liver oil
- fatty fish such as mackerel, sardines, and salmon
- fortified milks (dairy or non-dairy)
- mushrooms - some types of mushrooms that have been exposed to UV light contain vitamin D2
3. Get more sun - We’ve also been given the most effective tool for making vitamin D, the sun’s rays, but we’ve created a lifestyle that keeps us covered up and indoors most of the time. Just a few minutes a day with your arms and legs exposed, without sunscreen, will allow your body to naturally make vitamin D. If you’re really interested, there’s a site where you can find out based on latitude, longitude and time of year, how much sun you would need to make your vitamin D quota. You can look up the latitude and longitude of your city here.
Of course, if you live in a seasonal climate with cold winters, diet and supplementation are the best ways to ensure that your vitamin D levels stay optimal to help keep you healthy.