Wintertime Vitamin D
Vitamin D is often referred to as our “sunshine vitamin.” This is because sunlight serves as our primary provider of vitamin D; all it takes is about 10-15 minutes of unexposed skin to soak up a good portion of our daily requirement of vitamin D. But what do we do in the wintertime when the cold weather does not allow us to expose as much of our skin to the sun? Luckily, there are other ways besides sunlight to obtain an adequate intake of vitamin D.
Vitamin D is a fat-soluble, “essential” vitamin; “essential” meaning that we must get it from external sources to remain healthy. There are three sources from which we can get vitamin D: sunlight, food, or supplements. I already mentioned how sunlight is our primary source of vitamin D, but in the wintertime, when it may not be possible to expose our skin to the sun as often, we turn to food or supplements to meet our recommended needs.
It is challenging to find sources of foods that are naturally rich in vitamin D. The fact is that there are only a few of them out there; egg yolks, fatty fish like salmon and tuna, and beef liver. If none of these foods appeal to you, the good news is that many foods are fortified with vitamin D. These include most of our dairy products like milk, cheese, and yogurt, as well as juices, cereals, and soy beverages. However, not all brands of the previously listed foods are fortified with vitamin D, so be sure to check the nutrition facts panel on the food’s package to see if it is.
If you cannot meet your vitamin D needs through food alone, you can take it in supplement form, but check with your primary healthcare provider before beginning one. (Remember to take caution when using supplements because the FDA does not regulate them for quality or safety). Individuals who may benefit from a vitamin D supplement include those following a vegan diet since most of our dietary sources of vitamin D come from animal-based products. Older adults who are inside a lot, especially at this time of year, may also benefit from a supplement. Again, check with your doctor before starting any dietary supplement, including vitamin D.
We want to make sure we are getting enough daily vitamin D (400-800 IU/day for most people) because it helps calcium and phosphorus (two other important nutrients) get absorbed into our bodies. This allows us to have healthy bones and teeth, improved neurological and muscular function, as well as an enhanced immune response to infections.
What happens if we do not get enough vitamin D? Since it plays a role in bone structure and function, when we do not get enough, there’s a chance for the development of bone abnormalities such as rickets (bow legs) in children and osteomalacia (soft bones) in adults.
What happens if we get too much vitamin D? Like many other vitamins and minerals, more is not always better. If there is too much vitamin D in the body, calcium levels in the blood can become dangerously high, which can lead to further health problems including kidney stones, weak bones, and heart problems. This level is usually caused by a supplement overdose and is unlikely to be reached through dietary sources alone.
Since most Americans are not getting enough daily vitamin D, it has become a public health concern. You’ll even notice that vitamin D has been added to the new nutrition facts panel, which has begun to be displayed on food packages in grocery stores around the country. A little over a year ago, the FDA also approved to have the amount of vitamin D increased in the foods where it is fortified with the purpose of helping Americans meet their daily recommended needs.
If you are consuming adequate amounts of foods that are either fortified with vitamin D, such as dairy products, or foods that are naturally rich in it, such as fatty fish, you should not be concerned about developing a deficiency…even in the dead of winter.
Center for Food Safety and Applied Nutrition. “Constituent Updates - FDA Approves an Increase
to the Amount of Vitamin D for Milk and Milk Alternatives.” U S Food and Drug Administration Home Page, Center for Food Safety and Applied Nutrition, 15 June 2016, www.fda.gov/food/newsevents/constituentupdates/ucm510556.htm.
“Hypercalcemia.” Mayo Clinic, Mayo Foundation for Medical Education and Research, 7 July
Kohn, Jill. “What Is Vitamin D?” www.eatright.org, Academy of Nutrition and Dietetics, 15 June