Vitamin D is an essential nutrient that is responsible for a variety of processes in the human body. Specifically, Vitamin D:
- Promotes calcium absorption for bone growth and remodeling
- Maintains appropriate amounts of calcium in the blood for vital biological processes
- Helps to regulate cell growth
- Regulates the immune system and may help with cancer prevention
- Assists in neuromuscular processes
Knowing that vitamin D does so much for the body, it is important to be aware of your intake to avoid deficiency. Populations most susceptible to deficiency include:
- Exclusively breast-fed infants
- Older adults
- Limited sun exposure
- People with darker skin tones
- Those with inflammatory bowel disease or fat malabsorption
- People who are very overweight or have undergone gastric bypass
As we age, our needs for vitamin D increase, and recently, the recommended daily allowance (RDA) for vitamin D increased to 600 international units (IU) for normal, healthy adults. Other groups, such as the Endocrine Society, have recommended a minimum of 1,000 IU for adults. According to the NIH, the tolerable upper intake levels for vitamin D for individuals greater than 9 years are 4,000 IU per day.
So How Do We Get Vitamin D?
Vitamin D is present naturally in fatty fish, such as salmon, tuna and mackerel, along with cod liver oil. Other sources include fortified milk, egg yolks, and some cereals. Although it would be most ideal to get your vitamin D from food sources alone, most references indicate that it is difficult to obtain enough vitamin D strictly through diet.
Sunlight, in terms of other natural ways to meet your vitamin D needs, sunlight is the most readily available option. However, there is quite a bit of controversy over how much is enough, and how much is too much. In general, it seems that most experts agree that 10 minutes of sun exposure in shorts and a sleeveless shirt is adequate to maintain normal levels of vitamin D, but there is now discussion that sun exposure may not produce as much bio-available vitamin D as previously suspected.
Knowing all of this, your best bet is to get most of your vitamin D intake from natural food sources, as these will also contain co-nutrients that may be beneficial in the absorption and metabolism of vitamin D. Good ways to easily increase vitamin D include the addition of fatty fish into your diet two times per week. Not only will you be increasing your vitamin D intake naturally, you will also be taking in an excellent source of Omega 3 (essential) fatty acids, protein and other good-for-you nutrients. According to an analysis by Boston University, the breakdown for vitamin D in fish is as follows:
International Units (IU) per 3.5 oz serving
Wild Salmon (species unspecified) – 988 IU
Ahi Tuna – 404 IU
Farmed Trout – 388 IU
Bluefish – 280 IU
Farmed Atlantic Salmon – 245 IU
Cod – 104 IU
Gray Sole – 56 IU
Mackerel – 24 IU
Source: Lu Z et al. J Steroid Biochem Mol Biol. 2007
Additionally, minimal amounts of sun may or may not be beneficial, but are considered to be relatively safe. When it comes to adding a supplement, make sure to check the back of your multivitamin to determine if you are already getting supplemental vitamin D, keeping in mind the upper limit is 4,000 IU. If you have questions or concerns about your vitamin D levels, check with your doctor, as your levels can be assessed if needed.
For other health and wellness news, make sure to check the previous issues of our weekly blog. Vita Physical Therapy & Fitness is committed to bringing you relevant, up-to-date information so that you can live fit! If you have any questions about how Vita can help you get on the road to wellness, feel free to contact us!
Written by Colleen Baughn, OTR, CES