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Dietary Intake of Vitamin D

In clinical practice, nurse practitioners can recommend diets that are higher in vitamin D. These foods include milk fortified with vitamin D, fortified cereals, and oily fish. Oily fish are the best sources of vitamin D. A key point with these fish is that there is a difference in vitamin D content in farm-raised versus wild fish.[28] The only cooking style that affected vitamin D content was frying in vegetable oil, which significantly reduced the vitamin D content.
In comparison to fish, milk provides 97.60 IU of vitamin per 8-ounce serving; therefore, 2 servings of milk a day will provide approximately 200 IU of vitamin D. While these foods are helpful in maintaining adequate levels of vitamin D, daily supplementation is still recommended to ensure consistency in serum vitamin D levels.
Supplementation
Current research has determined that the daily recommended intake for most people is 1000 IU. Supplementation of vitamin D can be obtained through daily multivitamins in addition to diet. The average daily adult multivitamin contains 400 IU of vitamin D. Children's vitamins vary their formularies between 200 to 400 IU per tablet or teaspoon. Depending on the patient's diet and the formulary of their multivitamin, practitioners can recommend 1 to 3 vitamins daily, 1 vitamin every 8 to 12 hours. If the patient presents with a frank insufficiency (serum level less than 10 ng/mL) they can be treated with a prescription of vitamin D2 50,000 IU once per week for 6 to 8 weeks, with serum levels drawn afterward to ensure a level greater than 32 ng/mL.
Medications That Prevent Vitamin D Absorption
There are multiple drugs prescribed on a regular basis in primary care that can inhibit the absorption of vitamin D. These medications include anticonvulsants, thiazide diuretics, corticosteroids, nicotine, cimetidine, cholesterol-lowering agents (ezetimibe), heparin, and diet agents (Xenical and Alli) Vitamin D deficiency affects people of all races, age, religions, and regions of the world. If practicing in an area of northern latitude, it is important to help patients understand that sun exposure in the winter does not provide vitamin D absorption. In addition, use of sunscreen greater than SPF 8 will block the absorption of vitamin D. While sunscreen is important to prevent skin cancer, patients who obtain 15 minutes of sun exposure 2 to 4 days week without sunscreen can increase their vitamin D levels.
Recommendations from 1997 for vitamin D intake are 200 IU/day for young adults, 400 IU/day for ages 51 to 70, and 600 IU for those greater than 70 years of age. It has been shown that to maintain adequate serum levels of vitamin D requires higher daily intake. Through current research, it has been determined that the average recommended supplement intake is 1000 IU of vitamin D3 daily for all ages. Vitamin D supplements are relatively safe. To reach vitamin D toxicity, the serum 25(OH)D has to be at 150 ng/mL or above ’this serum level would require supplementation greater than 10,000 IU. Vitamin D affects disease processes in the heart, muscle, lungs, skin, bones, and GI tract. In clinical practice, it is important to encourage vitamin D supplementation daily for all patients.

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