Sources of Vitamin D

Vitamin D is unique because we can synthesize all of our needs for this vitamin from sunlight. When the ultraviolet rays of the sun hit our skin, the vitamin is then converted into its active form. Even though our bodies synthesize Vitamin D, it is still an essential nutrient that we need to get from food due to differences in sunlight throughout the year and limited sun exposure for some people (especially the elderly).

Food Sources of Vitamin D

• Salmon, canned, solids + bones or cooked: A serving size of 2 oz. will provide you with 343 IU of Vitamin D.
• Mackerel, cooked: A serving size of 2 oz. will provide you with 197 IU of Vitamin D.
• Sardines, canned + bones: 2 ounces of sardines will provide you with 150 IU of Vitamin D.
• Fortified milk: One cup of 1% or nonfat milk will provide you with 98 IU Vitamin D.
• Margarine, fortified: 1 tablespoon of fortified margarine will provide you with 60 IU of Vitamin D.
• Fortified, ready to eat cereals: A 1 oz serving will give you 40 IU of Vitamin D.

Fortified foods are a major source of vitamin D. Breakfast cereals, pastries, breads, crackers, cereal grain bars and other foods may be fortified with 10% to 15% of the daily value for vitamin D. It is important to read the nutrition facts panel of the food label to determine whether a food provides Vitamin D.

Sunlight and Vitamin D Synthesis

The amount of sunlight needed to produce an adequate supply of Vitamin D depends on several factors:

Time of Day: The sun’s rays are the most intense between 10 am and 2 pm.

Season: The sun delivers more radiation during the summer months.

Environment: 80% or more of the sun’s rays penetrate clouds. Window glass blocks UV radiation.

Location: Sunlight is less intense in the northern and southern latitudes than near the equator.

Skin Type: Light-skinned people absorb UV rays more quickly than dark-skinned people.

Use of Sunscreen: Sunscreen protects the skin against sun damage, but it also blocks the UV light necessary for Vitamin D synthesis. However, it is still extremely important to routinely use sunscreen whenever sun exposure is longer than 10-15 minutes to decrease your risk of skin cancer.

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