It is widely recognized that vitamin D, alongside calcium, is crucial for bone health, but what else can it do for you? Emerging research suggests that it might be a key player in maintaining heart health, improving immune function, and impacting overall longevity. What can vitamin D do for you? This article will answer that and will address how much you need and where you can get the vitamin D you require.
What can vitamin D do for you?
Based on current research, vitamin D might have a beneficial impact in the following ways:
- Enhances longevity. Emerging research suggests that vitamin D might have the ability to reduce mortality related to cancer, autoimmune diseases, and cardiovascular disease. Results from a large meta-analysis of 18 randomized controlled trials suggest that adults who take a daily supplement in the 400–830-IU range decreased their risk of all-cause death.
- Keeps your heart healthy. Research has shown that sufficient levels of vitamin D in the body help improve biomarkers, or indicators, of cardiovascular disease.
- Maintains a healthy blood pressure. Vitamin D helps maintain healthy blood vessel function. Studies have shown that if a person gets enough vitamin D (i.e., is not deficient), it will help reduce the risk of high blood pressure.
- Protects your bones. Vitamin D, with calcium, helps to protect the bones from softening (osteomalacia) and reduces the risk of fractures associated with osteoporosis.
How much vitamin D do you need?
Here are the current Recommended Daily Intake values for Vitamin D:
| Age | RDI |
| Infant 0–12 months | 400 IU |
| Toddler 1–4 years | 400 IU |
| 4 years and older | 400 IU |
|
Where do you get vitamin D?
There are three main ways to get enough vitamin D: dietary sources, safe sun exposure, and supplements. Each method has limitations; your health care provider can help you determine which mode of securing vitamin D is right for your lifestyle.
Dietary sources
Food sources of naturally occurring vitamin D include fatty fish, sun-dried mushrooms, and egg yolks. There are also vitamin D-fortified foods available: cow’s milk; non-dairy milks such as rice, soy, almond, and oat; orange juice; soft spreads; yogurt; and breakfast cereals.
Here are some foods that provide vitamin D:
Fatty fish
- 30–35 µg per 1 tbsp cod liver oil
- 8–13 µg per 3 oz pink salmon
- 5–9 µg per 3 oz sardines or mackerel
- 5 µg per 3 oz tuna, canned oil
Other natural sources
- 0.5 µg per 1 medium egg yolk
- 0.3 µg per 3 oz beef liver
- 0.4–63 µg per 100 grams of mushrooms
Fortified foods
- 2.5 µg per 1 cup cow’s milk (actual content might vary)
- 2.5 µg per 1 cup orange juice
- 1.0 µg per 1 cup ready-to-eat cereal
The sun
Getting 5–30 minutes of sun twice a week is one way to absorb enough vitamin D, according to some vitamin D researchers. Sun exposure should be on the face, arms, legs, or back — without sunscreen — during the peak hours of 10 a.m. to 3 p.m. We have the capacity to make at least 10,000 IU of vitamin D within 30 minutes of full-body exposure to the sun, with what is called a minimal erythemal dose. However, because UV radiation from the sun contributes to skin cancer, the American Academy of Dermatology recommends getting the vitamin through food or supplement sources.
There are also several factors that affect our ability to get the vitamin D we need from the sun alone:
- Geography
- Individuals living above the 37th parallel will find it difficult to obtain adequate amounts of vitamin D from the sun in the winter months.
- Cities north of the 37th parallel include locations such as San Francisco, Denver, St. Louis, Chicago, New York, and Richmond. This means that a majority of the United States is north of the line.
- Sunscreen
- Sunscreen with a rating as low as SPF 8 has the capability to block the absorption of the vast majority of UVB light.
- Cloud cover
- Cloudy days mean a reduction in UV energy by as much as 50%. Shade cover reduces this level by an additional 10%.
- The amount of melanin in the skin
- Research has shown that individuals with darker skin have a lower level of vitamin D compared to those with lighter skin.
- Additional research has shown that in order to absorb equal amounts of vitamin D, an African American individual requires 10 times as much sun exposure as a Caucasian individual.
- Clothing
- Clothing absorbs most ultraviolet radiation. Research has shown that in countries where culture dictates that the majority of skin be covered at all times, there is a higher incidence of vitamin D deficiency.
- Season
- During the winter, although the sun might shine brightly, vitamin-producing UVF photons pass through the ozone layer at an oblique angle and are therefore absorbed by the ozone — not by the individual’s skin. Throughout the year, however, most individuals who receive the recommended amount of sun can store the fat-soluble vitamin in their fat tissue for the winter.
Supplements
Although food comes first, many people find it difficult to consume the vitamin D they need. If you choose to supplement, consult your physician and remember that the current upper limit of vitamin D established by the Institute of Medicine is 2,000 IU for adults, so you should stay below that limit.
So . . . what can vitamin D do for you?
The answer: Vitamin D helps keep you healthy — it might protect your heart and immune system, as well as keep your bones strong!
References:
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Dietary Supplement Fact Sheet: Vitamin D. Office of Dietary Supplements. Last accessed 4/30/10: http://ods.od.nih.gov/factsheets/vitamind.asp.
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Holick MF. Sunlight and Vitamin D for Bone Health and Prevention of Autoimmune Diseases, Cancers, and Cardiovascular Disease. Am J Clin Nutr. 2004; 80 (6 Suppl): 1,678S–1,688S.
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