An estimated 75% of people living in the US have Vitamin D deficiency.
Why is vitamin D deficiency so common?
1) Sun Exposure: Americans are exposing their skin to less sunlight as precautions against skin cancer and aging. Vitamin D is often referred to as the sunshine vitamin because it is synthesized in the skin when exposed to sun, then metabolized in the liver and kidneys to its active form of 1,25-dihydroxyvitamin D. Therefore, less sun exposure= less vitamin D production. Additionally, many Americans are living in areas where sun exposure is limited in the winter months.
2) Obesity: Vitamin D is stored in fat tissue and is not readily available to the body.
3) Digestive Problems and Chronic Disease: When digestive health is impaired, digestion and absorption of vitamin D decreases and vitamin D requirements may increase.
4) Increased Aging Population: As we age our ability to manufacture vitamin D decreases.
Why is vitamin D so important?
Vitamin D has many roles in the body. It is a fat-soluble vitamin involved in regulating calcium and phosphorus levels, cell differentiation, immunity, insulin secretion, blood regulation, and reducing inflammation.
Recent studies have shown a relationship between vitamin D deficiency and autoimmune disease as well as severity of autoimmune disease. Furthermore, a relationship between vitamin D deficiency, impaired glucose intolerance and Type II Diabetes exists as well. Studies also show there may be a relationship between vitamin D deficiency, decreased sunlight exposure, and cancer risk.
The widespread impact of vitamin D throughout the body makes this nutrient essential to daily health. Vitamin D is critical for bone health because of its role in regulating calcium and phosphorus absorption. Deficiencies in vitamin D can lead to rickets in children and osteomalacia in adults. Additional symptoms of vitamin D deficiency may include muscle weakness, pain, and secondary hyperthyroidism.
Populations at risk for vitamin D deficiency include exclusively breast-fed children, those living in environments with little exposure to sunlight, including changes in the seasons, as well in individuals who specifically decrease their exposure to sunlight (staying indoors and covering their skin).
There are also factors that negatively affect the body’s ability to manufacture the active form of vitamin D including:
- dark skin pigmentation
- genetic variations
- old age
- chronic kidney disease
- gallbladder problems
- inflammatory bowel disease (Crohn’s and Ulcerative Colitis)
- magnesium deficiency.
How much vitamin D do I need?
Reviewing your health history, assessing your physical status, and/or lab tests are ways to assess your vitamin D status. Do you have rickets/osteomalacia, osteoporosis, and hypertension? Bone and joint pain, tenderness, tetany, and/or muscle cramps?
Has your doctor tested your vitamin D status in the blood? 25-dihydroxyvitamin D (25(OH)D) is the most common test to assess vitamin D status. A sufficient range for vitamin D is between 40 ng/ml – 80 ng/ml according to the Vitamin D council. There are differing opinions amongst health professionals on the optimal 25(OH)D range. This may help explain why there are differing opinions amongst health specialists.
The recommended dietary allowance (RDA) for vitamin D intake is 600 IU (15 mcg) daily for adults 19-70 years of age. Adults 71 years and over require additional vitamin D intake because the ability to make vitamin D declines with age. Therefore, adults over age 71 should take 800 IU (20 mcg). The RDA provides recommendations for maintenance for healthy populations, but it does not take into account variations in recommendations based on health status and health history so dose recommendations may vary depending on the individual.
Is possible to have too much vitamin D?
In short, yes. While it is rare to obtain too much vitamin D through food, supplementation with high dose vitamin D may cause negative side effects. Large doses of vitamin D can cause increased calcium levels in the blood and urine, and may result in calcium deposits in tissues in the body, kidney stone formation, and bone loss. Therefore, your health professional will provide an appropriate dose for your unique needs.
What foods contain vitamin D?
Vitamin D is naturally occurring in only a few foods (see below). Consequently, those who either don’t eat dairy or avoid seafood may benefit from supplementation.
|Food||IUs per Serving||Percent Daily Value|
|Cod liver oil, 1 tablespoon||1,360||340|
|Swordfish, cooked, 3 ounces||566||142|
|Salmon (sockeye), cooked, 3 ounces||447||112|
|Tuna fish, canned in water, drained, 3 ounces||154||39|
|Orange Juice, fortified with vitamin D, 1 cup (check product label, vitamin D content varies)||137||34|
|Milk, all varieties, vitamin –D fortified, 1 cup||115-124||29-31|
|Yogurt, fortified with 20% daily value for vitamin D, 6 ounces,||80||20|
|Margarine, fortified, 1 tablespoon||60||15|
|Sardines, canned in oil, 2 sardines||46||12|
|Liver, beef, cooked, 3 ounces||42||11|
|Egg, whole, 1 large||41||10|
|Ready to eat cereal, fortified with 10% daily value vitamin D, .75 – 1 cup||40||10|
|Cheese, Swiss, 1 ounce||6||2|
Should I take a vitamin D supplement?
If you show signs and symptoms of vitamin D deficiency, or if your vitamin D level is low, consider starting a vitamin D supplement under the supervision of a health professional. Those who do not eat foods high in vitamin D or those who have trouble synthesizing vitamin D may consider a supplement.
Vitamin D3, or cholecalciferol, is the preferred form to increase vitamin D levels over D2 or ergocalciferol. Vitamin D is a fat soluble vitamin. Therefore, healthy dietary fat helps improve vitamin D absorption. Either look for supplements that are emulsified in oil or take your vitamin D supplement with a meal that contains healthy fats.
I recommend this product because it is emulsified in oil and the dose (1000IU per drop) can be modified based on your specific needs. I take 5000IU vitamin D in the winter and then 1000IU vitamin D in the spring and summer when I am exposed to more sunlight.
Finally, for more information about vitamin D, visit: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
McGuire, M., & Beerman, K. A. (2013). Nutritional Sciences: From Fundamentals to Food. 3rd ed. Belmont, CA: Wadsworth.