Why We All Need a Little More Vitamin D


by Mary-Signe Kelly, CNM

As children, we spend a lot of time in the sun.  It kept us  – and our parents – happy and healthy.  The sun is needed for almost all plants and animals to live.  Humans are no different.  One of the main reasons we need the sun is for vitamin D.  It’s been a hot topic in health the past couple of years, and rightfully so, since we are finding that many people are deficient in vitamin D.  Why is this?  Our bodies can make vitamin D from sunlight, but many experts believe we cannot, or do not get enough sunlight to make enough vitamin D.  Vitamin D also plays many important roles in keeping us healthy.  Research shows that vitamin D deficiency can lead to cancer, diabetes, cardiovascular disease, osteoporosis, and muscle problems.

What is Vitamin D?
In scientific terms, vitamin D is a fat-soluble vitamin that is made in the body from sun exposure or fortified dietary intake.  The two parts that make vitamin D are ergocalciferol (D2) from plant or fish sources and cholecalciferol (D3) from sunlight (1).  The liver and kidney then change these forms into molecules that our body can use.  Also the parathyroid hormone, calcitriol, a derivative of vitamin D, helps maintain calcium and phosphorus levels in the body.  Calcium and vitamin D are the main nutrients which keep our bones healthy and strong.

Why is Vitamin D so important?
The main function of vitamin D is for bone health.  Vitamin D works with calcium for bone mineralization, bone growth, and bone remodeling.  Without vitamin D, bones become thin, brittle and misshapen.  Prolonged vitamin D deficiency leads to rickets in children and osteomalacia in adults.  Vitamin D deficiency can also cause generalized muscle aches and pains in bones and muscles and muscle weakness (2).  It also plays a part in cell growth, neuromuscular function, immune function, and reduction of inflammation.  Additionally, vitamin D helps with overall cell life (2) for example it can help prevent breast, colon and prostate cancers by causing the cancer cells to die.  Vitamin D has been shown to prevent Type 1 diabetes, rheumatoid arthritis and multiple sclerosis.  Vitamin D affects heart health – affecting the contractility of the heart, vascular tone, cardiac collagen and cardiac tissue maturation (1).

Who is at risk for vitamin D deficiency?
After looking at all the different research, it seems like everyone is at risk for vitamin D deficiency.  If you don’t spend enough time in the sun, don’t eat a lot of fortified foods or fish, have a mal-absorption issue, take certain drugs, are over 60, a child, pregnant, lactating, overweight, have dark skin, you could possibly have a vitamin D deficiency.  There are a lot of risk factors for vitamin D deficiency and it seems that since we can get it from the sun we ought to have enough vitamin D.  In fact, researchers have found we need to spend 15-30 minutes in the sun during peak hours 10 a.m. to 2 p.m., four to seven days a week, depending on our skin pigmentation.  But if you live north of Atlanta, the sun isn’t strong enough during the winter to make vitamin D (3).  With our concerns about skin cancer, wrinkles and our use of sunscreen daily, we just aren’t getting our vitamin D from the sun.

How much vitamin D do we need?
The Endocrine Society and the National Institutes of Health recommend that children less than 12 months get 400 IU (international units) of vitamin D daily.  Women and men need 400-600 IU per day.  Lactating women who do not supplement their children need between 4000-6000 IU/day (2, 3).  Pregnant women need 1000 IU of vitamin D every day.

How do we get enough vitamin D?
It is recommended that vitamin D levels in the body should be greater than 30 ng/ml.  But how do we get there?  We could move to the tropics and spend more time in the sun or we could try to increase our intake of vitamin D including foods that are high in vitamin D or fortified with vitamin D or taking supplements.  Vitamin D is a vital part of our life.  We all need to take more breaks in the sun to get our Vitamin D –Nurse-Midwife’s orders!


1. Syroney L & Franjesevic A. 2010. Vitamin D Deficiency: Screening and Treatment in Primary Care. Advance for Nurse Practitioners, May 2010: 37-40.

2. Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP, Murad H, Weaver CM. 2011 “Evaluation, Treatment, and Presentation of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. Journal of Clinical Endocrinology & Metabolism, 96(7):0000-0000.

3. National Institutes of Health. (2011) Dietary Supplement Fact Sheet: Vitamin D. Retrieved from http://ods.od.nih.gov/factsheets/vitamind Jan. 3, 2012.

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