Top 10 Myths About Vitamin D
08/25/2008
As more studies focus on the health benefits of vitamin D, many questions regarding deficiency and the “sunshine vitamin” are being raised. To help explain vitamin D a bit better, Jared M. Skowron, who specializes in pediatrics and the treatment of autistic spectrum disorders in children, created a list of the top 10 myths regarding vitamin D.
Myth 1: Vitamin D is a vitamin.
The truth: Vitamin D is a hormone. It's derived from cholesterol. It activates cellular processes and does not do so as a co-factor. Vitamin D receptors have direct effects on the following cells: adipose, adrenal, bone, brain, breast, cancer, cartilage, colon, endothelium, epididymis, ganglion, hair follicle, intestine, kidney, liver, lung, muscle, osteoblasts, ovary, pancreatic B, parathyroid, parotid, pituitary, placenta, prostate, skin, stomach, testis, thymus, thyroid and uterus.
Myth 2: Normal activity provides us enough vitamin D from sun exposure.
The truth: Most people do not get enough sunshine to maintain adequate vitamin D levels. Our ancestors spent most of the day in the sun while farming, fishing and hunting. Our bodies physiologically developed to need that much vitamin D. Today's indoor society of office workers, television watchers and hermits gets much less sun exposure and vitamin D production. Add clothing and sunscreen, which also inhibit vitamin D production, and you understand the problem.
Myth 3: Supplemented vitamin D in foods is adequate.
The truth: Vitamin D2 is one-third as effective in the body as naturally occurring vitamin D3. Most foods have D2 added. (Another thing to think about: A study that analyzed vitamin D2 levels in milk off supermarket shelves showed almost 50 percent had less than the label claim of 400 IU of D2.)
Myth 4: 1,25(OH)D3 is the best analysis for vitamin D levels.
The truth: Vitamin D is mostly stored in adipose and should not be routinely measured. It then converts to 25(OH) D3, which has a long half-life and is the best analysis of vitamin D levels. It then converts to bi-hydroxy forms such as 1,25(OH)D3 and other forms, which have the actual action of the cell receptors. However, 1,25(OH)D3 has a short half-life and is not a good measurement.
Myth 5: The reference range for vitamin D levels is accurate.
The truth: The reference range for 25(OH)D3 is horribly inaccurate and is resulting in vitamin D deficiency in this country. The current reference range of 20-100 is too low. Levels less than 25 are disease level. Levels between 25 and 75 are suboptimal. Levels between 75 and 200 are optimal.
Myth 6: Vitamin D supplementation is nontoxic.
The truth: The major consequence of vitamin D toxicity is hypercalcemia, which should be monitored periodically while under therapy. Changes in cardiac rhythms or lithiasis are common concerns. Urine calcium monitoring is not accurate. Serum calcium should be monitored monthly to check vitamin D toxicity, which normally occurs at 40,000 IU per day. Right now, 10,000 IU per day is being proposed as a safe upper limit.
Myth 7: The Recommended Daily Allowance (RDA) for vitamin D is accurate.
The truth: People taking only the RDA of vitamin D will lower their 25(OH) D3 levels. The RDA is too low. When treating with vitamin D supplementation, three months of daily dosing is sufficient to max out 25(OH)D3 levels. Five thousand IU per day for three months should elevate 25(OH) D3 by 80 nmol/L, and 10,000 IU/ day for three months should elevate 25(OH) D3 by 120 nmol/L. People on 1,000 IU per day will elevate their levels by only 10 nmol/L.
Myth 8: Different forms of vitamin D are all the same.

The truth: Vitamin D3 is the preferred form. D2 is derived either from plant sources or from lanolin but lanolin-derived D3 is more active and absorbable.
Myth 9: Vitamin D only treats osteoporosis and rickets.
The truth: The therapeutic benefits of vitamin D are still being discovered. Benefits have been noted in relation to cancer, heart problems, immune disease, diabetes and neurological problems, as well as low bone density.
Myth 10: Vitamin D should be avoided in pregnancy and breastfeeding.
The truth: Pregnant women should receive 4,000 IU of daily vitamin D supplementation. Breast-feeding women should receive 6,000 IU of daily vitamin D supplementation. Vitamin D, not 25(OH)D3, crosses into the breast milk, and daily doses are preferred over weekly doses. Avoid supplementing the infant and instead supplement the breast-feeding mother directly. If the infant is bottle-fed, supplement with 400-800 IU/day. 
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