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  • 2010

Vitamin D may reduce the risk of premature births

Published on

11 February 2010

Vitamin D supplementation may reduce the risk of premature births and boost the health of newborn babies, suggests a new study.

In the trial, researchers gave one group of pregnant women 4,000 IUs per day of vitamin D at about three months of pregnancy (1). They gave a second group 400 IUs per day – the amounts recommended by U.S. and UK governments. Trial participants were monitored by testing their blood and urine samples to make sure calcium and vitamin D levels were within safe ranges. No side effects were observed in both group and vitamin D levels in the women's blood increased by about 50 percent.

The researchers found pregnant women who took 4,000 IUs of vitamin D per day reduced their risk for premature birth by half compared to the controls and they were less likely to have small babies. Women on the high-dose vitamin D3 supplements compared with those on low dose-vitamin D supplementation were at a 25 percent reduced risk for infections, particularly respiratory infections such as colds and flu as well as infections of the vagina and the gums.

Women taking high doses of vitamin D also showed reduced risk for diabetes, high blood pressure, and preeclampsia. In addition, babies getting the most vitamin D after birth were less likely to experience colds and eczema.

The researchers recommend pregnant mothers to take 4,000 IUs and nursing mothers to take 6,400 IUs of vitamin D a day. More than 1 million babies born prematurely die each year before they are a month old. Globally, about 12.6 million babies are born prematurely or before 37 weeks of development in the womb. The scientists concluded that taking high dosages of vitamin D, like 4,000 IUs per day as used in the current trial, could save the lives of at least half million babies each year.

Vitamin D is rarely found in foods except in a few fortified with vitamin D and a few in nature such as fatty fish, mushroom and egg yolk. No one should expect to get enough vitamin D from fortified foods like orange juice or milk. The best source of vitamin D is ultra-violet rays in sunshine which trigger synthesis of vitamin D. Many people try to avoid sunshine fearing that ultraviolet rays increase risk of skin cancer.


  1. Hollis BW and Wagner CL. Randomized controlled trials to determine the safety of vitamin supplementation during pregnancy and lactation. 14th Workshop on Vitamin D, Bruges, Belgium, October 2009.

A new study from the UK reports that Asian people seem to need more sunlight for vitamin D synthesis due to their darker skins.

In the observational study, 51 healthy adults (20 60 years old) of South Asian ethnicity were exposed to different doses of simulated summer sunlight for 6 weeks and their serum vitamin D [25(OH)D] concentra-tions were measured weekly (1). The participants received one of six ultraviolet exposures ranging from 0.65 to 3.9 standard erythema doses (SEDs), equivalent to 15-90 mins unshaded noontime summer sunlight at 53.5°N (Manchester, United Kingdom), 3 times/week. In addition, dietary vitamin D intake was estimated. The results showed that at the beginning of the study all participants were vitamin D insufficient (below
20 ng/mL), including a high proportion of participants who showed a deficiency (below 10 or even below
5 ng/mL). During the study 25(OH)D concentrations rose significantly in all dose groups. By the end of the study, exposure to at least 45 minutes of simulated sunlight had significantly increased the vitamin D levels of all participants to 25(OH)D concentrations higher than 5 ng/mL, but only 6 subjects attained 25(OH)D concentrations above 20 ng/mL.

The researchers commented that the study findings indicate better advice on sun exposure is needed in order to safeguard Asian populations from vitamin D insufficiency and to help prevent related conditions such as osteoporosis. While government recommendations for Caucasian populations are that 10 20 minutes of summer sunlight daily is sufficient to ensure good vitamin D status (while minimizing the risk of burning), this advice may be not appropriate for Asian people living at latitudes distant from the equator, who may need more sunlight for vitamin D synthesis due to their darker skins. Sun exposure provides around 90% of the vitamin D in our blood, yet UV light is also a risk factor for skin cancer, leading some organizations to pro-mote messages about sun avoidance.


  1. Farrar M. D. et al. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure. Am J Clin Nutr. 2013; 97(6):

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