Vitamin D plays a crucial role in maintaining optimal health. Although most widely recognized for its role in bone health, vitamin D also helps regulate the immune system and modulate the body’s inflammatory response.
Despite the fact that our bodies produce thousands of units of vitamin D when exposed to the sun, approximately ⅓ of the world’s population is vitamin D deficient. There are several factors that play a role in this public health issue, including but not limited to, sunscreen use, indoor lifestyle, location, time of year and lack of supplementation.
In an effort to decrease the prevalence of vitamin D deficiency, the Institute of Medicine (IOM) increased the Recommended Daily Allowance (RDA) for vitamin D in the US and Canada from 200 IU to 600 IU per day for individuals between the ages of 1 and 70 years. According to the IOM, this dosage will enable 97.5% of the population to reach healthy vitamin D status. These guidelines were set with the expectation that the public would be receiving minimal to no sun exposure.
However, until now, the impact of the IOM’s recommendation of 600 IU on the public’s vitamin D status remains unknown. Therefore, a new study compared the prevalence of vitamin D sufficiency among Canadian children between the ages of 6 and 18 years between 2007-2009 and 2012-2013 using data from the Canadian Health Measures Surveys.
The researchers assessed a variety of variables, including season, location, sociodemographics, dietary intake of vitamin D, 25(OH)D status and body composition. Participants were considered vitamin D sufficient when they reached at least 20 ng/ml (50 nmol/l), the IOM’s threshold for optimal vitamin D status.
Here is what the researchers found:
- The average vitamin D level of children in 2007-2009 was 28 ng/ml (71 nmol/l); whereas the average vitamin D level of children in 2012-2013 was 24 ng/ml (60.8 nmol/l).
- A total of 79% of children were considered vitamin D sufficient from 2007-2009, while only 68% had levels of at least 20 ng/ml in 2012-2013 (p = 0.04).
- In 2012-2013 children were significantly less likely to reach vitamin D sufficiency compared to children in 2007-2009 (OR: 0.5; 95% CI: 0.3,0.9; p = 0.02).
- In 2007-2009, only 2.8% of children from and <1.0% of children from 2012-2013 reached vitamin D levels above 50 ng/ml (125 nmol/l).
- Vitamin D status was associated with season, as well as the participants age, income, weight and ethnicity (p < 0.01).
The researchers concluded,
“Vitamin D status declined after the upward revision of dietary guidelines for vitamin D, consequently, dietary intake was inadequate to meet sufficiency. Public health initiatives to promote vitamin D-rich foods and supplementation for Canadian children are needed.”
As our readers may already know, the Vitamin D Council does not support the IOM’s recommendation for vitamin D supplementation or threshold for optimal vitamin D status. Research continues to show that adults require 5,000 IU vitamin D3 per day and children require 1,000 IU/25 lbs body weight when they are unable to receive adequate sun exposure in order to reach optimal levels.
The Vitamin D Council deems 40-60 ng/ml the ideal range for vitamin D levels, as this is what our bodies would naturally maintain through safe sun exposure. According to the Vitamin D Council and the Endocrine Society, vitamin D levels of 20 ng/ml is still considered inadequate.
The researchers stated,
“In summary, our results indicate that revising dietary guidelines alone is insufficient to improve vitamin D status and likely requires additional public health actions to promote vitamin D nutrition for children.”
Sturges, M. Study finds updated vitamin D guidelines unsuccessful at improving Canadian children’s vitamin D status. The Vitamin D Council Blog & Newsletter, 9/2017.
Munasinghe, L et al. Vitamin D Sufficiency of Canadian Children Did Not Improve Following the 2010 Revision of the Dietary Guidelines That Recommend Higher Intake of Vitamin D: An Analysis of the Canadian Health Measures Survey. Nutrients, 2017.