KANSAS CITY — A surprising conclusion from an extensive scientific evaluation of vitamin D supplementation is that a compelling case is being made for the mandatory fortification of enriched cereals. The study was published in June in the Journal of Clinical Endocrinology and Metabolism.
Josh Sosland, editor of Milling & Baking News; Source: Sosland Publishing Co.
This conclusion is surprising because it is not the researchers’ conclusion. They reviewed numerous studies to identify which populations should not take vitamin D supplements and which should. In fact, they recommended against taking supplements for the largest population studied: adults ages 18-74. In 2020, 235 million Americans, or 71% of the entire U.S. population, fell into this age group.
This conclusion was also surprising because a literature review found no evidence that taking supplements reduces the risk of many major diseases, including cancer, heart attack, stroke, adult influenza, and tuberculosis. Scientists have been studying for years whether vitamin D deficiency increases the risk of many diseases.
Looking at the study, “Vitamin D for Disease Prevention: An Endocrine Society Clinical Practice Guideline,” from another perspective, produces a much more positive view of fortification. The number of adult Americans excluded from the supplement recommendation was found to be much smaller than the 235 million. This is because the researchers suggested that two adult subgroups would need supplements: pregnant women and those with prediabetes. Approximately 5 million women become pregnant each year, and approximately 90 million Americans have prediabetes. The researchers also recommended that 73 million children and more than 75 million adults, 23 million people, take supplements. In total, the study found that approximately 190 million Americans, more than 58% of the population, would benefit from supplements. Meanwhile, the researchers described the risks of vitamin D supplements as “negligible.”
To understand how the findings support the idea of universal vitamin D fortification, consider as a point of comparison the public health benefits achieved through mandatory folic acid fortification of enriched cereals since 1998. This program has been credited with reducing neural tube birth defects by about 25%.
In absolute numbers, folic acid fortification has reduced the number of neural tube birth defects in the United States by about 1,000 per year, a reduction that the National Institutes of Health has described as one of the great public health achievements of its time.
What about Vitamin D? Researchers found that adequate levels of Vitamin D intake could reduce the number of prediabetic people who go on to develop diabetes by 15%. Approximately 1.2 million prediabetic people “convert to diabetes” each year. A 15% reduction would mean 180,000 fewer diabetes cases per year. Importantly, researchers noted that 80% of people with prediabetes don’t know they have it. Universal fortification with Vitamin D would be much more effective at reaching prediabetic people than promoting the intake of supplements.
The researchers pointed to evidence that vitamin D provides many benefits for children, including promoting bone health and reducing the risk of respiratory infections, the most common infectious cause of death in infants. For pregnant women, vitamin D appears to slightly reduce the risk of stillbirth, neonatal death, premature birth, low birth weight, and gestational diabetes. Although the researchers were unable to quantify the risk reduction for stillbirth and children with vitamin D supplementation, 21,000 babies are stillborn each year in the United States, and hundreds of children die from respiratory diseases (almost 1 million worldwide). If vitamin D supplementation could reduce these numbers by even a few percent, it would save the lives of hundreds, perhaps thousands, of babies and children each year. Again, the study describes the risks of vitamin D supplementation as negligible.
The researchers briefly discussed fortification but did not examine the relative merits of increasing vitamin D intake through supplements or fortification. However, looking at the study through this filter, it is clear that the across-the-board fortification of vitamin D cereals deserves fresh and serious consideration.
