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People who consumed bread fortified with vitamin D daily experienced improvements in serum 25-hydroxyvitamin D (25[OH]D) levels, which were also accompanied by improvements in lipid profiles and reductions in visceral fat, according to a study from Iran.
Vitamin D deficiency is a public health concern that is not limited to any specific subpopulation and also appears to extend beyond racial or geographical boundaries, researchers wrote in the Journal of Clinical Endocrinology & Metabolism. They noted that a number of factors prevent people from increasing vitamin D supply through sun exposure alone. Intake of food fortified with vitamin D, however, may help address this problem, they explained.
“Many countries have established mandatory fortification programs for several staple food items whereas in some countries, fortification with vitamin D is voluntary. In any case, the key question arises as to ‘what is the appropriate food vehicle for fortification with vitamin D?’” the researchers wrote.
“The selected food source should be widely available especially to those with moderate to severe food insecurity and its consumption should not remarkably differ by such socioeconomic factors as education or income,” they added.
Noting that bread may be suitable for this purpose, the researchers conducted an 8-week, double-blind, placebo-controlled trial to assess the bioavailability of vitamin D from fortified Iranian bread and the possible effects of daily consumption of the bread on certain health aspects.
A total of 90 healthy participants aged 20 to 60 years were randomly assigned to consume fortified bread (50 g of bread fortified with 25 mcg of vitamin D3 plus placebo daily; n=31), vitamin D supplementation (50 g of plain bread plus 25 mcg of vitamin D supplement daily; n=30), or control (50 g of plain bread plus placebo daily; n=30).
The researchers found within-group changes in serum 25(OH)D concentrations of 39 nmol/L for the fortified bread group (P<.001), 28.9 nmol/L in the supplement group (P<.001), and -9.2 nmol/L in the control group.
Serum intact parathyroid hormone (iPTH) concentrations decreased about 13.5% in the fortified bread group and 14.5% in the supplement group but not in the control group. Visceral fat also decreased by 1.05% (P<.001) in the fortified bread group and 0.96% (P=.006) in the supplement group. The data also showed a 10.4-mg/dL reduction in LDL cholesterol in the fortified bread group (P<.001), but the 6.6-mg/dL reduction in the supplement group was insignificant (P=.083). Additionally, the researchers observed an increase in serum HDL in both the fortified bread group and the supplement group (9.7 mg/dL vs 5.7 mg/dL; P<.001).
Despite their findings, the researchers highlighted several limitations of the study, including the fact that the intervention was short-term and results cannot be extrapolated to long-term consumption of fortified bread.
“Considering bread as a staple food in Iran, fortification of flour with vitamin D could be a potentially effective strategy to raise circulating 25(OH)D of the population to almost adequate levels,” the researchers concluded. “This could be accompanied by several health outcomes including improvement of lipid profile and a reduction of visceral fat. Future effectiveness studies are warranted.”
