Dual supplementation can reduce bone loss more than supplementation with vitamin D alone.
Taking a combination of vitamin D and vitamin C supplements may reduce bone loss and risk of fracture more than supplementation with vitamin D alone in women with diabetes, according to the authors of a literature review published in Human Nutrition & Metabolism. Vitamin C is an antioxidant that inhibits inflammatory activity mediated by vascular cell adhesion molecule-1 (VCAM-1).
“Excess inflammation increases levels of inflammatory cytokines, including VCAM-1,” study authors wrote. “VCAM-1 stimulates osteoclast activity…[but] vitamin C inhibits VCAM-1 and inflammation, thus diminishing osteoclast activation and bone loss.”
Vitamin C is an antioxidant that modulates collagen, a key protein in bone biosynthesis. Since it reduces inflammation, it can also decrease the risk of osteoporosis and fractures associated with reduced BMD. People can get adequate vitamin C by consuming fruits and vegetables, and inadequate vitamin C can actually be considered a risk factor for diabetes.
Vitamin D is a fat-soluble vitamin that promotes bone health by modulating calcium and phosphorous absorption. Both minerals make up hydroxyapatite, which is part of our bone make-up. Vitamin D deficiency is common in patients with diabetes because the disease is associated with the depression of antioxidant defense mechanisms; this can result in an excess of oxidative stress and inflammation, according to the study authors.
Over time, this inflammation can lead to bone demineralization (reduction in bone mineral density [BMD]), which can increase the risk of bone fractures in this patient population;however, the results of previous studies—which evaluated the efficacy of taking a vitamin D supplement for BMD—suggest that there is no positive association.
Results of the current study, which evaluates combined supplementation of vitamin C and vitamin D for BMD and VCAM-1 levels in female patients with diabetes, suggest that vitamin D is not positively associated with BMD when taken alone. However, supplementation with vitamin C was linked to BMD.
Vitamin C was also inversely related to VCAM-1, while vitamin D was not inversely associated with the inflammatory mediator. But vitamin D has clinical benefits for bone health and critical mineral absorption.
More clinical studies are needed to evaluate the relationship between co-supplementation and BMD in this patient population. These studies can also evaluate how an increase in BMD compares to taking vitamin D in isolation.
“Co-supplementation of vitamin D with vitamin C appears to be a better strategy and will be more successful in promoting both bone mineralization and suppression of bone loss, thereby resulting in healthy bones and better quality of life in comparison to vitamin D-alone supplementation,” study authors wrote.
Stevens CM, Bhusal K, Levine SN, Dhawan R, Jain SK. The association of vitamin C and vitamin D status on bone mineral density and VCAM-1 levels in female diabetic subjects: Is combined supplementation with vitamin C and vitamin D potentially more successful in improving bone health than supplementation with vitamin D alone? Human Nut & Metab. 2023. doi:10.1016/j.hnm.2023.200221