Approximately 2–3% of the population carries a variant of the haptoglobin gene known as Hp2-2, which is associated with reduced antioxidant protection. Haptoglobin plays a role in binding free hemoglobin and limiting oxidative damage. When the Hp2-2 genotype is present in people with type 2 diabetes, oxidative stress may be higher, and this genotype has been linked to an increased risk of cardiovascular disease and other diabetes-related complications, including kidney and eye disease.
Research published in Arteriosclerosis, Thrombosis, and Vascular Biology (online November 21, 2007) examined this relationship more closely. The study followed 1,434 individuals with both type 2 diabetes and the Hp2-2 genotype. Participants were randomly assigned to receive either 400 IU of vitamin E daily or a placebo and were followed for 18 months.
During the study period, the group receiving vitamin E experienced approximately 50% fewer cardiovascular events, such as heart attacks and strokes, compared with the placebo group. The authors suggested that individuals with the Hp2-2 genotype may represent a subgroup of diabetic patients who are more vulnerable to oxidative stress and therefore may respond differently to antioxidant therapy than the general population.
Importantly, these findings apply to a genetically defined subgroup and should not be generalized to all people with diabetes or to antioxidant supplementation as a whole. The study highlights the emerging concept of genotype-specific nutrition, where the potential benefit of a nutrient may depend on underlying genetic differences.
