Associations Between Dietary Vitamin C, Serum Ascorbic Acid, and GSTT1 Genotype and Premenstrual Symptoms.

Objective: Premenstrual symptoms are a cyclically occurring combination of adverse psychological and somatic symptoms that impact the quality of life for most females of childbearing age. Growing evidence suggests that diet may attenuate premenstrual symptoms; however, the relationship between vitamin C and premenstrual symptoms remains unclear. The aim of the research was to determine the association between different measures of vitamin C status and premenstrual symptoms.

Method: Females (n = 555) aged 20 to 29 years from the Toronto Nutrigenomics and Health Study completed a General Health and Lifestyle Questionnaire, capturing 15 premenstrual symptoms. Dietary intake was measured using a 196-item Toronto-modified Harvard food frequency questionnaire. Serum ascorbic acid concentrations were measured, and participants were categorized into deficient (<11 µmol/L), suboptimal (11-28 µmol/L), and adequate (>28 µmol/L) ascorbic acid levels. DNA was genotyped for the GSTT1 (Ins/Del) polymorphism. Using logistic regression, odds of experiencing premenstrual symptoms were compared between vitamin C intake levels above and below the recommended daily allowance (75 mg/d) between ascorbic acid levels and between GSTT1 genotypes.

Results: Increased vitamin C intake was associated with premenstrual appetite changes (OR, 1.65; 95% CI, 1.01-2.68). Compared to deficient ascorbic acid levels, suboptimal levels were associated with premenstrual appetite changes (OR, 2.59; 95% CI, 1.02-6.58) and bloating/swelling (OR, 3.00; 95% CI, 1.09-8.22). Adequate serum ascorbic acid levels were not associated with premenstrual appetite changes (OR, 1.69; 95% CI, 0.73-3.94) or bloating/swelling (OR, 1.92; 95% CI, 0.79-4.67). Those with the GSTT1 functional variant (Ins*Ins) had an increased risk of premenstrual bloating/swelling (OR, 1.96; 95% CI, 1.10-3.48); however, the interaction between vitamin C intake and GSTT1 was not significant for any premenstrual symptoms.

Conclusions: Our findings suggest that indicators of higher vitamin C status are associated with increased premenstrual appetite changes and bloating/swelling. The observed associations with GSTT1 genotype suggest that these observations are not likely due to reverse causation.