Previous animal studies found beneficial effects of choline and betaine on maternal glucose metabolism during pregnancy, but few human studies explored the association between choline or betaine intake and incident gestational diabetes mellitus (GDM). We aimed to explore the correlation of dietary choline or betaine intake with GDM risk among Chinese pregnant women. A total of 168 pregnant women with GDM cases and 375 healthy controls were enrolled at the Seventh People’s Hospital in Shanghai during their GDM screening at 24–28 gestational weeks. A validated semi-quantitative FFQ was used to estimate choline and betaine consumption through face-to-face interviews. An unconditional logistic regression model was adopted to examine OR and 95 % CI. Compared with the controls, those women with GDM incidence were likely to have higher pre-pregnancy BMI, be older, have more parities and have higher plasma TAG and lower plasma HDL-cholesterol. No significant correlation was observed between the consumption of choline or betaine and incident GDM (adjusted OR (95 % CI), 0·77 (0·41, 1·43) for choline; 0·80 (0·42, 1·52) for betaine). However, there was a significant interaction between betaine intake and parity on the risk of GDM (Pfor interaction = 0·01). Among those women with no parity history, there was a significantly inverse correlation between betaine intake and GDM risk (adjusted OR (95 % CI), 0·25 (0·06, 0·81)). These findings indicated that higher dietary betaine intake during pregnancy might be considered a protective factor for GDM among Chinese women with no parity history.

Using hyperbaric oxygen (HBO) therapy as an in vivo oxidation model, we investigated the effect of a diet enriched in ascorbic acid (AA) on HBO-induced oxidative stress. Volunteers (n 46) were allocated to the AA-rich diet group or the control group. Blood samples were collected at the basal time, after the 1-week diet before and immediately after the HBO treatment, and 1 week after the HBO treatment. AA level, total antioxidant status (TAS), hydroperoxides (HP), lymphocyte DNA oxidation and DNA repair capacity were assessed. The expression of genes involved in oxidative stress was evaluated in lymphocytes and the protein activity of the modulated genes was determined in the plasma. The AA level and the antioxidant status of plasma were increased by AA-rich food consumption. HBO exposure did not affect the AA levels or TAS, but induced HP formation in the control group. The lymphocytes isolated from dietary-supplemented subjects were resistant to ex vivo DNA oxidation, showing an increased DNA repair capacity compared with controls. A difference in gene expression pattern was observed between the groups. AA-rich foods provide dual protection against oxidative stress, enhancing plasma antioxidant levels and stimulating genes involved in cell detoxification.