Effects of incorporating green leafy vegetables with meals on starch and lipid digestibility under simulated gastrointestinal digestion

Green leafy vegetables (GLV) are known for their cardiovascular health benefits. However, the effects of their serving size on delaying carbohydrate and lipid digestion remain unclear. This study investigated the impact of varying MyPlate-recommended GLV serving sizes on the digestibility of carbohydrates and lipids and antioxidant activity during in vitro gastrointestinal digestion. Eight GLV including Asteraceae (cos, green oak, red oak, loose-leaf) and Brassicaceae (cabbage, cauliflower, broccoli, Chinese cabbage) vegetables were incorporated into mixed meals at 0.5, 1.0, and 1.5 times the MyPlate recommendation. The results showed that the total phenolic content (TPC) ranged from 5.77 to 9.46 mg GAE/g extract. Nitrate accumulation exhibited a higher content in Asteraceae (590.90-1155.04 mg NO3-NE/g extract) than in Brassicaceae families (244.96-726.20 mg NO3-NE/g extract). Incorporating >= 1 serving of all GLV significantly decreased rapidly and slowly digestible starch fractions, while undigestible starch significantly increased, resulting in delaying glucose release. Antioxidant activity was significantly enhanced with >= 1 serving and free fatty acid concentrations decreased with higher vegetable servings. Post-digestion nitrate concentrations ranged from 127.3 to 188.5 mu g NO3-N/mL, positively correlating with GLV serving size. These effects were dose-dependent and varied across species. These findings suggest that incorporating GLV at or above the MyPlate recommendation may have protective effects on cardiovascular health.