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Q: Does cooking reduce the nutritional value of vegetables?
Not always. Some produce, such as tomatoes, don’t really release their nutritional goodies (like the antioxidant lycopene) unless they are cooked. And others, like Brussels sprouts, have hard cell walls that are softened by steaming or cooking, making it easier to access their nutrients. According to a paper in the Journal of Agriculture and Food Chemistry, an overall increase in antioxidant power was observed in cooked vegetables. That said, raw foods contain valuable enzymes that are sometimes reduced by cooking: Vitamin C is especially vulnerable, though its levels are typically reduced, not destroyed. Best advice is to eat a mix of raw and cooked.