In South Asian and Ayurvedic home cooking, a squeeze of fresh lemon or lime juice and a handful of chopped fresh cilantro are added at the very end—after the pot of dal or vegetable curry comes off the burner.
From a food-chemistry perspective, that traditional finishing step is ideal: vitamin C (L-ascorbic acid) is both water-soluble and heat-sensitive, so adding fresh citrus or raw herbs at the table delivers intact vitamin C alongside the cooked meal.
Adult vitamin C targets and why daily food sources matter
As Oregon State University's Linus Pauling Institute explains, vitamin C (L-ascorbic acid) is an essential water-soluble vitamin and antioxidant required for the biosynthesis of collagen, carnitine and neurotransmitters, and it also enhances non-heme iron absorption from plant foods. Unlike most mammals, humans cannot synthesize vitamin C internally and must obtain it from food.
The Recommended Dietary Allowance (RDA) for vitamin C is 90 mg/day for adult men and 75 mg/day for adult women (increasing to 85 mg/day during adult pregnancy and 120 mg/day during breastfeeding; smokers require an additional 35 mg/day due to oxidative stress, or 125 mg/day for men and 110 mg/day for women). On U.S. Nutrition Facts panels, the FDA Daily Value (DV) for vitamin C is 90 mg.
- Adult RDA: 90 mg/day for men; 75 mg/day for women (125 mg/day and 110 mg/day for men and women who smoke).
- FDA Nutrition Facts Daily Value: 90 mg/day.
- According to the Linus Pauling Institute, five varied servings (2.5 cup-equivalents) of fruits and vegetables typically supply about 150 to 200 mg of vitamin C.
Why boiling and long simmering reduce vitamin C in vegetables
Among everyday vitamins, vitamin C is one of the most vulnerable to kitchen processing. Because L-ascorbic acid dissolves readily in water and oxidizes when exposed to heat, oxygen and alkaline conditions, chopping vegetables finely and boiling them in a large pot of water causes a double loss: vitamin C leaches into the cooking water and degrades thermally during prolonged simmering.
Comparing food sources compiled by the Linus Pauling Institute from USDA FoodData Central shows why raw fruits, sweet peppers and briefly cooked brassicas stand out:
- Gold kiwifruit (1 fruit, 81 g): 130 mg of vitamin C (green kiwifruit: 48 mg)
- Strawberries, whole (1 cup): 85 mg of vitamin C
- Navel orange, raw (1 fruit, 140 g): 83 mg of vitamin C (6 oz orange juice: 68 mg)
- Sweet red pepper, raw (1/2 cup): 59 mg of vitamin C
- Broccoli, cooked (1/2 cup) or Brussels sprouts, cooked (1/2 cup): 48 to 51 mg of vitamin C
- Potato, baked with skin (1 medium): 22 mg of vitamin C
- Tomato, red, raw (1 medium): 17 mg of vitamin C
Three kitchen habits that protect vitamin C (and boost iron uptake)
You do not need to eat an all-raw diet to get plenty of vitamin C. Even cooked broccoli, Brussels sprouts and baked potatoes retain meaningful amounts when cooked briefly without excess water, and pairing a fresh finishing element with a simmered dish gives you the best of both worlds:
- Add lemon or lime juice off the heat: Squeeze fresh citrus over hot dal, chickpea curry or steamed greens right before serving rather than boiling the citrus juice for 20 minutes.
- Steam, microwave or stir-fry vitamin C-rich vegetables (like broccoli, bell peppers, cabbage and snow peas) until tender-crisp instead of boiling them in a large pot of discarded water.
- Pair fresh vitamin C with lentil and leafy-green meals: Adding raw bell pepper, tomato salad, citrus juice or fresh fruit alongside a plant-based meal simultaneously supplies vitamin C and enhances intestinal non-heme iron absorption.
Sources & Classical References
- Linus Pauling Institute, Oregon State University: Vitamin C — Provides adult vitamin C RDAs (90 mg/day men, 75 mg/day women, plus smoker, pregnancy and lactation targets), biological functions, and the food sources table (kiwifruit, strawberries, orange, sweet red pepper, broccoli, Brussels sprouts, baked potato, tomato).
- FDA: Daily Value on the Nutrition and Supplement Facts Labels — Confirms the 90 mg Daily Value for vitamin C on U.S. Nutrition Facts panels.
