Tomatoes are good for you. They’re a great source of lycopene, an efficient antioxidant. Cooking lowers lycopene content a tad. Reason enough to shun tomato sauce and chomp on raw salads at the risk of ingesting the odd parasite egg? Not really.
Apply heat for extra nutrition
Lycopene molecules come in several shapes. Cooking actually increases the kind your body can absorb more efficiently. Adding olive oil makes yet more lycopene available. Unfortunately, research shows sunflower oil doesn’t.
Heat also breaks up the cell matrix that traps nutrients such as beta-carotene and lycopene (carotenoid pigments, precursors of vitamin A), and folate (vitamin B9) in spinach, carrots and tomatoes.
Cooking also neutralizes antinutrients:
• Thiaminases, which render thiamin (vitamin B1) inactive, and are found in Brussels sprouts and red cabbage, are destroyed by cooking.
• Goitrogens stop your body from using iodine. They are found in cabbage-like veggies, turnips, tapioca, sweet potatoes, and beans. Cooking deactivates them.
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• Phytates interfere with mineral and niacin (vitamin B3) absorption. They are found in cereal grains and beans, especially the red ones. Beans and dals also have bitter tannins in the skin, and insoluble carbohydrates within that cause flatulence. Soaking and draining helps. Cooking (especially pressure cooking) and then draining improves things further. Adding a pinch of soda while soaking the beans makes for a more effective alkaline bath.
• People prone to kidney stones are often advised to avoid oxalate-rich foods such as leafy greens, colocasia, potatoes, beet, tomatoes, lady’s fingers, citrus fruits, berries, mangoes, nuts and seeds and soyabean. These also hamper the absorption of calcium. Drain the water after cooking and you will absorb the calcium in your meal normally.
Pick ‘processed’ for better health
As with cooking, “processing” isn’t always a pejorative:
• Sprouts, for instance, are more nutritious—providing nutrients such as zinc and iron—as is fermenting dal and grain batter used to make idlis and dosas.
• Hand-pounded rice, millet and maize are left with less phytates, yet have more vitamin than milled grain.
• Pasteurizing milk prevents curdling and destroys a host of bacteria.
• Many people who are lactose intolerant can digest yoghurt easily.
• Fish bones are full of calcium but make a prickly mouthful—unless you get yours from a can. Processing softens the bones, making extra calcium available.
The raw and the cooked: eat both
Water-soluble nutrients lost in cooking can be replaced (say, by eating fruits). At the same time, the nutrients are not totally lost in cooking. A study by Punjab Agricultural University in 2006 analysed 10 common vegetable dishes (from sarson ka saag to aloo-capsicum) and found they provided 269.9% and 77.5% of the vitamin C and beta-carotene you need daily.
Manidipa Mandal is deputy features editor at Mint.