Does Cooking Destroy Nutrients? The Honest Answer

"Raw is healthier" is one of the most repeated ideas in nutrition — and it's only half true. Cooking genuinely destroys some nutrients. But it also unlocks others that raw food keeps locked away. The skill isn't avoiding heat; it's knowing which method to use for which food.

What cooking can destroy

The casualties are mostly the water-soluble vitamins — vitamin C and the B vitamins, especially folate. They're fragile and they leach into cooking water. Boiling is the worst offender: prolonged boiling can discard a large share of a vegetable's vitamin C straight down the drain. Delicate omega-3 fats in oily fish are also vulnerable to high, harsh heat like deep-frying.

What cooking unlocks

Here's the part the "raw" crowd misses:

• Tomatoes: cooking raises their available lycopene, and eating them with a little olive oil increases how much your blood actually absorbs.
• Eggs: cooking nearly doubles how much of the protein your body can digest compared with raw.
• Carrots, spinach, sweet potato: gentle cooking breaks down tough cell walls, releasing carotenoids — which then need a little fat to be absorbed.
• Beans and grains: cooking (and cooling) makes them safe and, in the case of starches, more gut-friendly.

The rule of thumb

Match the method to the food. For vitamin-C-rich and leafy vegetables, steam instead of boil — steaming keeps far more of the vitamin in the food, and it's quick. For oily fish, bake, steam or poach at a gentle temperature rather than deep-frying. For tomatoes and carotenoid-rich vegetables, cook with a little fat. And if you do boil, keep the cooking liquid for a soup or sauce — the vitamins are in there.

Knowing exactly which method protects which nutrient — for every food in your kitchen — is what The Nourish Code lays out, one short chapter at a time.