“Raw keeps more vitamins” is too simple to be a rule. Heat can reduce some sensitive nutrients, but it can also break down plant structure and soften cell walls, making certain compounds easier to release during digestion. A cooked tomato or well-processed carrot can therefore contain less of one nutrient while making another one easier to absorb.
Better absorption does not mean cooking creates nutrients
Two ideas need to stay separate. The amount present in a food is one thing; bioaccessibility and absorption are another. Cooking does not create beta-carotene or lycopene. It can change the plant matrix so more of those compounds leave the cells and become available for the digestive steps that handle fat-soluble substances.
The effect varies by food, nutrient, temperature, time, and physical processing. There is no single cooking method that improves everything.
It also helps to distinguish bioaccessibility from bioavailability. Bioaccessibility describes how much is released from the food matrix and becomes available for absorption; bioavailability includes what is actually absorbed and used. Cooking mainly changes the early part of that chain, while digestion and individual physiology still matter.
Tomatoes are the classic lycopene example
Lycopene is relatively stable through tomato processing, and heating can shift some of it into forms that are easier to absorb. A review of tomato products found that total lycopene remained stable through juice and paste processing, while heating tomato juice with oil promoted cis forms considered more bioavailable.
That helps explain why cooked tomato sauce with some dietary fat can be a particularly useful source of lycopene. It does not make sauce nutritionally superior in every respect: heat-sensitive vitamin C can move in the opposite direction.
Tomato paste adds another factor: concentration. Removing water can make the amount of lycopene per spoonful high even before considering changes in absorption. Concentration and bioavailability are separate reasons a cooked tomato product may stand out.
With carrots, breaking the structure matters as much as heat
Beta-carotene is physically trapped inside plant cells. Human work comparing carrot preparations found carotene absorption was about two times greater from a commercial puree than from boiled-mashed carrots, while raw grated carrots fell between the cooked preparations.
The practical point is not that carrots must always be cooked. It is that heating, pureeing, chopping, and chewing all influence how much carotene becomes accessible. A smooth soup does not present the same structure to digestion as a large raw carrot chunk.
That also means particle size can matter without a long cooking time. Finely chopping, grating, blending, or chewing well changes the physical barrier around plant compounds before digestion even begins.
A little dietary fat helps with carotenoids
Lycopene and beta-carotene are fat-soluble. Eating them as part of a meal that includes some fat supports the digestive process that carries them. That does not require soaking vegetables in oil; olive oil, nuts, seeds, eggs, or avocado can provide the fat already present in the meal.
The meal context matters more than chasing an exact spoonful. Tomato with avocado, carrot soup finished with olive oil, or vegetables served alongside eggs already combine carotenoid-rich foods with some dietary fat.
The same heat that helps one compound can reduce another
Vitamin C is water-soluble and heat-sensitive. The NIH notes that prolonged storage and cooking can reduce vitamin C content, while steaming or microwaving may limit losses compared with longer cooking or cooking in plenty of water.
So the useful question is not simply “raw or cooked?” It is which nutrient, which food, and which preparation. Eating a mix of raw and cooked produce is a practical way to capture the strengths of both without treating every meal like a laboratory experiment.
If the cooking liquid stays in the dish, some nutrients that moved into the water are still eaten. Boiled vegetables that are drained and a vegetable soup made with the same water are therefore not nutritionally identical situations.
Other foods follow the same principle
Spinach, squash, peppers, and other vegetables contain carotenoids whose release can improve as plant tissue softens, although every food responds differently. A vegetable rich in vitamin C may lose some of that vitamin during long cooking even while carotenoids become easier to access.
Beans show another side of cooking. Heat and soaking make starch digestible and reduce some antinutritional factors, but that is not the same as saying the cooked beans suddenly contain more nutrients than the dry beans did.
The kitchen rule worth keeping
Cooked tomato with some fat, cooked or pureed carrot, and other softened vegetables can make carotenoids easier to access. For heat-sensitive nutrients, unnecessarily long cooking works against you.
Cooking is not universally better or worse; it changes the food matrix, and that changes what your body can get from it. A mix of raw and cooked foods is usually more sensible than looking for one perfect preparation method.
Sources
- NIH Office of Dietary Supplements — Vitamin C — Vitamin C heat sensitivity and cooking losses.
- Rao & Agarwal — Lycopene Content of Tomato Products — Lycopene stability and bioavailability in processed tomato products.
- Edwards et al. — Carotene bioavailability from carrot preparations — Human comparison of carotene absorption from differently processed carrots.