Neither raw nor cooked vegetables are always healthier. Raw vegetables keep more vitamin C and some B vitamins, which are sensitive to heat and leak into cooking water. Cooking, on the other hand, can make other nutrients easier to absorb, especially carotenoids such as lycopene in tomatoes and beta-carotene in carrots and spinach. In one study in the Journal of Nutrition, women absorbed about three times as much beta-carotene from cooked, puréed carrots and spinach as from the same vegetables raw. The method matters too: steaming and microwaving keep more nutrients than boiling. The healthiest approach is to eat a mix of raw and cooked vegetables, and plenty of them.
What cooking does to nutrients
| Nutrient | Effect of cooking | Best way to keep it |
|---|---|---|
| Vitamin C | Reduced by heat and lost into water | Eat some vegetables raw; steam or microwave briefly |
| Folate and some B vitamins | Lost into cooking water | Steam, or use the cooking water in soups and sauces |
| Beta-carotene (carrots, spinach, sweet potato) | Easier to absorb when cooked, especially with fat | Cook and add a little oil |
| Lycopene (tomatoes) | Much easier to absorb when cooked with oil | Tomato sauces, soups, roasted tomatoes |
| Glucosinolates (broccoli, cabbage) | Reduced by long boiling | Eat some raw, or steam lightly |
| Fiber | Mostly unchanged; softer and easier to digest | Either |
| Minerals | Some lost into water | Steam, roast or use the water |
When raw is better
Vitamin C
Vitamin C breaks down with heat and dissolves into water. Raw peppers, broccoli, cabbage, kiwi and citrus keep the most. In an experiment with broccoli, boiling, microwaving, stir-frying and stir-frying followed by boiling all caused significant losses of vitamin C, while steaming kept the most. Our list of vitamin C foods has more.
Broccoli and other cruciferous vegetables
Broccoli, cabbage, kale and Brussels sprouts contain glucosinolates, which an enzyme converts into compounds such as sulforaphane when the vegetables are chopped or chewed. Long cooking can destroy the enzyme. Eating some raw, or steaming lightly, keeps more of it. Our guide to cruciferous vegetables explains more.
When cooked is better
Tomatoes
Lycopene is absorbed far better from cooked tomato products than from fresh tomatoes, particularly with a little oil. Our guide to tomato nutrition explains the evidence.
Carrots, spinach and other orange and green vegetables
Cooking breaks down tough plant cell walls, releasing beta-carotene, which the body converts to vitamin A. Spinach is also lower in volume once cooked, so it’s easier to eat more. Our guide to carrots and eyesight covers beta-carotene.
Mushrooms, asparagus and others
Cooking makes many vegetables easier to digest and can increase some antioxidants. It also makes vegetables more appealing to many people, which matters: the vegetable you’ll actually eat is the healthiest one.
Food safety: when to cook
Some foods should always be cooked:
- Raw kidney beans contain a natural protein, phytohaemagglutinin, that can cause severe vomiting. Dried kidney beans must be soaked and boiled hard for at least 10 minutes. Canned beans are already cooked.
- Raw sprouts such as alfalfa and mung bean sprouts can carry bacteria including Salmonella and E. coli. The US Food and Drug Administration advises children, older adults, pregnant women and people with weakened immune systems to avoid raw sprouts.
- Frozen vegetables intended to be cooked, especially sweetcorn, are safest cooked before eating.
- Wild greens such as nettles should be cooked.
Wash all vegetables and fruit you’ll eat raw. Our guide to washing vegetables explains how.
Best cooking methods
- Steaming: keeps most water-soluble vitamins and color.
- Microwaving: quick, with little water, so nutrient losses are often low.
- Stir-frying: short cooking with a little oil helps carotenoid absorption, though high heat can reduce vitamin C.
- Roasting: develops flavor and helps absorb fat-soluble nutrients, with some vitamin C loss.
- Boiling: loses the most water-soluble vitamins, unless you use the water in soups or sauces.
Tips to get the most from vegetables
- Eat a mix of raw salads and cooked dishes every day.
- Cut vegetables just before cooking or eating, as cut surfaces lose nutrients faster.
- Cook for less time and keep some crunch.
- Use less water, and save it for stock or gravy.
- Add a little fat, such as olive oil, to help absorb fat-soluble vitamins and carotenoids.
- Don’t forget frozen vegetables. They’re frozen soon after harvest and keep their nutrients well. Our comparison of frozen vs fresh produce explains why.
Vegetables that are good either way
Many vegetables are nutritious whether raw or cooked, so choose whichever you enjoy most:
- Peppers: raw for maximum vitamin C, roasted for sweetness and carotenoids.
- Carrots: raw for crunch and vitamin C, cooked for more absorbable beta-carotene.
- Cabbage: raw in slaws, or lightly cooked in stir-fries and soups.
- Cucumber, lettuce and radishes are almost always eaten raw.
- Potatoes, sweet potatoes, squash, eggplant and beans need cooking.
Does roasting create harmful compounds?
When starchy foods such as potatoes and root vegetables are roasted, fried or toasted at high temperatures, a chemical called acrylamide can form. The UK government’s guidance on acrylamide advises cooking starchy foods to a golden yellow color or lighter, rather than dark brown or burnt. Steaming, boiling and microwaving don’t produce acrylamide. This isn’t a reason to avoid roasted vegetables, just a reason not to char them.
Common questions
Are cooked carrots healthier than raw?
They provide more absorbable beta-carotene, while raw carrots keep a little more vitamin C. Both are good choices.
Are raw food diets healthier?
Not necessarily. They’re high in fruit and vegetables but can be low in protein, calories, vitamin B12 and some minerals, and they lose the benefits of cooked foods such as tomatoes and legumes.
Does microwaving destroy nutrients?
No more than other methods, and often less, because cooking times are short and little water is used.
Should I eat raw or cooked spinach?
Both. Raw spinach keeps more vitamin C and folate; cooked spinach provides more absorbable beta-carotene and lets you eat more in one serving. Our guide to spinach nutrition covers it.
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
