Eating fresh, wholesome food that’s packed with nutrients is one of the most important things we can do to stay healthy. But while we do need to make sure we’re getting all the essential vitamins and minerals our body needs, being healthy isn’t just about eating the right stuff – it’s about cooking it the right way too.
The way we cook food is something that’s often overlooked but is incredibly important. After all, we can eat all the vegetables we like. But if we’re always deep frying them, we’ll probably be doing more harm than good.
So what’s the healthiest way to cook food? How can we best retain nutrients in our food? How do we cut down on salt without reducing flavour?
Here’s everything you need to know about cooking your food for the biggest health benefits.
How does cooking change the nutrient content of food?
Before we delve into the best ways to cook different types of food, it’s important to understand how and why the way you cook something can be so significant. Because, while most of us know that cooking food in vats of oil isn’t healthy, many of us aren’t actually aware of how cooking methods can alter the nutritional content of a food.
In many cases, cooking food makes it easier for us to digest. It also makes it easier for our bodies to absorb many key nutrients. However, some cooking methods actively reduce the amount of nutrients in food – and many of these are essential nutrients our bodies need to stay healthy.
Water-soluble vitamins like vitamin C and B vitamins, fat-soluble vitamins like vitamins A, D, E, and K, and minerals including potassium, magnesium, sodium, and calcium are all often reduced by cooking. The heat involved in cooking can destroy up to 20% of some vitamins in vegetables – particularly vitamin C, folate, and potassium.
It’s due to these reasons that some people follow a raw food diet. This diet is based on the belief that by not cooking food, it maintains its original nutritional value. But while many foods are best eaten raw, research suggests that other foods actually benefit from being cooked. So which foods should we cook and which should we eat raw?
Raw vs cooked
According to science, the reason why some foods are better cooked is that heat breaks down cell walls and allows antioxidants to enter the body more easily. Some examples of foods that are healthier when cooked include:
Tomatoes: When tomatoes are cooked, the amount of the antioxidant lycopene increases. Lycopene is linked to a lower risk of prostate cancer in men and reduced risk of heart disease. One study showed that while cooking tomatoes slashed their vitamin C content by 29%, their lycopene content doubled. Eating cooked tomatoes with olive oil can also increase blood lycopene levels by 80%.
Carrots: Cooked carrots contain more beta-carotene (a provitamin A and antioxidant), than raw carrots. One study found that when you cook carrots, you can absorb 6.5 times more beta carotene than from raw carrots.
Asparagus: When you cook asparagus, its fibrous cells break down, which allows vitamins A, C, E and folate to become more easily absorbed.
Spinach: Cooking spinach means that nutrients including iron, magnesium, calcium, and zinc are more easily absorbed.
Mushrooms: Cooking mushrooms releases ergothioneine, a powerful antioxidant. It also reduces agaritine, which is a potential carcinogen.
Legumes: Legumes like lentils, beans, and peas contain toxins called lectins. However, when you soak and/or cook legumes, the lectins are destroyed.
Meat, fish, and eggs: Raw meat, fish, and eggs can contain harmful bacteria that can lead to illnesses. Cooking these foods kills this bacteria.
On the other hand, foods that are healthier raw include:
Broccoli: Raw broccoli contains three times the amount of sulforaphane than cooked broccoli. Sulforaphane is a plant compound that research suggests can help fight cancer. For more information on eating raw broccoli, including some tasty, healthy recipes, check out this Healthline article.
Cabbage: When you cook cabbage, the enzyme myrosinase is significantly reduced. Research indicates that Myrosinase can also help to prevent cancer, so if you’re cooking cabbage try to only cook it for a short amount of time. Making a zingy slaw is a delicious way to eat raw cabbage.
Onions: Raw onion is an antiplatelet agent, which can help to prevent blood clots from forming in your blood vessels and heart, and protects against heart disease. When you cook onions, this benefit is reduced. Red onion is better eaten raw than white. You can try it in sandwiches and salads – and if it’s a bit too strong tasting for you, just soak it in cold water for a few minutes.
Garlic: Studies show that raw garlic contains sulphur compounds that may have anti-cancer properties. But scientists have also found that when you cook garlic, these compounds are destroyed. You can grate or mince a garlic clove and add it to salad dressings to enjoy it raw.
Healthy cooking methods
So, now we know why cooking can change nutrient content, what are some of the pros and cons of different methods of cooking?
1. Boiling
Boiling is quick and easy, and for a long time was the most common way to cook vegetables in the UK – and if you remember your school dinners, boiled, underseasoned veg almost certainly made a regular appearance! But boiling is actually one of the worst ways to cook vegetables.
When vegetables are boiled, vitamins are lost through two different ways: leeching, where the nutrients go into the water, and thermal destruction, when the nutrients are destroyed by heat. In terms of vitamin C alone, boiling eliminates it more than any other cooking method – and broccoli and spinach can lose up to half of their vitamin C content when boiled.
If you do boil your vegetables, always save the nutrient-rich water and use it for soup or stock.
2. Steaming
Steaming also uses hot water, but rather than plunging the food into the water, the heat from the steam does the actual cooking. Steaming is one of the best ways to cook vegetables, as it preserves those nutrients that are sensitive to heat and water. Studies show that steaming broccoli and spinach only reduces their vitamin C content by 9–15%.
Steaming is simple, although to steam your vegetables properly you should invest in a vegetable steamer or steaming basket. Generally, most vegetables only need to be steamed for three or four minutes, and when they turn a bright, vibrant colour, they’re done.
It’s not just vegetables that benefit from steaming. Steaming fish by wrapping it in foil parcels and allowing it to cook in its own juices is a great way to retain nutrients. It can help to add a bit of seasoning first, whether that’s a squeeze of lemon juice or a bit of salt and pepper.
3. Microwaving
While microwaves were typically used to reheat leftovers or cook ready meals, they’re actually one of the best ways to cook vegetables if you’re looking to retain nutrients.
Microwaves cook food from the inside out. They emit radio waves that activate the molecules in food, which generates heat – and due to the quick cooking time, fewer nutrients are destroyed than during other methods of cooking.
Studies show that cooking both garlic and mushrooms in microwaves allows them to retain the most antioxidants. Plus, when you cook green vegetables in the microwave they only lose around 20–30% of their vitamin C, which is less than most cooking methods.
Another perk of microwaves is that due to the way they cook food, you don’t need to add extra oil. Though, because it can be tricky to heat food all the way through so bacteria is killed, it’s not the best way to cook meat.
4. Grilling
Grilling is a popular way of cooking both meat and vegetables because it gives a delicious, smokey flavour while still keeping the meat and veg tender. However, if you’re cooking meat, up to 40% of the vitamins and minerals can be lost when juices drip from the meat.
It’s also been suggested by scientists that regularly eating grilled meat may increase the risk of pancreatic cancer and breast cancer. This is because when meat is grilled and fat drips onto a hot surface, polycyclic aromatic hydrocarbons (PAHs) can be produced. However, if fat drippings are removed and smoke is minimised, PAHs can be reduced by 41–89%.
5. Roasting
If you roast food for short amounts of time, there’s generally minimal vitamin loss, including vitamin C. However, if you’re cooking food (generally meat) at high temperatures for longer durations, you can lose as much as 40% of the B vitamins.
If extra fat is added, vitamins A and E may also be destroyed. There’s also evidence to suggest that baking, frying, grilling, roasting, or toasting starchy foods at high temperatures (above 120°C) can cause acrylamide to form, which is a compound that’s linked to cancer – although more research is needed before we can draw any firm conclusions here.
If you’re roasting meat, try to only cook it to a light brown colour, and to follow the cooking instructions on packaged foods.
6. Sautéeing
Sautéeing is a common way to cook vegetables and some types of tender meats, and in general, it’s a healthy method of cooking. Though oil or other fats are used to stop the food sticking to the pan, it’s only a small amount – and because the cooking time is shorter, minimal nutrients are lost.
Cooking without water means the loss of B vitamins is prevented, and the addition of fat means plant compounds and antioxidants are more easily absorbed. Studies show that blood lycopene levels increase by 80% when tomatoes are sautéed in olive oil.
However, for other foods, you might want to think about using an oil that has a higher smoke point than olive oil, like avocado oil, rapeseed oil, or peanut oil. When oil is heated past its smoke point – so when the oil burns and smokes – it loses all its healthy nutrients, and in some cases can lead to harmful free radicals being produced. So, if you’re using olive oil, be careful not to heat it too much.
To find out more about oil smoke points and why they’re important, you might want to check out this article from Very Well Fit.
7. Frying
And then there’s frying. Because fried food retains a seal, the inside stays moist while the outside can become crisp – and when cooked in fat, it can taste pretty good! But, unsurprisingly, it’s not a very healthy way to cook food.
While frying can actually preserve some vitamin C and B vitamins, it can decrease many other important nutrients. Many people love fried fish, and though fish is a great source of omega-3 fatty acids, frying it can reduce its omega-3 content by up to 85%.
Plus, when oil is heated to a high temperature for longer periods of time (compared to sautéeing, for example), toxic substances called aldehydes are formed, which have been linked to an increased risk of cancer.
If you’re going to fry food, try not to cook it for long, and think about using one of the healthier oils for frying.
Tips for cooking healthier
If you’re keen to cook as healthily as you can, there are many small things you can do to prevent nutrient loss, maximise the health benefits, and cut down on both salt and fat.
Preserving nutrients when preparing and cooking food
Rather than peeling vegetables, scrub them instead, as many nutrients are stored just beneath the skin.
If you boil vegetables, use as little water as possible to minimise the loss of B and C vitamins, then use the nutrient-rich water that’s left in stocks or soups. If you can’t use it right away, freeze the liquid for later use.
If meat is dripping juices while cooking, collect them and add them back to the pan.
If you have leftover cooked veg, try to consume it within a day or two, as vitamin C content can decline when exposed to air.
Cook vegetables as quickly as you can, ideally only for a few minutes.
Avoid cutting food before cooking; cut it after. This ensures a smaller amount of food is actually exposed to heat or water.
If you’re cooking meat or fish, pat it dry first so it browns more easily, and cook it for the shortest time possible for safe consumption. Though, be sure to check it’s cooked all the way through.
Because cooked foods lose some of their nutrients, try to consume some raw fruits and vegetables every day to make sure your vitamin C levels remain high.
Minimising fat content when preparing and cooking food
If you need to use oil to cook, try using oil sprays rather than bottles, or use a pastry brush to brush the food with oil.
Rather than sautéeing vegetables in oil, try sautéeing in liquids like stock or water.
If asked to use cream in a soup or sauce recipe, use low-fat yoghurt or low-fat milk instead.
Rather than browning vegetables in a hot pan with oil, microwave them until tender, then allow them to crisp up under the grill for a few minutes.
If you want to add fat to a meal to improve the taste, use olive oil instead of butter.
Instead of adding extra flavour with butter, creamy sauces or sauce cream, use pestos and chutneys instead.
Minimising salt content when preparing and cooking food
Always taste your food before adding salt – you may not need any!
When cooking vegetables, add a dash of olive oil, vinegar or lemon juice when it’s almost cooked – this can improve flavours in the same way as salt.
Try to avoid processed meat and fish that’s high in salt like salami, ham, smoked salmon, bacon, and sausages.
Check the salt content in bread and breakfast cereals before buying. These are often much higher in salt than you think.
Avoid processed foods that are high in salt, like flavoured instant noodles, crisps, canned soups, and salted nuts.
Try to cut down on soy sauce, tomato sauce, and other condiments that are high in salt, like ready-made salad dressings.
Enhancing flavour when preparing and cooking food
Use herbs and spices to replace the flavour of salt and oil.
Dried herbs are stronger than fresh herbs. Generally speaking, one teaspoon of dried herbs is the same as four teaspoons of fresh herbs.
If you’re cooking Asian cuisine, use plenty of garlic, ginger, chilli, lemongrass, and coriander.
Fresh herbs are delicate, so only add them to your cooking in the last couple of minutes.
Final thoughts…
While there’s no perfect way of cooking that retains all vitamins and nutrients, some cooking methods are better than others. Whatever you’re cooking, it’s generally best to cook foods for shorter periods of time and at lower temperatures, and use as little water as possible.
Ultimately, cooking healthy, nutritious meals should be a pleasure, so rather than becoming too focused on whether you’re cooking your meals in the healthiest possible way, why not try utilising some of the easy tips and tricks in this article? And if you can, try to eat some raw fruits and vegetables every day, to ensure you’re getting enough vitamin C.
For more diet tips and tricks, you might want to check out our article; 15 quick and easy diet swaps for a healthier lifestyle.
Do you make an effort to cook healthily as well as eat healthily? Or do you have any other suggestions for how to cook your food for the biggest health benefits? We’d love to hear about the efforts you go to to stay healthy in the comments below.