Is raw food healthier than cooked food? How do you maximise nutrient availability and minimise nutrient loss? What does cooking do to the nutrients? If you’re like me and interested in getting the most from your food, you’ll likely have come across several cooking myths. Here, I’m going to unpack four of them and offer healthy cooking tips to maximise your nutrition.

Myth 1: All raw foods are more nutritious than cooked ones.

The fact is that some foods (such as meat, poultry, and eggs) can be dangerous when consumed while raw (or undercooked). In fact, some foods are also less nutritious when they are raw because they contain substances that destroy or disarm other nutrients. For example, red cabbage, brussels sprouts, blueberries, and blackberries contain an enzyme that destroys thiamin (vitamin B1). Heating the food actually inactivates the enzyme. 

Thiamin-rich foods include fortified breakfast cereals, fish, beans, lentils, peas, sunflower seeds, and yoghurt among others. Now, in practice, you need not get worried when you are adding some fresh blueberries to your cereal and yoghurt. This act is the minutiae in the grand scheme of things, and you will not end up with a vitamin B1 deficiency if you are enjoying a variety of meals through the years.

Raw beans, legumes, and even eggs contain lectins, which are a type of indigestible protein. It is falsely claimed that these indigestible proteins travel through our digestive system unchanged and, in extremely large amounts, they could damage the gut wall. The reason this claim is false is that cooking renders them harmless – all the more reason to not eat just raw food! Plus, we do not eat lectins in isolation for them to be a problem. What does all this mean for steak-lovers? If the fresh meat is steak, roast, or chop, then medium-rare can be safe. The meat must reach 145˚F internally and stand for three or more minutes before cutting or consuming.

Myth 2: Cooking destroys all the minerals in food.

The truth is that virtually all minerals are unaffected by heat. Cooked or raw food has the same amount of calcium, phosphorus, magnesium, iron, zinc, iodine, selenium, copper, manganese, chromium, and sodium. The single exception to the rule is potassium, which – although not affected by heat or air – escapes from foods into the cooking liquid. This is why we ask patients with kidney disorders to boil their veggies and throw the water so as to regulate their potassium intake.

Myth 3: Cooking kills all the vitamins in food. 

This statement is not wholly correct because cooking does not kill all the vitamins. Vitamins K, B, and B3 are very stable and not affected by cooking. That being said, a lot of vitamins are extremely sensitive and easily destroyed when exposed to heat, air, water, or cooking oil (fats). To avoid specific types of vitamin loss, the below cooking tips and tricks can be used to your benefit. 

• Vitamins A, E, and D – these are fat-soluble vitamins, so to reduce their loss, it’s best to cook foods rich in them with very little oil. For example, it’s recommended to bake, grill, or air-fry vitamin A-rich liver instead of frying it. This also applies to vitamin D-rich oily fish, like salmon or sardines.

When it comes to fat/oil, a lot of people also don’t pay attention to moderation – they either go fat-free or bathe their meals in oil. Try to be mindful of the following tips, which can also be applied for preserving fat-soluble vitamins.

• Use a tablespoon – don’t pour oil directly from the bottle. One teaspoon (5ml) of any oil, ghee, or butter is approximately 45Kcal. Let’s say I use one tablespoon of oil, which is about 15ml (135Kcal) – this can multiply fast if you are not mindful, even when a dish is being shared.
• Use a low flame – this is key! It’s easy to burn food when you use less oil and high flame.
• Use other cooking methods besides deep-frying more often! Keep the deep-frying to special occasions as much as possible. Give the air fryer a shot. This also fits in with what we just said about fat-soluble vitamins.

B-Vitamins:

• You can conserve B vitamins from meat and poultry that leak out into cooking liquid or drippings by using the cooking liquid in soup or sauce.
• It’s best to bake or toast bread only until the crust is light brown to preserve heat-sensitive B vitamins.

Vitamin C:

To reduce the loss of water-soluble, oxygen-sensitive vitamin C, cook fruits and vegetables in the least possible amount of water. For example, when you cook cabbage covered in water, the leaves lose as much as 90% of their vitamin C. Reverse this and cook cabbage in one inch of water, which lets you hold on to more than 50% of the vitamin C. Consume the liquid left in the pan from cooking vegetables.

• It’s best to serve cooked vegetables quickly. After 24 hours in the fridge, vegetables lose a quarter of their vitamin C and, after two days, nearly half. In real life, this may not be possible and that’s fine because we also need to look at the bigger picture, which should always be that you are eating your veggies. There are a lot of other nutrients that you get from veggies, and perhaps eating fresh fruit with the meal should suffice for the lost vitamin C.  
• Root vegetables (like carrots, sweet potatoes, and potatoes) baked or boiled whole, in their skins, retain practically all of their vitamin C. As a general rule, when cooking vegetables grown above the ground, add the vegetables to boiling water. For vegetables grown under the ground, add the vegetables to cold water and bring them to a boil. 
• Avoid washing vegetables after chopping them to preserve vitamins B and C. It’s best to wash them before you chop them.

Myth 4: Cooking destroys and changes the macronutrients in foods.

Macronutrients – namely carbohydrates, fats, and proteins – are not lost with cooking. They only change their structure, which is why cooked rice or cooked fish looks very different to raw rice and raw fish. Cooking also improves the digestion and availability of many nutrients. In the grand scheme of things, there is no perfect cooking method that retains all nutrients – just like there are no perfect foods. Every food and cooking method comes with its pros and cons. A variety of meals eaten in varied ways will negate the effect of nutrients lost.