The relationship between cooked vegetables and their nutritional value

The RAW food movement has gained popularity in recent years. Indeed focussing on eating raw foods has many health benefits as following these principles has a tendency to direct you to eating more fresh foods. This is a massive improvement from eating processed or fast foods.

Based on the raw food ideology, it is often assumed that all foods are best raw. However, there are certain vegetables that instead are best eaten cooked. Some plants contain toxins that can be harmful when eaten raw, but that are neutralized when cooked. For other vegetables they are simply more tasty and nutritious when eaten cooked.  Here are 7 foods that are best eaten cooked - and some of them might surprise you:

Sweet Potato
Sweet potato is an excellent source of beta carotene and believe it or not, how you prepare sweet potatoes impacts the availability of the nutrients. Sweet potato is one of the richest sources of Vitamin A and it appears that roasting or boiling sweet potatoes makes this vitamin much more available than when it is raw.

Aubergine / Eggplant / Brinjale 
Aubergines are part of the nightshade family of edible plants. Aside from tasting bitter when raw, aubergines also contains solamine which can inhibit the absorption of calcium. It is recommended to eat only ripe aubergine and to salt them before cooking. This helps to draw out the bitter taste. Aubergine is delicious when sauteed in olive oil or roasted in the oven. It is a low calorie vegetable that has antioxidant properties and could have benefits for heart health.  

Asparagus contains a wide range of valuable nutrients, but raw it is stringy, tough and not very tasty. The best way to cook asparagus is to blanch it in boiling water for 2-3 minutes or to cook in broth for 3-5 minutes. The asparagus should remain al dente and a rich green colour. It can be enjoyed hot or cold.

Asparagus is a wonderfully nutritious vegetable. It is particularly rich in vitamin K, folate, copper and Vitamin B1. It also contains a host of other nutrients including selenium, vitamins C, E and B2, as well as manganese, phosphorous and potassium. Asparagus has shown to have anti-inflammatory and anti-oxidant benefits. It is also noted for improving digestive health, heart health and having a regulating effect on blood sugar levels.   

While there are many inedible and highly poisonous mushrooms that occur in nature, most people assume that all edible mushrooms can be eaten cooked or raw. However, mushrooms consist of mycochitin cellular walls that our digestive systems cannot break down. The result is that our system simply rejects the food along with all it’s nutritional value. Cooking mushrooms, especially in healthy oils such as olive oil or butter, helps to soften the mushrooms and makes the nutrients more available. In addition, some mushrooms contain toxins that could lead to digestive complaints if eaten raw.  

Keep in mind that pickled mushrooms are in fact cooked chemically. The combination of vinegar or lemon juice with herbs and spices also has the effect of softening the mushrooms and making them easier to digest.

While there are those that claim to eat raw button mushrooms with no ill effects, this is still a questionable practice. Many types of mushrooms including button mushrooms contain hydrazines. These are chemical compounds generally accepted as being carcinogenic. However, they are also heat sensitive and are destroyed by cooking making edible mushrooms safe to eat.

Cabbage & cruciferous vegetables
While cabbage and other cruciferous vegetables contain valuable nutrients including good levels of vitamin C & K, there is some research that suggests that eating raw cabbage in coleslaw on a regular basis may not be the best idea as it contains chemicals that can inhibit thyroid function. However, on the other side, cruciferous vegetables have shown to have many anti-oxidant capabilities and health promoting benefits. By cooking the vegetables for a short period of time, it is possible to still enjoy many of the nutritional benefits, and reduce the glucosinolates which can impact thyroid function. If you do have a history of thyroid issues, it may be wise to limit or avoid too much raw cabbage.   

Tomatoes are a versatile food that is often a staple for salads and sandwiches. They are a rich source of vitamins including Vitamin A, C, K, E & B as well as valuable phytonutrients. As we know that vitamin C is easily destroyed by heat, it may be assumed that tomatoes are best eaten raw to retain the levels of vitamin C. While this may be true, studies also show that the bioavailability of other nutrients actually increases when tomatoes are cooked.

Lycopene is one of these phytonutrients that increases in concentration in cooked tomatoes. Lycopene has shown to be a strong antioxidant, helping to decrease the signs of aging and have a protective and healing effect on many organs in the body. Lycopene is linked to improved cardiovascular health, kidney health, prevention of prostate cancer, and improved bone health. Cooked tomatoes or tomato paste can also help prevent sunburn according to recent studies.    

Carrots like tomatoes are a staple in many kitchens. They contain high levels of vitamin A and have been extensively researched for their high anti-oxidant abilities. A recent study showed that a short cooking time for carrots may increase the bioavilability of nutrients in carrots.   Exposure to heat actually increases the nutrient value and antioxidant abilities. This is not to say that raw carrots aren’t nutritious. They can still be enjoyed as a snack or in salads.

As this proves raw isn’t always best, and as more studies research the benefits of food types and preparation methods, we may find there are many more ways that we can enjoy our favourite foods and enjoy their nutritional value.