Vegetables are an integral part of a healthy, balanced diet. They’re excellent sources of vitamins, minerals, phytochemicals and fibre, all of which are good for our health, but does the way you prepare/cook your vegetables make a difference to their nutritional content?
It’s one of the most common cooking methods, but it comes with some shortcomings. The biggest issue is that boiling vegetables can reduce their vitamin C content. In addition to losing vitamin C, the content of minerals like potassium, magnesium and zinc are typically lower in boiled vegetables compared to raw vegetables. If you’re keen on boiling vegetables but don’t want to lose the nutrients, then one option is to use the vegetable cooking water in the dish. This is a good option when cooking curries or stews. Also, using as little water as possible and avoiding overcooking can help minimise vitamin loss.
Steaming vegetables is popular with dietitians because you lose less vitamins than boiling. When steamed, vegetables like broccoli, spinach and lettuce lose just 9-15% of their vitamin C content. Almost all vegetables can be steamed with good results and it may also enhance the flavour and texture. In particular, steaming root vegetables like artichoke and parsnips is said to provide a better sensory experience. (reference here)
Microwaving is a quick and convenient way to cook vegetables. There is some evidence showing microwaving can preserve nutrients like vitamin C and some phytochemicals in vegetables compared to other cooking methods. In fact, one study here showed microwaving spinach and carrots, allowed the vegetables to retain more than 90% of its vitamin C content. Primarily because the vegetables had limited contact with water and were cooked at lower temperatures.
There’s also evidence to suggest that microwaving some vegetables, including spinach and chard, helps to retain vitamin K, which is required for blood clotting and helping wounds to heal.
Roasting is a great way to enhance flavour in vegetables as it helps release natural sugars. It’s also considered to be a good method of retaining vitamin B1 (thiamine) and vitamin B2 (riboflavin).Â
Roasting is also recommended as a way of cooking tomatoes as it can help increase the lycopene content in them. This is particularly valuable because lycopene is an antioxidant that is believed to protect cardiovascular health and is easily absorbed in the body when tomatoes are cooked (such as homemade tomato sauce or roasted tomatoes). Roasting your vegetables is also hard to beat for flavour.
Sautéing
Sautéing involves cooking in a shallow pan using high heat with a small amount of oil. It could help when cooking tomatoes, with one study here showing that adding olive oil to diced tomatoes during cooking in this way, greatly increased the absorption of lycopene.
To get the largest amount of vitamin C, there are some vegetables that benefit from being eaten raw such as broccoli and lettuce.
However, some vegetables are more digestible and palatable when cooked. Cooking also releases some nutrients like carotenoids which, aren’t accessible when eaten raw.
Ultimately, cooking vegetables to your personal taste is better than not eating them at all. It is worth enjoying them in different forms to get the most from them nutritionally. So, if you decide to boil your vegetables one day, why not try a steamed vegetable recipe the next, or drizzling over some olive oil and roasting them the time after. That way you’ll get the most nutrients and a range of tastes and textures too.
wonderful roast vegetables
All the best Jan
