Broccoli hit the headlines last week with an interesting study showing that cooking methods affect it’s nutrient status and can seriously change its cancer fighting properties. I regularly eat broccoli and serve it up for the kids pretty much daily, but now I’m going to pay more attention to the way I cook and prepare it.
Scientists have shown that broccoli loses its cancer-fighting properties when boiled or microwaved. The researchers found that the best method was to steam it for three to four minutes to enhance the compounds – the main one being sulforophane which has been shown to be cancer protective by stimulating the body’s detoxifying enzymes. The key is that an enzyme called myrosinase is needed for sulforophane to form so when that is destroyed by cooking, sulforophane cannot form. Even one minute of boiling or microwaving destroys myrosinase. But raw broccoli, or steaming for up to five minutes, retains the enzyme.
To get even more out of your broccoli, cut it and leave for five minutes before cooking as this allows the myrosinase to work so some sulforophane is converted before you cook it. Vitamin C also helps with the conversion so squeezing lemon juice over the top, or consuming with some raw vegetables such as peppers helps ensure you are getting the maximum nutrients.
If you can’t avoid overcooked broccoli, for example in soup, there is another way – eating it with other foods containing myrosinase such as mustard, radish, rocket or uncooked cruciferous vegetables (cabbage, cauliflower, Brussels sprouts, kale).
For the really keen, a ‘super broccoli’ has been developed (using traditional methods) at the Institute of Food Research. Called Beneforte, it raises sulforophane levels up to four times as much compared with normal broccoli. Beneforte is available at Marks and Spencer, Asda and a few other supermarkets. It looks and tastes like normal broccoli but packs a heavier nutritional punch so is well worth the extra cost.
What I find interesting is that you can manipulate how you prepare foods to really extract all their goodness and massively increase the nutrient value of your meal without too much hassle or relying on supplements. Take garlic, crushing or chopping it, and leaving it for ten minutes before cooking allows its inactive powerful chemical allicin to become active. Lycopene, an antioxidant in foods that causes the red colour, is activated through cooking meaning tomatoes are much better cooked than raw, but heating berries destroys some of their powerful antioxidants.
Best ways to get more out of your vegetables
- Go for variety – different colours signify different nutrients. I try to make sure I have at least one serving of green leafy vegetables a day and as close to a rainbow of colours that I can.
- People worry that nutrients are lost through cooking but did you know that just as many can be lost through storage? Buy as fresh as you can, preferably seasonal, and don’t leave vegetables at the bottom of the fridge for ages.
- Frozen vegetables get a bad rap but can actually have better nutritional value as they’re usually frozen hours after picking so can be even more nutritious than those which have been transported, left on a shop shelf and then stored in the fridge.
- Eat some vegetables raw and don’t overcook the rest – I usually slice extra vegetables and snack on them whilst I’m cooking the others to get a daily raw quota. Cooking can enhance some nutrients as well as destroying fragile ones. With broccoli, cooked is better for lowering cholesterol and it’s easier to absorb the nutrients in the cooked version than raw.
- Water soluble nutrients, such as B vitamins, leech into cooking water so steaming is better, but if you are boiling vegetables, retain the water as it contains nutrients. You can use the liquid to cook grains, somehow incorporate it into your meal or simply drink as a vitamin-rich tea.
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