In the last nutrition blog post I spoke about the benefits of phytonutrients and how to get more of these compounds in your diet. Today I want to pay special attention to the phytonutrients found in the brassica group of veggies. Brassa- what I hear you say? Brassica’s are usually dark green veggies that have quite a distinctive bitter taste like broccoli, brussel sprouts, kale etc. You may have also heard these veggies referred to as cruciferous vegetables.
These veggies have received a lot of attention in recent years because of their cancer-protective benefits. They are unique sources of sulphur containing phytochemicals called glucosinolates. This phytonutrient is responsible for the taste and odour of these veggies. A general rule of thumb – the more bitter the veggie tastes the greater the concentration of glucosinolates.
When these veggies are chopped or well chewed an enzyme is released and it breaks glucosinolates down into two compounds – sulforaphane and indole-3-carbinol (I3C). These two compounds have been associated with a lower risk of developing certain cancers, in particular breast, colorectal and prostate cancers.
Sulforaphane has been shown to improve the livers detoxification processes which means that the body can more effectively clear and detoxify hormones like oestrogen, carcinogens and free radicals. This means that by altering the metabolism of hormones like oestrogen, sulfuraphane may help inhibit the development of hormone sensitive cancers.
Sulforaphane also assists in preventing the development of cancers by turning off genes that help promote the transformation of abnormal cells into cancer cells.
In the acidic environment of the stomach indole-3 carbinol (I3C) breaks down to a compound called 3,3′-diindolylmethane or DIM. 13Cs and DIMs may help slow the growth of cancer cells by increasing cell death and reducing formation of blood vessels to tumors. DIMs are also thought to have an effect on oestrogen metabolism and lead to positive changes in hormone markers.
Okay so these veggies have great cancer protective benefits and I need to eat more of them – but I’ve heard that these veggies can cause problems with thyroid hormones?
There is a lot of nutritional information on the internet suggesting that these veggies have negative effects on thyroid health because they contain goitrogens. Goitrogens basically block iodine – which is critical for thyroid function – from entering the thyroid gland. It is thought, by some, that if you consume too many goitrogens that you may develop an underactive thyroid. The thing is that you have to consume huge amounts of raw cruciferous veggies for the goitrogenic compounds found in them to make a significant impact on your thyroid. What’s huge amounts you may ask? Around 10 cups of raw brussel sprouts would be considered a lot.
Cooking like steaming, sautéing or baking also lowers the active goitrogenic levels in these veggies. So don’t worry about eating 1 – 2 cups of these veggies everyday!
What is the best way to prepare these veggies?
Firstly when grocery shopping try choose the best, most nutrient dense veggies you can. Colour is important – the darker and more vibrant green the veggie is the better. If it’s something like broccoli and it’s slightly yellow and sprouting little flowers choose something else. Also when buying veg with florets like broccoli – choose the one with the most tightly closed and compact florets. Leafy veg should look crisp and fresh and should snap cleanly with an audible ‘snap’. Cruciferous veg should also have a sharp, peppery smell.
In terms of preparing these veggies raw is usually best, but remember to chew your food well. Chewing helps activate the enzymes that break down your glucosinolates into the effective I3C and sulforaphane compounds. If you want to cook these veggies, chop them up first and allow them to sit for 10 – 15 minutes before applying heat, this allows enzymes to be released and break down the glucosinolates.
In terms of cooking, try steaming or sautéing rather then using a microwave or boiling.
My kids / husband / me really don’t like the taste of these veggies what can help?
- Salt can help block the bitter flavour of the veg so crack a small amount of good quality salt like Himalayan salt over the veg to finish the dish.
- As I have already mentioned do not overcook these veg, partly to preserve nutrient content but also because it makes them taste more bitter.
- Try to regularly include brassicas with milder flavours, I personally enjoy rocket (aragula) and watercress in my salads (see this recipe). Cabbage, radish and kohlrabi are also easy to include in salads or stir fries.
- Roasting brassicas can also help bring out their natural sweetness, roasted cauliflower, broccoli and even brussel sprouts taste quite delicious, for ideas have a look at this recipe on the blog.
Cruciferous vegetables can provide some significant health benefits particularly when it comes to their cancer fighting properties, aim to get 1 to 2 cups of these veggies in everyday.
However there is very little point simply adding these vegetables to a nutrient poor diet, thinking they will make all the difference. To obtain the great disease-fighting benefits out these veggies they need to be included in an already nutrient dense diet.