With that Spring feeling in the air everyone is thinking about cleansing and getting ready for the Summer. Something that I always want more of this time of year are green smoothies. I still drink them over Winter, but I definitely feel more inclined to have one for breakfast instead of my usual buckwheat and chia seed porridge. With the increase in having either juiced or blended greens everyday, something to be mindful of is mixing up the variety of greens you use.
There has been publicity in the past concerning cruciferous vegetables such as kale, brussel sprouts, broccoli, cauliflower, collard greens, horse radish, watercress and rocket causing thyroid problems. Mainly from one case in 1946 of a woman falling into a coma after eating 1.5kg of raw bok choy a day for several months - thats a serious amount of one vegetable and I wouldn't be recommending this level of consumption to anyone! These vegetables contain goitrogens which can affect the thyroid by blocking the uptake of iodine in the body which is essential in the conversion of thyroid hormones.
However they also contain some amazing other elements such as glucosinolates which are sulfur-containing compounds (they give the veggies that lovely stinky smell!!) that when broken down results in the formation of biologically active compounds, such as indoles - especially Indole-3-Carbinol and isothiocyanates. Scientists are currently interested in the potential for high intakes of cruciferous vegetables to prevent cancer. (1)
Oxalic acid (oxalates) are another area of concern from eating too many of the same greens. Some of the foods high in oxalic acid are spinach, nuts, seeds and soy. Oxalic acid combines with calcium and can be involved in the formation of kidney stones. 80% of kidney stones in patients in the USA are composed of calcium oxalate(2) Should this be of a concern? Only if you have a history of kidney stones or Hyperoxaluria. If so, you should be keeping an eye on the level of oxalates in your diet generally - not just in your smoothies. Here is a list of oxalates in foods.
So how do you balance the benefits of these amazing greens with the possible side effects? Firstly rotate the green vegetables that you use. Don't just use kale or spinach, but swap it around with dandelion greens, parsley, coriander, zucchini, beetroot, lettuces (romaine, iceberg, mignonette, butter), celery, Swiss rainbow chard, rocket (arugala) even cabbage can be an amazing addition to your smoothies or juice. Although some of these are an acquired taste!
You can also blanch your cruciferous vegetables as the goitrogens are broken down when cooked (3). A light blanching in boiling water just before blending is the best way to do this if you have thyroid issues. And rotating your greens should allow you to enjoy a daily juice or smoothie without any issues!
SUMMER LOVE makes 2 serves
- 2 cups kale
- 1 cup frozen berries
- 1 1/2 cups coconut water
- 1/2 banana
- 1 tablespoon coconut oil
- 3 Brazil nuts
- Top with fresh blueberries
Place all ingredients into a high powered blender on high until smooth. Serve immediately!