There are a lot of warnings about eating raw crucifers, like cabbage, broccoli, and cauliflower, because of their goitrogenic effect. But how worried should we really be?
Years ago I shared information about eating raw crucifers, and how they are linked to poor thyroid function or goiters. While I believe a lot of the information I came across when writing that post remains true, recently I came across more information that gives a wider grasp on this issue. I thought it was so helpful; I knew I needed to share it with you too!
First, to define a few terms.
Goitrogenic Foods: Foods that contain substances that could inhibit proper synthesis of thyroid hormones or prevent the absorption of iodine into the thyroid gland, leading to a goiter (or compromised thyroid function).
Goiter: Abnormal, enlarged thyroid gland, noncancerous
Goitrogenic foods include broccoli, cauliflower, Brussels sprouts, kale, watercress, arugula, maca, radishes, daikon, turnips, collard greens and bok choy.
Evidence that goitrogenic foods can be a problem
Chris Masterjohn wrote the original article that got me writing about this, which you can find here. It has a lot of information in it but is worth a read. He tells us the history of the science behind goitrogenic foods. It started when some scientists in 1929 at John Hopkins University produced goiters in rabbits when feeding them cabbage. A few important facts from his article:
- While sometimes goiters can be caused by excess iodine, usually it is caused by low amounts of iodine.
- Chris points out that while low amounts of goitrogens in your diet aren’t a problem if you get plenty of iodine from your diet. However, if you eat high concentrations of goitrogens, they can prevent the “incorporation of iodine into thyroid hormone.”
- He also points out that cruciferous goitrogens can prevent iodine from being transferred to nursing babies and that goitrogens pass directly through the placenta and through breastfeeding to babies. He also shared that “researchers believe that high maternal consumption during pregnancy and lactation of improperly detoxified cassava—a starchy vegetable with goitrogens similar to those that occur in crucifers—plays a role in the endemic cretinism that plagues the children of many third world populations.”
His recommendation includes the following:
- Steaming or Boiling crucifers vegetables, especially if you eat them on a regular basis. If you steam crucifers until fully cooked, he says the goitrogens will be decreased by one-third. Crucifers boiled for thirty minutes decreases goitrogens up to 90%.
- Increasing dietary iodine.
- Eating sauerkraut as a condiment (that is, not eating huge bowls of it).
But should we be scared of cruciferous foods?
While we information Chris presents is thorough and helpful, I, like many of you, found the information to be translated in my own head to “raw cruciferous vegetables are bad.” While his recommendations are moderate, all of the information on substances being given through the placenta, and goiters in animals created some anxiety for me. (And I’d rather not boil most of my cruciferous vegetables for 30 minutes! That’s just not appetizing.) Because I enjoy certain dishes that include raw cruciferous vegetables, such as arugula salads, this became a bit of a stumbling block for me. I think that the main message we should take away is that we should consider moderation, cooking some of our cruciferous vegetables, and making sure we have adequate iodine in our diet.
In fact, in a wonderfully informative book (affiliatelink), The Paleo Approach: Reverse Autoimmune Disease and Heal Your Body, by Sarah Ballantyne, PhD, Sarah presents some of the same information, but in a way that encourages the consumption of cruciferous foods. I found her different way of presenting information liberating. While she acknowledges that these foods are often discouraged, especially for those with autoimmune thyroid disorders, she believes that “avoiding these foods is not well justified”.
She makes a couple of important points:
Cruciferous vegetables are a great source of sulfur compounds that are potent antioxidants and prevent cancer. Two of these sulfur compounds, isothiocyanates and thiocyanates, are the ones known as goitrogens. She acknowledges that they can inhibit the enzyme thyroid peroxidase (which effects certain thyroid hormones).
Iodine is really the issue here
However, she points out that, “There is no evidence of a link between human consumption of isothiocyanates or thiocyanates and thyroid pathologies in the absence of iodine deficiency: these substances have been shown to interfere with thyroid function only people lacking adequate amounts of iodine. (If you are severely deficient in iodine or selenium, addressing that deficiency before eating tons of cruciferous vegetables is a good idea. Also note that myrosinase is deactivated by cooking, so cooked cruciferous vegetables can still be enjoyed while you’re working on correcting any deficiencies.) In fact eating cruciferous vegetables correlates with diverse health benefits, including reducing the risk of cancer (even thyroid cancer!).”
Eating cruciferous vegetables could be beneficial to our thyroid function
She goes on to explain that at low concentrations, like what we’d get from eating cruciferous vegetables, “thiocyanates stimulate T4 synthesis, meaning that these vegetables labeled as goitrogens actually support thyroid function.
Now that is an encouraging thought!
Instead of worrying about eating raw crucifers, make sure you don’t have deficiencies
Instead of worrying so much about whether or not we should be eating cruciferous, she encourages her readers to work on making sure that they have adequate amounts of iodine, iron, selenium and zinc. Deficiencies in these can impair thyroid function, especially when you are deficient in more than one. (I know that was true for me, as my thyroid function was abnormal until we corrected my low iron).
Free to enjoy cruciferous vegetables again! (My conclusion).
I’ve come to realize how much of popular thinking about “healthy food” is often about separating foods into “good food, bad food” categories, and so when presented with information about the goitrogen effects of certain foods, our minds place them in the “bad food” category. But that’s much too simplistic for many foods.
Instead, working on having a nutrient dense diet, with a wide variety of foods is important. Making sure we don’t lack crucial nutrients for our thyroid is important. Is fearing eating raw cruciferous needed? According to Sarah’s research, not unless we are especially low in iodine. And then the solution is not avoiding cruciferous vegetables long term, but correcting our iodine issues.
We still enjoy plenty of our cruciferous vegetables cooked (because they are delicious cooked!), but I don’t feel guilty for serving them raw either, especially since we don’t eat them raw every day. I am working on making sure we are eating more iodine rich foods, and eating a wide variety of nutrient dense, thyroid supporting foods. At this point, I’d only feel concerned if I was juicing a lot of raw cruciferous vegetables or eating a lot of cassavas.
I have found it a sensible and freeing plan.
Other articles you might enjoy:
- The suffering undiagnosed, I know you are not crazy
- 6 ways to maximize iron absorption
- Should we take supplements?