Last Updated on 9 June 2024 by Brisbane Livewell Clinic
Recently we discussed Phytates and Oxalates, so now let’s discuss Goitrogens. The impact of goitrogenic foods is quite specific since the term ‘goitrogen’ broadly refers to agents that interfere with thyroid function, increasing the risk of goitre (enlarged thyroid gland) and other thyroid diseases. While Goitrogens aren’t just limited to foods and include medications and environmental toxins, (1) we’re focusing on the plant-based foods to be mindful of in your daily diet.
How you’re getting Goitrogens in your diet
There are a variety of compounds with goitrogenic effects, including glucosinolates, cyanogenic glucosides, isoflavones, resveratrol and other flavonoids. Plant foods with the highest content of these compounds include: (1)(2)(3)
- Glucosinolates: cruciferous vegetables like cabbage, kale, broccoli, turnips, cauliflower, Brussel sprouts, mustard greens
- Cyanogenic glucosides: cassava, lima beans, sweet potatoes, sorghum and flaxseed
- Isoflavones (genistein and daidzein): found almost exclusively in soy
- Resveratrol and other flavonoids are widespread throughout the plant kingdom, with millet being the most notorious, which contains C-glycosylflavones
What you’ve got to know about Goitrogens
They vary a lot! There is always a variable amount of active goitrogen present. Factors such as soil conditions, weather, growing location, use of plant growth regulators or pesticides, and date of harvest and storage time can all impact. (1) Considering this, it’s best to focus on the food preparation techniques and ideal intake mentioned below.
They impact more when iodine levels are poor. The main way progoitrin-rich food sources impact our health poorly is by decreasing iodine uptake. (1) The evidence suggests there are negative impacts on thyroid health when there is pre-existing suboptimal iodine status (or iodine deficiency), especially with a long-term daily intake of dietary goitrogens. (1)
Goitrogens affect thyroid health more than you think Both soy and millet have demonstrated strong goitrogenic activity in human populations. Studies have shown that the use of soy-based formula without added iodide can produce hypothyroidism and goitre in healthy infants. (2) Equally as potent, even in people with adequate iodine intake, millet can still actually suppress thyroid gland function. (4)
Keeping Goitrogen-rich foods in your diet
Generally speaking, heating food could be beneficial since it denatures the goitrogenic compound into a less harmful metabolite. (4) Aside from boiling and cooking, soaking and washing can also help in reducing the goitrogenic potency. (3) Fermenting foods may lower total glucosinolate concentration (1) – think sauerkraut – and suddenly, cabbage is much more beneficial to eat.
The goodness in Goitrogens
Cruciferous vegetables also contain thousands of other bioactive compounds that may be protective against thyroid cancer, as well as phytochemicals, fibre, and essential vitamins and minerals. (1) it is important to recognise that phytonutrient-rich plant foods may have a downside, but there are still plenty of health benefits in consuming a balanced and varied diet, with Goitrogens having their place.
Sound dietary practices for consuming Goitrogens
- Rotate cruciferous vegetables from week to week and eat seasonally
- Limit intake of raw kale and raw cabbage in things like green smoothies and coleslaw to servings weekly rather than daily
- Stir fries are ok where veggies like broccoli and cauliflower are still ‘al dente’, but make sure they’re not super crunchy
- Use fermented foods like sauerkraut
- Soy foods are also best consumed fermented – so including tofu, tempeh and miso is preferable to soy milk
- Limit soy milk to no more than 500ml daily and consider having alternative plant-based milk on rotation
- Include iodine-rich seaweed in your daily diet
Get more advice on Goitrogens
Our diet-specialising team is passionate about maximising the nutrition in your daily diet with education about plant-based foods being all in a days work. Whether it’s because you eat predominantly plant-based or have concerns about thyroid health, helping you to make dietary changes to suit your needs better is how we serve you best – and yes, we’re still going to tell you to eat your broccoli!
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