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Anti-nutrients: could the veggies you’re eating be killing you? · Good Recipes
Anti-nutrients: could the veggies you’re eating be killing you?
Anti-nutrients: could the veggies you’re eating be killing you?
Are veggies secretly sabotaging your health? Here’s the real story on anti-nutrients.
Long read
August 28, 2025
Resolving the Anti-nutrient Controversy Once and For All
In this glorious golden age of nutritional clickbait, it was only a matter of time before vegetables - the food group practically synonymous with healthy eating - got their turn on the hot seat. Yes, the veggies we've been all told to eat more of for as long as we can remember now stand accused of harbouring dangerous anti-nutrients. These naturally occurring chemical tricksters are blamed for hampering mineral absorption, flaring up inflammation, and even contributing to the development of chronic diseases.
In this article, you'll learn:
What anti-nutrients are, and how concerned you should be
All about the most talked-about culprits: oxalates, lectins, phytates, goitrogens, and tannins,
How cooking methods and food pairings can make all the difference
Vegetables in Their Villain Era
To many in the carnivore and carnivore-adjacent camps, plant-defence molecules like oxalates, phytates, lectins, goitrogens, and tannins are nothing short of biological booby traps, and reason enough to avoid eating plants altogether. The logic is that since plants can't get up and run from pests and predators, they've evolved a variety of chemical weapons to defend themselves with weapons to which the human body is not at all immune.
Oxalates
Spinach, Swiss chard, beets, almonds, and cocoa are all rich in oxalic acids. These, in turn, bind to calcium and other minerals to form oxalates. This reduces absorption of those minerals, and the oxalates continue to aggregate together, forming sharp crystals in the body. The kidneys are tasked with filtering them out into urine, and most kidney stones are largely made of calcium oxalate crystals. It's not surprising, therefore, that individuals susceptible to kidney stone formation are sometimes counselled to embrace low-oxalate diets.
However, oxalate accumulation can happen just about anywhere in the body. This truth is enough for some people to blame almost any imaginable symptom- from pain in the joints or genitals to ocular or neurological disorders- on oxalates, and to make a long-term lifestyle of avoiding them.
Lectins
Lectins are small proteins found in a wide range of plant foods, especially legumes and whole grains- that stick to carbohydrates. Highly bio-active and capable of binding to the surfaces of cells, some have been shown to hamper nutrient absorption, trigger inflammation, and damage the intestinal lining, especially .
Phytates
Unique in the world of anti-nutrients, phytates and phytic acids are not chemical defence systems, but storage forms of phosphorus. Found mainly in grains, seeds, nuts, and legumes, they're designed by plants to store energy and enable plant growth. But in the human gut, they can bind up positively charged minerals like calcium, iron, and zinc, making them more difficult to absorb.
Goitrogens
Up next are the 'goiter' molecules. The most well-known goitrogens are glucosinolates, naturally abundant in cruciferous veggies like kale, cabbage, broccoli, and Brussels sprouts. In the body, these glucosinolates metabolize into other compounds like goitrin and thiocyanate- both of which can potentially affect iodine uptake and thyroid hormone production.
The more thyroid-conscious among us can take heart in knowing that boiling or steaming brassicas . Broccoli deserves special mention as it's both relatively low in progoitrin, the glucosinolate most strongly associated with negative thyroid effects, and generously endowed with glucoraphanin, a precursor to the legendary sulforaphane, which is .
Tannins
Tannins are polyphenolic compounds found in high amounts in wine, tea, coffee, and chocolate. Unlike other anti-nutrients, these are readily detectable: that dry or astringent flavour left on the palate after a sip of English Breakfast? That's the unmistakable taste of tannins on the tongue. Like the other anti-nutrients we've seen, tannins can bind to minerals, , and reduce its absorption when consumed alongside food.
The Bottom Line on Anti-nutrients
In the final analysis, it is 100 per cent true that anti-nutrients and their effects are very real and well-documented. A basic knowledge of these fascinating chemicals in plants can add nuance to our perspective of foods and their amazing complexity. However, if our awareness of anti-nutrients threatens to veer into paranoia or any type of disordered eating, we would likely be better off forgetting the whole issue altogether.
FAQ: What's the Deal with Plant-Based Anti-nutrients?
Q: Do anti-nutrients in plant foods cause nutrient deficiencies?
Not in balanced and varied diets. Most concerns come from isolated cases, specific health conditions, or food-insecure populations lacking in dietary diversity and nutrient intake.
Q: Are raw veggies dangerous to eat?
Only certain ones and in very large quantities. For example, raw red kidney beans are indeed toxic. But such examples are few and far between.
Q: Do I need to always soak dried beans?
You don't need to, but pre-soaking them helps reduce the effects of anti-nutrients like phytates and lectins. Whether you soak them or not, cooking them thoroughly is the most important thing.
Q: Should people with thyroid conditions avoid cruciferous vegetables?
Not according to the science. Especially if iodine intake is adequate and the veggies are cooked, most people with thyroid issues tolerate them quite well, and indeed benefit from them. Since cruciferous veggies tend to be high in FODMAPs, IBS sufferers sometimes find benefit in reducing them, but even this is generally best as a temporary strategy.
Sources
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Armah, S. M., Boy, E., Chen, D., Candal, P., & Reddy, M. B. (2015). Regular consumption of a high-phytate diet reduces the inhibitory effect of phytate on nonheme-iron absorption in women with suboptimal iron stores,. The Journal of Nutrition, 145(8), 1735–1739. https://doi.org/10.3945/jn.114.209957
Bashar, A., & Begam, N. (2020). Role of dietary factors in thyroid disorders: Current evidences and way forwards. Thyroid Research and Practice, 17(3), 104. https://doi.org/10.4103/trp.trp_7_20
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Damien ZielinskiA cloud-based functional medicine practitioner with a focus on mental health and insomnia
Related Recipes
To many others in the omnivorous or plant-based camps, anti-nutrients are not only harmless but in most cases misunderstood allies with beneficial effects depending on dose, context, and preparation.
So, what's going on? Is it true that you should start eyeing your salad with suspicion? Or, is this yet another case of online dietary paranoia getting totally out of control? As you'll see, anti-nutrients are neither to be feared and avoided, nor completely ignored - there is an important middle ground to consider. Some nuance will be required to really give this issue the treatment it's due, so let's peel back the layers and take a close look, one by one, at the anti-nutrients standing trial.
The issue is a confusing one because oxalate-rich foods are also some of the most nutritious on the planet (spinach being a prime example). Large population studies have found only a weak link between dietary oxalates and stone risk - and diets like the Mediterranean and DASH, both loaded with oxalate-containing foods, are protective against kidney stones and many other health conditions.
Soybeans, kidney beans, and whole wheat contain some of the most well-studied lectins, such as phytohemagglutinin (PHA) and wheat germ agglutinin (WGA). Both of these resist digestion and remain problematically 'sticky' unless properly prepared. Undercooked kidney beans, in particular, have caused many well-documented food poisoning outbreaks, and it's all down to lectins.
The good news is that risk plummets with proper preparation. Pre-soaking beans, followed by boiling them for at least 10 minutes, eliminates nearly all lectin activity. In controlled trials on humans, diets rich in cooked legumes have been associated with reductions, not increases, of inflammation. Fascinatingly, emerging research is exploring the ability of lectins to selectively bind to cancer cells. The hope is that the cytotoxic properties of plant-derived lectins can soon be incorporated into viable anti-tumour treatments.
There is no question that the biological activity of lectins is very real. Nevertheless, the significance of dietary lectins in well-cooked foods remains minimal- and well worth the effort.
If you're prone to low iron status or anemia, you might consider some clever pairings. For example, since vitamin C boosts non-heme iron availability inhibitory, the negative effects of tannins on iron absorption can be effectively counteracted with even small amounts of it. A quick squeeze of lemon on the salad can make all the difference. Additionally, spacing tannin-rich drinks like tea or red wine at least an hour before or after meals can significantly help to minimize the nutrient interference.
A major lesson from anti-nutrients is that how we handle food makes all the difference: sprouting and fermenting, strategic combining, or even just soaking and cooking are great practices for every one of the potentially troublesome compounds listed above. In a way, modern science has confirmed that our ancestors knew what they were doing, and these traditional methods of food prep evolved with a lot of wisdom and understanding.
If we do have a certain health condition that invites specific awareness around a type of anti0nutrient in particular, then it makes even more sense to empower ourselves by learning about it. For example, someone with Hashimoto's might do well to consider goitrogens, and someone with a tendency toward kidney stones could very likely benefit from oxalate awareness or even a low-oxalate diet.
But even in those fairly specific situations, avoiding all plants for fear of anti-nutrients is ill-advised. The nutritional consensus, overwhelmingly, is that getting more whole plant-based foods in our diet is something almost all of us should be trying to do, and none of the conversations about anti-nutrients, in the final analysis, do anything to undermine this recommendation. Boil them or sprout them, or even have them raw… but eat them!
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