In today’s age of information –and misinformation– we often hear about “toxins” in food, especially in plant foods. Terms like lectins, oxalates, or other so-called antinutrients are frequently presented as threats to our health, while the real culprits, such as ultra-processed foods, are often sitting in our kitchen cupboards not worrying us at all. Many people, when asking for my advice as a dietitian specializing in autoimmune conditions, inflammation and plant-based nutrition, tell me they stopped eating flax seeds, nuts, or even legumes because they were scared off by plant toxins they read about on social media.
Indeed, plants contain toxins –but it’s worth understanding how they benefit us and why, without them, our immune system would have no resilience.
Plant toxins as biological signals
Unlike animals, plants cannot run away to protect themselves. Instead, they evolved chemical defenses to deter insects, microbes, or animals from eating them. These include lectins (found in legumes and grains), oxalates (in spinach and beets), glycoalkaloids (in potatoes and tomatoes), saponins, tannins, and other so-called “antinutrients.” However, unlike highly toxic substances or industrial chemicals, these plant compounds, when consumed in small, normal amounts as part of a balanced diet, create a mild biological challenge to the body – and this challenge is precisely what makes them beneficial.
The phenomenon of hormesis
In biology, hormesis describes the process by which a small dose of a stressor activates the body’s defense systems, ultimately increasing resilience and promoting better health. Plant toxins often work this way. Consuming small amounts of these compounds, primarily through raw or lightly processed foods, stimulates detoxification enzymes (like glutathione, catalase, and superoxide dismutase). At the same time, DNA repair genes such as p53 are activated, along with pathways that enhance mitochondrial function (NRF1, PGC-1α, AMPK), improving cellular health and energy production.
No challenge, no strength
Constantly avoiding all forms of stress – whether from food or life conditions – can lead to a sluggish immune and metabolic system. In contrast, small doses of controlled stressors, such as intermittent fasting, exercise, exposure to heat or cold, and natural plant toxins, strengthen our biological resilience. This partly explains why diets rich in plant foods are associated with longevity. It’s not just vitamins and minerals that matter; it’s also this “training” effect, which makes the body more resistant to inflammation, oxidative stress, and metabolic instability.
Often, social media spreads oversimplified, fear-driven messages demonizing natural plant compounds, based on isolated lab studies or exaggerated doses. Yet, nutritional science relies on context: dose matters, and interactions within a whole diet matter. Our bodies are not passive receivers; they are incredibly sophisticated biological systems shaped by constant interaction with natural foods. Plant toxins are part of that evolutionary journey. When we respect them in moderation and variety, instead of fearing them, they become allies rather than threats.
Resources
https://pubmed.ncbi.nlm.nih.gov/2182395/
https://nutrifix-health.com/blog/introduction-to-anti-nutrients/
https://nutritionsource.hsph.harvard.edu/anti-nutrients/
