What the f are antinutrients?

There’s a moment in every nutrition journey where someone casually drops the word “antinutrients”, and you’re expected to nod like you know exactly what that means. Most people don’t.

Most of us have done the classic wellness pipeline…start by treating plant foods as universally wholesome (leafy greens for glowing skin, grains for fibre, nuts and seeds as the elite snacks of the health-conscious and ‘almond mums’) and then, somewhere along the way, dip a cautious toe into the world of carnivore or animal-based, where those same foods are suddenly treated like digestive villains.

Two extremes. Same confusion. It’s no wonder no one knows what antinutrients actually are.

What actually are antinutrients?

Plants are living organisms with one primal objective: stay alive long enough to reproduce.

They can’t sprint away from predators. They can’t grow teeth. So they do the next best thing, protect themselves using chemistry. Plants didn’t create these to ruin your smoothie bowl. They evolved them to stop animals (including us) from overeating their seeds, leaves and roots. And once you understand the logic, the whole picture becomes less mysterious, and much more interesting. Here are the major plant defence strategies, decoded:

1. Lectins (the “don’t eat my seeds” molecules)

Lectins are proteins that bind to carbohydrate receptors along the gut lining. Their job? Make the seed harder to digest, so the plant has a chance to pass through the digestive tract intact and grow elsewhere. When humans consume high-lectin foods without proper preparation, those sticky proteins can irritate the gut lining and interfere with nutrient uptake.

• Common sources: beans, lentils, grains, peanuts, nightshades
• In sensitive people: bloating, joint stiffness, headaches, brain fog

It’s no accident traditional cultures soaked, sprouted, fermented and slow-cooked their beans.

2. Phytates (the mineral thieves)

Phytates (phytic acid) bind to positively charged minerals like iron, zinc, magnesium and calcium. Once bound, the minerals are locked away, unavailable for absorption.

This is why diets heavy in unprepared grains and nuts can create deficiencies even when intake looks adequate.

• Common sources: grains, nuts, seeds, legumes
• Possible effects: low iron, brittle nails, fatigue, slower thyroid function

If you’ve ever eaten a saintly bowl of oats at 8am and felt inexplicably drained by midday, phytates are a good suspect.

3. Oxalates (the crystal formers)

Oxalates are sharp, reactive compounds that latch onto calcium and form tiny crystals. In small amounts the body manages them well, but in excess, especially with gut dysbiosis or low mineral intake, they can irritate tissues.

• Common sources: spinach, almonds, cacao, beetroot, sweet potato
• Possible symptoms: bloating, kidney stones, vulva pain, joint pain, calcium depletion

This is why “green juice all day” works for approximately three people, and only on the internet.

4. Tannins (bitter bodyguards)

Tannins are polyphenols that give plants their astringent, mouth-drying bite. Their biological role is to discourage overeating by making the plant taste defensive. They also bind to proteins and iron, reducing absorption.

• Common sources: tea, coffee, wine, legumes, nuts
• Possible effects: low iron, digestive heaviness, nausea on a

5. Enzyme inhibitors (digestion blockers)

Enzyme inhibitors are compounds that interfere with the enzymes your body uses to break down food:

• Protease inhibitors slow protein digestion
• Amylase inhibitors reduce carb break down, increasing internal fermentation
• Lipase inhibitors affect fat digestion

When these enzymes are blocked, digestion becomes less efficient. Food sits longer in the gut, which can lead to bloating, gas, unpredictable hunger and a sense of being full yet under-fuelled.

• Common sources: soybeans, legumes, raw nuts, raw seeds, whole grains
• Possible effects: bloating, gas, loose stools, cravings shortly after eating, difficulty tolerating beans or certain nuts on an empty stomach

So, can you still eat plants?

Yes, of course. The goal isn’t to avoid plants. It’s to understand them, so you can prepare and combine them in ways your body actually benefits from.

Every traditional culture that relied on plant foods developed techniques to neutralise or reduce antinutrients long before the term existed. They didn’t have PubMed, they had observation. And they learned that plants often need a little processing to become truly nourishing.

Here’s how they did it:

1. Soaking 

Soaking kick-starts the germination process, activating enzymes inside the seed that naturally reduce phytates, lectins and enzyme inhibitors. It’s why traditional beans rarely cause the same digestive issues modern ones do.

• Soak beans, lentils, nuts and seeds for 6–24 hours
• Add an acidic medium (lemon, vinegar) or a pinch of salt to accelerate the breakdown
• Discard the soaking water, always
  

This single step transforms most legumes.

2. Sprouting (nature’s nutrient unlock)

Sprouting takes soaking one step further. As the seed begins to grow, antinutrient levels drop significantly, and mineral availability increases.

Sprouted grains, lentils and mung beans are far easier on digestion and have a higher micronutrient profile. Sprouting sounds intimidating, but it’s as simple as draining soaked seeds and rinsing them twice a day.

3. Fermenting (the most powerful)

Fermentation uses microbes to do what our ancestors understood instinctively: break down the difficult bits so you can access the nutrients.

Think:

• Sourdough bread (reduced phytates, improved mineral absorption)
• Fermented oats or porridges in many traditional diets
  
• Fermented buckwheat pancakes
• Kvass

Beyond reducing antinutrients, fermentation also improves flavour, increases B-vitamins and (as you probably know and love) supports the gut microbiome.

4. Long, slow cooking

Particularly for lectins and enzyme inhibitors, heat is a powerful deactivator. This is why pressure cookers, stews and broths make legumes tolerable for people who can’t digest them otherwise.

5. Pairing plants with animal foods

Traditional diets rarely ate plant foods in isolation. Beans were eaten with broth. Grains with butter or ghee. Vegetables with eggs or cheese. Seeds with dairy or meat.

The reason? Fat-soluble vitamins (A, D, K2) and minerals in animal foods counteract antinutrient losses and dramatically improve absorption.

Context matters more than the plant itself.

Who tends to be most sensitive?

Some people feel the effects of antinutrients more than others. You might react more strongly if you have:

• Low stomach acid
• IBS or IBD
• A history of antibiotics (microbiome disruption)
• Thyroid issues
• Mineral deficiencies (iron, magnesium, zinc)
• A vegan or plant-heavy diet without traditional preparation methods
• Chronic stress, which reduces digestive enzyme output
  
• You've spent a long time believing “more plant = more health” and have as a result overconsumed high-oxalate or high-phytate foods

If you recognise yourself anywhere in this list, it doesn’t mean “cut out plants completely", at least not permanently. It simply means you’re the type of person who can noticeably benefit from minimising certain plant foods, or preparing them properly (soaking, sprouting, fermenting, pressure-cooking, etc.).

Your body’s not overreacting. It’s just asking for a little support.