What are anti-nutrients, and how do they affect your body

Just like we have an immune system that protects us, plants have their own version of defence. These are natural compounds known as ‘anti-nutrients’ to protect themselves against insects, animals, fungi, microbes. We call them ‘anti-nutrients’ because when we eat them, they can reduce how well we absorb certain nutrients and can interrupt proper digestion. They are found in plant-based foods such as beans, wholegrains, greens and nuts. It’s important to note that quantities and how you prepare this matter. The most talked about anti-nutrients are lectins, oxalates, glucosinolates and phytates.

Lectins:

• Found mostly in legumes, such as red and white kidney beans, soya and lentils

• Levels are highest when the beans are raw or undercooked. Some lectins resist certain digestive enzymes, causing potential irritation in the gut lining and cause digestive upset

• Proper soaking and cooking deactivate most of them

Oxalates:

• Found in spinach, rhubarb, beetroot, nuts, chocolate, tea, strawberries and wheat bran

• They bind mainly to calcium, magnesium and iron, which can make these minerals harder to absorb

• They are mainly a concern for people prone to calcium oxalate kidney stones

Phytates (phytic acid):

• Found in wholegrains, beans (including fava beans), lentils, nuts and seeds

• They bind mainly to iron and zinc, but also to calcium and magnesium, reducing the bioavailability when absorbing them

Glucosinolates:

• Found in cruciferous vegetables such as brussels sprouts, cabbage, cauliflower, broccoli, kale and bok choy.

• When broken down, they release goitrogens. These can reduce iodine uptake into the thyroid by competing with the release of sodium and iodide

• This is mainly relevant for people who are low in iodine or who eat very large amounts raw. Cooking reduces the effect

Here are some tips to reduce them:

• Soak: leave dried beans and grains in water overnight. Drain and rinse them the next day, then cook them as usual

• Cook: boil beans well, and never eat raw or undercooked kidney beans. Tinned beans are already cooked, so they’re ready to use

• Lightly cook your greens: cooking spinach and cruciferous vegetables lowers their oxalates and goitrogens

• Sprout or ferment: sprouting and fermenting help break anti-nutrients down. Think sprouted grains, sourdough, tempeh and miso

• Pair wisely: calcium-rich foods like yoghurt or cheese bind oxalates in the gut, so eat them with spinach. Vitamin C foods like peppers or lemon help you absorb more iron from plants, so add them to beans and grains

• Mix it up: eat a variety of plant foods rather than large amounts of just one

These foods are part of a balanced diet, and simple steps like soaking, cooking and variety take care of most anti-nutrients. The best guide is your own body. Notice how you feel after eating certain foods: do beans leave you bloated or gassy? Do you get tummy discomfort after a big bowl of raw greens? Logging your meals in the Lifestack app for a week or two makes this much easier. You can look back at everything you ate that week and spot what might be behind a day when you felt more bloated than usual. If something seems to bother you, try changing how you prepare it (soaking, cooking or a smaller portion) before cutting it out completely!

If you have ongoing digestive symptoms, kidney stones, low iron or a thyroid condition, that’s when it’s worth paying closer attention and getting more personalised support!

https://www.sciencedirect.com/science/article/pii/S1756464622000081

https://escholarship.org/uc/item/2n05q2rk#main

https://www.tandfonline.com/doi/pdf/10.1080/10942910903326056?utm_source=sciencedirect_contenthosting&getft_integrator=sciencedirect_contenthosting