Quick answer: Anti-nutrients are plant compounds that can reduce absorption of some nutrients. Phytates bind minerals like iron and zinc, lectins can irritate the gut in sensitive people, oxalates bind calcium and can contribute to kidney stones in some people, and gluten damages the gut in celiac disease. Soaking, sprouting, fermenting and cooking reduce many of them.
Key takeaways
Anti-nutrients such as phytates, lectins and oxalates can bind minerals or bother a sensitive gut, but the foods that contain them are often still nutritious.
Soaking, sprouting, fermenting and thorough cooking can lower anti-nutrients in grains, legumes, nuts and seeds.
Gluten is a real concern for people with celiac disease or gluten sensitivity, and oxalates matter most for people prone to kidney stones.
We’re not eliminating all anti-nutrients
Many foods with anti-nutrients are also rich in fiber and nutrients. The goal is awareness and preparation, not fear.
Phytates
Found in grains, legumes, nuts and seeds. Phytic acid binds iron, zinc and calcium. Soaking, sprouting and fermenting reduce it.
Lectins
Proteins in grains, legumes and some vegetables. In sensitive people, they may irritate the gut lining. Soaking and thorough cooking reduce lectins.
Oxalates
Found in spinach, rhubarb, beets and almonds. They bind calcium and iron and can contribute to kidney stones in people prone to them. Boiling and steaming lower oxalates.
Gluten
A protein in wheat, barley and rye. In celiac disease it damages the intestinal lining; some people have non-celiac sensitivity. See celiac disease and gut health.
Practical tips
Soak and sprout grains, legumes, nuts and seeds, cook legumes thoroughly, and rotate leafy greens. Pair plant iron with vitamin C, and see foods to avoid.
Healthy aging lens
Good mineral absorption supports bones, energy and immunity with age.
When to see a naturopathic doctor
It may be time to see a naturopathic doctor if you have a chronic inflammatory, autoimmune or digestive condition, or if you have diabetes, kidney disease or take medications affected by diet changes. The same is true if you are pregnant, breastfeeding, or have a history of disordered eating, or if you want a plan tailored to your labs, symptoms and goals.
See a medical provider promptly for severe abdominal pain, signs of an allergic reaction such as swelling or trouble breathing, or fainting.
What the research shows
Phytates are the best-studied anti-nutrient. In a 1989 iron absorption study by Hallberg and colleagues, adults ate wheat rolls with labeled iron, with or without added phytate, on alternating days. As little as 2 mg of phytate phosphorus cut iron absorption by 18%, 25 mg cut it by 64% and 250 mg by 82%. Adding vitamin C largely counteracted the effect, while meat had a smaller effect that showed up only at the highest phytate dose. These were single-meal tests, and the body adapts over a whole diet, so the effect on iron status over time is smaller than these numbers suggest.
This is why soaking, sprouting, fermenting and cooking beans and grains, and pairing them with vitamin C-rich foods, are practical ways to keep the benefits of these foods while improving mineral absorption. For most people eating a varied diet, anti-nutrients are not a reason to avoid whole grains, beans or vegetables.
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Questions to bring to your clinician
These questions can help you get the most out of your next visit.
Should I pay attention to oxalates, lectins or gluten based on my history?
Should I be concerned about phytates, lectins or oxalates in my own diet?
Could soaking, sprouting or cooking methods make these foods easier for me to digest?
Do my kidneys or gut sensitivities mean I should limit high-oxalate foods?
Frequently asked questions
What are anti-nutrients?
Plant compounds that can reduce absorption of some nutrients.
Should I avoid foods with anti-nutrients?
Usually not; preparation reduces them.
Do oxalates cause kidney stones?
They can contribute in people prone to stones.
Is gluten an anti-nutrient?
It harms people with celiac disease or gluten sensitivity.
Sources
- Hallberg L, Brune M, Rossander L. Iron absorption in man: ascorbic acid and dose-dependent inhibition by phytate. Am J Clin Nutr 1989. PMID: 2911999. https://pubmed.ncbi.nlm.nih.gov/2911999/
- Gupta RK, Gangoliya SS, Singh NK. Reduction of phytic acid and enhancement of bioavailable micronutrients in food grains. J Food Sci Technol 2015. PMID: 25694676. https://pmc.ncbi.nlm.nih.gov/articles/PMC4325021/
- Mitchell T, et al. Dietary oxalate and kidney stone formation. Am J Physiol Renal Physiol 2019. PMID: 30566003. https://pmc.ncbi.nlm.nih.gov/articles/PMC6459305/
- Chai W, Liebman M. Effect of different cooking methods on vegetable oxalate content. J Agric Food Chem 2005. PMID: 15826055. https://pubmed.ncbi.nlm.nih.gov/15826055/
- Rubio-Tapia A, et al. American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease. Am J Gastroenterol 2023. PMID: 36602836. https://pubmed.ncbi.nlm.nih.gov/36602836/
- MedlinePlus: Kidney Stones
- MedlinePlus: Celiac Disease
This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before starting supplements or changing medications, especially if you are pregnant, nursing, or managing a health condition.
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