Summary
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What's really in oats?
Oats and oat-based cereals are healthful sources of complex carbohydrates, protein, and fiber, particularly when the whole grain is used. The fiber includes beta-glucan, which can help lower levels of bad cholesterol, reducing the risk of heart disease (See Background). On the other hand, oats can be contaminated with yeast and mold and toxins that they produce, heavy metals such as cadmium, and, due to cross-contamination, gluten. ConsumerLab.com purchased popular rolled oats and steel-cut oats and tested them for these contaminants (See Tests Performed and How Products Were Evaluated).
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Do oats contain gluten?
Although oats don't naturally contain gluten, oat cereals may become cross-contaminated with gluten from wheat products during processing, a potential concern for some people. ConsumerLab.com tested products against the FDA standard for "gluten-free (< 20 ppm)," as well as its own, more stringent "ultra gluten-free (<5 ppm)" standard (See Tests Performed).(Also see our separate review of other gluten-free grains: quinoa, buckwheat, sorghum, millet, and teff).
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Which oats are best?
ConsumerLab found many oat products to have no detectable gluten, but it found gluten in two popular products – one of which had nearly 700 ppm of gluten – and should be avoided by people on a gluten-free diet (See What CL Found). 
Heavy metals, particularly cadmium, were found in all products, but at levels that did not exceed strict safety limits. Small amounts of yeast and mold were found in two products.
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Which are the best oats overall?
Based on quality and cost, ConsumerLab.com chose its Top Picks for steel-cut oats and rolled (“old fashioned”) oats.
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Cautions with oats and oat bran:
If you have celiac disease, be aware that some oat cereals contain high amounts of gluten, although this is much less likely if a product is labeled as gluten-free (See Concerns and Cautions).
+— 20 sources
In addition the results of its expert testing, ConsumerLab uses only high-quality, evidence based, information sources. These sources include peer-reviewed studies and information from agencies such as the FDA and USDA, and the National Academy of Medicine. On evolving topics, studies from pre-print journals may be sourced. All of our content is reviewed by medical doctors and doctoral-level experts in pharmacology, toxicology, and chemistry. We continually update and medically review our information to keep our content trustworthy, accurate, and reliable. The following sources are referenced in this article:
- Xu, Food Res Int 2022
- Mannila, Mol Nutr Food Res 2025
- Ho, Br J Nutr 2016
- Cicero, Nutrients 2020
- Rioux-Labrecque, Am J Clin Nutr 2023
- Wolever, Br J Nutr 2019
- Wolever, Eur J Clin Nutr 2019
- Aberg, Diabetes Care 2020
- Song, Gastroenterology 2015
- Aune, BMJ 2011
- Song, JAMA Oncol 2017
- Schlezinger, Toxicol Appl Pharmacol 2024
- Wolever, J Nutr 2021
- Arentz-Hansen, PLOS Medicine 2004
- Center for Food Safety, 11-22-21
- Lu, Regul Toxicol Pharmacol 1995
- EPA, 5-26-2020
- EWG, 12-31-23
- Frolich, J Cereal Sci 1998
- Peterson, J Cereal Sci 2000
You must
be a member to get the full test results along with ConsumerLab.com recommendations and quality ratings. You will get results for 8 oat products, including rolled, "old fashioned" oats and steel-cut oats, selected for testing by ConsumerLab.
In this comprehensive review, you'll discover:
Which rolled and steel-cut oats passed or failed testing- Which oat cereals offer the best quality and value and are CL's Top Picks
- If oat cereals that claim to be gluten-free really are
- Amounts of gluten, as well as heavy metals (lead, cadmium, arsenic, and mercury) found in each oat cereal
- How to save money by finding top-quality, lowest cost cereals
- How to avoid problems with oat cereals
- The health benefits of oat cereals, including the best oat cereals for lowering blood sugar
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