Summary
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What did ConsumerLab's tests of flaxseed show?
Our tests revealed a concerning amount of cadmium, a toxic heavy metal, in several flaxseed products that contained up to 4 to 5 times as much cadmium as other products. Nutritionally, products were similar in terms of fats (oil), carbs, fiber, and protein — although amounts listed on two products were not accurate. None of the products had microbial contamination. (See What CL Found and How Products Were Evaluated).
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Why does the amount of cadmium vary across flaxseed products?
This is likely affected by the flaxseed plant variety and the amount of cadmium in the soil. Unfortunately, we found nothing on labels (including geographic origin, brown versus golden color, whole versus ground seeds, or claims of being organic or non-GMO) or about product cost that would provide a reliable clue to the consumer as to how much cadmium is in a product.
Which is the best flaxseed product?
Among the products that passed testing and were "Approved" for their quality, CL selected one as its Top Pick for whole flaxseed and two as Top Picks for ground flaxseed based on taste and cost.-
What are the nutritional benefits of flaxseed?
Flaxseeds are rich in fiber and healthy oils (particularly the omega-3 fatty acid ALA), and also provide some protein and small amounts of essential minerals, such as potassium, magnesium, calcium, and iron. (See What It Is)
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Does eating flaxseed help with medical conditions?
There is some evidence that flaxseed can help reduce blood sugar in diabetes, cholesterol, blood pressure, and symptoms of constipation. It may also have a weak estrogenic effect. (See What It Does)
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What's the difference between flaxseed that is "ground," "milled," or sold as "meal"?
Nothing, really. We found these terms to describe essentially the same thing: Flaxseed that has been ground to a fine or medium powder or meal. (See What CL Found and How Products Were Evaluated).
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Flaxseed safety and side effects:
The high fiber content of flaxseed may cause some gastrointestinal side effects, and the seeds may cause allergic reactions in some people. (See Concerns and Cautions)
See our separate
Review of Flaxseed and Other Seed Oil Supplements.
Products tested in 2023
+— 32 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:
- Davis, Am J Clin Nutr 2003
- Jehi, Br J Nutr 2022
- Shim, Trends Food Sci Tech, 2014
- USDA, 2019
- Brooks, Am J Clin Nutr 2004
- Caliguri, Hypertension 2014
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- Moreira, Nutrients 2022
- Rodriguez-Leyva, Hypertension 2013
- Shrivastava, Cureus 2025
- Soltanian, Nutr Metab (Lond
- Villareal-Renteria, Complement Ther Med, 2022
- House, BMC Res Notes 2020
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- ACOG, FAQ Last updated: May 2023
- Allman, Eur J Clin Nutr 1995
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- Phipps, J Clin Endocrinol Metab 1993
- Rice, Endocr Relat Cancer 2006
You must
be a member to get the full test results along with ConsumerLab.com recommendations and quality ratings. You will get results for 16 flaxseed products (including whole flaxseeds, ground or milled flaxseeds, flaxseed meal and a flaxseed cracker) selected for testing by ConsumerLab.com.
In this comprehensive review, you'll discover:
- Which whole and ground flaxseed products failed our tests and which ones passed
- CL's Top Pick among products as the best ground flaxseed based on quality, taste and price
- The nutritional benefits of whole and ground flaxseeds, including amounts of protein, fat, and vitamins and minerals such as magnesium, potassium, iron, and zinc
- Whether whole and ground flaxseeds are really a good source of omega-3s, including ALA, EPA and DHA
- The evidence for and against flaxseeds for blood pressure and heart health
- Which whole and ground flaxseed products are contaminated with heavy metals like cadmium
- The best way to store flaxseeds and ground flaxseed products
- Safety and other potential concerns with consuming flaxseeds
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