If you eat ground flaxseed instead of whole seeds, your body absorbs way more of the healthy compounds that your gut bacteria turn into beneficial substances—crushing or grinding helps your body get more out of them.

What we've found so far is that ground flaxseed appears to lead to higher levels of beneficial compounds in the body compared to whole flaxseed in healthy adults. Our analysis of the available research suggests this is because grinding the seeds makes it easier for the body to access the nutrients inside. We looked at one claim from the evidence, which states that when people eat ground flaxseed instead of whole flaxseed, their bodies absorb more of the plant compounds that gut bacteria convert into enterolignans—substances linked to various health benefits [1]. The data supporting this claim is consistent, with 54.0 studies backing it and none contradicting it. These findings indicate that the physical form of flaxseed matters: whole seeds often pass through the digestive tract undigested, meaning the valuable compounds stay locked inside. Grinding breaks open the seed coat, releasing those compounds so they can be used by the body. Our current analysis shows the evidence leans toward ground flaxseed being more effective than whole flaxseed for increasing the availability of these compounds. However, we base this on a single claim that aggregates many supporting studies. We don’t have direct access to those individual studies, so we can’t assess their methods or quality. Also, we don’t have any studies that refute this idea, which limits our ability to weigh opposing views. We don’t yet know how much of a difference this makes for long-term health, only that the body accesses more of the key compounds from ground flaxseed. Practical takeaway: If you want your body to get more of the beneficial substances from flaxseed, grinding it before eating may help. Whole seeds might not deliver as much because they can pass through your system intact.