Flaxseed has a claim to being one of the very oldest crops cultivated by humans, with archaeological evidence of flax cultivation in the Fertile Crescent dating back over nine thousand years — used both for its fiber (linen textiles) and its nutritious, oil-rich seeds. Ancient Egyptians valued flax so highly that they wrapped mummies in linen cloth and included flaxseed among grave goods.
The Frankish King Charlemagne reportedly believed so strongly in flaxseed's health benefits that he passed laws in the 8th century requiring his subjects to consume it. Flax remained a dual-purpose crop — textile and food — across European agriculture for centuries before modern nutritional science turned attention specifically to its seed's cholesterol and cardiovascular effects, which now represent some of the better-documented evidence in this Atlas.
Flaxseed has an unusually large and consistent body of clinical evidence for a dietary seed. A comprehensive 2019 meta-analysis pooling 62 randomized controlled trials (3,772 participants) found flaxseed supplementation significantly reduced total cholesterol, triglycerides, and LDL cholesterol, though it had no significant effect on HDL ("good") cholesterol. Multiple independent meta-analyses on blood pressure reached consistent conclusions in the same direction: a 2025 meta-analysis of 18 trials found significant reductions in both systolic and diastolic blood pressure, while an earlier, separate meta-analysis of 14 trials also found significant, if more modest, reductions in both measures.
The consistency across so many independent meta-analyses — cholesterol and blood pressure both moving in the expected direction across multiple separate research teams — is what earns flaxseed a "Moderate-Strong" rating, among the stronger evidence bases for any seed in this Atlas. Researchers do note significant heterogeneity between individual trials (differences in dose, form, and population), which is why "Strong" alone isn't quite warranted, but the overall signal is genuinely robust.
Whole seeds ground fresh (whole seeds pass through the digestive system largely undigested) and added to food, or pressed into oil.