For me, the best sources of omega 3's are chia and flax seeds. Both of these have very low fat, high fiber, and decent protein and other nutrients. They can easily be incorporated into smoothies, sprinkled on salads, hot or cold cereals, sauces, and just about any meal, and they don't have too much of a flavor. You can get them just about anywhere, from online at Amazon to discount grocers like Aldi, so they're very widely available and easily accessible. Flax and chia have also been known to help control cholesterol, high blood pressure, and other issues.
Other good sources of vegan omega 3's include hemp seeds, leafy greens, seaweed, cabbage family vegetables, and berries. For more information about omega 3's, omega 6's, and how they convert in the body, check out this very helpful post: plenteousveg.com/vegan-sources-omega-3. Here is further info with sources as well: healthline.com/nutrition/7-plant-sources-of-omega-3s. One more source illustrating the importance of proper omega 3:6 ratio is: vegsource.com/sarah-taylor/the-new-vegan-health-issue-omega-6-omega-3-fatty-acid-ratio.html, which includes lots of information from doctors, research studies, and other sources.
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