ALA is generally considered to be safe and well-tolerated; however, there is a lack of research reporting on adverse effects.
There are some important limitations to ALA research. Most trials provide ALA as foods or oils (e.g., flaxseed, walnut, canola, ALA-enriched-margarine), which means there are other bioactive compounds present, such as different fatty acids, fiber, vitamins and minerals, and polyphenols).[1] These compounds could influence the observed effects and make it challenging to disentangle the effects of ALA from the food as a whole. Additionally, ALA is ubiquitous in the diet, and many clinical trials do not account for baseline intakes of ALA which could impact the observed effects (or lack thereof).