Erucic acid is a monounsaturated omega-9 fatty acid found mainly in the Brassica family of plants such as canola, rapeseed, wallflower seed, mustard seed as well as Brussels spouts and broccoli. Erucic acid has many of the same uses as mineral oils but with the advantage that it is more readily biodegradable. Its high tolerance to temperature makes it suitable for transmission oil. Its ability to polymerize and dry means it can be - and is - used as a binder for oil paints. Increased levels of eicosenoic acid (20:ln9) and erucic acid (22:1n9) have been found in the red blood cell membranes of autistic subjects with developmental regression. While studies done on laboratory animals in the early 1970s show that erucic acid appears to have toxic effects on the heart at high enough doses, an association between the consumption of rapeseed oil and increased myocardial lipidosis, or heart disease, has not been established for humans. While there are reports of toxicity from long-term use of Lorenzo's oil (which contains erucic acid and other ingredients), there are no reports of harm to people from dietary consumption of erucic acid. In 2003, Food Standards Australia set a provisional tolerable daily intake (PTDI) for an average adult of about 500 mg/day of erucic acid, extrapolated based on "the level that is associated with increased myocardial lipidosis in nursing pigs."

Poppy acid occurs in opium (Papaver somniferum) and other Papaver species. Meconic acid has been described as a mild narcotic, but it has little or no physiological action, and is not now used medicinally. Its chemical reactions are of importance in toxicology as a valuable indication of the presence of opium.

Poppy acid occurs in opium (Papaver somniferum) and other Papaver species. Meconic acid has been described as a mild narcotic, but it has little or no physiological action, and is not now used medicinally. Its chemical reactions are of importance in toxicology as a valuable indication of the presence of opium.