Commercially available fat choy has been found to be adulterated with strands of a non-cellular starchy material, with other additives and dyes.

Due to its high price, fat choy is considered a luxury food, and only used in limited occasions.

[4] N. flagelliforme has no nutritional value,[dubious – discuss] and also contains beta-N-methylamino-L-alanine (BMAA), a toxic amino acid that could affect the normal functions of nerve cells and is linked to degenerative diseases such as ALS, Alzheimer's, Parkinson's, and dementia.

[4] Across a 28-day duration, laboratory rats fed N. flagelliforme and the control group did not exhibit significant differences in any toxicological parameters.

[6] The algae and its extracts reduce the inflammatory action of white blood cells, specifically macrophages and splenocytes, in vitro.