When first harvested, Chlorella was suggested as an inexpensive protein supplement to the human diet. Advocates sometimes focus on other supposed health benefits of the algae, such as claims of weight control, cancer prevention, and immune system support. According to the American Cancer Society, "available scientific studies do not support its effectiveness for preventing or treating cancer or any other disease in humans".
Under certain growing conditions, Chlorella yields oils that are high in polyunsaturated fats. Chlorella minutissima has yielded eicosapentaenoic acid at 39.9% of total lipids.
Lysine is one of the nine essential amino acids in humans. The human nutritional requirements varies from ~60 mg·kg−1·d−1 in infancy to ~30 mg·kg−1·d−1 in adults. This requirement is commonly met in a western society with the intake of lysine from meat and vegetable sources well in excess of the recommended requirement. In vegetarian diets, the intake of lysine is less due to the limiting quantity of lysine in cereal crops compared to meat sources.
Taurine occurs naturally in fish and meat. The mean daily intake from omnivore diets was determined to be around 58 mg (range from 9 to 372 mg) and to be low or negligible from a strict vegan diet. In another study, taurine intake was estimated to be generally less than 200 mg/day, even in individuals eating a high-meat diet. According to a third study, taurine consumption was estimated to vary between 40 and 400 mg/day.
The availability of taurine is affected depending on how the food is prepared, raw diets retaining the most taurine, and baking or boiling resulting in the greatest taurine loss.
Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine was 29%.