Insects pack antioxidant punch, study finds

Grasshoppers can be modified into more nutritious food for humans
Credit: Praisaeng

A new study has found that grasshoppers and silkworms have a similar antioxidant capacity as fresh orange juice.

The first-of-its-kind study, published in Frontiers in Nutrition, found that crickets have 75% the antioxidant power of fresh orange juice, and silkworm fat twice that of olive oil.

“At least 2 billion people – a quarter of the world’s population – regularly eat insects,” says senior study author Prof. Mauro Serafini from the University of Teramo in Italy, quoted on the Frontiers blog. “The rest of us will need a bit more encouragement.”

This is a similar sentiment expressed in a recent report from the University of Leeds and the University of Veracruz in Mexico.

Providing selfish and immediate incentives could help consumers to make the environmentally friendly choice, says Serafini. Taste and image are key – but for many, health is also an incentive.

“Edible insects are an excellent source of protein, polyunsaturated fatty acids, minerals, vitamins and fibre. But until now, nobody had compared them with classical functional foods such as olive oil or orange juice in terms of antioxidant activity.”

Antioxidant activity is that free-radical scavenging ability that typically designates a ‘superfood’ – although this poorly defined term is eschewed by researchers, says Serafini.

The researchers tested a range of commercially available edible insects and invertebrates, using various measures of antioxidant activity.

Inedible parts like wings and stings were removed, then the insects were ground and two parts extracted for each species: the fat, and whatever would dissolve in water. Each extract was then tested for its antioxidant content and activity.

“For perspective, using the same setup we tested the antioxidant capacity of fresh orange juice and olive oil – functional foods that are known to exert antioxidant effects in humans,” Serafini explains.

Water-soluble extracts of grasshoppers, silkworms and crickets displayed the highest values of antioxidant capacity – fivefold higher than fresh orange juice – while giant cicada, giant water bugs, black tarantula and black scorpions showed negligible values.

“There’s a clear trend: the vegetarians have markedly higher antioxidant capacity,” notes Serafini.

Interestingly, the total content of polyphenols – the major source of plant-derived antioxidant activity – followed a similar pattern across species, but was far lower in all insects compared to OJ.

“These results suggest that besides polyphenols, the antioxidant capacity of insects also depends on other, as yet unknown compounds,” Serafini adds.

The results for the insect fat were similarly impressive: “Fat from giant cicadas and silkworms showed twice the antioxidant activity of olive oil, while black tarantula, palm worm and black ants are placed in the bottom of the ranking.”

The group’s key message is: edible insects like grasshoppers and silkworms are a rich source of antioxidants.

“A high content of antioxidant in the food matrix is a primary requisite for a first screening of antioxidant potentiality of novel foods, so these are promising results.”

But the questions remains: what are these antioxidants, and do they work in humans?

“The in vivo efficiency of antioxidant-rich food is highly dependent on bioavailability and the presence of an ongoing oxidative stress. So as well as identifying other antioxidant compounds in insects, we need tailored intervention studies to clarify their antioxidant effects in humans.

“In the future, we might also adapt dietary regimens for insect rearing in order to increase their antioxidant content for animal or human consumption.”