It’s no gag: cockroach milk is one of the world’s most nutritious and calorie-rich substances, scientist says
The milk crystals of the Pacific beetle cockroach are beautiful. Slice open an embryonic roach under a microscope, and the crystals spill out in a shower of nutrient-dense glitter.
But the flavour of cockroach milk is nothing to write home about. Subramanian Ramaswamy, a biochemist at the Institute for Stem Cell Biology and Regenerative Medicine in Bangalore, India, admits as much. As a party dare - he’d lost a drinking competition - one of Ramaswamy’s colleagues once ate a sprinkling of the crystals.
“He said it doesn’t taste like anything special,” Ramaswamy said.
Most roaches lay eggs. Not the Pacific beetle cockroach. It gives birth to live young, popping out babies by the dozen in fleshy organs called brood sacs. And like humans, mother Pacific beetle cockroaches produce food for their offspring. The embryos dine on a liquid substance packed with fats, sugars and protein. You can think of this like cockroach milk.
It gets weirder.
Insect experts have long known that this cockroach species secreted liquid food. But they thought baby roaches simply digested the stuff. When Barbara Stay, a zoologist at the University of Iowa, first stumbled upon a cache of crystals tucked inside the embryos, scientists were stumped.
“We didn’t believe these crystals were actually protein crystals,” Ramaswamy said.
Close inspection of the crystals using X-rays proved otherwise. Experiments suggest that cockroach milk is among the most nutritious and highly caloric substances on the planet, according to research published recently in the journal for the International Union of Crystallography, IUCRJ. Gram-for-gram, cockroach milk crystals contain three times more energy than buffalo milk, according to the analysis by Ramaswamy and his colleagues. Buffaloes, he said, were the previous top contender for producing a protein with the most calories.
“It’s a complete food,” Ramaswamy said of the roach crystals. In the brood sac, the embryos gulp down the liquid. There, the proteins turn to hard crystals in their guts. Nothing is wasted - “the mouth is open and the backside is closed,” as Ramaswamy described the embryos. Within the sac, the baby roaches rely on these concentrated nutrients to grow large with uncanny speed.
The discovery comes at a time when dairy milk is under increasing environmental scrutiny, as cow burps add to greenhouse gases. Alternatives like almond milk, too, have not always fared better; growing the nuts is a famously water-intensive process.
So what about a roach drink? When asked if the energy-efficient cockroach crystals might end up in more human mouths, Ramaswamy described the potential as fantastic. “I could see them in protein drinks,” he said. Then he described the hurdles.
Lacking nipples, cockroaches cannot be milked in the county fair sense. A cockroach-inspired thirst-quencher, if it ever existed, would more likely come via yeast, he said. Bioengineered yeast is already used in the food industry to produce synthetic sweeteners, for instance.
Plus, the roach brand is bad for business.
“I don’t think anyone is going to like it if you tell them, ‘We extracted crystals from a cockroach and that is going to be food,’ ” Ramaswamy said. Further examination of the crystals will also tell if the roach crystals are toxic to humans.
The researchers certainly did not set out to find the next great protein shake. “In the US there is a big thrust that all research has to be translational,” he said, meaning directly applicable to human health. “This was just born out of curiosity.”
If curiosity can kill the Western aversion to drinking bug milk remains to be seen.