A popular dietary supplement, Coenzyme Q, accelerates aging and death in a microscopic worm studied by UCLA biochemists.
Adult worms on a diet without Coenzyme Q live 60 percent longer than those on a diet rich in the lipid, reports Pamela Larsen, UCLA research associate in chemistry and biochemistry, and Catherine Clarke, UCLA associate professor of chemistry and biochemistry, in the Jan. 4 issue of the journal Science.
"Our research indicates that too much Coenzyme Q for adults can be harmful," said Clarke, who has studied Coenzyme Q for 10 years. "Too little is harmful, but so is too much."
In this respect, Coenzyme Q, a component of the cell necessary for growth and development, is similar to cholesterol, the UCLA biochemists said.
"Like cholesterol, Coenzyme Q is produced naturally by the body, and cells require it for life, but like cholesterol, too much of it is harmful," Clarke said.
Scientists do not yet know how much is too much or how much is optimal, Clarke said, adding that research on Coenzyme Q is still in its "infant stage."
Also called ubiquinone, Coenzyme Q supplements are sold as a means of boosting the immune system and promoting longevity.
The biochemists analyzed hundreds of Caenorhabditis elegans worms, giving one adult group a diet without Coenzyme Q, and another adult group a standard diet with Coenzyme Q. Surprisingly, the lower amounts of Coenzyme Q significantly extended their life span.
Because their entire life span lasts just a few weeks, C. elegans nematodes are frequently used by scientists to study aging, Larsen said.
"They go from eggs to reproductively active adults in just three-and-a-half days, then they age, they get wrinkled and slow down, and they die," she said.
Most of the worms, with mutations in different genes, developed normally on a diet with Coenzyme Q during their first three-and-a-half days of life, but those with a mutation in a particular gene (known as the clk-1 gene) were an exception. Research published last January (by Tanya Jonassen, a UCLA postdoctoral scholar in chemistry and biochemistry; Larsen; and Clarke) has established Coenzyme Q's importance in growth and development.
The adult worms without Coenzyme Q in their diet did not start to look old until later than the other group of worms, Larsen said. Why would adult worms have a much shorter life span, and age faster, with Coenzyme Q?
"Our findings suggest the reason for the shorter life span is that Coenzyme Q causes more oxidative damage than it prevents," Clarke said. She and Larsen plan to test this hypothesis in future research.
One theory of aging holds that "free radicals" damage lipids, proteins and DNA, and that anti-oxidants can reduce the damage from free radicals.
"Coenzyme Q is an anti-oxidant, fighting free radicals that damage our lipids, but it's likely that it's also a pro-oxidant," Clarke said. "This means that Coenzyme Q generates reactive oxidants in the mitochondria of the cells, which can generate free radicals."
Coenzyme Q plays an important role in energy metabolism, and performs several other functions in cells, some of which are understood only poorly or not at all, Clarke and Larsen said.
The optimal amount of Coenzyme Q may vary among individuals, and that amount may differ over the life cycle, the biochemists said.
Cells produce their own supply of Coenzyme Q, but produce less of it as we age. This knowledge leads many people to take Coenzyme Q as a daily supplement. Larsen and Clarke said their research in Science does not establish whether doing so is beneficial or harmful for humans.
Human cells produce Coenzyme Q-10, while the worms produce the "isoform" Coenzyme Q-9, which differs slightly. Larsen and Clarke plan to study different forms of Coenzyme Q, and learn more about its fundamental biochemistry.
"What we would like to know in future research," Larsen said, "is what are the Coenzyme Q levels in the worms that age very differently."
"We hope to learn how cells produce and transport Coenzyme Q, and learn more about Coenzyme Q's role in aging," Clarke said.
Their research published in Science was funded by the Glenn Foundation for Medical Research. Their newest research on Coenzyme Q, not yet published, is funded by the National Institutes of Health and the Ellison Foundation.