The quest for immortality has become serious business

Meaning:To peddle something is to sell it, especially by going around promoting it, and the word often hints that the goods are cheap, dubious, or oversold. A peddler used to carry wares from door to door. In the article, influencers who peddle “elixirs” are pushing supplements and potions whose benefits are not proven.

Meaning:An evangelist is someone who spreads a belief with burning enthusiasm, hoping to convert others. The word began in religion, for those who preached the Gospel, but now describes anyone who eagerly champions a cause, product, or idea. Here, Bryan Johnson is a longevity evangelist because he loudly urges people to adopt his anti-ageing routine.

Meaning:Arduous means demanding a lot of effort, endurance, and time, like climbing a steep mountain. It is stronger than “hard”: an arduous task wears you out and cannot be rushed. Proving that a drug really slows ageing takes years of trials, which is why the article calls the process arduous compared with simply selling supplements.

Biology. Your chronological age is simply the number of birthdays you have had. Your biological age is how worn-out your body is, and two people born on the same day can differ by years: one may have the arteries and energy of someone much younger, the other of someone older. Doctors cannot read biological age off a birthday, so scientists build ageing clocks: tests that measure chemical marks on DNA, or the mix of proteins in the blood, and compare them with patterns found in many people of known age. A body whose marks look like those of an average 50-year-old is said to be biologically 50, whatever its birth certificate says.

Why it matters here: testing whether a drug slows ageing by waiting to see who lives longest could take decades. A clock offers a quick stand-in. Novo's data put the heart's biological age up to four years younger in patients on its drug than in those on a placebo (a dummy treatment used for comparison).

The catch: a clock is a proxy, a measurement standing in for the thing we really care about, living longer and healthier. A proxy can move without the real outcome following, and the studied patients were overweight or diabetic, so it is unknown whether healthy people would see the same change.

Regulation. Before a medicine can be sold in America, the FDA (Food and Drug Administration) must approve it, and approval is granted for a specific indication: a named medical condition the drug is shown, in trials, to treat safely. A drug is not simply “approved”; it is approved for something, such as diabetes. Ageing is not on the FDA's list of diseases, so a company cannot run a trial, show that its pill slows ageing, and get a licence.

That shapes the whole business. Companies pick a recognised condition linked to ageing, win approval for it, and then try to widen the drug's use. GLP-1s followed this path: first approved for diabetes, then obesity, and later shown to help hearts, kidneys and sleep apnoea, conditions that grow more common with age. Insilico's “dual-purpose” drug treats a lung-scarring disease while also being studied for ageing.

The unregulated side is the opposite: clinics and online sellers face no such test, so supplements and injections can be sold on hope and anecdotes. Regulators' rules create a gap between what is proven and what is for sale.