A leading longevity expert says there are 4 things you can do today to scientifically reduce your body's biological age

• Epigenetic clock expert Steve Horvath says don't waste your money on expensive biological age tests.
• Instead, he offers four simple & cheap things you can do to lower your biological age, right now.

Steve Horvath figured out how to calculate a biological age way before anyone cared.

In 2011, Horvath, then a genetics professor at UCLA, published pioneering research showing that chemicals tucked inside our saliva can closely track human health and decline.

"At the time it was a very curious finding, that you spit in a cup and you measure the age," Horvath told Insider. "It was largely ignored."

More than a decade later, there are a whole crop of longevity companies who'll promise to measure your biological age through spit or blood analyses based on Horvath's discovery.

"It's nice to see," he said. "But, there's also a danger that overly enthusiastic people offer something, and the science isn't quite there. That makes me so nervous."

Test kits now cost hundreds of dollars, and require DNA collected from your spit, cheek cells, blood, or urine. (Researchers are also more easily determining the age of wild polar bears, elephants, zebras, horses, and more than 100 other non-human mammal species with the same technique.)

All of these tests work by measuring chemical signatures in DNA, which change over time, and in response to both environmental and biological influences, like our genetics and our lifestyle. Essentially, the tests measure how fast or slow we are aging.

But Horvath — who now works as a principal investigator at the secretive longevity startup Altos Labs — said consumers should, for now, take all of these flashy DNA-based biological age estimates in stride.

"The most important thing I want to tell the consumer is: do it only if you have a sense of humor," he said. "People should be relaxed about it."

The most accurate way to test your biological age

A biological age test doesn't provide a full picture of a person's health. There are other meaningful indicators, like blood pressure, weight, cholesterol, and blood sugar to consider.

Horvath's gold standard GrimAge clock, which he named after the Grim Reaper, is "our best mortality risk predictor" to date, he said.

The GrimAge test measures chemical changes on 1,030 different letters of our DNA, to roughly determine the speed of our aging. But even GrimAge shouldn't be used as a death calculator, Horvath warned.

Biological age tests simply measure how your health stacks up to your lived years today, and therefore don't accurately predict your future health, many decades away.

For now, the tests aren't very clinically meaningful. But Horvath hopes that some day, doctors might be able to order up a biological age test for their patients, and then recommend anti-aging pills, or other yet-to-be-invented interventions, to help improve longevity and decrease biological age.

"We are not there yet for a variety of reasons," Horvath said. "And the most important is: we don't have a pill."

4 things that really do slow aging

Horvath says people hoping to boost their health and lifespan should focus on the simple, evidence-based things science has already shown us can slow down human aging. These actions can measurably lower a person's biological age, and include:

• Not smoking

• Increasing vegetable intake

• Exercising

• Reducing chronic inflammation (which can eventually lead to issues like cancer and heart disease).

"Everything you know about a healthy lifestyle does seem to affect these biomarkers," Horvath said.

He advises his closest friends not to waste their money on expensive DNA testing.

"Just don't smoke, exercise, eat your vegetables," he said.

One of the fastest ways to improve your biological age, he's personally discovered, is to stop smoking (as he did when he turned 40). He also eats less sugar and chocolate than he used to, and adheres to a "health nut" diet.

Using his own clock as a gauge, he's noticed his biological age decrease over time, as a result of these changes.

"It did have an effect on me," he said.