Feeling suddenly older? Scientists see aging ‘waves’ at 44 and 60

livemint.com:

The oldest millennials have entered their 40s and are noticing the effects of aging. It might not be in their heads. A growing body of research says the aging process might resemble rolling hills more than a slow and steady climb.

Age-related changes—slowing metabolism, wrinkling skin—pile up over time but may crescendo at specific points in your life. In a study published in the journal Nature Aging in August, a team of Stanford scientists described “waves" of aging, where major biomolecular shifts happen in the body around ages 44 and 60. The researchers found people in their mid-40s, for example, had meaningful changes in biological markers and pathways related to their abilities to metabolize alcohol and fats.

These types of changes can lead to gradual weight gain or greater sensitivity to that nightly glass of wine. “People assume everybody’s kind of aging gradually," says Michael Snyder, a professor of genetics at Stanford University and senior author of the study. “It turns out that most changes are not linear." It is possible that paying special attention to healthy exercise and eating habits ahead of these waves could help lessen their blows, researchers say.

In addition, people age differently, so no one number will be representative of how old or young everyone feels. The Stanford team analyzed data from repeated collections of blood and stool samples and oral, skin and nasal swabs from 108 healthy people between the ages of 25 and 75. They tracked changes in more than 100,000 molecules and microbes, from proteins and RNA to standard lipid measures such as LDL and HDL over roughly two years and compared results between older and younger people.