By the second half of the 14th century, peasants there were living five to seven years longer than in the previous 50 years. However, the average life expectancy for ducal families in England between 1330 and 1479 generally was only 24 years for men and 33 for women. In Florence, laypeople in the late 1420s could expect to live only 28.5 years (men) and 29.5 years (women).Not quite correct, average lifespan in earlier eras is highly skewed by a high infant and child mortality rate. If you made it past 7 you were good to go.
But regardless.advances in lifespan are primarily due to sanitation, not processed foods. Intact processed food consumption may be decreasing lifespan compared to earlier
https://www.historyextra.com/period...e-die-danger-medieval-period-life-expectancy/