How turnover works -- the truth and myths of the 28-day cycle

"Turnover takes 28 days" -- if you're interested in skincare, you've heard this phrase. However, this number contains a major misconception.

The 4 stages of turnover

New cells are born through division in the deepest epidermal layer, the "basal layer." These cells are pushed upward through the spinous layer, granular layer, and stratum corneum, gradually changing shape and function. Eventually, they serve as dead cells providing barrier function in the stratum corneum, then shed as flakes.

"28 days" is just the average for people in their 20s

The "28-day cycle" is the average for healthy skin in your 20s. Turnover slows with age -- approximately 45 days in your 40s and 75+ days in your 60s. Assuming your skin "renews every 28 days" can lead to misaligned care expectations.

"Faster" does not equal "better"

The idea of "speeding up turnover" with peeling or scrubs exists, but overly fast turnover actually causes problems. Immature cells reach the stratum corneum with incomplete barrier function, leading to dryness, sensitivity, and redness.

The goal should not be "speeding up" but rather "normalization". Maintaining an appropriate rhythm for your age -- neither too slow nor too fast -- is the shortcut to healthy skin.

Main factors that disrupt turnover

UV exposure, sleep deprivation, stress, nutritional imbalance, excessive exfoliation -- all of these disrupt the turnover rhythm. Not just skincare products, but your entire lifestyle impacts skin turnover.

KAIAN develops skincare products based on scientific evidence.
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