A Nature article edible skin care underscored an opportunity provided by the skin's rapid turnover.

Our entire outer layer of skin is completely regrown every month from the nutrients we provided, so we are what we eat,

not just years down the road, but on a month-to-month basis.

For example, the amount of vitamin C we eat maps directly onto the amount of vitamin C we

have in our skin.

Take skin frailty.

Skin atrophy with age is not just a cosmetic issue. It can result in skin tears,

bruising, itching. A cross-sectional study of dietary intake and skin frailty found that dietary

patterns characterized by higher vegetable and fruit intake was associated with better skin condition.

To test the effects of greens, Korean researchers randomized women to one or two

doses of chlorophyll, equivalent to up to a few tablespoons of cooked spinach a day. After three months,

skin biopsy showed a significant increase in collagen production, accompanied by an increase in

skin elasticity, and a decrease in facial wrinkles.

This may have been due in part to an inside-out sunscreen effect

as less DNA damage was noted after the same degree of UV radiation.

Unfortunately, these were all just comparisons to baseline, as there was no control arm included.

Still, this is the kind of evidence cited by Dermatology Journal commentaries with titles

like,

Eat Plenty of Green Leafy Vegetables for Photo Protection, Protection Against the Sun.

There have been placebo-controlled randomized trials,

compared to placebo, 10 months, but not five, of an extract of curly kale

caused a significant improvement in a non-invasive measure of skin collagen status.

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