Your skin ages on two clocks, and you can set the pace of one

Key takeaways

• Sunlight is the biggest outside factor in skin aging, linked to about 80% of visible facial aging signs in a study of 298 women¹.
• Your body starts making less collagen in your 20s, and by age 40 you may be losing about 1% of it each year².
• In a 4.5 year Australian trial, adults who used sunscreen every day were 24% less likely to show increased skin aging than people who used it only when they chose³.
• Reviews of up to 26 clinical trials found that people taking collagen peptides for about 12 weeks had better skin hydration and elasticity than placebo groups⁴⁵⁶.
• Staying smoke-free, sleeping 6 to 8 hours and eating healthy fats and colorful produce all support healthy aging for your skin⁷.

Hold your inner arm next to the back of your hand. Same person, same birthday, yet the skin often looks years apart. Much of that gap comes from sunlight, a reminder that a large share of skin aging comes from daily life rather than the calendar¹.

Skin experts describe two kinds of aging. Intrinsic aging is the slow change built into your genes and your years. Extrinsic aging comes from the outside world, including sun, smoke, polluted air, sugary eating and short nights⁷⁸.

The second clock is the one you can influence. A 2013 study looked closely at the faces of 298 women ages 30 to 78. The researchers concluded that ultraviolet (UV) light appeared to account for about 80% of visible facial aging¹. That leaves plenty of room for daily habits, smart food choices and well-studied supplements to support firm, healthy-looking skin at every age.

Two clocks shape how your skin ages

Two proteins in the skin’s deeper layer (the dermis) keep it smooth and springy. Collagen gives skin its strength and firmness, while elastin lets it stretch and bounce back. As both slowly decline with age, skin becomes looser and less firm⁸.

Collagen production starts to slow as early as your 20s, and by age 40 you are likely losing about 1% of your collagen each year². The collagen that remains breaks down faster and is lower in quality than it was in your youth⁹. Women make much less collagen after menopause, and production drops for everyone after age 60⁹.

Other inside changes add up slowly too. The outer layer (epidermis) and the dermis both thin, so skin looks more see-through and bruises more easily⁸. The face loses some fat and bone over the years, which gradually changes its shape⁸. Fewer oil and sweat glands can leave older skin feeling drier⁸.

Skin even holds less vitamin C as the years pass, and UV light drains it further¹⁰. That matters because your body needs vitamin C to build collagen¹⁰. Heredity helps set the basic pace of this first clock⁸.

Sunlight is the biggest outside factor

Sunlight speeds up the second clock more than anything else. In the 2013 study, researchers compared women who sought out the sun with women who avoided it. Pigment spots were more common in the sun seekers, while sagging tracked more closely with age itself¹. Wrinkles and rough texture reflected a mix of both clocks, with years and sunlight each playing a part¹.

UV light also changes skin below the surface, according to the Linus Pauling Institute at Oregon State University¹¹. In one study it describes, sun-damaged skin made about 56% less of the main type of collagen than sun-protected skin¹¹.

Daily protection makes a measurable difference. In the Nambour trial in Australia, researchers randomly assigned 903 adults under age 55 to use sunscreen every day or only when they chose³. After 4.5 years, the daily group showed no detectable increase in skin aging, and they were 24% less likely than the comparison group to show increased aging³.

The type of UV light most tied to aging (UVA) passes through car and office windows, so protection matters on indoor days too¹². Choose a broad-spectrum sunscreen with SPF 30 or higher that you enjoy wearing, and reapply about every two hours when you are outdoors⁸¹².

Cleveland Clinic dermatologist Melissa Piliang, MD, puts it simply: apply sunscreen every single day as part of your morning routine⁷. Her colleague Alok Vij, MD, adds that it is never too late to begin protecting yourself from the sun⁸.

Good nutrition can lend a hand from the inside. In human studies, people who took vitamins C and E together needed a stronger dose of UV light before their skin turned red¹⁸. The pair was also linked with less DNA damage in skin after UV exposure¹⁸.

These nutrients work alongside sunscreen, never in place of it. The library’s guides to sunscreen and UV exposure cover sun protection in depth.

Smoking, sugar and short nights leave marks too

Smoking is the next big outside factor. Cleveland Clinic notes that smoking cuts collagen production, and smokers tend to have more wrinkles⁸⁹. Smoking narrows the tiny blood vessels in the skin, which damages collagen and elastic fibers over time⁷. Pursing the lips again and again can also etch fine lines around the mouth⁷.

What you eat shows up in the mirror as well. Extra sugar can attach to collagen and leave it weak, dry and brittle⁹. Dr. Piliang suggests easing up on sugar and refined carbs, which send blood sugar and insulin up⁷.

Air quality counts too. Soot and car exhaust can harm skin, so a walk in a park beats a stroll along a busy road when you have the choice⁷. Gravity and years of smiling, frowning and squinting add their own lines and drooping, which is a normal part of a well-lived face⁸.

Sleep is the quiet habit that ties it together. Dr. Piliang recommends 6 to 8 hours a night on a steady schedule, since poor sleep can stir up the same insulin-related inflammatory response⁷. How you sleep matters a little, too. Creases from pressing your face into a pillow can deepen over the years, and changing positions may keep them from setting in⁸.

Gentle daily care rounds things out. Fragrances and harsh products can irritate skin, and Dr. Piliang notes that irritation leads to dryness and more damage⁷. A mild cleanser and a fragrance-free moisturizer go a long way. Cleveland Clinic also suggests managing stress and drinking plenty of water as part of a skin-friendly routine⁷¹².

Foods linked with firmer, younger-looking skin

Your plate supplies the raw materials your skin uses every day. Vitamin C is needed to make collagen, and it also works as an antioxidant in the skin¹⁰¹². Citrus fruits, bell peppers, strawberries, kiwi and broccoli are all rich sources.

Diet surveys point the same way. In a U.S. survey of women ages 40 to 74 (NHANES), those eating more linoleic acid were less likely to have dry or thin skin¹³¹⁴. Higher vitamin C intake was linked with fewer wrinkles and better-looking skin in this survey and another diet study¹⁰¹⁴.

Linoleic acid is an omega-6 fat found in nuts, seeds and vegetable oils, and skin uses it to build a strong moisture barrier¹³. Healthy fats deserve a regular spot on the menu. Dr. Piliang recommends olive oil, avocado and nuts, along with antioxidant-rich produce, lean protein and plenty of water⁷. Walnuts, flaxseed, chia seeds and fatty fish such as salmon and sardines add omega-3 fats to the mix.

Cooked tomatoes are worth adding too, since they are rich in lycopene, the red plant pigment behind their color. In one study, people who ate 40 grams of tomato paste with olive oil every day for 10 weeks had about 40% less sunburn¹⁵. That is about two and a half tablespoons a day, and researchers believe lycopene is behind this added UV protection¹⁵.

Cocoa has its own research story. In a 12 week trial, 24 women drank a cocoa beverage every day¹⁶¹⁷. It was either high in plant compounds called flavanols (326 mg) or low in them (27 mg)¹⁷.

The high-flavanol group showed less redness after UV exposure, more blood flow in the skin, and smoother, less scaly skin¹⁷. They also lost less water through the skin, while the low-flavanol group saw no change¹⁷. The flavanols in that cocoa, epicatechin and catechin, also turn up in tea and many fruits¹⁷.

Put together, a skin-friendly day of eating is easy to picture. Start with oatmeal topped with strawberries and walnuts. Have a big salad with olive oil and peppers at lunch, then enjoy salmon, broccoli and a tomato sauce at dinner.

Collagen peptides lead a growing list of skin supplements

Collagen peptides, also called hydrolyzed collagen, are collagen broken into small pieces that are easy for your body to digest and absorb². They usually come as powders or capsules made from beef, pork or fish collagen². The idea, as one Cleveland Clinic dietitian explains, is that they may help firm the skin and plump it up².

Researchers have tested collagen peptides in many clinical trials, and several reviews have pooled the results. A 2021 review in the International Journal of Dermatology combined 19 randomized, double-blind trials⁴. Together they included 1,125 people ages 20 to 70, and 95% were women⁴. In double-blind trials, neither the volunteers nor the researchers know who is taking collagen and who is taking a look-alike placebo.

People taking hydrolyzed collagen scored better than placebo groups on skin hydration, elasticity and wrinkles⁴. The authors pointed to about 90 days of daily use as the time frame for these results⁴.

A 2023 review in the journal Nutrients pooled 26 randomized trials with 1,721 people⁵. Those taking hydrolyzed collagen had better skin hydration than those on placebo, and the authors concluded it can have positive effects on skin health⁵. A third review that same year covered 14 trials with 967 people and saw better skin moisture and elasticity after a 12 week routine⁶.

Results vary from study to study, and researchers are still working out the best forms and doses. Daily amounts in the trials ranged from about 0.3 grams to 10 grams⁶. Cleveland Clinic notes that 2.5 to 15 grams a day is generally considered safe². The unflavored powders stir easily into coffee, smoothies or oatmeal.

Plant oils rich in gamma-linolenic acid (GLA), an omega-6 fat, have their own encouraging trials. One 12 week study gave 40 healthy adults 1.5 grams of evening primrose oil a day¹³. They scored better than the placebo group on skin moisture, elasticity, firmness and smoothness¹³.

In another trial, 45 women with dry, sensitive skin took 2.2 grams a day of flaxseed oil or borage oil for 12 weeks. Both groups scored better than placebo on every skin measure checked¹³.

Supplement studied	Daily amount in studies	Study length	What researchers observed
Collagen peptides (hydrolyzed collagen)	About 0.3 to 10 grams	About 12 weeks	Better skin hydration and elasticity than placebo in reviews of 14 to 26 trials
Cocoa flavanols (in a cocoa drink)	326 mg flavanols	12 weeks	Less redness after UV light, smoother skin and more blood flow in 24 women
Evening primrose oil	1.5 grams	12 weeks	Better moisture, elasticity and firmness than placebo in 40 adults
Flaxseed oil or borage oil	2.2 grams	12 weeks	Smoother, better-hydrated skin in 45 women with dry, sensitive skin

Sources:^456131617

Vitamin C and retinol support skin from the outside

Some well-studied skin nutrients work right on the surface. Cleveland Clinic suggests keeping the routine simple: a gentle cleanser, vitamin C, retinol, moisturizer and sunscreen¹². Lower-cost products can work as well as pricey ones¹².

Topical vitamin C has a strong research record. In trials, strengths of 3% to 10% used for at least 12 weeks were linked with fewer wrinkles, smoother skin and more collagen production¹⁰.

The natural form, L-ascorbic acid, works best on skin but is also the least stable¹⁰. A low pH (below 4) helps it soak in¹⁰. Look for a serum in an opaque container, since light breaks vitamin C down, and replace it about every six months¹².

Retinol is a form of vitamin A that skin turns into its active form, retinoic acid¹¹. In a study of 36 older adults with an average age of 87, people applied 0.4% retinol three times a week for 24 weeks. They saw smoother fine wrinkles¹¹. In adults 80 and older, one week of 1% retinol led to more new collagen in the skin¹¹.

Retinoids often cause some redness, flaking and dryness at first¹¹. Start slowly and add one new product at a time. If your skin feels irritated, apply a thin layer of moisturizer first, and avoid doubling up on retinol in both a serum and a cream¹². Plan to wait about three months to see results¹².

A daily moisturizer replaces some of the oils skin makes less of with age and can lend a temporary look of fullness¹². If you are pregnant, set retinoid creams aside for now, as the Linus Pauling Institute advises¹¹.

Smart supplement use and a daily habits checklist

Skin supplements work best as part of a steady routine. Start with the amounts used in studies, shown in the table above. For collagen peptides, trials used about 0.3 to 10 grams a day⁶.

Give any new supplement the 8 to 12 weeks used in many skin studies before you judge the results⁴⁶. Taking it at the same time each day makes that easy. A quick photo in the same window light at the start and at week 12 helps you see changes.

Adding one new product at a time also makes it easier to tell what your skin likes¹². Pairing your collagen with a vitamin C food at breakfast is a simple habit, since your body needs vitamin C to build collagen¹⁰.

Look for a third-party quality seal such as USP Verified, NSF Certified for Sport or ConsumerLab approved. These seals show that an independent lab checked the product’s contents against its label. If you avoid certain animal foods, check the source, since collagen peptides usually come from beef, pork or fish².

Share your full supplement list with your doctor or pharmacist, especially if you take prescription medicine. That way everything in your routine works together. The library’s guide to supplement and medication interactions has more.

Daily habits checklist

• Put on broad-spectrum SPF 30 or higher every morning, even on cloudy or indoor days

• Add a hat and seek shade when you are outside at midday

• Eat a vitamin C food at most meals, such as citrus, peppers, strawberries or broccoli

• Cook with olive oil and enjoy tomato sauce or paste a few times a week

• Reach for nuts, seeds, avocado or fish for healthy fats

• Go easy on sugar and refined carbs

• Aim for 6 to 8 hours of sleep on a steady schedule

• Use a gentle, fragrance-free moisturizer

• Take your skin supplement at the same time each day and check your progress at 12 weeks

• Stay smoke-free

The bottom line

Skin aging runs on two clocks. Heredity and time set the first. Sun, smoke, sugar and sleep set the second, and you can shape that one every day.

Daily sun protection is the anchor. Around it, build meals with colorful produce and healthy fats, keep a steady sleep schedule and be gentle with your skin. Collagen peptides lead the supplement research, and cocoa flavanols and GLA-rich plant oils add encouraging results of their own.

Give any new routine about 12 weeks and keep your care team in the loop. Your skin renews itself all the time, so the habits you start today can show up in the mirror this season.

Sources

1. Flament F, Bazin R, Laquieze S, Rubert V, Simonpietri E, Piot B. Effect of the sun on visible clinical signs of aging in Caucasian skin. Clinical, Cosmetic and Investigational Dermatology. 2013. dovepress.com

2. Cleveland Clinic. What Are Collagen Peptides? And Do They Work? Cleveland Clinic Health Essentials. 2026. health.clevelandclinic.org

3. Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Annals of Internal Medicine. 2013. pubmed.ncbi.nlm.nih.gov

4. de Miranda RB, Weimer P, Rossi RC. Effects of hydrolyzed collagen supplementation on skin aging: a systematic review and meta-analysis. International Journal of Dermatology. 2021. pubmed.ncbi.nlm.nih.gov

5. Pu SY, Huang YL, Pu CM, Kang YN, Hoang KD, Chen KH, Chen C. Effects of oral collagen for skin anti-aging: a systematic review and meta-analysis. Nutrients. 2023. pmc.ncbi.nlm.nih.gov

6. Dewi DAR, Arimuko A, Norawati L, Yenny SW, Setiasih NL, Perdiyana A, Arkania N, Nadhira F, Wiliantari N. Exploring the impact of hydrolyzed collagen oral supplementation on skin rejuvenation: a systematic review and meta-analysis. Cureus. 2023. pubmed.ncbi.nlm.nih.gov

7. Cleveland Clinic. 7 Ways to Prevent Wrinkles for Aging Skin. Cleveland Clinic Health Essentials. 2021. health.clevelandclinic.org

8. Cleveland Clinic. What You Need to Know About Aging Skin. Cleveland Clinic Health Essentials. 2020. health.clevelandclinic.org

9. Cleveland Clinic. Collagen. Cleveland Clinic Health Library. 2022. my.clevelandclinic.org

10. Michels AJ. Vitamin C and Skin Health. Linus Pauling Institute Micronutrient Information Center, Oregon State University. 2011. lpi.oregonstate.edu

11. Angelo G. Vitamin A and Skin Health. Linus Pauling Institute Micronutrient Information Center, Oregon State University. 2012. lpi.oregonstate.edu

12. Cleveland Clinic. Best Ingredients and Products for Your Anti-Aging Skin Care Routine. Cleveland Clinic Health Essentials. 2023. health.clevelandclinic.org

13. Angelo G. Essential Fatty Acids and Skin Health. Linus Pauling Institute Micronutrient Information Center, Oregon State University. 2012. lpi.oregonstate.edu

14. Cosgrove MC, Franco OH, Granger SP, Murray PG, Mayes AE. Dietary nutrient intakes and skin-aging appearance among middle-aged American women. American Journal of Clinical Nutrition. 2007. pubmed.ncbi.nlm.nih.gov

15. Cleveland Clinic. What Are the Health Benefits of Tomatoes? Cleveland Clinic Health Essentials. 2023. health.clevelandclinic.org

16. Heinrich U, Neukam K, Tronnier H, Sies H, Stahl W. Long-term ingestion of high flavanol cocoa provides photoprotection against UV-induced erythema and improves skin condition in women. Journal of Nutrition. 2006. pubmed.ncbi.nlm.nih.gov

17. Angelo G. Flavonoids and Skin Health. Linus Pauling Institute Micronutrient Information Center, Oregon State University. 2012. lpi.oregonstate.edu

18. Michels AJ. Vitamin E and Skin Health. Linus Pauling Institute Micronutrient Information Center, Oregon State University. 2012. lpi.oregonstate.edu

This article is for general education and is not medical advice. Talk with your healthcare professional about your own health, especially before starting a new supplement if you are pregnant, nursing, taking medicine, or managing a health condition. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Reviewed October 2026.