 I hear from lots of people every day who are concerned about how their diet is affecting their health. They need answers based on facts, in other words, from the peer-reviewed medical literature, and that is what I'm here for. Welcome to the Nutrition Facts Podcast. I'm your host, Dr. Michael Greger. If you think the claim of younger-looking skin overnight sounds a bit too good to be true, you may be right. Today's the first in our two-part series on the efficacy of anti-aging creams. What is the truth about over-the-counter anti-aging products, which constitute a billion-dollar industry? There is a psychological effect from spending more, wrote a team of dermatologists. But don't be seduced by fancy packaging and high prices. Many products advertise dramatic results that are frequently exaggerated and misleading, and are rarely scientifically supported. An independent product testing institute questioned the efficacy of anti-aging creams generally, finding that beneficial effects could only be picked up using sensitive instruments without becoming clinically or noticeably detectable. They suggest these products may not work any better than typical moisturizers. Cross-sectional studies of Chinese and British women found that those who regularly used facial moisturizers were guessed to be about two years younger than those of the same age who didn't. However, a third larger Dutch study did not, and regardless, snapshot and time studies can never establish cause and effect. Studies on moisturizers are limited, but they can improve the appearance of dry skin, which can otherwise look discolored, flaky, and rough. Moisturizers can hydrate the skin and may reduce the appearance of fine lines by 15 to 20 percent, called the oldest trick in the cosmetic industry, but may not do anything to treat the underlying cause. Whether a facial foundation or night cream or anti-aging serum, the formulations of most skin products are basically a moisturizer, combined with purported active ingredients for marketing appeal. Which ingredients are actually active anti-aging agents? I'll give you a hint. Up to 90 percent of visible aging of someone's face is due to sun exposure. From an anti-aging standpoint, the most biologically active ingredient in skin products is sunscreen. Consider the most important thing to maintain youthful skin is the daily application of sunscreen and other protective measures like wearing a hat. All other things you can do for your skin pale in comparison, especially for those with pale skin. To prevent skin cancer, the American Academy of Dermatology recommends sunscreen with a SPF of 30 or higher, but an SPF of 15 can prevent skin aging. How do we know? Because it's been put to the test. 900 adults were randomized to years of daily sunscreen use or to continue their own discretionary use. It was considered unethical to withhold protection by giving people placebo sunscreen. In the end, 77 percent of the recommended daily sunscreen group were applying sunscreen at least three to four days per week, compared with 33 percent in the discretionary use group. Would that be enough of a difference to make a difference? Yes, there was significantly less skin aging in the instructed daily use group. In fact, they suffered no detectable increase in skin aging over that 4.5-year study. The researchers concluded daily sunscreen use protects against skin aging. Although sunscreens are primarily intended to prevent further facial aging, rather than reverse photo damage already done, some in the daily sunscreen use group did show an improvement in skin texture. The results are all the more striking, given the control group was told to continue to use sunscreen and hats whenever they thought necessary, suggesting people are poor judges or planners for excess UV exposure when left to their own devices. So, a daily facial moisturizer with an SPF15, and it is recommended, even if it's cloudy or raining outside, considered the gold standard for anti-aging skin care, daily use of sunscreens in the daytime, and retinoids at night. Retinoids? I'll cover them next. Sunscreens are intended to prevent further facial photo aging, but can't dramatically reverse damage presently visible, whereas topical retinoids are the most important drug class to reverse the signs of aging. Also known as all-trans retinoic acid, tritinoin, sold under a variety of brands, including Retin-A, is a prescriptionally topical form of vitamin A that can visibly improve mild to moderate photo damage, including fine and coarse wrinkles, freckles, other pigmentation, improve overall skin texture after months of daily use. This is accompanied by a restoration of collagen formation, skin biopsy taken before and after 10 to 12 months of tritinoin versus placebo, found that while skin collagen formation dropped 14% in the control group, it rose 80% in the retinoic acid group. The downsides are the side effects. So common they have their own name, retinoid reaction, plaguing a high proportion of patients, including redness, stinging, burning, itching, and peeling. Ironically, the constant irritation may be a causal mechanism, constantly forcing the skin to renew. The adverse effects do tend to improve over time, after a peak, after about two weeks of daily use, and you can minimize the irritation by starting at a lower concentration, for example 0.025% instead of 0.1%, and slowly ramping up from applying at first twice a week for a few weeks then to every other night for a few more weeks before finally advancing to nightly application as tolerated. Given that a small amount is systemically absorbed out of an abundance of caution, women of child-bearing capacity may want to steer clear, given the severe birth defects caused by a similar drug, isotrotinoin, sold formally as the acne drug, acutane. There are gentler, less potent over-the-counter topical retinoids, retinol, retinol, and retinol. There's retinol acetate, retinol palmitate, propionate, retinol, retinaldehyde, once absorbed into your skin, your body can convert them into small amounts of retinoic acid. However, data is limited on these non-prescription retinoids. The results of clinical trials on the retinol esters have been routinely disappointing. Even 48 weeks of daily use were found to be ineffective for reducing wrinkles compared to placebo. Retinoldehyde and retinol, however, hold some promise. There was a 48-week head-to-head trial of retinoldehyde versus retinoic acid versus placebo. Now retinoids can be so irritating that it's hard to blind participants as to whether or not they're in the control group so objective measures that may be less susceptible to placebo effects are especially important. So what they did is make silicone molds of the crow's feet wrinkles around the eyes of the participants before and after being randomized to one of those three groups, and then analyze scans of the molds using high-resolution digital image processing. The retinoldehyde group showed a similar reduction fine lines and wrinkles as the retinoldehyde group with less irritation. Only 23% of the retinoldehyde group experienced skin irritation compared to 71% in the retinoldehyde group versus 4% in the placebo cream group. Of all the non-professional retinoid options, retinol may be the preferred choice, though. It causes even less irritation in the retinoldehyde in significantly different than placebo and a randomized double-blind placebo-controlled trial found that 52 weeks of use improved crow's feet fine lines by 44% and modeled pigmentation by 84%. But tritinolid retinoldehyde acid has by far the most robust track record of efficacy, so why not just ask your doctor for a prescription? Because long-term topical tritinoldehyde use may increase your risk of an even more stinging side effect, death. Topical tritinoldehyde therapy in all-cause mortality. The Veterans Affairs topical tritinoldehyde chemo prevention trial was to be a six-year randomized controlled trial to see if it could help prevent skin cancer. But the trial had to be stopped early because significantly more people were dying in the retinoic acid group than the placebo cream group. At the time the study was halted, 19% of the subjects in the tritinoldehyde group had died, compared to 14% in the placebo group. Between 1 to 8% of topically applied retinoic acid is absorbed into the bloodstream. Could it be killing people? We don't know if the increase in deaths was a statistical flu because it happened by chance or a real biological effect. The probability that we'd see such a discrepancy just by chance is about 1 in 100. Tritinoldehyde continues to be banned in Europe for cosmetic purposes. We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutritionfacts.org slash testimonials. We may be able to share it on social media to help inspire others. If you see any graphs, charts, graphics, images, or studies mentioned here, please go to the Nutrition Facts podcast landing page. There you'll find all the detailed information you need, plus links to all the sources we cite for each of these topics. My latest book, How Not to Age, is out now, premiering at No. 2 on the New York Times best sellers list. Check it out at your local public library. Of course, all the proceeds of the sales of all my books goes directly to charity. NutritionFacts.org is a non-profit science-based public service where you can sign up for free daily updates on the latest nutrition research with bite-sized videos and articles. Everything on the website is free there. No ads, no corporate sponsorships, no kickbacks, strictly non-commercial. I'm not selling anything. I just put up as a public service as a labor of love as a tribute to my grandmother, whose own life was saved with evidence-based nutrition.