Do apples have any anti-aging properties?

The anti-aging effect of apples is not groundless, and its root lies in the various bioactive compounds contained in the fruit. These components work together to build a natural defense against the invasion of time.

1.1 Apple polyphenols: the main force of antioxidants
Apple polyphenols are the core of its anti-aging properties. According to multiple studies, apple polyphenols are a general term for a class of complex compounds, mainly including flavonoids, phenolic acids, and dihydrochalcones.[5] Among them, proanthocyanidins are the most abundant component in apple polyphenols, typically accounting for 71% to 90% of the total polyphenol content.

The multiple specialized databases established by the United States Department of Agriculture (USDA) provide us with detailed data support. For example, in its "USDA Database for the Proanthocyanidin Content of Selected Foods," the precise content of monomers, dimers, trimers, and even polymers of anthocyanins in different varieties of apples (such as golden crown, red snake fruit, Australian green apple, etc.) and their processed products is recorded in detail.[7] These data show that the content of anthocyanins in apple peel is much higher than that in fruit pulp, providing a theoretical basis for the development of apple peel extracts.

After understanding the key components in apples, we need to explore further how they exert anti-aging effects at the cellular and molecular levels.

2.1 Powerful free radical scavenging ability
The "free radical theory" of aging suggests that excessive free radicals produced during the body's metabolic processes can attack cell membranes, proteins, and DNA, leading to cell damage and functional decline, thereby triggering aging. Apple polyphenols and vitamin C neutralize these unstable free radicals by providing electrons, thereby blocking their disruption of the chain reaction.[4] Multiple in vitro studies have confirmed the excellent antioxidant activity of apple extracts using methods such as DPPH and ABTS.

2.2 Protect and activate stem cells
In recent years, plant stem cell technology has become a hot topic in the cosmetics industry. Among them, stem cell extracts derived from an ancient Swiss apple variety, "Uttwiler Spätleuber," have attracted much attention. This type of apple is famous for its ultra-long preservation ability. Research has found that the stem cell extract of this apple can protect the vitality of human skin stem cells and delay their aging process.[3] A clinical trial report on 20 women said that after using the cream containing the extract for four weeks, the depth of crow's feet was reduced by an average of 8%, and after eight weeks, it was reduced by 15%. This indicates that apple stem cell extract achieves anti-aging effects at the root by maintaining the skin's own regenerative ability.

2.3 Inhibit the activity of key aging enzymes
The elasticity of the skin mainly depends on elastin in the dermis layer. Elastase is an enzyme that can degrade elastin, and its activity increases with age, leading to skin sagging and wrinkles. A study on the unique Italian variety 'Annurca Apple' has brought exciting results. Research has found that Annurca Apple Oleolite (AAO) can effectively inhibit the activity of elastase in both in vitro and in vivo experiments, thereby protecting elastin and improving skin elasticity and water retention capacity.[6]

Theoretical and mechanistic research has painted a bright future for us, but for rigorous industry applications, clinical trial evidence from humans is the ultimate 'gold standard'.

3.1 Significant effects of local application
At present, clinical evidence on the local application of apple extract is relatively more concentrated and clear.

Wrinkle improvement: As mentioned earlier, Swiss apple stem cell extract has shown clear quantitative effects in reducing wrinkle depth.
Skin density and elasticity enhancement: A human study on Anurka apple polyphenol extract, published in 2023, deserves attention. The study recruited 32 female participants, and after using the relevant products for 28 days, instrument measurements showed that 78% of the participants had a significant increase in skin density, and 67% of the participants had a statistically significant increase in average skin elasticity (p<0.05).
Moisturizing and Barrier Function: An experimental study also found that skincare creams containing wild apple fruit extract can significantly increase the skin's electrical capacity, indicating that the barrier function and moisturizing ability of the stratum corneum are enhanced.
3.2 Oral supplements: potential and challenges coexist
The research on oral apple extract as an "inside-out" anti-aging method is still being explored. A randomized, double-blind, placebo-controlled clinical trial has been registered on the treatment of healthy women's skin conditions with apple polyphenol supplements, indicating that research in this field is moving towards standardization. However, some systematic reviews and meta-analyses have also pointed out that there is currently inconsistent research on the improvement effect of oral fruits or their extracts on skin wrinkles and elasticity, with high heterogeneity among studies and generally small sample sizes.[2] In addition, in some studies, apple extract is used as part of a composite formula, making it difficult to evaluate its exact efficacy alone.[1] This indicates that the anti-aging effect of oral apple extract still requires more high-quality, large-scale randomized controlled trials (RCTs) to confirm.

For more details about apple polyphenols, connect with Serrisha from APPCHEM. (Email: cwj@appchem.cn; +86-138-0919-0407)

Reference
[1]Effect of supplement containing Silybum marianum extract, soy extract, collagen peptide, bifidobacteria, and apple extract on skin: A randomized placebo-controlled, double-blind, parallel group comparative clinical study.. Yuri Ishii et al. [2016-06-24]
[2]Haoying Li, Lu Wang et al. "Effects of oral intake of fruit or fruit extract on skin aging in healthy adults: a systematic review and Meta-analysis of randomized controlled trials." Frontiers in Nutrition (2023). [2023-08-04]
[3]Ewelina Rostkowska, E. Poleszak et al. "Dermatological Management of Aged Skin." Cosmetics (2023). [2023-03-27]
[4]TECHNOLOGINIŲ PRIEMONIŲ IR BIOLOGINIŲ VEIKSNIŲ INTENSYVIUOSE OBELŲ (MALUS × DOMESTICA BORKH.) SODUOSE ĮTAKA VAISIŲ KOKYBEI. Jonas Viškelis. [2018-10-15]
[5]USDA Database for the Flavonoid Content of Selected Foods Release 3.1. Seema Bhagwat et al. [2013-05]
[6]皮膚のアンチエイジング成分として期待されるアンヌルカ(Malus pumila Miller cv. Annurca)リンゴオレオライト：南イタリアで実施された in vitro アッセイと RCT の結果から. 南イタリアのフェデリコ 2 世ナポリ大学薬学部(Department of Pharmacy, University of Naples Federico II [2,3]).[2024-01-06]
[7]USDA Database for the Proanthocyanidin Content of Selected Foods Release 2. Seema Bhagwat et al.[2015-09]