Very little is known about what raspberry ketone does for skin. The only human data come from one small 2008 study in which a 0.01% raspberry ketone preparation applied to the face increased cheek skin elasticity in five women after two weeks. No published study has tested raspberry ketone supplements taken by mouth for skin, and laboratory studies suggest its skin-lightening effect comes at concentrations that can also harm pigment cells.
Key Takeaways
- Raspberry ketone is the compound that gives red raspberries their aroma. Raspberries contain only up to about 4.3 mg per kilogram.
- The one human skin study was tiny: five women applied a 0.01% preparation, and cheek elasticity rose after two weeks. It has not been confirmed by larger trials.
- We found no published studies of oral raspberry ketone supplements and skin health.
- In cell, zebrafish and mouse studies, raspberry ketone reduced melanin production, but a study in human pigment cells found that lightening concentrations were close to toxic ones.
- Supplements supply 100 to 1,400 mg a day, far more than food, and toxicology data for those amounts are limited.
- Patch-test any topical product first, and talk to your healthcare provider before taking raspberry ketone supplements.
Evidence grade: Emerging. Skin evidence is limited to one very small topical study in people plus cell and animal research; there are no controlled human trials of raspberry ketone for skin, taken by mouth or applied.
What Is Raspberry Ketone?
Raspberry ketone, chemically 4-(4-hydroxyphenyl)-2-butanone, is a natural aroma compound found in red raspberries. It is used as a flavoring substance, and it is also sold as a dietary supplement.
The amounts differ enormously between food and supplements. Raspberries contain up to about 4.3 mg of raspberry ketone per kilogram of fruit, while supplement labels reviewed by Danish food-safety researchers in 2015 recommended 100 to 1,400 mg a day. Even the lowest of those doses is far beyond what anyone could get from eating raspberries.
Researchers became interested in raspberry ketone because its chemical structure resembles capsaicin, the compound that makes chili peppers hot, and synephrine, two compounds studied for their effects on fat metabolism. Much of the research has looked at body weight and fat metabolism in animals. Skin research is much thinner.
What Does Raspberry Ketone Do for Skin? The One Human Study
The skin claims trace back to a single 2008 paper by Harada and colleagues in Japan. The team had previously reported that applying capsaicin to the skin increased a growth factor called IGF-1 in the deeper skin layer by activating sensory nerves. Because raspberry ketone is structurally similar to capsaicin, they tested whether it could do the same.
In mice, raspberry ketone triggered sensory nerve cells to release a signaling molecule (CGRP), and a 0.01% preparation applied to the skin raised IGF-1 in the skin within 30 minutes and promoted hair regrowth after four weeks. The effect did not occur in mice bred without CGRP.
The human part of the study was small:
- Five women applied 0.01% raspberry ketone to facial skin, and cheek skin elasticity increased after two weeks.
- Ten people with hair loss applied it to the scalp, and half showed hair growth after five months.
These are interesting early findings, but they are not proof. The groups were tiny, the published summary does not describe a placebo comparison, and we found no later trials that repeated the results. The study also tested raspberry ketone applied to the skin. It tells us nothing about raspberry ketone capsules taken by mouth.
Raspberry Ketone and Skin Lightening
A second line of research looks at pigment. In a 2011 study, raspberry ketone reduced melanin production in mouse pigment cells grown in the lab by lowering the activity and amount of tyrosinase, the enzyme that makes melanin. It also reduced pigment in zebrafish, and gels containing 0.2% or 2% raspberry ketone lightened mouse skin within a week.
That sounds promising for cosmetics, but a 2016 study in human pigment cells raised a safety flag. It found that the concentrations of raspberry ketone needed to reduce melanin were similar to the concentrations that were toxic to the cells, and ultraviolet B light made the toxicity worse. The researchers grouped raspberry ketone with rhododendrol and monobenzone as agents linked to leukoderma, a loss of skin color.
That concern has real-world precedent. In Japan, people who used skin-lightening cosmetics containing 2% rhododendrol developed leukoderma more often than users of other lightening products, a problem that has generated a body of medical research since 2013. Rhododendrol is a different compound, but the experience shows why lab evidence of lightening is not the same as evidence of safe lightening.
Raspberry Ketone Supplements: What Has Been Studied
Raspberry ketone supplements are marketed mainly for metabolism and weight management, not skin. Here is what that research actually covers:
- Animal studies. In a 2005 study, mice fed a high-fat diet with 0.5% to 2% raspberry ketone gained less weight and liver and abdominal fat than mice on the high-fat diet alone.
- Human trials of combination products. In a 2013 eight-week trial, 70 overweight adults were randomly assigned to a placebo or a supplement containing raspberry ketone, caffeine, capsaicin, garlic, ginger and bitter orange, alongside a calorie-restricted diet and exercise. Among the 45 who finished, body weight fell 2.0% with the supplement and 0.5% with placebo. A 2018 trial of a similar formula in 36 adults also combined it with diet and exercise. Because these products contained several active ingredients, the results cannot be credited to raspberry ketone alone.
Neither trial measured skin. For a broader look at the research, see our guide to raspberry ketone benefits, and for timing questions, when to take raspberry ketones.
Raspberry Ketone Skin Claims Compared With the Evidence
| Claim | What the evidence shows | Strength |
|---|---|---|
| Improves skin elasticity | One topical 0.01% study in five women found higher cheek elasticity at two weeks | Very limited |
| Supports hair growth | Same 2008 study: hair growth in half of 10 people after five months of topical use; supported by mouse data | Very limited |
| Lightens skin or dark spots | Reduces melanin in cells, zebrafish and mouse skin; lightening concentrations were close to toxic in human pigment cells | Lab and animal only, with a safety concern |
| "Antioxidant glow" from capsules | We found no human studies of oral raspberry ketone and skin appearance | No human evidence |
| Better skin through weight loss | Weight trials tested multi-ingredient products with diet and exercise; none measured skin | Not studied |
A Realistic Approach to Skin Care
If your goal is healthier-looking skin, raspberry ketone is not a well-supported place to start. It is reasonable to treat any topical raspberry ketone product as an experimental cosmetic ingredient rather than a proven one. For an overview of nutrients and compounds that have been studied for skin aging, read our article on antioxidants and skin aging.
Safety and Interactions
Raspberry ketone has a long history as a flavoring, but the doses in supplements are a different matter.
- Limited toxicology. A 2015 review by researchers at the Technical University of Denmark found that toxicology studies were limited to short-term studies in rats. The lowest recommended supplement dose of 100 mg was 56 times a widely used threshold of toxicological concern, and the margin of safety based on rat data fell from about 165 at 100 mg a day to about 12 at 1,400 mg a day.
- Computer-model warnings. The same review found that structure-based computer models flagged possible effects on the heart and on reproduction and development. These are predictions, not observed harms, but they are a reason for caution until better studies exist.
- Pregnancy and breastfeeding. There are no safety data for these groups, so avoid raspberry ketone supplements if you are pregnant, trying to conceive or breastfeeding.
- Combination products. The products tested in the 2013 and 2018 trials also contained caffeine and bitter orange. If you take prescription medicines, especially for the heart or blood pressure, or are sensitive to caffeine, talk to your doctor or pharmacist before using a raspberry ketone product.
- Topical use. Test any product on a small patch of skin first. Stop using it if you notice irritation or any lightening or loss of color, and see a dermatologist if a change in color persists.
For more detail, see our guide to raspberry ketone side effects.
Frequently Asked Questions
Are raspberry ketones safe for skin application?
Raspberry ketone is used as a flavoring substance, but its safety as an active skin treatment has not been well studied. A study in human pigment cells found that the amounts needed to lighten pigment were close to amounts that damaged the cells. Patch-test any product and stop if you notice irritation or color changes.
Does raspberry ketone improve skin elasticity?
Possibly, but the evidence is very thin. In one 2008 study, five women who applied 0.01% raspberry ketone to their faces had higher cheek elasticity after two weeks. No larger trial has confirmed this, and there is no evidence that taking raspberry ketone by mouth has the same effect.
Can you use raspberry ketones for skin whitening?
Raspberry ketone reduced melanin in lab cells, zebrafish and mouse skin, but it has not been tested for skin lightening in people. In human pigment cells, effective concentrations were close to toxic ones, and the researchers grouped it with compounds linked to patchy loss of skin color. It is not a proven or established-safe lightening ingredient.
Do raspberry ketone supplements improve your skin?
There is no published evidence that they do. The only human skin data come from a topical preparation, and the human supplement trials tested multi-ingredient weight-management products without measuring skin.
Is taking raspberry ketone the same as eating raspberries?
No. Raspberries contain up to about 4.3 mg of raspberry ketone per kilogram of fruit, while supplements recommend 100 to 1,400 mg a day.
Sources
- Harada N, Okajima K, Narimatsu N, Kurihara H, Nakagata N. Effect of topical application of raspberry ketone on dermal production of insulin-like growth factor-I in mice and on hair growth and skin elasticity in humans. Growth Horm IGF Res. 2008.
- Bredsdorff L, Wedebye EB, Nikolov NG, Hallas-Møller T, Pilegaard K. Raspberry ketone in food supplements: High intake, few toxicity data. A cause for safety concern? Regul Toxicol Pharmacol. 2015.
- Lin CH, Ding HY, Kuo SY, et al. Evaluation of in vitro and in vivo depigmenting activity of raspberry ketone from Rheum officinale. Int J Mol Sci. 2011.
- Lee CS, Joo YH, Baek HS, et al. Different effects of five depigmentary compounds, rhododendrol, raspberry ketone, monobenzone, rucinol and AP736 on melanogenesis and viability of human epidermal melanocytes. Exp Dermatol. 2016.
- Matsunaga K, Suzuki K, Ito A, et al. Rhododendrol-induced leukoderma update I: Clinical findings and treatment. J Dermatol. 2021.
- Morimoto C, Satoh Y, Hara M, Inoue S, Tsujita T, Okuda H. Anti-obese action of raspberry ketone. Life Sci. 2005.
- Lopez HL, Ziegenfuss TN, Hofheins JE, et al. Eight weeks of supplementation with a multi-ingredient weight loss product enhances body composition, reduces hip and waist girth, and increases energy levels in overweight men and women. J Int Soc Sports Nutr. 2013.
- Arent SM, Walker AJ, Pellegrino JK, et al. The Combined Effects of Exercise, Diet, and a Multi-Ingredient Dietary Supplement on Body Composition and Adipokine Changes in Overweight Adults. J Am Coll Nutr. 2018.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. 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. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
