Carotenoids – Colorful plant compounds with scientifically proven effects on eyes, skin and metabolism

They give carrots their orange color, tomatoes their vibrant red, and autumn leaves their golden splendor: Carotenoids are among nature's most fascinating groups of compounds. For a long time, they were primarily considered vitamin A precursors and antioxidants. But current research from 2025 and 2026 paints a far more complex picture. Carotenoids are proving to be highly effective signaling molecules that directly influence our gene expression via transcription factors such as NF-κB and Nrf-2, as well as nuclear receptors like RAR/RXR. From the prevention of age-related eye diseases and systemic sun protection for the skin to the activation of fat burning – the scientific evidence for these colorful plant compounds is growing rapidly.

What are carotenoids? An introduction to the world of color pigments

Carotenoids are C-30, C-40, or C-50 terpenoids produced by a variety of bacteria, fungi, and plants. Humans cannot synthesize them themselves and therefore rely on dietary intake. To date, over 750 different carotenoids have been identified, of which approximately 50 are detectable in human blood and are regularly ingested through food.

Two main groups are distinguished:

• Carotenes (hydrocarbons) : These include β-carotene (in carrots), α-carotene and lycopene (in tomatoes)

• Xanthophylls (oxygen-containing derivatives) : These include lutein and zeaxanthin (in green leafy vegetables and corn) as well as β-cryptoxanthin (in oranges and other fruits)

For a long time, their function as a vitamin A precursor was the primary focus – in particular, beta-carotene can be converted into retinol by the body. However, this view is too simplistic. Current research shows that carotenoids exert their health-promoting effects through a complex interplay of various mechanisms:

• Direct antioxidant effects : They neutralize reactive oxygen species and protect against oxidative stress.

• UV protection : Certain carotenoids absorb high-energy blue light.

• Regulation of gene expression : They influence transcription factors such as NF-κB, Nrf-2 and nuclear receptors (RAR/RXR)

Carotenoids and eye health – protection for eyesight

Lutein and zeaxanthin: The retina's natural sunglasses

Perhaps the best-researched effect of carotenoids concerns eye health. Lutein and zeaxanthin occupy a special position here: they are the only carotenoids that are selectively concentrated in the macula of the human retina. There, they reach concentrations that are 1000 times higher than in the blood.

This enrichment is no accident. Lutein and zeaxanthin perform two key protective functions:

1. Blue light absorption : They filter out high-energy, potentially harmful blue light.

2. Neutralization of free radicals : They protect the sensitive photoreceptors from oxidative stress.

The AREDS studies: Milestones in ophthalmology

Since the large AREDS (Age-Related Eye Disease Study) trials, it has been scientifically proven that taking high doses of antioxidants in combination with lutein and zeaxanthin can slow the progression of dry age-related macular degeneration (AMD) in intermediate or advanced stages. The AREDS2 trial confirmed the safety and benefit of supplementation with 10 mg lutein and 2 mg zeaxanthin in patients at high risk for AMD.

Current research: Synergies with Omega-3 fatty acids

A Japanese research group investigated in a mouse model whether the combination of lutein and omega-3 fatty acids could influence the formation of new blood vessels in the eye (choroidal neovascularization) in wet age-related macular degeneration (AMD). The results were remarkable: Dietary intake of both nutrients significantly reduced the development of new blood vessels—additively. The simultaneous administration of lutein and omega-3 fatty acids had a greater protective effect than administration of either alone. At the same time, the production of inflammatory mediators and reactive oxygen species in the eye was suppressed.

The German Ophthalmological Society (DOG) therefore recommends a balanced, Mediterranean diet rich in red, yellow, and green vegetables, as well as fatty fish and olive oil. "It is important to obtain carotenoids through the consumption of fruit and leafy green vegetables, as our bodies cannot produce them themselves," emphasizes Prof. Dr. Andreea Gamulescu of the DOG.

Night vision and contrast sensitivity

A completed clinical study investigated the relationship between macular repigmentation with carotenoids and visual acuity under stressful conditions, particularly during simulated night driving. The background: Older drivers are especially susceptible to visual impairment when driving at night, as both their contrast sensitivity and glare sensitivity decline. The results underscore the importance of adequate lutein and zeaxanthin intake for visual function in challenging lighting conditions.

Supply situation in Switzerland, Germany and Austria

In Germany, the daily intake is approximately 1–2 mg of lutein and 0.1–0.2 mg of zeaxanthin. However, there is considerable variation. Since only 15% of women and 7% of men reach the recommended five portions of fruits and vegetables per day, an insufficient supply of these carotenoids must be assumed.

Carotenoids for the skin – Systemic sun protection from within

Photoprotective effect scientifically proven

Numerous studies have demonstrated that carotenoids, a class of substances, are effective antioxidants in lipophilic systems. Particularly interesting is the fact that carotenoids not only protect algae and plants from intense sunlight, but also exert a photoprotective effect in humans.

Studies show that supplementation with approximately 20 to 25 mg of carotenoids per day over a period of eight to twelve weeks achieves protective effects equivalent to a three- to fourfold increase in the body's own sun protection. Skin reddening at the peak of erythema after irradiation was reduced by 20 to 30 percent. In contrast, no effects were observed in placebo groups.

Improvement of skin physiological parameters

A twelve-week application of a product containing various natural carotenoids in combination with selenium and vitamin E led to a significant increase in skin density and thickness, which could be demonstrated using ultrasound. At the same time, the skin's surface structure was positively affected.

The increase in skin density leads to a strengthening of the collagen structure of the dermis, which has a positive effect on the elasticity and firmness of the skin.

Synergies with vitamins

Bioavailability, and therefore efficacy, can be improved by combining carotenoids with vitamins such as α-tocopherol or vitamin C. Synergistic effects appear to play a key role here. Technologies such as the coupling of lycopene to lactoproteins can also increase bioavailability.

Carotenoids and cognitive health – protection for the brain

Recent study: Higher carotenoid levels, lower risk of dementia

A study published in the journal Neurology in 2022 investigated the link between carotenoid blood levels and the risk of dementia. The results show that people with higher blood levels of certain carotenoids have a lower risk of developing dementia such as Alzheimer's disease.

The blood levels of 7,283 people were analyzed for an average of 16 to 17 years. The correlation was particularly pronounced for lutein, zeaxanthin, and beta-cryptoxanthin. These carotenoids are abundant in green leafy vegetables, corn, oranges, and other yellow-red fruits and vegetables.

A systematic review confirms that several epidemiological studies suggest a link between carotenoid intake and the reduction of chronic diseases, including cognitive functions.

Carotenoids and metabolism – New insights into fat burning

Surprising discovery: Carotenoids activate thermogenesis

A highly topical review article from January 2026, published in the Journal of Current Obesity Reports , investigated the effects of retinoids and carotenoids (β-carotene, lycopene, lutein, and β-cryptoxanthin) on adipose tissue. The results open up entirely new perspectives for obesity research.

The researchers found that compounds such as retinoic acid, lycopene, β-cryptoxanthin, and zeaxanthin reduce fat cell formation (adipogenesis) and fat production (lipogenesis) by suppressing the expression of key transcription factors (PPARγ, C/EBPα, SREBP1-c). At the same time, they increase energy expenditure and promote the conversion of white to beige adipose tissue—a process known as "browning" that is associated with increased thermogenesis.

Molecular mechanisms

This effect is mediated by the activation of AMP-activated protein kinase (AMPK) and the upregulation of thermogenic genes such as UCP1, PRDM16, and PGC-1α. The result: reduced adipocyte enlargement, increased mitochondrial activity, and decreased systemic inflammation.

The authors conclude: "Overall, the evidence suggests that vitamin A derivatives and carotenoids represent promising nutrition-based strategies for combating obesity through the conversion of adipose tissue and improved metabolic efficiency."

Prevention of chronic diseases – The epidemiological evidence

Several epidemiological studies have linked the intake of carotenoids with a reduced risk of various chronic diseases:

• Type 2 diabetes and cardiometabolic diseases : Inverse association between carotenoid levels and disease risk

• Certain types of cancer : Reduced incidence with higher carotenoid intake

• Age-related macular degeneration : Lutein and zeaxanthin are considered conditionally essential for older people.

Bioavailability and practical application

Fat makes the difference

Carotenoids are fat-soluble – their bioavailability is therefore significantly influenced by simultaneous fat intake. The ideal combination is vegetables with high-quality oils or fatty fish.

Overview of food sources

Safety and precautionary measures

Despite the predominantly positive evidence, a nuanced view of the safety of carotenoids is necessary. Current research indicates that some intervention studies have shown negative effects of high doses of β-carotene in smokers. This could be due to effects related to the activation of cytochrome enzymes.

The authors emphasize: "However, there is increasing evidence that these colorful pigments do indeed contribute to a healthy life and well-being. Further research is needed, however, to better understand the factors that influence the variable interindividual responses to carotenoid consumption and to establish more detailed dietary recommendations."

Conclusion

Carotenoid research from 2025 and 2026 has fundamentally expanded our understanding of these fascinating plant compounds. They are far more than simple antioxidants or vitamin A precursors – they are proving to be highly effective signaling molecules that intervene in our gene expression via complex networks and mediate a wide range of health effects.

In practical terms, this means that a varied, colorful diet rich in fruits and vegetables is the best strategy to benefit from the health-promoting effects of carotenoids. Combining them with high-quality fats improves absorption, and targeted supplementation can be beneficial for certain risk groups (older people, those with insufficient vegetable intake) – ideally in combination with other micronutrients such as omega-3 fatty acids, vitamins, and selenium, which have synergistic effects.

Sources

• Beydoun MA et al.: Association of Serum Vitamins and Carotenoids With Incident Alzheimer Disease (Neurology, 2022) – jem.at

• Vitamin A Derivatives and Adipose Tissue Differentiation (Curr Obes Rep, 2026) – PMC/NIH

• Bohn T et al.: State-of-the-art methodological investigation of carotenoid activity (Food and Function, 2023) – FAO/AGRIS

• DOG: A balanced diet can strengthen eyesight (Nutrition Review, 2024)

• Heinrich U: Nutritive Anti-Aging (Current Dermatology, Thieme, 2017)

• Night vision and carotenoids – Clinical study (ICHGCP, NCT04741763)

• Micronutrients for wet AMD – Orthomol Science News