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September 1, 2026
Lena Sämann
Beta-carotene supports vision, skin, and immune function. A recent study shows that preparation can make a surprising difference to how well the body absorbs it.
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Carrots have long been held up as the gold standard of healthy eating, not least because of their high beta-carotene content. Yet with this particular plant compound, what ends up on the plate is only part of the story. Whether vegetables are eaten raw, cooked, or processed can make a significant difference to how much beta-carotene the body actually absorbs. And while beta-carotene from vegetables supports vitamin A intake, high-dose supplements can actually pose a risk for certain people.
Beta-carotene belongs to the carotenoid family — natural plant pigments that give many fruits and vegetables their yellow, orange, or red color. Dark green vegetables can also contain large amounts of carotenoids; in those cases, the color is simply masked by chlorophyll.
From a health perspective, beta-carotene is of particular interest as a precursor to vitamin A, which is why it is also known as provitamin A. The body converts beta-carotene into vitamin A as needed. Vitamin A is essential, among other things, for normal vision, a healthy immune system, and for skin and mucous membranes. The German Nutrition Society (DGE) summarizes the functions of vitamin A and beta-carotene here.
Beta-carotene also has antioxidant properties and can interact with reactive oxygen species. However, this does not mean that a particularly high intake automatically offers better protection against disease. Research shows that, especially with high-dose beta-carotene supplements, more is by no means always better.
The idea that carrots are "good for the eyes" is one of the most familiar nutritional beliefs around. It is not entirely wrong — but it is often overstated.
The connection runs primarily through vitamin A. One form of the vitamin is a component of the visual pigment rhodopsin in the retina, making it essential for the ability to see in dim light. A severe vitamin A deficiency can, among other things, lead to night blindness.
That said, people who are already adequately supplied with vitamin A will not improve their eyesight further simply by eating large quantities of carrots.
Research into age-related macular degeneration (AMD) is also relevant here. In the large AREDS2 study by the US National Eye Institute, beta-carotene in the original AREDS nutrient combination was replaced, among other things, by lutein and zeaxanthin. The efficacy of the formulation was not diminished; at the same time, former smokers who took the beta-carotene-containing formulation showed a higher incidence of lung cancer.
When it comes to eye health, then, the blanket claim that "lots of beta-carotene protects the eyes" is an oversimplification.
Vitamin A is also essential for skin and mucous membranes, which serve as key barriers between the body and its environment — including pathogens. Vitamin A also plays a role in the normal functioning of the immune system.
Carotenoids themselves can accumulate in the skin. People who consume large amounts of carotenoid-rich foods over an extended period may develop a slightly yellowish-golden skin tone. This condition, known as carotenemia, tends to be most noticeable on the palms and soles of the feet. At high intakes from food, it is generally harmless.
Researchers have also investigated whether beta-carotene can make the skin more resistant to UV radiation. A meta-analysis of seven intervention studies found evidence that longer-term beta-carotene supplementation may reduce sensitivity to sun-induced skin redness. However, the effect only appeared after at least ten weeks.
Beta-carotene should therefore not be thought of as "internal sun protection." Any effect it may have is not comparable to the protection offered by sunscreen, clothing, and avoiding intense UV exposure.
This is where the research becomes particularly thought-provoking. Observational studies had suggested early on that a carotenoid-rich diet might be associated with a lower risk of certain diseases, raising hopes that isolated beta-carotene could offer similar protection.
Large intervention studies, however, could not confirm these expectations. In the Physicians' Health Study, which involved more than 22,000 men, long-term beta-carotene intake showed neither a meaningful benefit nor harm with regard to cancer, cardiovascular disease, or overall mortality.
This does not mean that beta-carotene-rich foods have no health value. People who eat plenty of carrots, green leafy vegetables, peppers, and other plant-based foods are also taking in fiber, vitamins, minerals, and a wide range of other plant compounds at the same time.
This points to an important lesson for nutrition: the health benefits of a vegetable-rich diet cannot simply be attributed to any single isolated plant compound.
Carrots are probably the best-known source — after all, carotene takes its name from them. Sweet potatoes, pumpkin, kale, and spinach are also rich in beta-carotene. Red peppers, apricots, mango, and certain varieties of melon contribute to intake as well.
However, the beta-carotene content listed on paper tells only part of the story. What also matters is how much is actually released from food during digestion and subsequently absorbed into the bloodstream.
And this is where preparation comes into play.
Just how large the difference can be is illustrated by a study published in 2025 in the journal "Nutrition Research and Practice". In this randomized crossover study, 16 healthy adults each received 25 milligrams of beta-carotene — once from raw carrots and once from freshly pressed carrot juice.
The researchers then measured blood beta-carotene concentrations over 24 hours. After consuming carrot juice, the peak beta-carotene level was 2.33 times higher than after eating raw carrots. Total absorption measured over the study period was also approximately twice as high with the juice.
The researchers attribute the difference in part to the fact that juicing breaks down the plant's cell structures, making beta-carotene easier to release during digestion.
That said, the study was small, involving only 16 young, healthy participants, and it looked only at short-term absorption following a single meal. It therefore does not demonstrate that carrot juice is inherently healthier than a whole raw carrot.
Juicing is not the only preparation method that affects beta-carotene availability. Chopping and heating can also break down plant cell structures, making carotenoids more accessible to the body.
This may seem to contradict the common belief that vegetables are always at their most nutritious when eaten raw. In fact, it depends on the specific nutrient: while certain heat-sensitive vitamins can be partially lost during cooking, the availability of beta-carotene can actually increase through processing.
Fat is another important factor. Beta-carotene is fat-soluble. The DGE therefore recommends eating provitamin A-containing plant foods alongside a small amount of fat, citing a teaspoon of oil as an example.
In practice, this is easy to achieve: a drizzle of olive or rapeseed oil over cooked vegetables, a handful of nuts or seeds in a salad, or any other fat source as part of the same meal will do the job.
For anyone looking to get the most out of beta-carotene, three simple principles are worth keeping in mind: chop, heat where appropriate, and combine with a little fat.
The DGE does not set a separate reference value for beta-carotene. Recommendations instead refer to vitamin A and are expressed as retinol activity equivalents (RAE).
For adult women, the DGE recommends 700 micrograms RAE of vitamin A per day, and 850 micrograms for men between the ages of 19 and 65. One microgram RAE corresponds to twelve micrograms of beta-carotene from food.
A varied diet that includes plenty of vegetables can make a substantial contribution to meeting these levels. Targeted supplementation is not normally necessary for healthy people who eat a balanced diet.
Beta-carotene offers one of the clearest examples of why a nutrient must be assessed differently depending on whether it comes from food or from high-dose dietary supplements.
In the large ATBC study, which involved more than 29,000 male smokers, participants received, among other things, 20 milligrams of beta-carotene daily. Contrary to expectations at the time, lung cancer occurred more frequently in the beta-carotene group.
A similar warning signal emerged from the CARET study, which involved more than 18,000 smokers, former smokers, and people with occupational asbestos exposure. Participants in the intervention group received a combination of 30 milligrams of beta-carotene and vitamin A. The risk of lung cancer in this group was 28 percent higher than in the placebo group, and the study was terminated early.
For smokers and certain at-risk groups, high-dose beta-carotene supplements are therefore not without risk. This concern, however, does not apply to beta-carotene obtained from food.
Beta-carotene serves important functions in the body, primarily as a precursor to vitamin A — supporting eye health, skin and mucous membrane integrity, and immune function. However, the health benefits associated with beta-carotene-rich foods cannot simply be transferred to high-dose dietary supplements.
There is also something else that makes this plant compound particularly interesting: how much of it actually reaches the body depends strongly on how it is prepared. The recent carrot study demonstrates that significantly more beta-carotene can be absorbed from processed vegetables than from raw ones. With beta-carotene, then, it is not only what is on the plate that matters — but also how it got there.
