What Are Carotenoids and Why Do They Matter?

If you've ever sliced into a bright orange carrot, admired the deep red of a ripe tomato, or noticed the rich green color of spinach, you've seen carotenoids at work.

These naturally occurring pigments help plants survive and have become one of the most extensively studied groups of phytochemicals in nutrition science.

Researchers have spent decades investigating how carotenoids are absorbed, stored, and used throughout the body, and more recently, how they can even serve as objective markers of fruit and vegetable intake. 

What Are Carotenoids? 

Carotenoids are a family of naturally occurring pigments synthesized by plants, algae, and certain bacteria and fungi. More than 600 carotenoids have been identified in nature, although only around 40 are regularly consumed in the human diet, and an even smaller number are commonly found in human blood and tissues. 

Some of the best-known carotenoids include: 

• Beta-carotene: found in carrots, sweet potatoes, pumpkin 
• Alpha-carotene: found in carrots, winter squash  
• Lycopene: found in tomatoes, watermelon, pink grapefruit  
• Lutein: found in spinach, kale, peas  
• Zeaxanthin: found in corn, orange peppers, leafy greens 
• Beta-cryptoxanthin: found in papaya, oranges, tangerines

These compounds belong to a broader group of plant chemicals known as phytochemicals: naturally occurring substances that plants produce to help them grow, reproduce, and respond to their environment.

Unlike vitamins or minerals, phytochemicals aren't considered essential nutrients because humans don't develop a classic deficiency disease without them. Yet growing evidence suggests they play important roles in supporting normal health, which is one reason they've become such an active area of nutrition research.  

Why Do Plants Produce Carotenoids? 

One of the most fascinating things about carotenoids is that plants didn't evolve them for our benefit.

Plants make carotenoids because they need them to survive.

Inside plant cells, carotenoids work alongside chlorophyll during photosynthesis, the process that converts sunlight into chemical energy.

While chlorophyll captures much of the sunlight plants need, too much light can actually become damaging. Excess energy can generate highly reactive oxygen molecules capable of damaging plant cells.

Carotenoids act as part of the plant's built-in defense system. They help dissipate excess light energy before it can cause damage and neutralize reactive oxygen species that form during photosynthesis. Without carotenoids, plants would be far more vulnerable to light-induced oxidative stress. 

Carotenoids also give many fruits and flowers their vivid colors, helping attract pollinators and animals that disperse seeds—an evolutionary advantage that helps plants reproduce.  

Image source: Stanescu et al., Nutrients (2025).

What Happens When We Eat Carotenoids? 

Unlike water-soluble nutrients, carotenoids are fat-soluble, meaning they're absorbed alongside dietary fat during digestion. After a meal, they're incorporated into microscopic particles called chylomicrons, which transport fats and fat-soluble compounds from the small intestine into the lymphatic system and eventually the bloodstream. From there, carotenoids are delivered throughout the body and can accumulate in tissues such as the liver, adipose tissue (body fat), skin, and eyes. 

Not all carotenoids behave the same way once they're absorbed.

Some, including beta-carotene, alpha-carotene, and beta-cryptoxanthin, are known as provitamin A carotenoids. The body can convert these compounds into vitamin A as needed, although the efficiency of that conversion varies considerably from person to person and depends on factors such as genetics, food preparation, and the structure of the food itself.

Other carotenoids, including lycopene, lutein, and zeaxanthin, cannot be converted into vitamin A. Instead, they circulate and accumulate in tissues in their original form, where researchers continue to investigate their physiological roles. Lutein and zeaxanthin, for example, are found in especially high concentrations in the retina, while carotenoids as a group are also deposited in the skin.   

How Do Scientists Measure Carotenoids? 

Studying nutrition is notoriously difficult.

Most nutrition studies rely on food-frequency questionnaires or diet recalls, asking participants to remember what they ate over the previous day, week, or even year. As you might imagine, memory isn't perfect, and people often overestimate or underestimate how many fruits and vegetables they actually eat.

Researchers have spent years looking for more objective ways to measure dietary intake.

Carotenoids have become one of the most promising tools.

Because these compounds accumulate in the blood and skin after they're absorbed, scientists can measure them directly using noninvasive optical devices. Two of the most common techniques are resonance Raman spectroscopy and reflection spectroscopy, which use light to estimate the concentration of carotenoids in the skin, no needles required. 

Over the past decade, numerous validation studies have shown that skin carotenoid measurements correlate well with fruit and vegetable intake. In fact, many researchers now consider skin carotenoid status to be one of the most useful objective biomarkers of habitual fruit and vegetable consumption because it avoids many of the limitations of self-reported diet records. 

That doesn't mean a skin scan can tell you exactly how many carrots you ate last Tuesday.

It does mean that, over time, people who consistently eat more carotenoid-rich fruits and vegetables tend to have higher carotenoid levels in their skin. 

Can Eating More Colorful Foods Actually Change Your Skin? 

This is one of the most talked-about areas of carotenoid research, and one of the most misunderstood.

Several controlled studies have asked participants to increase their intake of carotenoid-rich fruits and vegetables over a period of weeks. Rather than relying on photographs or subjective observations, researchers measured changes in skin carotenoid levels and skin color using specialized instruments.

Across multiple studies, participants who consumed more carotenoid-rich foods developed measurable increases in skin carotenoid concentrations. In several interventions, these changes were detectable after approximately four to six weeks of consistent dietary changes. 

Some studies also found subtle increases in skin yellowness, a change caused by carotenoid deposition rather than sun exposure. In separate experiments, observers often rated faces with higher carotenoid coloration as appearing healthier than those without those changes.

It's important to keep these findings in perspective.

The goal of these studies wasn't to create cosmetic advice, nor do they suggest that eating carrots will dramatically change the way you look.

Instead, they demonstrate something much more fundamental:

The foods we eat can create measurable changes within our bodies. 

Beyond Skin: Why Do Carotenoids Matter? 

The skin color studies have captured public attention, but they're only one small part of a much larger body of research.

Scientists have been studying carotenoids for decades because of the many roles they play in both plants and humans. While research continues to evolve, several functions are already well established. 

Some Carotenoids Help Us Meet Our Vitamin A Needs 

Three carotenoids found in food, beta-carotene, alpha-carotene, and beta-cryptoxanthin, are known as provitamin A carotenoids because the body can convert them into vitamin A when needed. Vitamin A is an essential nutrient that supports normal vision, immune function, reproduction, and the growth and maintenance of healthy cells. 

It's important to note that the body regulates this conversion. Unlike preformed vitamin A found in animal foods and supplements, beta-carotene from whole plant foods isn't converted indiscriminately. Instead, the body adjusts conversion based on its needs, making carotenoid-rich foods a safe and effective way to obtain vitamin A for most healthy individuals.  

Others Accumulate in Specialized Tissues 

Lutein and zeaxanthin, for example, accumulate in the macula of the eye, the central region of the retina responsible for sharp, detailed vision. Because of this unique distribution, these carotenoids have been the subject of extensive research in vision science and healthy aging. 

Researchers are also studying carotenoids found in the skin, brain, and other tissues to better understand their biological functions. While much remains to be learned, one thing is clear: different carotenoids are distributed throughout the body in different ways, suggesting they may each play distinct physiological roles.  

More Than Antioxidants 

Carotenoids are often described as antioxidants, and that's true, but it's only part of the story.

In plants, carotenoids help protect cells from damage caused by excess light during photosynthesis. In humans, laboratory and experimental research shows they can interact with reactive oxygen species and other cellular signaling pathways. Scientists continue to investigate how these properties contribute to human health, but it's important not to assume that antioxidant activity observed in the laboratory automatically translates into specific health effects in people. 

This is a common theme in nutrition science: promising biological mechanisms are an important starting point, but they must ultimately be supported by well-designed human studies. 

Getting More Carotenoids in Your Diet 

The good news is that you don't need to memorize the names of individual carotenoids or worry about calculating how much you're eating.

If you regularly include a variety of colorful fruits and vegetables in your meals, you're already doing most of the work.

Different colors tend to provide different carotenoids. Orange vegetables like carrots, sweet potatoes, pumpkin, and butternut squash are especially rich in beta-carotene. Tomatoes and watermelon are excellent sources of lycopene, while dark leafy greens such as spinach, kale, and Swiss chard provide lutein and zeaxanthin. Fruits like mangoes, papaya, apricots, and oranges contribute additional carotenoids, including beta-cryptoxanthin.

There are also a few simple ways to help your body absorb these compounds.

Because carotenoids are fat-soluble, they're best absorbed when eaten with a source of fat. That doesn't mean you need large amounts. A handful of walnuts, pumpkin seeds, avocado, or a meal containing other naturally occurring fats can all support absorption.

Researchers have also found that gently cooking certain vegetables, particularly tomatoes and carrots, can make some carotenoids more available by breaking down the plant's cell walls. That means both raw and cooked vegetables have an important place in a healthy diet. 

The Bigger Picture 

Carotenoids are only one family within the thousands of phytochemicals found in plant foods.

They aren't magic compounds, and they certainly aren't the only reason fruits and vegetables are good for us. Whole plant foods also provide fiber, vitamins, minerals, polyphenols, and countless other naturally occurring compounds that scientists are still working to understand.

But carotenoids offer something unique: they're visible.

Every bright orange carrot, deep red tomato, golden mango, and dark green handful of spinach is a reminder that plants contain remarkable compounds shaped by millions of years of evolution. By eating a variety of colorful plant foods, we benefit from that incredible biological diversity.

That's one of the reasons we created the Plant Strong Glow Challenge.

Not because we're chasing perfect skin.

Not because we believe one nutrient is the secret to health.

But because the science consistently points in the same direction: eating a wider variety of colorful fruits and vegetables is a simple, practical way to improve diet quality and expose your body to an incredible diversity of beneficial plant compounds.

So the next time you build your plate, don't worry about making it perfect.

Start by adding a little more color.