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Carotenoids

Carotenoids featured article

Carotenoids are orange/yellow pigments in various foods, such as carrots, pumpkins, avocados, and salmon. While carotenoids are a highly diverse group of organic pigments, with over 1,100 known carotenoids , this overview will focus on lutein and zeaxanthin, which are of particular interest due to their notable roles in eye and brain health.

Carotenoids are one of the most common classes of bioactive compounds found in plants, along with alkaloids (e.g., berberine), organosulfur compounds (e.g., sulforaphane), and polyphenols (e.g., anthocyanins). Carotenoid molecules are long chains of carbon atoms connected via double bonds. Because of this unique electron structure, carotenoids can donate multiple electrons to free radicals, quenching oxidative stress.

Carotenoids are antioxidants that specialize in photoprotection.

Yellow and orange carotenoids absorb light in the high-frequency blue/violet range, making them particularly well-suited for protecting the body from...

Episodes

Posted on January 15th 2024 (over 1 year)

Dr. Rhonda Patrick explores iodine supplementation, choline & TMAO, curcumin safety, and red yeast rice in her latest Q&A.

Posted on April 3rd 2022 (about 3 years)

In this clip, Bruce Ames explains that two carotenoids in the eye, lutein and zeaxanthin, are able to mitigate the harmful effects of singlet oxygen produced by sunlight.

Topic Pages

  • Carotenoids

    Carotenoids, isoprenoid pigments, absorb blue-green photons, dissipate excess excitation energy, and scavenge singlet oxygen within photosystems.

News & Publications

  • Tomatoes are a rich source of lycopene, a powerful antioxidant that may help protect against cancer and cancer-related death. A recent study found that people with the highest blood levels of lycopene were 11% less likely to develop cancer and 24% less likely to die from it than those with the lowest levels.

    Researchers analyzed data from 121 prospective studies involving more than 100,000 people with cancer and more than 10,000 cancer-related deaths. They focused on studies that reported tomato intake, lycopene levels in the blood, or dietary lycopene consumption and how those related to cancer risk and death.

    Compared with people who had the lowest lycopene levels, those with the highest had an 11% lower risk of developing cancer. High tomato and lycopene intake were each linked to a 5% lower cancer risk. When looking at cancer deaths, people who consumed the most tomatoes were 16% less likely to die from cancer, and those who consumed the most lycopene were 24% less likely. Higher blood levels of lycopene also lowered the risk of dying from lung cancer (the leading cause of cancer deaths) by 35%. In addition, a modest increase in blood lycopene—about 10 micrograms per deciliter—was tied to a 5% drop in overall cancer risk.

    These findings suggest that a diet rich in tomatoes and other lycopene-containing foods could offer modest protection against cancer and may even reduce the risk of dying from it. Lycopene is a carotenoid compound found in tomatoes and watermelon. Learn more about lycopene and other carotenoids in our overview article.

  • Fatigue is a common condition characterized by persistent tiredness or exhaustion that can affect daily activities. Inflammation is critical in fatigue because it disrupts normal cellular function and energy production. A recent review and meta-analysis found that astaxanthin, a potent antioxidant and anti-inflammatory carotenoid compound, reduces fatigue.

    Researchers analyzed the findings of studies investigating the effects of astaxanthin supplementation on fatigue, cognition, and exercise efficiency. The analysis included 11 randomized controlled trials involving 346 healthy participants. Four of the studies included amateur or professional athletes.

    The researchers found that supplementing with astaxanthin for eight to 12 weeks improved cognition slightly but did not improve reaction time. However, when combined with exercise, astaxanthin enhanced fat oxidation and improved physical performance. Further analysis revealed that the benefits of astaxanthin were more pronounced with aerobic exercise but were dose-dependent, with doses of 20 milligrams or more and supplementation for longer than 12 weeks providing the greatest benefit.

    These findings suggest that astaxanthin reduces fatigue and improves aspects of performance. Astaxanthin is widely available as a dietary supplement but is also present in salmon and salmon roe. Learn more about salmon roe in our overview article.

  • Higher blood levels of antioxidant compounds called carotenoids may lower a person’s risk of having high blood pressure, a 2022 study found. The greatest risk-lowering benefit was seen with the carotenoid compound beta-carotene, which cut the risk of having high blood pressure in half.

    The study involved more than 11,000 adults enrolled in NHANES, an ongoing assessment of the health and nutritional status of people living in the United States. Researchers measured the levels of six carotenoids (alpha-carotene, beta-cryptoxanthin, lutein/zeaxanthin, trans-lycopene, trans-beta-carotene, and cis-beta-carotene) in the participants' blood and took their blood pressures.

    They found that having higher levels of all six of the carotenoids markedly reduced the risk of having high blood pressure. However, trans-beta carotene reduced the risk by 50 percent, and cis-beta-carotene reduced the risk by 53 percent.

    Carotenoids are antioxidant compounds naturally present in many red, yellow, or orange fruits and vegetables. Beta carotene is found in carrots, sweet potatoes, and winter squash. Epidemiological data suggest that consumption of carotenoid-rich foods reduces the risk of many diseases, including type 2 diabetes, macular degeneration, and prostate cancer.

  • Omega-3 fatty acids, folic acid, and CoQ10 reduce the risk of cardiovascular disease.

    Some nutritional components benefit cardiovascular health, but others have no effect on cardiovascular health or may even harm it, according to a recent study. Nutritional components providing the greatest benefit include omega-3 fatty acids, folic acid, and coenzyme Q10 (CoQ10), a vitamin-like compound produced in the body.

    Researchers analyzed the findings of more than 880 trials involving more than 880,000 participants that investigated the benefits of various macronutrients, micronutrients, and bioactive compounds on cardiovascular health.

    They found that the nutritional components had varied effects on cardiovascular health. For example, while omega-3 fatty acids, folic acid, and CoQ10 reduced the risk of cardiovascular disease, selenium and vitamins C, D, and E had no effect on the risk for either cardiovascular disease or type 2 diabetes (which often coincides with cardiovascular disease). On the other hand, beta-carotene (a vitamin A precursor) increased the risk of death from all causes. The researchers did not investigate the effects of the various nutritional components in combination versus alone.

    This analysis demonstrates that nutrition plays important roles in maintaining cardiovascular and metabolic health and supports the findings of large, epidemiological studies that have demonstrated that adherence to dietary patterns that are rich in omega-3 fatty acids, folic acid, and CoQ10, such as the Mediterranean Diet, for example, improves cardiometabolic health.

  • From the article:

    The researchers, including Barbara Kahn and Timothy Graham of Harvard Medical School and Matthias Blüher of the University of Leipzig in Germany, showed that “retinol-binding protein 4” (RBP4) is produced in much greater amounts by visceral fat compared to the subcutaneous fat that lies just beneath the skin. Moreover, they report that blood serum levels of RBP4 jump in people who are obese, who have double or even triple the concentrations found in individuals of normal weight.

    […]

    The only known function of RBP4 was to carry vitamin A (also known as retinol) in the blood, Kahn said.

    Large gene expression changes in visceral fat:

    n a study of 196 people, the researchers now reveal that RBP4 is indeed preferentially produced in the deep fat that covers organs of the belly. RBP4 gene expression activity levels spiked about 60-fold in the visceral fat of viscerally obese relative to lean study participants, they found. By comparison, visceral fat RBP4 concentrations were increased just 12-fold in obese individuals with a preponderance of subcutaneous fat.

  • “Pregnancy and lactation can change the maternal nutrient reserve. We evaluated the association of macular pigment optical density (MPOD) with dietary and breastmilk carotenoids in postpartum women.

    MPOD measurements and dietary intake of five carotenoids were obtained from 80 mothers in the first three months postpartum. Breastmilk samples from a subset of mothers were analyzed to determine their nutrient composition. The association between MPOD and dietary or breastmilk carotenoids was quantitatively assessed to better understand the availability and mobilization of carotenoids.

    Our results showed that dietary α-carotene was positively correlated with MPOD. Of the breastmilk carotenoids, 13-cis-lutein and trans-lutein were correlated with MPOD when controlled for the total lutein in breastmilk. Other carotenoids in breastmilk were not associated with MPOD. Maternal MPOD is positively correlated with dietary intake of α-carotene in the early postpartum period, as well as with the breastmilk content of lutein."

  • Cognitive function, including complex executive functions like working memory and basic functions like sensory processing, progressively declines with age. While executive function loss is highly variable and easily measurable in older adult populations, younger adults usually perform at a level consistent with their peers, which makes studying cognitive decline in younger adults difficult. In a 2014 report, researchers measured visual processing ability in young adults before and after supplementation with lutein and zeaxanthin.

    Visual processing refers to the brain’s ability to utilize and interpret visual information. Because visual processing utilizes similar brain architecture as more complex tasks such as working memory, it is a useful measure in assessing brain health and cognitive decline.

    Lutein and zeaxanthin are carotenoid pigments found in foods that accumulate in the retina and throughout the brain and perform light-absorbing, antioxidant, and anti-inflammatory functions. Animal research has demonstrated that the density of these pigments in the eye is a good indicator of their density in the brain, providing researchers a non-invasive means to measure the relationship between pigmentation and cognitive function. Higher pigment density in the eye[has been associated with better cognitive performance and visual processing speed in older adults with or without cognitive decline.

    Researchers measured the baseline visual processing speed and retinal concentration of lutein and zeaxanthin in healthy young adults (average age, 22 years). They assigned participants to consume either placebo, zeaxanthin only (20 milligrams), or a combination of zeaxanthin (26 milligrams), lutein (8 milligrams), and mixed omega-3 fatty acids (190 milligrams) per day for four months. They measured retina pigmentation and visual processing speed again following the intervention.

    The authors reported a moderate, yet statistically significant, relationship between baseline retinal pigment levels and visual processing speed. Following the intervention, both supplement groups demonstrated a significant increase in retinal pigmentation compared to placebo. Finally, participants in the supplement groups also performed 12 percent better on the critical flicker fusion test and decreased visual motor reaction time by 10 percent, two measures of visual processing.

    The authors conclude that lutein and zeaxanthin supplementation may be an effective way to increase visual processing speed, even in young healthy adults.

    Link to full study.

  • Carotenoids are red, yellow, and orange pigments found in fruits and vegetables that exert antioxidant, anti-inflammatory, and anticancer properties. Lycopene (which is found in tomatoes and watermelon) and lutein (which is found in green leafy vegetables) are among the most abundant carotenoids in the human diet. Findings from a recent study suggest that consuming vegetables that are high in lycopene and lutein can help reduce visceral fat in obese men.

    Visceral fat is body fat that is stored in the abdominal cavity close to internal organs such as the liver, pancreas, and intestines. In contrast to subcutaneous fat, which is located under the skin, visceral fat plays a central role in the interrelationship between obesity and systemic inflammation through its secretion of proinflammatory cytokines. The accumulation of visceral fat is linked to type 2 diabetes, insulin resistance, inflammatory diseases, certain types of cancer, cardiovascular disease, and other obesity-related diseases.

    The randomized, double-blinded, controlled clinical trial involved 28 men between the ages of 40 and 65 years who were overweight or obese. The authors of the eight-week study randomly assigned the participants to consume a beverage containing one of four edible pastes that contained high lycopene/high lutein; high lycopene/low lutein; low lycopene/high lutein; or low lycopene/low lutein. The authors measured the levels of carotenoids in the participants' plasma.

    The participants' carotenoid levels increased in every group and they experienced no adverse effects. Their visceral fat levels decreased for all groups, too, but waist circumference decreased only for the men in the high lycopene/low lutein group.

    These findings suggest that high carotenoid intake can help with weight loss. They also support epidemiological data indicating that vegetable intake can play a positive role in modulating body weight. For a tasty way to include more carotenoids in your diet, check out this video in which Dr. Rhonda Patrick shows how to make her carotenoid-rich smoothie.

  • A new study by my mentor Dr. Bruce Ames proposes that 10 known compounds be classified as potential longevity vitamins due to their interaction with proteins that protect against diseases of aging. The concept is based on the Triage Theory, which classifies proteins and enzymes as either survival proteins, needed for survival and reproduction, or longevity proteins, which protect against future damage and are sacrificed in case of vitamin shortage, leading to an acceleration of insidious diseases of aging.

    These putative “longevity vitamins” include: ergothioneine (a fungal antioxidant found in mushrooms), queuine (a bacterial metabolite found in the gut), PQQ (a bacterial metabolite in soil that is taken up by plants ), lutein and zeaxanthin (concentrated in leafy greens), lycopene (found in tomatoes), alpha- and beta-carotene, and cryptoxanthin (all plant antioxidant carotenoids), astaxanthin (a marine carotenoid found in salmon and krill), and taurine (found in meat).