Carotenoids in fruits and vegetables range in color from yellow to orange to red. Dark green vegetables contain carotenes, but the orange, yellow, or red color is masked by the green of chlorophyll. It is possible to divide fruits and vegetables into three categories based on their carotenoid content:

1. Green fruits and vegetables, such as green beans, lima beans, broccoli, Brussels sprouts, green cabbage, kale, kiwi fruit, lettuce, honeydew melon, green peas, and spinach contain lutein, alpha-carotene, beta-carotene, and zeaxanthin. Of these, lutein, alpha-carotene, betacarotene, and zeaxanthin are found in high concentrations in the blood, and lutein and zeaxanthin are found in the retina and macula of the eye.
2. Yellow/red fruits and vegetables, such as apricots, cantaloupe, carrots, pumpkin, and sweet potato are sources of alpha-carotene and beta-carotene, which are found in high concentrations in blood. Red fruits and vegetables such as pink grapefruit, tomatoes, and watermelon are sources of lycopene, zeta-carotene, beta-carotene, phytofluene, and phytoene, all of which are found in high concentrations in the blood.
3. Yellow/orange fruits and vegetables, such as mango, papaya, peaches, prunes, acorn squash, oranges, and other winter squashes contain lutein, zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin, alpha-carotene, beta-carotene, zeta-carotene, phytofluene, and phytoene, all of which are absorbed into the blood.

Beta-Carotene and Lutein/Zeaxanthin Content of Certain Foods

Absorption

Carotenoids are fat-soluble compounds. Therefore, when eating carotenoid-rich foods or taking carotenoid supplements, it is best to also eat some fat to maximize absorption. Also, cooking or grinding carotenoid-rich foods often increases the absorption of carotenoids.

Uses of Carotenoids for Health

Carotenoids, general

Serum levels of alpha-carotene, beta-carotene, beta-cryptoxanthin, and lutein/zeaxanthin were all inversely associated with impaired glucose metabolism—that is, the lower the carotenoids, the worse the glucose intolerance. Beta-carotene showed the greatest inverse relationship, becoming more extreme as glucose intolerance progressed to type 2 diabetes.²

Beta-carotene

Beta-carotene is a powerful antioxidant, protecting the cells of the body from damage caused by free radicals. It is also one of the carotenoids believed to enhance the function of the immune system. In addition to their antioxidant and immune-enhancing activity, carotenoids including beta-carotene have shown the ability to stimulate cell-to-cell communication. Researchers now believe that poor communication between cells may be one of the causes of the overgrowth of cells, a condition which eventually leads to cancer. It is also believed that beta-carotene may participate in female reproduction. Although its exact function in female reproduction has not yet been identified, it is known that the corpus luteum has the highest concentration of beta-carotene of any organ in the body, suggesting that this nutrient plays an important role in reproductive processes.³

Lycopene

Lycopene promotes healthy cell proliferation and cellular differentiation; however, lycopene seems to also require vitamin D to exert this effect. Lycopene also promotes proper cell-to-cell communication.

Lycopene can reduce circulating insulin-like growth factor-I (IGF-I), high levels of which are associated with high risk for cancer. In a placebo-controlled trial with colon cancer patients, dietary supplementation with a tomato lycopene extract significantly decreased plasma IGF-I.⁴

Lycopene can also inhibit progression of Benign Prostatic Hypertrophy (BPH). Supplements of 15 mg lycopene/day for 6 months given to elderly men with BPH decreased PSA (prostate specific antigen) levels and arrested further enlargement of the prostate, whereas for men receiving a placebo, there was no change in PSA levels, and prostate enlargement progressed.⁵

Lycopene was effective in treatment of gingivitis in a placebo-controlled trial. Subjects with clinical signs of gingivitis took either 8 mg lycopene/day or placebo for two weeks. The decrease in the gingivitis index was significantly greater for the lycopene-treated group than for the group taking placebo.⁶

Lutein/Zeaxanthin

Lutein and zeaxanthin are highly concentrated in the macula lutea, a spot of yellow pigment near the center of the retina of the human eye, which is responsible for clear, detailed, central vision. Age-related macular degeneration (AMD) is associated with low levels of lutein and zeaxanthin in the macula lutea. However, it is not known whether the low levels are a cause or an effect of AMD and whether raising the macular levels of lutein and zeaxanthin will prevent AMD.⁷ Higher dietary intake of lutein and zeaxanthin has been associated with a reduced likelihood of having neovascular (wet) AMD.⁸

Supplementation with lutein – 10 mg/day for 12 weeks and then 30 mg/day for 12 weeks – resulted in improved visual field in patients with retinitis pigmentosa, a family of conditions in which the rods and cones of the eye die. In this randomized, double-blind, placebo-controlled trial, the rate of loss of vision was reduced by lutein supplementation.⁹

Interestingly, scientists have discovered a link between high concentrations of lutein and zeaxanthin in the retina of the eye and improved cognitive function in older adults. In one study, older women taking 12 milligrams of lutein a day had improved verbal fluency scores, and when the lutein was combined with 800 milligrams of the omega-3 fatty acid docosahexaenoic acid (DHA), memory and rate of learning also significantly improved.¹⁰ This suggests the carotenoids, specifically lutein and zeaxanthin may play an important role in brain function.

Astaxanthin

Astaxanthin is produced by the microalgae Haematoccous pluvialis whenever its water supply dries up to protect itself from intense sunlight. It is found in the aquatic animals that consume this algae, including krill, shrimp, and wild salmon. In humans, astaxanthin seems to be particularly effective at protecting skin against photodamage (damage from UV light). A recent study found that astaxanthin “exhibited a pronounced photoprotective effect” on human skin cells exposed to moderate UVA radiation. The astaxanthin prevented cell death, reduced levels of reactive oxygen species (ROS) and other damaging free radicals, and protected cell membranes. The cells were treated with astaxanthin 24 hours before exposure to the UVA radiation.¹¹ Unlike most carotenoids, astaxanthin also has the ability to cross the blood-brain and blood-retinal barrier, allowing it to provide antioxidant protection to the brain and eyes. In a 2022 study, 60 healthy Japanese men and women who regularly performed computer work and experienced frequent eye fatigue were given 9 mg/day supplemental astaxanthin. At the end of six weeks, those 40 and older taking the astaxanthin had less visual acuity loss from prolonged screen time and experienced significantly less change in near-vision acuity (meaning objects further away were less blurry) than those taking the placebo.¹² In a 2022 study, 60 healthy Japanese men and women who regularly performed computer work and experienced frequent eye fatigue were given 9 mg/day supplemental astaxanthin. At the end of six weeks, those 40 and older taking the astaxanthin had less visual acuity loss from prolonged screen time and experienced significantly less change in near-vision acuity (meaning objects further away were less blurry) than those taking the placebo.¹³ Astaxanthin has also been shown to promote a healthy inflammatory response in the body.

References

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2. Coyne T, Ibiebele TI, Baade PD et al. Diabetes mellitus and serum carotenoids: findings of a population-based study in Queensland, Australia. American Journal of Clinical Nutrition 2005; 82(3): 685-693.
3. http://www.whfoods.com/genpage.php?tname=nutrient&dbid=125
4. Walfisch S, Walfisch Y et al. Tomato lycopene extract supplementation deceases insulin-like growth factor-I levels in colon cancer patients. European Journal of Cancer Prevention 2007; 16(4):298-303.
5. Schwarz S, Obermuller-Jevic UC et al. Lycopene inhibits disease progression in patients with benign prostate hyperplasia. Journal of Nutrition 2008; 138(1):49-53.
6. Chandra RV, Prabhuji ML et al. Efficacy of lycopene in the treatment of gingivitis: a randomized, placebocontrolled clinical trial. Oral Health Prev Dent 2007; 5(4):327-336.
7. Whitehead AJ, Mares JA et al. Macular pigment (review). Archives of Ophthalmology 2006; 124:1028-1045.
8. Age-Related Eye Disease Study Research Group. The relationship of dietary carotenoid and vitamin A, E, and C intake with age-related macular degeneration in a case-control study: AREDS Report No. 22. Archives of Ophthalmology 2007; 125(9):1225-1232.
9. Bahrami H, Melia M et al. Lutein supplementation in retinitis pigmentosa: PC-based vision assessment in a randomized double-masked placebo-controlled clinical trial [NCT00029289]. BMC Ophthalmology 2006; 6:23.
10. Johnson EJ. A possible role for lutein and zeaxanthin in cognitive function in the elderly. Am J Clin Nutr. 2012;26(supp1):1161S-1165S
11. Camera E, Matrofrancesco A, Fabbri C, Daubrawa F, Picardo M, Sies H, Stahl W. Astaxanthin, Canthaxanthin and Beta-carotene Differently Affect UVA-induced Oxidative Damage and Expression of Oxidative Stressresponsive Enzymes. Exp Dermatol 2008 (Sep 18).
12. Sekikawa T, Kizawa Y, Li Y, and Miura N. “Effects of diet containing astaxanthin on visual function in healthy individuals: a randomized, double-blind, placebo-controlled, parallel study.” J. Clin. Biochem. Nutr. 18 October 2022 doi: 10.3164/jcbn.22-65
13. Sekikawa T, Kizawa Y, Li Y, and Miura N. “Effects of diet containing astaxanthin on visual function in healthy individuals: a randomized, double-blind, placebo-controlled, parallel study.” J. Clin. Biochem. Nutr. 18 October 2022 doi: 10.3164/jcbn.22-65