carotenoids

Foods Richest in carotenoids

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About carotenoids

Description

What are carotenoids?

Carotenoids represent one of the most widespread groups of naturally occurring pigments. These compounds are largely responsible for the red, yellow, and orange color of fruits and vegetables, and are also found in many dark green vegetables. The most abundant carotenoids in the North American diet are beta-carotene, alpha-carotene, gamma-carotene, lycopene, lutein, beta-crpytoxanthin, zeaxanthin, and astaxanthin.

How it functions

What are the functions of carotenoids?

Preventing vitamin A deficiency

Until late in the 20th Century, the functions of carotenoids were discussed only in terms of their potential vitamin A activity. Certain members of the carotenoid family, approximately 50 carotenoids of the known 600, are called “provitamin A” compounds because the body can convert them into retinol, an active form of vitamin A.

As a result, foods that contain carotenoids can help prevent vitamin A deficiency. The most commonly consumed provitamin A carotenoids are beta-carotene, alpha-carotene, and beta-cryptoxanthin, but gamma-carotene and beta-zeacarotene also have provitamin A activity.

Antioxidant & immune-enhancing activity

In recent years, carotenoids have received a tremendous amount of attention as potential anti-cancer and anti-aging compounds. Carotenoids quench singlet oxygen and scavenge peroxyl radicals, protecting cell membranes from oxidative damage. Beta-carotene in particular is associated with modulation of immune cell function, including T-lymphocyte proliferation.

Promoting proper cell communication

Carotenoids stimulate gap junctional intercellular communication (GJIC) between cells. Impaired GJIC is associated with uncontrolled cell proliferation, a hallmark of carcinogenesis. By upregulating connexin proteins that form gap junctions, carotenoids may help maintain normal growth regulation.

Carotenoids appear to participate in female reproduction. The corpus luteum has the highest beta-carotene concentration of any organ in the body, suggesting a functional requirement, though the specific mechanism remains uncharacterized.

Deficiency symptoms

What are deficiency symptoms for carotenoids?

Low dietary intake of carotenoids is not known to directly cause disease in the short term. When vitamin A intake is simultaneously low, deficiency of provitamin A carotenoids (beta-carotene, alpha-carotene, and beta-cryptoxanthin) can produce symptoms of vitamin A deficiency.

Long-term inadequate carotenoid intake is associated with increased incidence of cardiovascular disease and certain cancers. Diets low in carotenoids reduce the body’s capacity to quench reactive oxygen species, leaving cell membranes more vulnerable to lipid peroxidation. Over decades, this diminished antioxidant defense may accelerate chronic disease processes.

Many adolescents and young adults consume insufficient carotenoids due to low fruit and vegetable intake. Cigarette smokers and regular alcohol drinkers tend to have lower serum carotenoid levels. This reflects both reduced consumption of carotenoid-containing foods and probable accelerated carotenoid degradation by cigarette smoke. Carotenoid supplementation in smokers warrants caution (see Toxicity section).

Toxicity symptoms

What are toxicity symptoms for carotenes?

A tell-tale sign of excessive consumption of beta-carotene is a yellowish discoloration of the skin, most often occurring in the palms of the hands and soles of the feet. This condition is called carotenodermia, and is reversible and harmless. Excessive consumption of lycopene can cause a deep orange discoloration of the skin. Like carotenodermia, lycopenodermia is harmless.

High intake of carotenoid-containing foods or supplements is not associated with any toxic side effects. As a result, the Institute of Medicine at the National Academy of Sciences did not establish a Tolerable Upper Intake Level (UL) for carotenoids when it reviewed these compounds in 2000.

However, the results of two research studies indicate that those who smoke heavily and drink alcohol regularly, may increase their chance of developing lung cancer and/or heart disease if they take beta-carotene supplements in amounts greater than 20-30 milligrams per day.

Impact of cooking, storage and processing

How do cooking, storage, or processing affect carotenoids?

In certain cases, cooking can improve the availability of carotenoids in foods. For example, the availability of lycopene from tomato products is increased when the foods are processed at high temperatures. As a result, your body absorbs the lycopene in canned, pasteurized tomato juice more easily than the lycopene in a fresh tomato. Lightly steaming carrots and spinach disrupts cell walls, improving intestinal carotenoid absorption.

Prolonged cooking, however, decreases carotenoid bioavailability by isomerizing the molecule from its natural all-trans configuration to less bioavailable cis forms. Fresh carrots contain 100% all-trans beta-carotene; canned carrots retain only about 73% in the all-trans form.

Factors that affect function

What factors might contribute to a deficiency of carotenoids?

Carotenoids are fat-soluble and require dietary fat for absorption through the digestive tract. Carotenoid status may be impaired by extremely low-fat diets or by conditions that reduce fat absorption: pancreatic enzyme deficiency, Crohn’s disease, celiac sprue, cystic fibrosis, partial or total gastrectomy, gall bladder disease, and liver disease.

Nutrient interactions

How do other nutrients interact with carotenoids?

Beta-carotene supplements reduce blood levels of lutein, suggesting that carotenoids may compete with each other for absorption.

Pectin supplementation may decrease carotenoid absorption.

Health conditions

Food sources

What foods provide carotenoids?

The orange-colored fruits and vegetables including carrots, apricots, mangoes, squash, papaya, and sweet potatoes contain significant amounts of beta-carotene, alpha-carotene, and beta-cryptoxanthin.

Green vegetables, especially spinach, kale, and collard greens, also contain beta-carotene, and are the best sources of lutein.

Lycopene is found in tomatoes, guava, and pink grapefruit. Salmon, shellfish, milk, and egg yolks also provide carotenoids.

Spices contribute measurable carotenoids to the U.S. diet, with cayenne pepper and chili pepper being particularly concentrated sources.

 

Food Source Analysis not Available for this Nutrient

Public health recommendations

What are current public health recommendations for carotenoids?

To date, no recommended dietary intake levels have been established for carotenoids. In an effort to set such recommendations, the Institute of Medicine at the National Academy of Sciences reviewed the existing scientific research on carotenoids in 2000.

Despite the large body of population-based research that links high consumption of foods containing beta-carotene and other carotenoids with a reduced risk of several chronic diseases, the Institute of Medicine concluded that this evidence was not strong enough to support a required carotenoid intake level because it is not yet known if the health benefits associated with carotenoid-containing foods are due to the carotenoids or to some other substance in the food.

However, the National Academy of Sciences supports the recommendations of various health agencies, which encourage individuals to consume five or more servings of fruits and vegetable every day. This level of intake of fruits and vegetables provides approximately three to six milligrams of beta-carotene.

Drug-nutrient interactions

What medications affect carotenoids?

The cholesterol-lowering medications referred to as bile acid sequestrants (Cholestyramine, Colestipol, and Colestid) lower blood levels of carotenoids. In addition, margarines enriched with plant sterols such as Benecol and Take Control, may decrease the absorption of carotenoids. Olestra, a fat substitute added to snack foods, may also decrease the absorption of carotenoids.

Form in dietary supplements

What forms of carotenoids are found in dietary supplements?

In dietary supplements, carotenoids are available as synthetic all-trans beta-carotene, beta- and alpha-carotene from the algae Dunaliella, and mixed carotenes from palm oil.

Due to inconsistent results from beta-carotene supplement trials, the National Academy of Sciences cautions against high-dose carotenoid supplementation except for preventing vitamin A deficiency.

Related Articles

References

  1. Agarwal S, Rao AV. Carotenoids and chronic diseases. Drug Metabol Drug Interact 2000;17(1-4):189-210. 2000. PMID:15130. https://doi.org/10.1093/jnci/58.4.1047
  2. Burri BJ. Carotenoids and gene expression. Nutrition 2000 Jul-2000 Aug 31;16(7-8):577-8. 2000. PMID:15140. https://doi.org/10.1001/JAMA.1977.03270420029011
  3. Delgado-Vargas F, Jimenez AR, Paredes-Lopez O. Natural pigments: carotenoids, anthocyanins, and betalains-- characteristics, biosynthesis, processing, and stability. Crit Rev Food Sci Nutr 2000 May;40(3):173-289. 2000. PMID:15150.
  4. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995. 1995.
  5. Handelman GJ. The evolving role of carotenoids in human biochemistry. Nutrition 2001 Oct;17(10):818-22. 2001. PMID:15100. https://doi.org/10.1016/s0022-3565(25)30832-3
  6. Krinsky NI. Carotenoids as antioxidants. Nutrition 2001 Oct;17(10):815-7. 2001. PMID:15110.
  7. Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000. 2000.
  8. Pizzorno J, Murray M. The Textbook of Natural Medicine. The Textbook of Natural Medicine. 1998. https://doi.org/10.1016/c2015-0-02243-2
  9. Young AJ, Lowe GM. Antioxidant and prooxidant properties of carotenoids. Arch Biochem Biophys 2001 Jan 1;385(1):20-7. 2001. PMID:15120. https://doi.org/10.1093/jmedent/13.4-5.515
  10. Agarwal S, Rao AV. Carotenoids and chronic diseases. Drug Metabol Drug Interact 2000;17(1-4):189-210 2000. PMID:15130. https://doi.org/10.1093/jnci/58.4.1047
  11. Burri BJ. Carotenoids and gene expression. Nutrition 2000 Jul-2000 Aug 31;16(7-8):577-8 2000. PMID:15140. https://doi.org/10.1001/JAMA.1977.03270420029011
  12. Delgado-Vargas F, Jimenez AR, Paredes-Lopez O. Natural pigments: carotenoids, anthocyanins, and betalains-- characteristics, biosynthesis, processing, and stability. Crit Rev Food Sci Nutr 2000 May;40(3):173-289 2000. PMID:15150.
  13. Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995 1995.
  14. Handelman GJ. The evolving role of carotenoids in human biochemistry. Nutrition 2001 Oct;17(10):818-22 2001. PMID:15100. https://doi.org/10.1016/s0022-3565(25)30832-3
  15. Krinsky NI. Carotenoids as antioxidants. Nutrition 2001 Oct;17(10):815-7 2001. PMID:15110.
  16. Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000 2000.
  17. Pizzorno J, Murray M. The Textbook of Natural Medicine. The Textbook of Natural Medicine 1998. https://doi.org/10.1016/c2015-0-02243-2
  18. Young AJ, Lowe GM. Antioxidant and prooxidant properties of carotenoids. Arch Biochem Biophys 2001 Jan 1;385(1):20-7 2001. PMID:15120. https://doi.org/10.1093/jmedent/13.4-5.515