Beta Carotene

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beta carotene rich foods

What is Beta Carotene

Beta-carotene is a red-orange pigment found in plants and fruits, especially carrots and colorful vegetables. Beta-carotene is the yellow/orange pigment that gives vegetables and fruits their rich colors. In Latin, the word “carotene” stands for carrot. This is the origin of the present name. Beta-carotene is one of the most widely consumed provitamin A carotenoids. Fruit and vegetables provide most of the 40 to 50 carotenoids found in the human diet. There are more than 50 provitamin A carotenoids, but only beta-carotene, alpha-carotene, lutein, lycopene, and beta-cryptoxanthin are present in significant amounts in the human diet 1. Currently, the only essential function of carotenoids recognized in humans is that of the provitamin A carotenoids, alpha-carotene, beta-carotene, and beta-cryptoxanthin, to serve as a source of vitamin A 2. The human body is not able to produce vitamin A, therefore, it is necessary to obtain it from the diet either as preformed vitamin A or in the form of provitamin A carotenoids. The human diet contains two sources for vitamin A: preformed vitamin A (retinol and retinyl esters) and provitamin A carotenoids 3, 2. Preformed vitamin A is found in foods from animal sources, including dairy products, eggs, fish, and organ meats 3, 4. Provitamin A carotenoids are plant pigments that include beta-carotene, alpha-carotene, and beta-cryptoxanthin 3. The body converts provitamin A carotenoids into vitamin A in the intestine via the beta-carotene monooxygenase type 1 BCMO1 enzyme 3, 2, 5. Although beta-carotene can be converted to vitamin A, the conversion of beta-carotene to vitamin A decreases when body stores of vitamin A are high and the conversion rates may have genetic variability 6, 7, 8, 9. This may explain why high doses of beta-carotene have never been found to cause vitamin A toxicity. High doses of beta-carotene (up to 180 mg/day) have been used to treat erythropoietic protoporphyria (EPP), a photosensitivity disorder, without toxic side effects 2.

Beta-carotene is a precursor for vitamin A biosynthesis with antioxidant properties including free radical scavenging, singlet oxygen quencher, and an ability to inhibit lipid peroxidation with high-fat solubility 10, 11. Other carotenoids in food, such as lycopene, lutein, and zeaxanthin, are not converted into vitamin A and are referred to as non-provitamin A carotenoids; they might have other important activities not involving vitamin A formation 3.

Studies have found out that majority of the vitamin A in our diet comes from provitamin A carotenoids like beta-carotene. There are also other sources for beta-carotene. Beta-carotene can be manufactured as a synthetic compound in laboratories or also can be isolated from different fungi or algal sources. Palm oil is another rich product containing beta-carotene 12.

Humans obtain vitamin A primarily from beta-carotene and other provitamin A carotenoids present in most fruits and vegetables. Vitamin A is involved in immune function, cellular communication, growth and development, and male and female reproduction 3, 4, 13. Vitamin A supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, eyes, and other organs 3, 4. Vitamin A is also critical for vision as an essential component of rhodopsin, the light-sensitive protein in the retina that responds to light entering the eye, and because it supports the normal differentiation and functioning of the conjunctival membranes and cornea 14. Epidemiological studies recommended the daily intake of beta-carotene protect against diabetes, cardiovascular diseases, rheumatoid arthritis, atherosclerosis, inflammatory bowel disease, and cancer 15, 16.

Provitamin A carotenoids (alpha-carotene, beta-carotene, and beta-cryptoxanthin) are less easily absorbed than preformed vitamin A (retinol and retinyl esters) and must be converted to retinol and other retinoids by the body 17. The efficiency of conversion of provitamin A carotenoids (alpha-carotene, beta-carotene, and beta-cryptoxanthin) into preformed vitamin A retinol is highly variable, depending on factors like food matrix, food preparation, and one’s digestive and absorptive capacities 18.

The most recent international standard of measure for vitamin A is retinol activity equivalent (RAE), which represents vitamin A activity as retinol. It has been determined that 2 micrograms (µg) of beta-carotene in oil provided as a supplement could be converted by the body to 1 µg of retinol, giving it an RAE ratio of 2:1. However, 12 µg of beta-carotene from food are required to provide the body with 1 µg of retinol, giving dietary beta-carotene an RAE (retinol activity equivalent) ratio of 12:1. Other provitamin A carotenoids in food are less easily absorbed than beta-carotene, resulting in RAE ratios of 24:1. RAE ratios are shown in Table 1.

There has been an extensive number of studies carried out and research papers published on the health benefits and harms of beta carotene such as increase the risk of lung cancer, cardiovascular disease morbidity and mortality, and all-cause mortality. Examples are provided below.

In Finland, the Α-Tocopherol Βeta-Carotene (ATBC) cancer prevention trial 19 evaluated the effects of 20 mg/day of beta-carotene and/or 50 mg/day of vitamin E (alpha-tocopherol) on more than 29,000 male smokers and in the United States, the Beta-Carotene And Retinol Efficacy Trial (CARET) 20 evaluated the effects of a combination of 30 mg/day of beta-carotene and 25,000 IU/day of retinol (preformed vitamin A) in 18,314 men and women who were smokers, former smokers, or had a history of occupational asbestos exposure. Unexpectedly, the risk of lung cancer in the groups taking beta-carotene supplements was increased by 16% after six years in the ATBC participants and by 28% after four years in the CARET participants. The risk of lung cancer is increased with high doses of beta-carotene. In contrast, the Physicians’ Health Study (PHS) examined the effect of beta-carotene supplementation (50 mg every other day) on cancer risk in 22,071 male physicians in the United States, of whom only 11% were current smokers 21. In that lower risk population, beta-carotene supplementation for more than 12 years was not associated with an increased risk of lung cancer. In addition, in the Linxian General Population trial conducted in about 29,000 Chinese participants, randomization to 15 mg/day of beta-carotene, 30 mg/day of vitamin E (alpha-tocopherol) and 15 µg/day of selenium, was not found to be associated with lung cancer mortality 10 years after the intervention ended 22. Moreover, five-year follow-up of the Age-Related Eye Disease Study 2 (AREDS2) trial found that beta-carotene supplementation nearly doubled the risk of developing lung cancer in former smokers compared to nonsmokers (current smokers did not receive beta-carotene supplements) 23. Age-Related Eye Disease Study 2 (AREDS2) was a multicenter, randomized double-blind, placebo-controlled trial that evaluated the effects of supplementation with antioxidant vitamins and minerals for five years to treat age-related macular degeneration (AMD). Finally, a meta-analysis of four randomized controlled trials, including but not limited to trials in high-risk populations like smokers, found beta-carotene supplementation alone or with retinol; 3.7 to 12 years increased the risk of lung cancer by 20% compared to control 24.

Although the reasons for the increase in lung cancer risk in people taking carotenoids supplement are not yet clear, several mechanisms have been proposed 25. Baseline beta-carotene status might be one factor that influences whether with beta-carotene supplementation promotes carcinogenesis in the lungs of smokers 26. The US Preventive Services Task Force (USPSTF) estimated that the risks of high-dose beta-carotene supplementation outweigh any potential benefits for cancer prevention and recommended against supplementation, especially in smokers or other high-risk populations 24, 27.

When taken by mouth, beta-carotene is likely safe when taken in appropriate amounts for certain medical conditions 3. But beta-carotene supplements are not recommended for general use. Beta-carotene supplements are possibly unsafe when taken by mouth in high doses, especially when taken long-term. The Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine advises against the use of beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency 28.

Figure 1. Provitamin A carotenoids

Provitamin A carotenoids
[Source 29 ]

Figure 2. Beta carotene chemical structure

Beta carotene chemical structure
[Source 12 ]

Table 1. Retinol Activity Equivalent (RAE) Ratios for Preformed Vitamin A and Provitamin A Carotenoids

Quantity ConsumedQuantity Bioconverted to RetinolRAE Ratio
1 µg of dietary or supplemental preformed vitamin A1 µg of retinol1:1
2 µg of supplemental beta-carotene1 µg of retinol2:1
12 µg of dietary beta-carotene1 µg of retinol12:1
24 µg of dietary alpha-carotene1 µg of retinol24:1
24 µg of dietary beta-cryptoxanthin1 µg of retinol24:1

Footnote: RAE = retinol activity equivalent

The units of measurement for vitamin A are now mcg RAE (retinol activity equivalent), but International Units (IUs) were previously used 30. To convert International Unit (IU) to mcg RAE (retinol activity equivalent), use the following 31:

  • 1 IU retinol = 0.3 mcg RAE
  • 1 IU supplemental beta-carotene = 0.3 mcg RAE
  • 1 IU dietary beta-carotene = 0.05 mcg RAE
  • 1 IU dietary alpha-carotene or beta-cryptoxanthin = 0.025 mcg RAE
[Source 29 ]

Beta Carotene uses and health benefits

Beta-carotene is a natural carotenoid that usually occurs as red-orange pigment found in plants and fruits, especially carrots and colorful vegetables. The only known function of beta-carotene in humans is a precursor for vitamin A biosynthesis. Therefore, beta-carotene is also known as pro-vitamin A and thereby function as precursors. Apart from this, beta-carotene is also authorized for addition to foods as a coloring agent in several food products and for use in supplements.

Vitamin A is involved in immune function, cellular communication, growth and development, and male and female reproduction 3, 4, 13. Vitamin A supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, eyes, and other organs 3, 4. Vitamin A is also critical for vision as an essential component of rhodopsin, the light-sensitive protein in the retina that responds to light entering the eye, and because it supports the normal differentiation and functioning of the conjunctival membranes and cornea 14. Epidemiological studies recommended the daily intake of beta-carotene protect against diabetes, cardiovascular diseases, rheumatoid arthritis, atherosclerosis, inflammatory bowel disease, and cancer 15, 16.

Several studies have shown that beta-carotene, in addition to its effects on vision, also functions as a potent free radical scavenger (antioxidant). It is now known that much of the damage to the cells internally is caused by free radicals and sources of free radicals through oxidative reactions. Chronic exposure to damaging oxidative radicals can allow several diseases in the body. A number of authors have mentioned that antioxidants and free radical scavengers can enhance immunity and shield our bodies from several diseases 32.

There has been an extensive number of studies carried out and research papers published on the health benefits and harms of beta carotene such as increase the risk of lung cancer, cardiovascular disease morbidity and mortality, and all-cause mortality. Examples are provided below.

The effect of beta-carotene supplementation on the risk of developing lung cancer has been examined in large randomized, placebo-controlled trials 20. Studies looking at the possible role of vitamin supplements in reducing lung cancer risk have had disappointing results. In fact, multiple studies found that people who smoked and took beta-carotene supplements actually had an increased risk of lung cancer. The results of these studies suggest that people should avoid taking beta-carotene supplements 19, 20, 33.

The Carotene and Retinol Efficacy Trial (CARET) included 18,314 male and female current and former smokers (with at least a 20 pack-year history [equivalent to smoking 1 pack per day for 20 years or 2 packs per day for 10 years, for example] of cigarette smoking) as well as some men occupationally exposed to asbestos (who also have a higher risk of lung cancer), all age 45–74 years 20. The study randomized participants to take supplements containing 30 mg beta-carotene plus 25,000 IU (7,500 mcg RAE) retinyl palmitate or a placebo daily for about 6 years to evaluate the potential effects on lung cancer risk 34. The trial was ended prematurely after a mean of 4 years, partly because the supplements were unexpectedly found to have increased lung cancer risk by 28% and death from lung cancer by 46%; the supplements also increased the risk of all-cause mortality by 17% 34.

A subsequent study followed Carotene and Retinol Efficacy Trial (CARET) participants for an additional 6 years after they stopped taking the study supplements 35. During this time, the differences in lung cancer risk between the intervention and placebo groups were no longer statistically significant, with one exception: women in the intervention group had a 33% higher risk of lung cancer 35. In a separate analysis of CARET study data 36, men who took the two supplements had a 35% lower risk of nonaggressive prostate cancer during the 4-year active trial but not during the 6-year postintervention period. In contrast, men who took these two supplements in addition to another self-prescribed supplement (typically a multivitamin) had a 52% higher risk of aggressive prostate cancer during the active trial, but not during the postintervention period 36.

In Finland, the Alpha-Tocopherol, Beta-Carotene (ATBC) Cancer Prevention Study also found that beta-carotene supplements increased the risk of lung cancer in smokers 19. In this study, 29,133 male smokers age 50–69 years who smoked an average of 20.4 cigarettes a day for an average of 35.9 years took a supplement containing 50 mg/day alpha-tocopherol, 20 mg/day beta-carotene, both alpha-tocopherol and beta-carotene, or a placebo for 5–8 years 19. The beta-carotene supplements increased the risk of lung cancer by 18%, although they had little to no effect on the incidence of other cancers. The overall rate of death, primarily from lung cancer and ischemic heart disease, was 8% higher in participants who took beta-carotene 19. A subsequent study followed 25,563 of these participants for an additional 18 years 37. During this period, participants were no longer taking the supplements, but most continued to smoke. Participants who had taken beta-carotene in the original trial did not have a higher risk of lung cancer, but they had a 20% higher risk of death due to prostate cancer 37.

The Age-Related Eye Disease Study 2 (AREDS2) was a 5-year randomized clinical trial with 4,203 participants age 50–85 years examining the effects on age-related macular degeneration (ARMD or AMD) of a dietary supplement containing several ingredients with or without beta-carotene (15 mg [7,500 mcg RAE]) 38. No current smokers received the supplements containing beta-carotene. At the end of the trial, more lung cancers were discovered in the beta-carotene group than in the no beta-carotene group (23 vs. 11 cases), and 31 of the 34 affected were former smokers 38. In a follow-up analysis of 3,882 of the participants 5 years after the end of AREDS2 (during which they took the AREDS2 formulation containing lutein and zeaxanthin instead of beta-carotene), the increased lung cancer risk persisted, with an 82% higher risk among participants who took the supplement containing beta-carotene during the 5-year AREDS2 trial 23. The risk of advanced AMD was also 18% lower in participants who took the modified AREDS supplement containing lutein and zeaxanthin but not beta-carotene than in participants who took the formulation with beta-carotene but not lutein or zeaxanthin 23. After 10 years, participants who had taken the AREDS2 supplement with lutein and zeaxanthin had an additional 20% reduced risk of progression to late AMD compared with those who took the supplement containing beta-carotene. This finding confirmed the benefit of replacing beta-carotene with lutein and zeaxanthin 23.

Three other clinical trials have found no relationship between taking vitamin A or beta-carotene supplements and lung cancer incidence or mortality 39. One trial randomized 22,071 male physicians age 40–84 years to take 50 mg beta carotene on alternate days or a placebo for 12 years 21. Eleven percent of the physicians were current smokers, and 38% were former smokers at the start of the study. The results showed no differences between the groups in number of cases of lung cancer or any malignant neoplasms or number of deaths from cancer 21. Another trial randomized 7,627 women (mean age 60.4 years) to take 50 mg beta-carotene on alternate days, 600 IU vitamin E on alternate days, 500 mg vitamin C daily, or a placebo for a mean of 9.4 years 40. Fifteen percent of the women were current smokers, and 41% were former smokers at the start of the study. None of the supplements had any significant effect on total cancer incidence or cancer mortality, including from lung cancer 40. A third trial included 29,584 healthy men and women age 40–69 years who were living in Linxian, China, where micronutrient deficiencies are common 22. The study randomized participants to take either a placebo or one of four vitamin and mineral combinations (including one providing retinol and zinc and another providing beta carotene, vitamin E, and selenium) for 5.25 years 22. The investigators followed participants for an additional 10 years after they stopped taking the supplements. The nutrient doses in the supplements were equivalent to or twice as high as U.S. recommended intakes, but the study report did not provide the exact doses 22. During both the intervention and follow-up periods, lung cancer death rates did not differ among the five groups, even when the investigators further analyzed the results for differences by age, sex, and smoking status 22.

The Carotene and Retinol Efficacy Trial (CARET) and Alpha-Tocopherol, Beta-Carotene (ATBC) study results suggest that large supplemental doses of beta-carotene with or without retinyl palmitate have detrimental effects in current or former smokers and workers exposed to asbestos. However, the other studies described above that used similar vitamin A doses but had smaller proportions of current or former smokers do not raise this concern. Among nonsmokers, beta-carotene and vitamin A supplements do not appear to affect the risk of cancer.

A case-control study nested within the large multicenter European Prospective Investigation into Cancer and Nutrition (EPIC) study found a 31% lower risk of colorectal cancer with the highest versus lowest quartile of beta-carotene intake, while no associations were shown with blood concentrations of other carotenoids or total carotenoids 41. The nested case-control study was included in a meta-analysis of 22 observational studies that failed to find associations between carotenoid intakes and colorectal cancer 42.

Evidence from observational studies that cataracts were less prevalent in people with high dietary intakes and blood concentrations of carotenoids led to the inclusion of beta-carotene supplements in several large randomized controlled trials of antioxidants. The results of those trials have been somewhat conflicting. Beta-carotene supplementation 20 mg/day for more than six years did not affect the prevalence of cataracts or the frequency of cataract surgery in male smokers living in Finland 43. In contrast, a 12-year study of male physicians in the US found that beta-carotene supplementation (50 mg every other day) decreased the risk of cataracts in smokers but not in nonsmokers 44. Note that use of beta-carotene supplements have been shown to increase the risk of lung cancer in smokers 23, 24, 19, 20. Three randomized controlled trials examined the effect of an antioxidant combination that included beta-carotene, vitamin C, and vitamin E on the progression of cataracts. Two trials found no benefit after supplementation for five years 45 or more than six years 46, but one trial found a small decrease in the progression of cataracts after three years of supplementation 47. Overall, the results of randomized controlled trials suggest that the benefit of beta-carotene supplementation in slowing the progression of age-related cataracts does not outweigh the potential risks.

In contrast to the results of observational studies suggesting that high dietary intakes of carotenoid-rich fruit and vegetables may decrease cardiovascular disease risk, four randomized controlled trials found no evidence that beta-carotene supplements in doses ranging from 20 to 50 mg/day were effective in preventing cardiovascular disease 19, 21, 48, 34. Based on the results of these randomized controlled trials, the US Preventive Health Services Task Force (USPSTF) found good evidence to suggest that beta-carotene supplements provided no benefit in the prevention of cardiovascular disease in healthy adults 27. The United States Preventive Services Task Force (USPSTF) in 2013 indicated no effect of beta-carotene on cardiovascualr disease prevention but an increased risk for lung cancer; thus, it was not recommended to use beta-carotene supplements for prevention or treatment 49. A 2022 meta-analysis of 12 randomized, placebo-controlled trials found that beta-carotene supplementation increased mortality related to cardiovascular disease 11. Furthermore, several studies have shown that beta-carotene was associated with an increased risk of all-cause mortality 49, 50, 51. Therefore, although diets rich in beta-carotene have generally been associated with reduced cardiovascular disease risk in observational studies, there is no evidence that beta-carotene supplementation reduces cardiovascular disease risk 52.

Beta-carotene has also been studied for treating sun sensitivity in a condition called as erythropoietic protoporphyria (EPP). Erythropoietic protoporphyria (EPP) is one of the skin porphyrias. Erythropoietic protoporphyria (EPP) is due to an inherited deficiency of the enzyme ferrochelatase. Reduced activity of ferrochelatase enzyme causes a build-up of protoporphyrin in red blood cells, plasma, liver, and skin that causes acute, painful, non-blistering sensitivity to sunlight and potential liver disease 53. However, consuming beta-carotene with oral doses of 30 to 300 mg/day for adults and 30 to 150 mg/day for children will render people with erythropoietic protoporphyria (EPP) with increase the sunlight tolerance 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66. Beta-carotene doses should maintain plasma carotene levels in the range between 600 to 800 mcg/dL, and the serum carotene levels should be checked every three to four weeks because high doses of beta-carotene increase risk of lung cancer 54. The consumption of beta-carotene is gradually tapered down over a certain period of time.

Although small studies have suggested that beta-carotene supplements could increase CD4 cell counts, clinical trials have not been able to replicate these results. Available data of beta-carotene supplementation for HIV-positive patients and its effects on CD4 counts 67 as well as cardiovascular disease are conflicting 11. A meta-analysis demonstrated a small but significant increase in all-cause mortality and cardiovascular death for the beta-carotene arm over placebo 68, 11, whereas other studies reported no such effects 69 nor any benefits of beta-carotene supplementation against cardiovascular disease 21, 70 or its risk factors 71. However, higher intake of fruits and vegetables, but not antioxidant supplements, reduced intra-abdominal visceral fat and was associated with reduced risk of cardiovascular disease, total cancer, and all-cause mortality 72. Supplementation with or without vitamin A may actually increase the risk of cardiovascular mortality 24. Beta-carotene has also been inversely correlated with metabolic syndrome 73.

Beta carotene possibly effective for 74:

  • Breast cancer. Eating more beta-carotene in the diet is linked to a lower risk of breast cancer in high risk, pre-menopausal females. In people with breast cancer, eating more beta-carotene in the diet is linked to an increased chance of survival. In a meta-analysis of 12 prospective cohort studies, no association was found between total and individual carotenoid intake and risk of breast cancer, except with beta-carotene for which a 5% reduction in breast cancer risk was estimated for every 5 mg/day increment in consumption 75. In a pooled analysis of 14 nested case-control studies and one follow-up study of a clinical trial, reductions in breast cancer risk were found to be associated with blood concentrations of total carotenoids (-26%), alpha-carotene (-20%), and lutein (-30%) 75. Another study that recalibrated data for consistency across eight large prospective cohorts before pooled analysis found reduced breast cancer risk to be associated with the highest versus lowest quintile of blood concentrations of total carotenoids (-21%), beta-carotene (-17%), and lycopene (-22%) 76. Further analyses found an inverse association between the blood concentrations of beta-carotene and α-carotene and risk of estrogen receptor-negative (ER-), but not estrogen receptor-positive (ER+), breast tumors 76. A similar result was reported in a case-control study nested within the large multicenter European Prospective Investigation into Cancer and Nutrition (EPIC) study 77. In a nested case-control study of the Nurses’ Health Studies (NHS and NHSII), a 20% reduction in risk of breast cancer was seen in those with the highest total plasma carotenoids (≥142.1 µg/dL) compared to the lowest (<84.6 µg/dL), and this association was strongest in those presumed to be at higher risk of breast cancer 78. Protective associations were observed for higher circulating levels of the carotenoids, alpha-carotene (-20%), beta-carotene (-18%), as well as lutein and zeaxanthin (-17%) 78. In contrast to the abovementioned pooled analysis, this study found a protective association between higher circulating carotenoids and estrogen receptor-positive (ER+), but not receptor-negative (ER-), breast tumors 78.
  • Complications after childbirth. Taking beta-carotene by mouth before, during, and after pregnancy might decrease the risk of diarrhea and fever after childbirth. It also seems to reduce the risk of pregnancy-related death.
  • Sunburn. Taking beta-carotene by mouth might decrease sunburn risk in people sensitive to the sun.

Beta carotene possibly ineffective for 74:

  • Ballooning of a blood vessel wall (aneurysm). Taking beta-carotene by mouth doesn’t reduce the risk for an aneurysm in the stomach in male smokers.
  • Alzheimer disease. Eating a diet high in beta-carotene does not seem to reduce the risk of Alzheimer disease.
  • Cataracts. Taking beta-carotene by mouth, alone or together with vitamin C, vitamin E, and zinc, doesn’t seem to reduce the risk or progression of cataracts.
  • Cystic fibrosis. Taking beta-carotene by mouth does not improve lung function in people with cystic fibrosis.
  • Diabetes. Taking beta-carotene by mouth doesn’t reduce the risk of developing diabetes or diabetes-related complications.
  • Non-cancerous moles (dysplastic nevi). Taking beta-carotene by mouth does not reduce the development of new moles.
  • Cancer of the esophagus. Taking beta-carotene by mouth doesn’t seem to reduce the risk of esophageal cancer.
  • Liver cancer. Taking beta-carotene by mouth, alone or with vitamin E, does not prevent liver cancer in male smokers.
  • Liver disease. Taking beta-carotene by mouth, alone or with vitamin E, does not prevent death due to liver disease in male smokers.
  • Death from any cause. Taking beta-carotene by mouth doesn’t seem to reduce the risk of death from any cause.
  • Stroke. Taking beta-carotene by mouth does not reduce the risk of stroke in male smokers. It might actually increase the risk in people who drink alcohol.

Beta carotene likely ineffective for 74:

  • Cancer. Taking beta-carotene by mouth does not reduce the risk for most types of cancer.
  • Heart disease. Taking beta-carotene by mouth does not reduce the risk for heart disease. It might actually increase the risk for heart disease-related death in some people.
  • Non-cancerous growths in the large intestine and rectum (colorectal adenoma). Taking beta-carotene by mouth does not decrease the risk of these growths. In people who smoke cigarettes and drink alcohol, taking beta-carotene supplements might actually increase the risk for these growths.
  • Lung cancer. Taking beta-carotene supplements by mouth seems to increase the risk of lung cancer in some people. Beta-carotene from food does not seem to have this effect.
  • Prostate cancer. Taking beta-carotene supplements by mouth does not prevent prostate cancer in most people. In fact, taking beta-carotene supplements might actually increase the risk of prostate cancer in some people.

There is interest in using beta-carotene for a number of other purposes, but there isn’t enough reliable information to say whether it might be helpful.

Beta-carotene food sources

Beta-carotene is a provitamin A carotenoid, meaning beta-carotene is converted in your body to vitamin A. The vitamin A activity of beta-carotene in food is 1⁄12 that of retinol (preformed vitamin A). What that means is that it would take 12 µg of beta-carotene from food to provide the equivalent of 1 µg of retinol (see Table 1 above). The vitamin A activity of alpha-carotene from foods is 1⁄24 that of retinol, so it would take 24 µg of α-carotene from food to provide the equivalent of 1 µg of retinol. Orange and yellow vegetables like carrots and winter squash are rich sources of alpha- and beta-carotene. Spinach is also a rich source of beta-carotene, although the chlorophyll in spinach leaves hides the yellow-orange pigment. Some foods that are good sources of alpha-carotene and beta-carotene

The following foods are rich in beta-carotene:

  • Apricots
  • Asparagus
  • Broccoli
  • Cantaloupe
  • Carrots
  • Chinese cabbage
  • Chives
  • Dandelion leaves
  • Grapefruit
  • Herbs and spices – chilli powder, oregano, paprika, parsley
  • Kale
  • Ketchup
  • Many margarines
  • Onions
  • Papaya
  • Peas
  • Peppers
  • Plums
  • Pumpkin
  • Spinach
  • Squash
  • Sweet potatoes.

If you follow a healthy diet rich in beta-carotene you do not need supplements. As mentioned above, supplements can lead to undesirable excesses in beta-carotene levels – this cannot occur if your source is from the food you eat.

beta carotene rich foods

Table 2. Beta-carotene content in selected foods

Food Source
Beta-Carotene Content
Orange-red vegetables
Sweet potato20–22,600 a
Bitter gourd17,040 b
Winter squash (butternut)12,340–15,770 a
Chili pepper100–15,400 a
Carrot4350–8840 a
Pumpkins70–6070 a
Cantaloupe2448–3861 a
Red pepper1441–2390 a
Tomato59–1500 a
Green vegetables
Drumstick leaves19,700 a
Amaranth8600 a
Kale1020–10,000 a
Garden rocket7960 a
Chicory3940–7310 a
Wild rocket7010 a
Dandelion6340 a
Onion leaf4900 a
Coriander4800 a
Parsley4440–4680 a
Spinach3100–4810 a
Endive1340–4350 a
Cress2720–3690 a
Leek3190 a
Lettuce870–2960 a
Broccoli291–1750 a
Fruits
Apricot585–3800 a
Mango109–3210 a
Persimmon3000 b
Dates2950 a
Guava1–2669 a
Red grapefruit2580 a
Papaya190–1050 a
Cereals
Golden rice160–3700 a
Maize171–1500 a
Medicinal plants and herbs
Rose hips3600 a
Marigold flowers940–20,600 a
Dill5450 a
Basil4820 a
Others
Spirulina184,100–272,500 a
Sea buckthorn oil16,740 c
Red palm oil5000–5602 c

Footnotes: a µg/100 g of fresh weight, b CE-β-carotene equivalent (µg/100 g of fresh weight)—also includes other carotenoids (content of β-carotene + 1/2 content of other vitamin A active carotenoids), c µg/100 g of oil.

[Source 14 ]

Table 3. Beta carotene in selected foods

FoodServingBeta-carotene (mg)
Carrot juice, canned1 cup (8 fl. oz.)21.9
Pumpkin, canned1 cup17
Spinach, frozen, cooked1 cup13.8
Sweet potato, baked1 medium13.1
Carrots, cooked1 cup13
Collards, frozen, cooked1 cup11.6
Carrots, raw1 medium10.1
Pumpkin pie1 piece7.4
Turnip greens, cooked1 cup6.6
Winter squash, cooked1 cup5.7
Cantaloupe, raw1 cup4.5
Kale, cooked1 cup2
[Source 29 ]

Beta carotene supplement

Beta-carotene is sold as individual supplements and also found in supplements marketed to promote visual health 79. Commercially available beta-carotene supplements usually contain between 1.5 mg and 15 mg of either synthetic beta-carotene or natural beta-carotene (mainly from the algae Dunaliella salina) per softgel capsule 80. As a provitamin A carotenoid, beta-carotene may be used to provide all or part of the vitamin A in multivitamin supplements. The provitamin A activity of beta-carotene from supplements is much higher than that of beta-carotene from food: it takes only 2 micrograms [µg] (0.002 mg) of beta-carotene from supplements to provide 1 µg of retinol (preformed vitamin A) compared to 12 µg of dietary beta-carotene.

The beta-carotene content of supplements is often listed in international units (IU) rather than µg: 3,000 µg (3 mg) of supplemental beta-carotene provides 5,000 IU of vitamin A.

Is beta carotene safe?

When taken by mouth, beta-carotene is likely safe when taken in appropriate amounts for certain medical conditions 3. But beta-carotene supplements are not recommended for general use. Beta-carotene supplements are possibly unsafe when taken by mouth in high doses, especially when taken long-term. The Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine advises against the use of beta-carotene supplements for the general population, except as a provitamin A source to prevent vitamin A deficiency 28.

  • Increased lung cancer risk: Two randomized controlled trials in smokers and former asbestos workers found that supplementation with 20 to 30 mg/day of beta-carotene with or without 50 mg/day vitamin E for 4 to 6 years was associated with significant 16%-28% increases in the risk of lung cancer and mortality (mainly from lung cancer and ischemic heart disease) in male smokers compared to placebo 19, 20. The Carotene and Retinol Efficacy Trial (CARET) trial also showed that supplementation with a large amount of beta-carotene (30 mg/day) plus 7,500 mcg RAE (25,000 IU)/day retinyl palmitate for 4–8 years in current and former smokers as well as some men occupationally exposed to asbestos increased the risk of lung cancer and death from lung cancer 34. Although the reasons for these findings are not yet clear, the potential risk of lung cancer in smokers and other high-risk groups supplemented with high-dose beta-carotene outweigh any possible benefits for chronic disease prevention 27.
  • Carotenodermia: High doses of beta-carotene supplements (≥30 mg/day) and the consumption of large amounts of carotene-rich food have resulted in a yellow discoloration of the skin (xanthoderma) known as carotenodermia, also called carotenemia 2. Carotenodermia is not associated with any underlying health problems and resolves when supplementation with beta-carotene is discontinued or dietary carotene intake is reduced.
  • Taking high doses of beta-carotene supplements might also increase the chance of death from all causes, increase the risk of certain cancers, and possibly cause other serious side effects. Beta-carotene from food does not seem to have these effects 74.

Pregnancy and breastfeeding

Beta-carotene is likely safe when taken by mouth in pregnant women at appropriate amounts 2. But there isn’t enough reliable information to know if high doses of beta-carotene are safe to use when pregnant or breastfeeding. Although there is no reason to limit dietary beta-carotene intake, pregnant and breastfeeding women should avoid consuming more than 3 mg/day (1,500 µg RAE/day; 5,000 IU/day) of beta-carotene from supplements unless they prescribed under medical supervision.

Children

Beta-carotene is likely safe when taken by mouth in appropriate amounts.

History of asbestos exposure

In people who have been exposed to asbestos, beta-carotene supplements might increase the risk of cancer. Don’t take beta-carotene supplements if you have been exposed to asbestos.

Smoking

In people who smoke, beta-carotene supplements might increase the risk of colon, lung, and prostate cancer. Don’t take beta-carotene supplements if you smoke.

Interactions with medications

Orlistat (Alli, Xenical), a weight-loss treatment, can decrease the absorption of vitamin A, other fat-soluble vitamins, and beta-carotene, resulting in low plasma levels in some patients 81, 82. The manufacturers of Alli and Xenical recommend that patients on orlistat take a multivitamin supplement containing vitamin A and beta-carotene as well as other fat-soluble vitamins 83, 84.

Interactions with plant sterol- or stanol-containing foods

Some studies found that the regular use of plant sterol-containing spreads resulted in modest, 10%-20% decreases in the plasma concentrations of some carotenoids, particularly alpha-carotene, beta-carotene, and lycopene 85, 86. However, people who use plant sterol- or stanol-containing margarines and consume an extra serving of carotenoid-rich fruit or vegetables daily prevented decreases in plasma carotenoid concentrations 87.

Interactions with alcohol

The relationships between alcohol consumption and carotenoid metabolism are not well understood. There is some evidence that regular alcohol consumption inhibits the conversion of beta-carotene to retinol 88. Increases in lung cancer risk associated with high-dose beta-carotene supplementation in two randomized controlled trials were enhanced in those with higher alcohol intakes 33, 20.

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