Serum Beta-carotene Research Articles

Effects of alcohol drinking and cigarette smoking on serum alpha- and beta-carotene concentrations in healthy adults.

The effects of alcohol and cigarette consumption on serum concentrations of alpha-carotene and beta-carotene in 312 healthy male adults, aged from 20 to 58 years, were investigated. Serum concentrations of beta-carotene were lower in alcohol drinkers (17.8 micrograms/dl; 0.33 mumol/l) than in nondrinkers (23.2 micrograms/dl; 0.43 mumol/l). Serum concentrations of alpha- and beta-carotenes were higher in nonsmokers (alpha-carotene: 7.4 micrograms/dl; beta-carotene: 22.6 micrograms/dl) than in current smokers (alpha-carotene: 5.9 micrograms/dl; beta-carotene: 18.4 micrograms/dl). In simple correlation and multiple regression analyses, smoking, smoking and alcohol drinking were inversely correlated with serum concentrations of alpha- and beta-carotenes in healthy adults. In contrast, serum concentrations of alpha- and beta-carotenes rose significantly with an increasing intake frequency of green-yellow vegetables or fruits. In addition, the effect of alcohol drinking on the serum beta-carotene concentration was more pronounced that that of smoking.

Serum beta-carotene and subsequent risk of cancer: results from the BUPA Study.

In the BUPA Study, a prospective study of 22,000 men attending a screening centre in London, serum samples were collected and stored. The concentration of beta-carotene was measured in the stored serum samples from 271 men who were subsequently notified as having cancer and from 533 unaffected controls, matched for age, smoking history and duration of storage of the serum samples. The mean beta-carotene level of the cancer subjects was significantly lower than that of their matched controls (198 and 221 micrograms l-1 respectively, P = 0.007). The difference was apparent in subjects from whom blood was collected several years before the diagnosis of the cancer, indicating that the low beta-carotene levels in the cancer subjects were unlikely to have been simply a consequence of pre-clinical disease. Men in the top two quintiles of serum beta-carotene had only about 60% of the risk of developing cancer compared with men in the bottom quintile. The study was not large enough to be able to indicate with confidence the sites of cancer for which the inverse association between serum beta-carotene and risk of cancer applied, though the association was strongest for lung cancer. The association may be due to beta-carotene affecting the risk directly or it may reflect an indirect association of cancer risk with some other component of vegetables or with a nonvegetable component of diet that is itself related to vegetable consumption.

HPLC method for the simultaneous determination of beta-carotene, retinol and alpha-tocopherol in serum

A method is described for the simultaneous analysis of α-tocopherol, β-carotene, and retinol in n-hexane extracts of serum. The technique uses normal-phase HPLC in a silica gel column with n-hexane-2-propanol (97:3, v/v) as the mobile phase. The compounds are eluted from the column in the order α-tocopherol, β-carotene, tocol (internal standard) and retinol. The compounds are quantified by use of the following detectors connected in series: retinol and tocol by a spectrophotometer, β-carotene by a filter photometer, and α-tocopherol and tocol by a spectrophotofluorimeter. The time taken for separation is less than 6 min but a further 14 min is allowed for elution of the more polar compounds before the next run. With an automatic injector, the method is suitable for the analysis of a large number of samples because of the relatively short time for analysis and the small volume (0.2 ml) of serum required. The method has been used in a study of the relationships between serum levels of the fat-soluble vitamins and subsequent cancer in 2332 subjects.

Endocrine responses and estrous activity in Holstein heifers fed supplemental beta-carotene

Three trials involving 56 Holstein heifers were conducted to determine the effect of feeding supplemental beta-carotene (BC) on several reproductive parameters. Heifers were maintained in a loose housing system and group fed year-old brome hay ad libitum. All heifers were individually fed 2.73 kg of a concentrate mix daily. Half of the heifers received 300 mg BC/d (Trials 1 and 2) or 600 mg BC/d (Trial 3) blended in the concentrate mix. After 4 wk of dietary treatment, estrus was synchronized to facilitate observation for estrous activity and collection of blood samples. Two weeks after the treatment was initiated, concentrations of BC in blood serum were greater in the heifers that were fed supplemental BC as compared to control heifers. This difference increased to 6 wk. However, feeding supplemental BC had no effect on any of the reproductive parameters measured, including incidence of estrus and changes in progesterone and luteinizing hormone (LH) concentrations after PGF 2α, intervals from PGF 2α to estrus and LH peak, estrual activity or first service conception rate. The results indicate that feeding supplemental BC does not alter reproductive performance in Holstein heifers.

Serum beta-carotene, vitamin A and E, selenium, and the risk of lung cancer

Serum beta-carotene, vitamin A and E, selenium, and the risk of lung cancer

Serum beta-carotene, retinol, and alpha-tocopherol levels during mineral oil therapy for constipation.

Twenty-five children with chronic constipation underwent serial monitoring of serum beta-carotene, retinol (vitamin A1), and alpha-tocopherol (vitamin E) levels during mineral oil therapy. Mineral oil was administered between meals. Patients were monitored for up to four months of therapy. Mean serum beta-carotene levels fell from 1.0 +/- 0.5 mumol/L (55.7 +/- 26.0 micrograms/dL) to 0.7 +/- 0.4 mumol/L (35.9 +/- 22.1 micrograms/dL) after the first month of mineral oil therapy and remained depressed throughout the remainder of the study. Serum alpha-tocopherol levels remained unchanged throughout the observation period. There was a modest increase in serum retinol levels during the study, especially after three months (from 1.48 +/- 0.84 mumol/L [42.3 +/- 24.1 micrograms/dL] to 2.22 +/- 0.77 mumol/L [63.5 +/- 22.1 micrograms/dL]). We conclude that while a short course of mineral oil can induce a reduction in the serum level of beta-carotene, the treatment has no adverse effect on serum levels of retinol and alpha-tocopherol.

Determination of retinol, alpha-tocopherol, and beta-carotene in serum by liquid chromatography with absorbance and electrochemical detection.

We describe a method for the determination of retinol, alpha-tocopherol, and beta-carotene in serum, using a liquid-chromatographic separation with wavelength-programmed ultraviolet/visible absorbance and amperometric electrochemical detection with a glassy carbon electrode. After protein denaturation and addition of an internal standard, tocol, 250-microL samples are twice extracted with hexane. The reversed-phase, gradient-elution chromatographic separation provides baseline resolution of: the all-trans isomer of retinol from the cis isomers, alpha- from gamma-tocopherol, and all-trans-beta-carotene from alpha-carotene and from cis-beta-carotene isomers. The linearity of response and the detection limits for the two detectors for the three analytes are measured. A comparison of the values obtained for serum extracts shows good agreement between the absorbance and electrochemical detectors.

The effect of beta-carotene on BP-induced respiratory tract tumors in hamsters.

The modifying effect of beta-carotene on benzo[a]pyrene (BP)-induced tumors of the respiratory tract was investigated in Syrian hamsters. Groups of hamsters were fed a semisynthetic diet supplemented with either no or 56 mg/kg beta-carotene. Respiratory tract tumors were induced by intratracheal instillation of BP attached to ferric oxide. The beta-carotene and vitamin A contents of the liver were increased in the high beta-carotene group, but the serum beta-carotene levels were very low when compared with those commonly observed in humans. beta-Carotene supplementation did not affect the tumor response of the respiratory tract. Neither the incidence and severity of preneoplastic changes were influenced. However, there was a statistically significant inverse relationship between serum retinol content and the presence of respiratory tract tumors in survivors, regardless of the dietary treatment.

Serum beta-carotene, vitamins A and E, selenium, and the risk of lung cancer.

We studied the relation of serum vitamin A (retinol), beta-carotene, vitamin E, and selenium to the risk of lung cancer, using serum that had been collected during a large blood-collection study performed in Washington County, Maryland, in 1974. Levels of the nutrients in serum samples from 99 persons who were subsequently found to have lung cancer (in 1975 to 1983) were compared with levels in 196 controls who were matched for age, sex, race, month of blood donation, and smoking history. A strong inverse association between serum beta-carotene and the risk of squamous-cell carcinoma of the lung was observed (relative odds, 4.30; 95 percent confidence limits, 1.38 and 13.41). Mean (+/- SD) levels of vitamin E were lower among the cases than the controls (10.5 +/- 3.2 vs. 11.9 +/- 4.90 mg per liter), when all histologic types of cancer were considered together. In addition, a linear trend in risk was found (P = 0.04), so that persons with serum levels of vitamin E in the lowest quintile had a 2.5 times higher risk of lung cancer than persons with levels in the highest quintile. These data support an association between low levels of serum vitamin E and the risk of any type of lung cancer and between low levels of serum beta-carotene and the risk of squamous-cell carcinoma of the lung.

Cancer of the cervix uteri and vitamin A.

The concentrations of retinol and beta carotene were measured in serum samples taken from 113 women with cervical cancer, 32 with invasive and 81 with pre-invasive disease, and compared with those from 226 age-matched control women. There was little difference in serum retinol levels between women with cancer of the cervix, at any stage, and the control women, after adjusting for potential confounding factors. Serum beta carotene concentrations were likewise similar in women with invasive disease and the controls. However mean beta carotene levels were significantly reduced in women with pre-invasive disease compared to the controls (221.3 cf. 291.6 micrograms l-1, P less than 0.05). This reduction was more evident amongst women with a diagnosis of carcinoma-in-situ (mean 213.1 micrograms l-1 than amongst those with severe dysplasia (mean 228.7 micrograms l-1. There is a negative trend between beta carotene and risk of pre-invasive disease which is of borderline significance. These data have also been used to investigate the effects of smoking and oral contraceptive usage on the serum levels of retinol and beta carotene. Both habits tend to increase retinol and decrease beta carotene concentrations.

Comparative Reliability of d-Xylose Absorption and Serum β-Carotene Measurements in Small Intestinal Disease

Comparative reliability of D-xylose absorption and serum beta-carotene measurements was studied in 63 healthy and sick children suspected of having proximal small intestinal disease. Group 1 included children with newly diagnosed celiac disease (CD) who were on a normal diet (xylose, n = 46; carotene, n = 43); group 2 included children with CD in remission (xylose, n = 17; carotene, n = 15); group 3 included children with CD in remission, but who were exposed to a gluten-containing diet for an average of 1.4 years (xylose, n = 19; carotene, n = 17); and group 4 included 17 healthy children, insofar as this study is concerned, in whom serum carotene was examined. The means of serum xylose of groups 1 and 3 were significantly lower than the mean of group 2 (p less than 0.001 in both cases). D-Xylose had a sensitivity of 76.9% and a specificity of 100%. The mean serum carotene concentration for group 2 patients with CD in remission was equal to the mean of group 4, which included healthy children. The means of groups 1 and 3 were significantly lower than the means of groups 2 and 4 (p less than 0.001 in all cases). Serum beta-carotene had a sensitivity of 95% and a specificity of 87.5%. The use of these two serum tests in combination would give a specificity of 100% and a sensitivity of 94.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary beta-carotene on the survival of young and old mice.

Feeding 0.5% beta-carotene in the diet for life beginning at 29 days of age improved the average life span of C57BL/6J male mice by 5.0% but decreased the life span of mice started at 608 days of age by 11.5%. Neither difference, however, proved to be statistically significant. Feeding beta-carotene increased the concentration of beta-carotene in the serum by 60% but did not change the beta-carotene content of heart, liver or kidney. We conclude that singlet oxygen, which is very efficiently quenched by beta-carotene, is an important factor in senescence only if it is produced at organ sites not accessible to serum beta-carotene. Since we have found that beta-carotene feeding is not a useful means for increasing tissue concentrations of beta-carotene, other more sophisticated means must be developed for accomplishing this purpose. It is also clear that while dietary beta-carotene is not an effective means for prolonging life span, it is nontoxic when fed continuously at high concentrations.

Separation and quantitation of serum beta-carotene and other carotenoids by high performance liquid chromatography.

We describe a specific assay for serum provitamin A (alpha- and beta-carotene) by high pressure liquid chromatography (HPLC). The system separates alpha- and beta-carotene in 7.4 min using a C18 muBondapak, 10-micron particle size column with a mobile phase of acetonitrile-chloroform 92:8 at 2 ml per min and a 462 nm detector. The HPLC assay had a recovery of 94.8% of added beta-carotene and, at a serum concentration of 215.2 micrograms/L, had within-run and between-run precisions of 3.1% and 3.6%, respectively. In 65 subjects, the HPLC-determined provitamin A (alpha- and beta-carotene) value was 343 +/- 166 micrograms/L and averaged 23.4 +/- 7.9% (range 9-43%) of the values obtained by a traditional colorimetric assay for total serum "carotenes." Although total serum carotenes showed no relationship to serum vitamin A (r = -0.048; P = 0.78), HPLC-determined alpha- and beta-carotene was significantly inversely correlated (r = -0.357; P = 0.05).

Beta-carotene determined in serum by liquid chromatography with an internal standard.

We describe a procedure for quantitative determination of beta-carotene in human serum. The 0.1-mL serum sample is precipitated with ethanol containing the internal standard, dimethyl-beta-carotene, then extracted with hexane. This extract is injected onto a reversed-phase, "high-performance" liquid-chromatography column, and the carotenes are resolved and eluted with an acetonitrile/methylene chloride isocratic solvent system. They are quantified from the peak-height ratios of their absorbance at 450 nm. About 14 min is required for each chromatogram. The procedure has excellent precision and is appropriate for routine use in analysis of large numbers of samples. The method should be particularly useful for clinical studies on the relationship of serum beta-carotene and cancer incidence in human populations.

Skin content and plasma transport of vitamin A and beta-carotene in chronic renal failure.

The serum and cutaneous concentrations of beta-carotene and vitamin A and the serum concentrations of retinal-binding protein (RBP) and prealbumin were investigated in ten patients with chronic renal failure. The serum beta-carotene concentration was lower in the patients 1.3 +/- 0.7 mumol/l) than in the twenty-two healthy controls (2.4 +/- 0.9; P less than 0.01). The skin carotene concentration was also lower in patients than in controls (18.7 +/- 5.5 v. 24.6 +/- 9.9 nmol/g protein; P less than 0.05). By contrast, the patients' mean concentration of vitamin A in the skin was twice that of the healthy controls (11.0 +/- 4.8 v. 5.9 +/- 1.4 nmol/g protein; P less than 0.005) and in serum 3 times that of the controls (4.8 +/- 1.7 v. 1.8 +/- 0.3 mumol/l; P less than 0.001). The increase of serum vitamin A was accompanied by a rise in the RBP concentration, but the concentrations of vitamin A-esters and prealbumin remained in the normal range. It is suggested that vitamin A may accumulate in the skin as a result of an increased transfer of the vitamin by RBP. A possible relationship between high skin levels of vitamin A and uraemic skin symptoms is discussed.

Vitamin A and the susceptibility of respiratory tract tissues to carcinogenic insult.

The influence of vitamin A on the development of chemically induced lung carcinomas in rats was investigated. Rats were maintained on low, "normal" and excess levels of retinyl acetate (RA). Respiratory tract-squamous carcinomas were induced by intratracheal injections of 3-methylcholanthrene (3-MCA). The carcinogen doses used ranged from 1.25 to 10.0 mg of 3-MCA. Serial sacrifices conducted during the first 20 weeks following carcinogen exposure showed that metaplastic lung nodules, presumed to be precursors of later appearing carcinomas, occurred earlier and at higher incidence in rats maintained on low levels of RA than in rats maintained on moderate or high levels of RA. The development of invasive pulmonary carcinomas was enhanced at all four carcinogen doses in rats receiving low levels of RA as compared to rats receiving moderate or high levels of RA. No consistent difference in lung cancer incidence existed between the groups receiving normal and high levels of RA. The data clearly show an increased susceptibility of vitamin A-deficient rats to develop chemically induced lung cancers. Possible mechanisms underlying this effect are discussed.

Transport of Beta-Carotene in Serum of Individuals with Carotenemia

Abstract We studied distribution of carotene in the various serum lipid fractions of carotenemic and noncarotenemic individuals. We found that the amount of carotene in each lipoprotein fraction is increased in the serum from carotenemic individuals, but that the relative increase is significant only in the low-density lipoprotein and high-density lipoprotein fractions. There was no significant difference between the cholesterol concentrations of each fraction of the carotenemic individuals' and noncarotenemic individuals' sera, indicating that serum betalipoprotein is not increased in carotenemia.