From carotenoid intake to carotenoid blood and tissue concentrations – implications for dietary intake recommendations

Abstract

There is uncertainty regarding carotenoid intake recommendations, because positive and negative health effects have been found or are correlated with carotenoid intake and tissue levels (including blood, adipose tissue, and the macula), depending on the type of study (epidemiological vs intervention), the dose (physiological vs supraphysiological) and the matrix (foods vs supplements, isolated or used in combination). All these factors, combined with interindividual response variations (eg, depending on age, sex, disease state, genetic makeup), make the relationship between carotenoid intake and their blood/tissue concentrations often unclear and highly variable. Although blood total carotenoid concentrations <1000 nmol/L have been related to increased chronic disease risk, no dietary reference intakes (DRIs) exist. Although high total plasma/serum carotenoid concentrations of up to 7500 nmol/L are achievable after supplementation, a plateauing effect for higher doses and prolonged intake is apparent. In this review and position paper, the current knowledge on carotenoids in serum/plasma and tissues and their relationship to dietary intake and health status is summarized with the aim of proposing suggestions for a “normal,” safe, and desirable range of concentrations that presumably are beneficial for health. Existing recommendations are likewise evaluated and practical dietary suggestions are included.

Dietary β-Cryptoxanthin and α-Carotene Have Greater Apparent Bioavailability Than β-Carotene in Subjects from Countries with Different Dietary Patterns

“…These carotenoids profile proportions follow the same pattern in dietary intake as in blood (β-carotene > β-cryptoxanthin > α-carotene). There was a correlation between α-carotene and β-carotene in dietary intake and blood concentrations as in other studies [56], as can be expected because both are supplied by the major dietary food contributors (Table 3) and are often found in the same foods [3]. In contrast, β-cryptoxanthin is mainly supplied by red-orange fruits and juices [3,5].…”

“…A similar pattern was found in the mean values of the compiled studies, 60% β-carotene, 25% β-cryptoxanthin and 15% α-carotene. Although the proportions of β-cryptoxanthin and α-carotene in blood are similar in some studies [39,45,55], in others, β-cryptoxanthin concentration is higher than that of α-carotene in blood but not in the dietary intake [56], or the percentage of blood β-cryptoxanthin is half that of α-carotene [48] and β-cryptoxanthin is slightly higher than β-carotene [37]. These differences are clearly seasonal in some population groups [8,56] but could also be due to factors related to the subjects included in the studies since, although in general, no characteristics were reported that could affect carotenoid metabolism, there could be exceptions.…”

“…Although the proportions of β-cryptoxanthin and α-carotene in blood are similar in some studies [39,45,55], in others, β-cryptoxanthin concentration is higher than that of α-carotene in blood but not in the dietary intake [56], or the percentage of blood β-cryptoxanthin is half that of α-carotene [48] and β-cryptoxanthin is slightly higher than β-carotene [37]. These differences are clearly seasonal in some population groups [8,56] but could also be due to factors related to the subjects included in the studies since, although in general, no characteristics were reported that could affect carotenoid metabolism, there could be exceptions. For instance, carotenoid concentrations in blood may be not comparable in normo-or hypercholesterolemic subjects [26,28] or in subjects with deficient or adequate vitamin A nutritional status, as their conversion into retinol depends on retinol concentration in the bloodstream, among other factors [14,17].…”

“…In this study, we approached the bioavailability assessment of the individual provitamin A carotenoids by means of their dietary intake and concentrations in blood in apparently healthy and normolipemic adults (age 20-75) and identified their major food contributors in their dietary intake. Dietary intake showed a wide range of concentrations, mainly for β-carotene, as described in other studies [8,27,56], and we therefore reported the median intake values to gain a more realistic idea of the intake. However, in the literature, mean rather than median values are typically reported as can be observed from the data compiled in Table 2, sometimes making it difficult to draw comparisons.…”

β-Carotene in the human body: metabolic bioactivation pathways – from digestion to tissue distribution and excretion

“…However, highly dosed supplemental use of β-carotene has been correlated with smokers with negative outcomes, increasing total mortality ( 9 , 10 ) and enhancing lung cancer rate ( 11 , 12 ) . While nutritional relevant levels of β-carotene have been in the range of 0·1–8·8 (median 3·9) mg/d as reviewed recently ( 13 ) , isolated administered β-carotene at rather high doses (>30 mg/d) may initiate previously mentioned negative effects. The reasons for these negative effects are not entirely clear but indicate that such high levels of β-carotene, which are usually non-harmful, may affect precancerous lesions, which are a hallmark of cancer development, and result from smoking ( 14 ) .…”