Biomarkers of carotenoid bioavailability.

The use of biomarkers constitutes an essential tool to assess the bioavailability of carotenoids in humans. The present article aims to review several methodological, host-related and modulating factors relevant on assessing and interpreting carotenoid bioavailability. Markers for carotenoid bioavailability can be broadly divided into direct, biochemical or "analytical" markers and indirect, physiological or "functional" indicators. Analytical markers usually refer to biochemical indicators of intake and/or status (short and long term exposure) while functional measures may be interpreted in terms of cumulative exposure, biological effect (bioactivity) or modification of risk factors. Both types of markers display advantages and limitations but, in general, a relationship exists among the type of marker, the biological specimen needed and the time required for a change. Humans may absorb a wide range of carotenes and xanthophylls and many of them may be found in serum and tissues. However, under physiological conditions, the several classes of dietary carotenoids may behave unequally leading to a different systemic profile and, moreover, they can be selectively accumulated at target tissues. In addition, some carotenoids may be chemically and enzymatically modified generating different oxidative metabolites and apocarotenoids. Quantitatively, the biological response upon carotenoid intervention (assessed by analytical and functional markers) is highly variable but the use of large doses and long-term protocols may lead to saturation effects and the loss of linearity in the response. Also, despite carotenoid exposition is considered to be safe, markers of overexposure include clinical signs (i.e. carotenodermia, corneal rings and retinopathy) and biochemical indicators (hypercarotenemia, xanthophyll esters). Overall, both host-related and methodological factors may influence analytical and functional markers to assess carotenoid bioavailability although the different subclasses of carotenoids may not be equally affected.

Prevalence of hypercalcemia related to hypervitaminosis D in clinical practice.

BACKGROUND & AIMS: Recent interest in vitamin D has led to a substantial increase in the use of vitamin D supplements. Vitamin D intoxication may be a concern as hypervitaminosis D can result in irreversible calcification of soft tissues so that it is important to detect early markers of vitamin D intoxication. Our aim was to assess the simultaneous presence of biochemical markers of vitamin D toxicity (i.e. hypervitaminosis D, hypercalcemia) and determine the concentrations of 25-OH-vitamin D at which the risk of hypercalcemia, and thus toxicity, might begin. METHODS: We evaluated retrospectively a 6-year period during which 25.567 samples were assessed for 25-OH-vitamin D status by UHPLC. Hypervitaminosis D was defined at serum 25-OH-vitamin D >160 nmol/L. Serum and urine calcium, phosphorus and iPTH were also recorded, if available. Medical history revision was performed in subjects displaying simultaneously hypervitaminosis D and hypercalcemia. RESULTS: Overall, hypervitaminosis D was found in 475 samples (1.86%) of which 51 displayed hypercalcemia (11.1%). A total of 382 samples were identified as the first record of hypervitaminosis D and 39 presented hypercalcemia (10.2%), most of them at 25-OH-vitamin D levels between 161 and 375 nmol/L. Only in 15 subjects, hypercalcemia could be directly attributed to vitamin D and serum 25-OH-vitamin D ranged between 164 and 1139 nmol/l. In no case, serum calcium achieved concentrations considered as critical values (>13 mg/dl). CONCLUSION: Hypercalcemia due to vitamin D represented <4% of the total hypervitaminosis D detected and <0.1% of the tests performed. However, a highly variable response was observed and most subjects presented hypercalcemia at serum concentrations of 25-OH-vitamin D < 375 nmol/L.

ß-Cryptoxanthin modulates the response to phytosterols in post-menopausal women carrying NPC1L1 L272L and ABCG8 A632 V polymorphisms: an exploratory study.

Phytosterol (PS) intake may be used for hypercholesterolaemia in some groups although the presence of non-responders is well known. Carotenoids and PS/cholesterol may compete for the same transporters during absorption. As part of a randomized, double-blind, crossover, multiple-dose supplementation study with ß-cryptoxanthin (ß-Cx) and PS, single and combined, polymorphisms of ABCG8 (A632V) and NCPL1 (L272L) were determined in 19 post-menopausal women. Subjects carrying CC polymorphism for NCP1L1 (L272L) showed a net increase in total cholesterol and LDL after PS intake but, interestingly, displayed a decrease in both lipid fractions after consuming PS plus ß-Cx. For the ABCG8 (A632V) gene, CT/TT carriers consuming PS also displayed an increase in total cholesterol and LDL, but this increment was much lower after the intake of PS plus ß-Cx. Additionally, in CC carriers for ABCG8 (A632V), a greater decrease in total cholesterol and LDL was found after the intake of PS plus ß-Cx compared to that observed after PS alone. Overall, our results suggest that ß-Cx improves the response to PS in individuals carrying specific genetic polymorphisms (i.e. non-responders), opening the possibility to modulate the response to PS by food technology. (ClinicalTrials.gov NCT01074723).

Effect of ß-cryptoxanthin plus phytosterols on cardiovascular risk and bone turnover markers in post-menopausal women: a randomized crossover trial.

BACKGROUND AND AIM: Post-menopausal women are at higher risk of cardiovascular disease and bone demineralization. Phytosterols (PS) may be used for hypercholesterolemia in some groups and ß-cryptoxanthin (ß-Cx) displays a unique anabolic effect on bone. Our aim was to assess the changes in cardiovascular and bone turnover markers from the oral intake of ß-Cx and PS in post-menopausal women. METHODS AND RESULTS: A randomized, double-blind, crossover study with ß-Cx (0.75 mg/day) and PS (1.5 g/day), single and combined, was performed in 38 postmenopausal women. Diet was supplemented with 1 × 250 mL milk-based fruit drink/day for 4 weeks with a wash-out period of 4-weeks in between. Serum ß-Cx and PS were determined by UPLC and CG-FID respectively. Outcome variables included markers of bone turnover and cardiovascular risk. Biological effect was assessed by paired t test and generalized estimating equations analysis that included the previous treatment, the order of intervention and the interactions. The intake of beverages containing ß-Cx and PS brought about a significant increase in serum levels of ß-Cx, ß-sitosterol and campesterol. Intervention caused changes in almost all the markers while the order, previous treatment and the interaction did not reach statistical significance. Only the intake of the beverage containing ß-Cx plus PS brought about significant decreases in total cholesterol, c-HDL, c-LDL and bone turnover markers. CONCLUSIONS: ß-Cx improves the cholesterol-lowering effect of PS when supplied simultaneously and this combination may also be beneficial in reducing risk of osteoporosis. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov number NCT01074723.

Independent sources of condition dependency and multiple pathways determine a composite trait: lessons from carotenoid-based plumage colouration.

Many colour ornaments are composite traits consisting of at least four components, which themselves may be more complex, determined by independent evolutionary pathways, and potentially being under different environmental control. To date, little evidence exists that several different components of colour elaboration are condition dependent and no direct evidence exists that different ornamental components are affected by different sources of variation. For example, in carotenoid-based plumage colouration, one of the best-known condition-dependent ornaments, colour elaboration stems from both condition-dependent pigment concentration and structural components. Some environmental flexibility of these components has been suggested, but specifically which and how they are affected remains unknown. Here, we tested whether multiple colour components may be condition dependent, by using a comprehensive 3 × 2 experimental design, in which we carotenoid supplemented and immune challenged great tit nestlings (Parus major) and quantified effects on different components of colouration. Plumage colouration was affected by an interaction between carotenoid availability and immune challenge. Path analyses showed that carotenoid supplementation increased plumage saturation via feather carotenoid concentration and via mechanisms unrelated to carotenoid deposition, while immune challenge affected feather length, but not carotenoid concentration. Thus, independent condition-dependent pathways, affected by different sources of variation, determine colour elaboration. This provides opportunities for the evolution of multiple signals within components of ornamental traits. This finding indicates that the selective forces shaping the evolution of different components of a composite trait and the trait's signal content may be more complex than believed so far, and that holistic approaches are required for drawing comprehensive evolutionary conclusions.

Serum levels of 3-epi-25-OH-D3 during hypervitaminosis D in clinical practice.

CONTEXT: Intoxication from vitamin D supplements has been rarely reported, but nowadays, it occurs more frequently. The presence of the C-3 epimer of 25-hydroxyvitamin D(3) (3-epi-25-OH-D(3)) is highly prevalent in adults, although there is little information regarding its in vivo relevance, if any, especially under pathological conditions. OBJECTIVE: Our aim was to assess the presence of the 3-epi-25-OH-D(3) in serum samples displaying 25-OH-D(3) concentrations indicative of hypervitaminosis D. DESIGN, SETTING, PATIENTS, AND MAIN OUTCOME MEASURE: A total of 58 samples displaying a wide range of concentrations of 25-OH-D(3) (>64-439 ng/ml) by ultrafast liquid chromatography were consecutively recruited and reassessed for the presence of 3-epi-25-OH-D(3) using a second chromatographic system. Data from additional biochemical tests performed as part of the patient evaluation were also recorded. RESULTS: Mean relative contribution of 3-epi-25-OH-D(3) was less than 4%, and concentrations ranged from 2-28.6 ng/ml. Serum levels of the C3 epimer, but not the relative contribution, correlate with serum 25-OH-D(3). Overall, in subjects with 25-OH-D(3) concentrations indicative of hypervitaminosis D, the presence of the C-3 epimer and its levels were apparently unrelated to age, serum markers of renal and liver function, acute-phase reactants, and the presence of hypercalcemia. 3-Epi-25-OH-D(3) did not correlate with PTH, but subjects displaying PTH suppression (<14 pg/ml) showed higher concentrations of 3-epi-25-OH-D(3). CONCLUSION: The relative contribution of 3-epi-25-D(3) was not significantly altered during hypervitaminosis D, although the absolute levels reached in serum may be biologically relevant. From a clinical viewpoint, although the small size of the group may affect the lack of relationships, the presence of 3-epi-25-OH-D(3) was apparently unrelated to serum markers of renal and liver function, acute-phase reactants, PTH, and the presence of hypercalcemia.

Hypercalcemia, hypervitaminosis A and 3-epi-25-OH-D3 levels after consumption of an "over the counter" vitamin D remedy. a case report.

Intoxication from vitamin D supplements has been rarely reported but, nowadays, it occurs more frequently. 3-epi-25-OH-D(3) is highly prevalent in adults and it is considered of biological relevance. We report a case of vitamin D toxicity with hypercalcemia, acute renal failure and hypervitaminosis A after consuming an over-the-counter vitamin D supplement. Our data suggest that the contribution of 3-epi-25-OH-D(3) is not altered during vitamin D toxicity, although the serum levels of 25-OH-D(3) and 3-epi-25-OH-D(3) may display a different rate of clearance. The patient also displayed hypervitaminosis A unrelated to diet, possibly caused by renal failure related to the hypercalcemia induced by vitamin D toxicity. Because of the increasing use of over-the-counter vitamin D supplements and the potential iatrogenic hypercalcemia related to hypervitaminosis A, the present case highlights the importance of evaluating both the use of (non-) prescribed medication and vitamin A status during vitamin D toxicity.

Bioavailability of carotenoids and alpha-tocopherol from fruit juices in the presence of absorption modifiers: in vitro and in vivo assessment.

The food industry is playing an increasing role in the development and marketing of new products although little is known regarding the bioavailability of the phytochemicals they contain. Our aim was to assess the effect of the presence of absorption modifiers (milk and iron) on the in vitro bioaccessibility and the serum response in vivo of carotenoids and alpha-tocopherol from fruit juices. Thirty-two young women participated in a three-period (21 d each) supplementation study with a 2-week wash-out in between. Subjects consumed consecutively 2 x 250 ml/d vitamin C-fortified juices supplied as fruit juice, fruit juice containing milk and fruit juice containing milk and iron. Fasting blood samples were collected before and after each supplementation period. In vitro bioaccessibility of carotenoids and alpha-tocopherol was assessed by a static digestion model. Vitamin E and carotenoids from both studies were determined by HPLC. In vitro, xanthophyll ester hydrolysis and transference of free xanthophylls and alpha-tocopherol into the micellar phase were higher in the presence of absorption modifiers. In vivo, consumption of the fruit juices provoked significant increments (within-subject) of alpha-tocopherol and some carotenoids in serum. Dose-adjusted increments in serum of some carotenoids were higher when subjects consumed juices with milk and milk plus iron, although differences did not reach statistical significance. In conclusion, the presence of milk and milk plus iron do not influence the bioavailability of carotenoids and alpha-tocopherol from fruit juices in vivo. Our results support the use of in vitro models to assess food-related factors affecting bioavailability of carotenoids and tocopherols from foods.

Hypocarotenemia after bariatric surgery: a preliminary study.

BACKGROUND: Dietary carotenoids have attracted a great deal of attention due to their potential clinical relevance in conditions such as age-related maculopathy, osteoporosis, cardiovascular disease, and cancer. Surgical procedures have become the primary treatment of severe obesity, although nutrient deficiencies are common and long-term metabolic sequelae remain unknown. Thus, our aim was to assess the carotenoid status in serum of subjects after obesity surgery. METHODS: We evaluated the status of lutein, zeaxanthin, alpha- and beta-cryptoxanthin, lycopene, alpha- and beta-carotene, and fat-soluble vitamins by a quality-controlled high-performance liquid chromatography method in serum of 53 patients. Subjects were consecutively included as they were monitored for nutritional status after Roux-en-Y gastric bypass (RYGBP) or biliopancreatic diversion (BPD). Average follow-up time was 18 and 14 months for each protocol, respectively. RESULTS: After obesity surgery, a consistent and continuous decline in all carotenoids to almost undetectable levels occurs, especially in those who underwent BPD diversion who, on average, displayed serum levels about one half to one third of those found in RYGBP patients. CONCLUSION: The hypocarotenemia observed after bariatric surgery may compromise the availability of carotenoids to tissues and the vitamin A status, reducing the fat-soluble antioxidant capacity and constituting an additional risk factor for several clinical conditions. Given the emerging role of carotenoids in disease prevention, dietary advice on carotenoid-rich and fortified foods or the use of supplements in these patients should be considered.

Seasonal variation of serum alpha- and beta-cryptoxanthin and 25-OH-vitamin D(3) in women with osteoporosis.

UNLABELLED: beta-Cryptoxanthin displays a unique anabolic effect on bone calcification. In women with osteoporosis, serum beta-cryptoxanthin and 25-OH-vitamin D(3) showed a weak but significant correlation and exhibited a complementary seasonal distribution. The potential role of beta-cryptoxanthin as a nutritional approach to improving bone health deserves further evaluation. INTRODUCTION: Dietary intake and serum levels of beta-cryptoxanthin have been inversely related to different bone and joint disorders and in vitro and animal studies have shown that beta-cryptoxanthin displays a unique anabolic effect on bone calcification. Due to the emerging role of beta-cryptoxanthin in bone biology, we aimed to assess the serum distribution and variability of beta-cryptoxanthin and their potential relation to 25-OH-vitamin D(3) in women with osteoporosis. METHODS: Serum concentrations of alpha- and beta-cryptoxanthin and 25-OH- D(3) in women with osteoporosis (N = 644) were analyzed using a quality-controlled high-performance liquid chromatography (HPLC) method. RESULTS: Overall, significant seasonal variations were found for the three analytes and inter-individual variation was also high (60-73%). beta-cryptoxanthin and 25-OH-vitamin D(3) exhibited a marked complementary seasonal distribution in serum, with vitamin D displaying the highest values in summer and beta-cryptoxanthin in winter. CONCLUSIONS: Given the anabolic effect of beta-cryptoxanthin on bone calcification and its complementary seasonal distribution with respect to 25-OH-vitamin D(3), the potential role of beta-cryptoxanthin as a sustainable nutritional approach to improving bone health deserves to be further evaluated.