Effects of mayonnaise on postprandial serum lutein/zeaxanthin and beta-carotene concentrations in humans

Ingestion of vegetable salads before rice inhibits the increase in postprandial serum glucose levels in healthy subjects

This study aims to confirm the "vegetable-first" effect. In addition, because we aimed dietary fiber in vegetable salad, the effect after the ingestion of vegetable salad extract (vegetable salad from which solids have been removed) before carbohydrates on postprandial serum glucose level was also evaluated. A total of 13 healthy men were given meals after one-night of fasting: rice-vegetable salad, vegetable salad-rice, and vegetable salad extract-rice. Blood samples were taken at 0, 30, 45, 60, 90, and 120 min after the ingestion of the test meal to measure serum glucose levels. Serum glucose levels were significantly lower after 45 and 60 min in the vegetable salad-rice group compared to the rice-vegetable salad group. No significant difference was found between the vegetable salad extract-rice group and the vegetable salad-rice/rice-vegetable salad group. The result suggested that it might be important to ingest vegetables to obtain the "vegetable-first" effect.

Effects of dietary fats on the bioaccessibility and bioavailability of carotenoids: a systematic review and meta-analysis of in vitro studies and randomized controlled trials

CONTEXT

Dietary fats are one of the well-known stimulators of carotenoid absorption, but the effects of the quantity and the type of dietary fats on carotenoid absorption have not yet been studied systematically.

OBJECTIVE

This review aimed to analyze data from both in vitro studies and randomized controlled trials (RCTs) to examine the effects of dietary fats on the bioaccessibility and bioavailability of carotenoids.

DATA SOURCES

A systematic search of 5 databases (Scopus, PubMed, Embase, CINAHL and the Cochrane Library) was conducted.

STUDY SELECTION

In vitro studies and RCTs were selected according to the PICOS criteria and were reviewed independently by 2 investigators.

DATE EXTRACTION

Key study characteristics from the eligible in vitro studies and RCTs were extracted independently by 2 investigators using a standardized table.

RESULTS

A total of 27 in vitro studies and 12 RCTs were included. The meta-regression of in vitro studies showed that the bioaccessibility of carotenoids, except for lycopene, was positively associated with the concentration of dietary fats. The meta-analysis of RCTs showed that the bioavailability of carotenoids was enhanced when a higher quantity of dietary fats was co-consumed. Moreover, fats rich in unsaturated fatty acids resulted in greater improvement in carotenoid bioavailability (SMD 0.90; 95%CI, 0.69-1.11) as compared with fats rich in saturated fatty acids (SMD 0.27; 95%CI, 0.08-0.47).

CONCLUSIONS

Co-consuming dietary fats, particularly those rich in unsaturated fatty acids, with carotenoid-rich foods can improve the absorption of carotenoids.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42020188539.

The Influence of Iron and Zinc Supplementation on the Bioavailability of Provitamin A Carotenoids from Papaya Following Consumption of a Vitamin A-Deficient Diet

Iron deficiency anemia, zinc and vitamin A deficiencies are serious public health problems in Cameroon, as in many developing countries. Local vegetables which are sources of provitamin A carotenoids (PACs) can be used to improve vitamin A intakes. However, traditional meals are often unable to cover zinc and iron needs. The aim of this study was to determine the bioavailability of 3 PACs (α-carotene, β-carotene, and β-cryptoxanthin) in young men, who were fed with a vitamin A-free diet and received iron and zinc supplementation. Twelve healthy participants were divided into three groups and were supplemented with elemental iron (20 mg of iron fumarate), 20 mg of zinc sulfate or iron+zinc (20 mg of iron in the morning and 20 mg of zinc in the evening) for 11 d. They were given a vitamin A- and PAC-free diet from the 6th to the 11th day, followed by a test meal containing 0.55 kg of freshly peeled papaya as a source of PACs. Blood samples were collected four times successively on the 11th day (the test meal day), at T0 (just after the test meal), after 2 h (T2), after 4 h (T4) and after 7 h (T7). Ultracentrifugation was used to isolate serum chylomicrons. Retinol appearance and PAC postprandial concentrations were determined. The supplementation with zinc, iron and iron+zinc influenced the chylomicron appearance of retinol and PACs differently as reflected by retention times and maximum absorption peaks. Iron led to highest retinol levels in the chylomicron. Zinc and iron+zinc supplements were best for optimal intact appearance of α-carotene, β-carotene and β-cryptoxanthin respectively. Supplementation with iron led to the greatest bioavailability of PACs from papaya and its conversion to retinol.

Postprandial Paraoxonase 1 Activity Following Consumption of Recommended Amounts of Mixed Meals in Healthy Males

AIM

Postprandial lipid level increases induce oxidative stress, which is involved in atherogenesis. The antioxidant properties of paraoxonase 1 (PON1) have attracted attention. However, changes in postprandial PON1 levels differ across prior studies, and changes in PON1 lactonase activity, potentially relevant to PON1 physiology, after the consumption of ordinary meals are unknown. Herein we evaluated postprandial serum lipid levels and PON1 changes following mixed-meal consumption of the amounts recommended for ordinary meals.

METHODS

Nine healthy male volunteers consumed three different meals in a randomized cross-over design. The test meals were as follows: S, white rice; SMF, S with fat-containing protein-rich main dishes; and SMFV: SMF with vegetable dishes. The serum lipid concentrations and PON1 lactonase and arylesterase activities were determined during a three-hour period after the consumption of these meals.

RESULTS

The postprandial triglyceride levels were higher after consuming the SMF and SMFV meals than after consuming the S meal. Despite postprandial high-density lipoprotein cholesterol being unchanged, PON1 lactonase activity was decreased, while PON1 arylesterase activity was increased in the postprandial state after all test meals. Postprandial changes in lactonase and arylesterase activities did not differ among the test meals.

CONCLUSIONS

Inverse changes in PON1 lactonase and arylesterase activities were observed after consuming recommended ordinary meals. This observation provides useful information for choosing PON1 species as postprandial markers.

An Evidence-Based Systematic Review of Lutein by the Natural Standard Research Collaboration

An evidence-based systematic review of lutein by the Natural Standard Research Collaboration consolidates the safety and efficacy data available in the scientific literature using a validated, reproducible grading rationale. This article includes written and statistical analysis of clinical trials, plus a compilation of expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.