The bioavailability of iron picolinate is comparable to iron sulfate when fortified into a complementary fruit yogurt: a stable iron isotope study in young women.

PURPOSE: A technological gap exists for the iron (Fe) fortification of difficult-to-fortify products, such as wet and acid food products containing polyphenols, with stable and bioavailable Fe. Fe picolinate, a novel food ingredient, was found to be stable over time in this type of matrix. The objective of this study was to measure the Fe bioavailability of Fe picolinate in a complementary fruit yogurt. METHODS: The bioavailability of Fe picolinate was determined using stable iron isotopes in a double blind, randomized cross-over design in non-anemic Swiss women (n = 19; 25.1 ± 4.6 years). Fractional Fe absorption was measured from Fe picolinate (2.5 mg 57Fe per serving in two servings given morning and afternoon) and from Fe sulfate (2.5 mg 54Fe per serving in two servings given morning and afternoon) in a fortified dairy complementary food (i.e. yogurt containing fruits). Fe absorption was determined based on erythrocyte incorporation of isotopic labels 14 days after consumption of the last test meal. RESULTS: Geometric mean (95% CI) fractional iron absorption from Fe picolinate and Fe sulfate were not significantly different: 5.2% (3.8-7.2%) and 5.3% (3.8-7.3%) (N.S.), respectively. Relative bioavailability of Fe picolinate versus Fe sulfate was 0.99 (0.85-1.15). CONCLUSION: Therefore, Fe picolinate is a promising compound for the fortification of difficult-to-fortify foods, to help meet Fe requirements of infants, young children and women of childbearing age.

A reduced carbohydrate diet improves glycemic regulation in hyperglycemic older people in a retirement home: The SAGE study.

Poor glucose regulation associated with gradual insulin resistance is a significant risk factor in several age-related chronic diseases. An eating plan that promotes a lower carbohydrate intake may have a beneficial effect on glucose metabolism. This study aimed to evaluate how a diet reduced carbohydrate by 32% (RCHO) over a 2-month period would influence the metabolic profile of older individuals (N = 24) living in a retirement home (RH). A continuous glucose monitor was used to measure blood glucose during four periods: the standard diet before (baseline) and after (washout) the intervention, during the 4 initial days of the RCHO diet (RCHO-early), and the final days of the 2-month intervention (RCHO-end). The blood metabolic profile was also measured (glucose, ketones, insulin, triglycerides and cholesterol). RCHO intake decreased average blood glucose compared to the standard diet in hyperglycemic participants: RCHO-early 7.8 ± 1.0 vs 7.5 ± 1.1 mM (p = 0.012) and RCHO-end 7.8 ± 1.0 vs 7.0 ± 0.9 mM (p = 0.050). In the hyperglycemic participants, the percentage of time spent in hyperglycemia (> 10.0 mM) decreased by 50% during the RCHO-early (p = 0.012) and by 66% at RCHO-end (p = 0.021) compared to baseline. Glycated hemoglobin was significantly lower at RCHO-end in both hyperglycemic and normoglycemic participants compared to baseline (p < 0.008). Plasma ketones increased 3-fold in hyperglycemic participants at RCHO-end compared to baseline (p < 0.028). This study shows that an RCHO diet has metabolic health benefits in an older population and confirms its safety, tolerability, and acceptability in a RH. (NCT06022094).

Effects of protein quantity and type on diet induced thermogenesis in overweight adults: A randomized controlled trial.

BACKGROUND & AIMS: Protein content of a meal is hypothesized to drive DIT dose-dependently. However, no single meal study exists comparing two different doses of protein on DIT. In addition, the source of protein, particularly whey protein, was shown to have a higher DIT than casein and soy in the acute setting, however the mechanism behind this difference is not yet clear. The aim of the present work is therefore to evaluate the efficacy of two different doses and types of protein (whey protein and casein) on DIT in overweight adults. METHODS: Randomized, double blind crossover including seventeen overweight men and women assigned to four isocaloric study treatments where protein and carbohydrate were exchanged: control, 30 g of whey protein microgels (WPM30), 50 g WPM (WPM50) or 50 g micellar casein (MC50). Energy expenditure was measured by indirect calorimetry. Blood, breath and urine samples were collected in order to measure substrate oxidation, amino acid profile, glucose and insulin, protein turnover and other metabolic parameters. RESULTS: DIT was 6.7 ± 3.7%, 13.0 ± 5.0%, 18.0 ± 5.0% and 16.0 ± 5.0% for control, WPM30, WPM50 and MC50, respectively. There was a significant difference between WPM50 and WPM30 (p < 0.005) and a trend was observed between WPM50 and MC50 (p = 0.06). WPM50 resulted in the highest total, essential, and branched-chain plasma amino acid concentrations when compared with the other study treatments (p < 0.005) and a higher insulin concentration than MC50 (p < 0.005). Protein oxidation was higher for WPM50 than MC50. Protein turnover was significantly correlated with DIT through total leucine oxidation (r = 0.52, p = 0.005). CONCLUSIONS: Our findings show that DIT does increase at a dose beyond 30 g of WPM and that the type of dairy protein may have an effect on DIT with WPM tending towards a higher DIT than casein. Although further research is required to understand the mechanism behind the effect of different protein sources on thermogenesis, we suggest that amongst the components of protein turnover, protein oxidation may be an important driver of thermogenesis at doses higher than 30 g. These results have concrete implications when choosing a dose of protein to optimize its thermogenic effect. CLINICAL TRIAL REGISTRY NUMBER: NCT02303080 www.clinicaltrials.gov.