Alkalinization with potassium bicarbonate improves glutathione status and protein kinetics in young volunteers during 21-day bed rest.

BACKGROUND & AIMS: Physical inactivity is associated with lean body mass wasting, oxidative stress and pro-inflammatory changes of cell membrane lipids. Alkalinization may potentially counteract these alterations. We evaluated the effects of potassium bicarbonate supplementation on protein kinetics, glutathione status and pro- and anti-inflammatory polyunsaturated fatty acids (PUFA) in erythrocyte membranes in humans, during experimental bed rest. METHODS: Healthy, young, male volunteers were investigated at the end of two 21-day bed rest periods, one with, and the other without, daily potassium bicarbonate supplementation (90 mmol × d-1), according to a cross-over design. Oxidative stress in erythrocytes was evaluated by determining the ratio between reduced (GSH) and oxidized glutathione (GSSG). Glutathione turnover and phenylalanine kinetics, a marker of whole body protein metabolism, were determined by stable isotope infusions. Erythrocyte membranes PUFA composition was analyzed by gas-chromatography. RESULTS: At the end of the two study periods, urinary pH was 10 ± 3% greater in subjects receiving potassium bicarbonate supplementation (7.23 ± 0.15 vs. 6.68 ± 0.11, p < 0.001). Alkalinization increased total glutathione concentrations by 5 ± 2% (p < 0.05) and decreased its rate of clearance by 38 ± 13% (p < 0.05), without significantly changing GSH-to-GSSG ratio. After alkalinization, net protein balance in the postabsorptive state improved significantly by 17 ± 5% (p < 0.05) as well as the sum of n-3 PUFA and the n-3-to-n-6 PUFA ratio in erythrocyte membranes (p < 0.05). CONCLUSIONS: Alkalinization during long-term inactivity is associated with improved glutathione status, anti-inflammatory lipid pattern in cell membranes and reduction in protein catabolism at whole body level. This study suggests that, in clinical conditions characterized by inactivity, oxidative stress and inflammation, alkalinization could be a useful adjuvant therapeutic strategy.

Effect of Oral Docosahexaenoic Acid (DHA) Supplementation on DHA Levels and Omega-3 Index in Red Blood Cell Membranes of Breast Cancer Patients.

Rationale: Docosahexaenoic acid (DHA) in cell membrane may influence breast cancer (BC) patients' prognosis, affecting tumor cells sensitivity to chemo- and radio-therapy and likely modulating inflammation. The possibility of identifying BC patients presenting with low DHA levels and/or low ability of DHA incorporation into cell membrane might help to treat this condition. Methods: We enrolled BC patients and healthy controls, recording their seafood dietary intake. DHA in form of algal oil was administered for 10 consecutive days (2 g/day). Blood samples were collected at baseline (T0) and after 10 days of supplementation (T1) to assess DHA, omega-3 index, as the sum of DHA + eicosapentaenoic acid (EPA), in red blood cells (RBC) membranes and plasma tumor necrosis factor-alpha and interleukin-6 levels. Pre- and post-treatment fatty acid profiles were obtained by gas-chromatography. Parametric and non-parametric tests were performed, as appropriate, and P-value < 0.05 was considered statistically significant. Results: Forty-three women were studied, divided into 4 groups: 11 patients with BRCA1/2 gene mutation (M group), 12 patients with familiar positive history for BC (F group), 10 patients with sporadic BC (S group), and 10 healthy controls (C group). DHA and omega-3 index increased from T0 to T1 in the 3 groups of BC patients and in controls (P < 0.001). No difference was found in DHA incorporation between each group of BC patients and between patients and controls, except for M group, which incorporated higher DHA levels with respect to controls (ß = 0.42; P = 0.03). No association was documented between cytokines levels and DHA and omega-3 index at baseline and after DHA supplementation. Independent of the presence of BC, women considered as "good seafood consumers" showed at baseline DHA and omega-3 index higher with respect to "low seafood consumers" (P = 0.04; P = 0.007, respectively). After supplementation, the increase in DHA levels was greater in "low seafood consumers" with respect to "good seafood consumers" (P < 0.0001). Conclusion: DHA supplementation was associated with increased DHA levels and omega-3 index in RBC membranes of BC cancer patients, independent of the type of BC presentation, and in controls. BRCA1/2 mutation, as well as low seafood consuming habits in both BC patients and healthy controls, seem to be associated with greater ability of DHA incorporation. Larger samples of BC patients are necessary to confirm our observation.

Anabolic resistance assessed by oral stable isotope ingestion following bed rest in young and older adult volunteers: Relationships with changes in muscle mass.

BACKGROUND & AIMS: Aging and experimental bed rest are associated with muscle atrophy and resistance to post-prandial stimulation of protein synthesis or anabolic resistance (AR). We have used in young and older adult volunteers, during short-term bed rest, a quick and non-invasive method, based on a single oral bolus of the stable isotope L[ring-2H5]phenylalanine (D5Phe), to determine post-prandial AR, defined as ratio between irreversible hydroxylation and incorporation into body protein of ingested phenylalanine. METHODS: We compared in older (O, 59 ± 1 y) and young (Y, 23 ± 1 y) healthy male volunteers the effects of two-week bed rest on post-prandial protein kinetics, assessed during absorption of a standard ready-to-use oral nutritional supplement, through stable-labeled isotope amino acid D5Phe, diluted in water, given as single oral load. The metabolic fate of D5Phe is either utilization for protein synthesis or irreversible hydroxylation to L[ring-2H4]tyrosine (D4Tyr). AR was defined as ratio between the areas under the curves of D4Tyr-to-D5Phe plasma concentrations over 6 h meal absorption. To determine the relationships between AR and muscle changes following bed rest, quadriceps muscle volume (QMV) was determined by magnetic resonance imaging (MRI). RESULTS: At baseline, in pooled Y and O subjects, values of AR were inversely correlated with QMV (R = -0.75; p < 0.03). Following 2-weeks of inactivity, there were significant bed rest effects on AR (p < 0.01) and QMV (p < 0.03), as well as significant bed rest × group interaction for AR (p < 0.03; +9.2% in Y; +21.9% in O) and QMV (p < 0.05; -5.7% in Y; -%7.3 in O). In pooled subjects, the percentage delta changes in AR and QMV, induced by bed rest, were inversely correlated (R = -0.57; p < 0.05). CONCLUSION: Bed rest-induced AR is much greater in the older than in younger adults. We have developed a new, simple, non-invasive method for the assessment of AR. The results indicate that this metabolic abnormality is a key mechanism for sarcopenia of aging and inactivity.

Roasting intensity of naturally low-caffeine Laurina coffee modulates glucose metabolism and redox balance in humans.

OBJECTIVE: Coffee consumption is negatively associated with risk of type 2 diabetes and cardiovascular mortality. Coffee roasting can greatly modify the quality-quantitative characteristics of bioactive compounds. We compared the effects of two different roasting intensities of the same naturally low-caffeine Arabica coffee variety (Laurina) on glucose and lipid metabolism as well as oxidative stress. METHODS: We performed a double-blind, crossover intervention study. Fourteen healthy male volunteers consumed four cups daily of light roasted coffee (LRC) and dark roasted coffee (DRC), each for 1 wk (intervention period 1 and 2 respectively). One wk washout, with total abstinence from coffee and other possible caffeine sources, preceded each intervention. Data were collected at the end of washout and intervention periods. RESULTS: Changes between washout and intervention periods in glucose concentrations at 2 h post-oral glucose tolerance test, were significantly lower after DRC than LRC intake (-0.6 ± 0.3 and 0.4 ± 0.3 mmol/L, P < 0.03). Changes in ß-cell function, assessed as insulin secretion-sensitivity index-2, were significantly greater after DRC than LRC (34.7 ± 25.0 and -18.8 ± 21.0, P = 0.03). The initial (30 min) post-oral glucose tolerance test area under the curve of glucagon-like peptide-1 was 24± 9% greater (P = 0.03) after DRC than LRC. LRC or DRC did not affect insulin sensitivity. Changes from basal of reduced-to-oxidized glutathione ratio (GSH/GSSG) in erythrocytes were significantly greater after DRC than LRC (+1437 ± 371 and -152 ± 30, P < 0.05). The omega-3 index in erythrocyte membranes was 16± 4% greater (P < 0.001) after DRC than LRC. CONCLUSIONS: DRC consumption improved postload glucose metabolism by increasing incretin and insulin secretions. DRC compared to LRC improved redox balance and increased omega-3 fatty acids. Thus, we suggest greater metabolic benefits related to DRC.

Omega-3 fatty acids and protein metabolism: enhancement of anabolic interventions for sarcopenia.

PURPOSE OF REVIEW: The increased age observed in most countries, with the associated higher rates of chronic illnesses and cancer, and a diffuse sedentary lifestyle, will increase the number of patients with clinically relevant anabolic resistance, sarcopenia and its complications. The need for solutions to this major health issue is, therefore, pressing. RECENT FINDINGS: The metabolic derangements and other consequences associated with sarcopenia can be slowed or even prevented by specific nutritional interventions. New evidence is available about the efficacy of omega-3 fatty acid dietary supplementation to improve protein metabolism and counteract anabolic resistance through indirect effects. Studies show that the anabolic stimuli from substrates (e.g. amino acids or proteins), hormones (e.g. insulin) and/or physical activity in skeletal muscle can be enhanced by long-term fish oil administration. SUMMARY: The review of data from recent studies on this topic suggests that dietary omega-3 fatty acid supplementation, in association with an anabolic stimulus, could potentially provide a safe, simple and low-cost intervention to counteract anabolic resistance and sarcopenia. This intervention may contribute to prevent cachexia and disabilities. Supplementation should be given in the earlier stages of sarcopenia (e.g. precachexia). Further research should, however, be performed to better understand the mechanisms involved and the best dosage and timing of administration.

Treatment with n-3 polyunsaturated fatty acids reverses endothelial dysfunction and oxidative stress in experimental menopause.

Menopause is associated with endothelial dysfunction and oxidative stress. In this condition, reduced n-3 polyunsaturated fatty acids (n-3 PUFAs) contribute to cardiovascular disease. We investigated whether treatment with n-3 PUFA reverses endothelial dysfunction and oxidative stress in experimental menopause. Thirty female rats underwent either sham-surgery or bilateral ovariectomy or bilateral ovariectomy+oral n-3 PUFA (0.8 g kg(-1) day(-1) for 2 months). Ovariectomy caused endothelial dysfunction to acetylcholine, which was reversed by superoxide scavenger Tiron. Erythrocyte membrane lipid composition was characterized by reduced n-3 PUFA total content and omega-3 index, and by concomitant increase in n-6:n-3 PUFA ratio. Ovariectomy-related oxidative stress, demonstrated by both enhanced superoxide production and 3-nitrotyrosine expression in aorta, was associated with increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit NOX-4 protein expression. Endothelial nitric oxide synthase (eNOS) functional inhibition by l-NG-nitroarginine methyl ester, protein expression and activity did not change. In ovariectomized rats, treatment with n-3 PUFA increased n-3 PUFA total content and omega-3 index and decreased n-6:n-3 PUFA ratio in erythrocyte membrane, reversed vascular oxidative stress, endothelial dysfunction, aortic 3-nitrotyrosine and markedly lowered NOX-4 protein expression; eNOS protein expression also increased, paralleled by reversal of inhibitory binding to Caveolin-1, while ex-vivo functional inhibition and NOS synthesis were unchanged. These findings demonstrate in vivo a therapeutic benefit of n-3 PUFA on menopause-associated endothelial dysfunction by reversal of alterations in membrane lipid composition induced by ovariectomy and by reduction of vascular oxidative stress. In this setting they also identify NOX-4 as a potential target to reduce oxidative stress-mediated vascular complications.