Chronic dietary exposure to branched chain amino acids impairs glucose disposal in vegans but not in omnivores.

BACKGROUND/OBJECTIVES: Branched chain amino acids (BCAA) are among nutrients strongly linked with insulin sensitivity (IS) measures. We investigated the effects of a chronic increase of BCAA intake on IS in two groups of healthy subjects differing in their basal consumption of BCAA, that is, vegans and omnivores. SUBJECTS/METHODS: Eight vegans and eight matched omnivores (five men and three women in each group) received 15 g (women) or 20 g (men) of BCAA daily for 3 months. Anthropometry, blood analyses, glucose clamp, arginine test, subcutaneous abdominal adipose tissue (AT) and skeletal muscle (SM) biopsies (mRNA levels of selected metabolic markers, respiratory chain (RC) activity) were performed at baseline, after the intervention and after a 6 month wash-out period. RESULTS: Compared with omnivores, vegans had higher IS at baseline (GIR, glucose infusion rate: 9.6±2.4 vs 7.1±2.4 mg/kg/min, 95% CI for difference: 0.55 to 5.82) that declined after the intervention and returned to baseline values after the wash-out period (changes in GIR with 95% CI, 3-0 months: -1.64 [-2.5; -0.75] and 9-3 months: 1.65 [0.75; 2.54] mg/kg/min). No such change was observed in omnivores. In omnivores the intervention led to an increased expression of lipogenic genes (DGAT2, FASN, PPARγ, SCD1) in AT. SM RC activity increased in both groups. CONCLUSIONS: Negative impact of increased BCAA intake on IS was only detected in vegans, that is, subjects with low basal amino acids/BCAA intake, which appear to be unable to induce sufficient compensatory changes within AT and SM on a BCAA challenge.

Excess of free fatty acids as a cause of metabolic dysfunction in skeletal muscle.

Obesity is often associated with metabolic impairments in peripheral tissues. Evidence suggests an excess of free fatty acids (FFA) as one factor linking obesity and related pathological conditions and the impact of FFA overload on skeletal muscle metabolism is described herein. Obesity is associated with dysfunctional adipose tissue unable to buffer the flux of dietary lipids. Resulting increased levels and fluxes of plasma FFA lead to ectopic lipid deposition and lipotoxicity. FFA accumulated in skeletal muscle are associated with insulin resistance and overall cellular dysfunction. Mechanisms supposed to be involved in these conditions include the Randle cycle, intracellular accumulation of lipid metabolites, inflammation and mitochondrial dysfunction or mitochondrial stress. These mechanisms are described and discussed in the view of current experimental evidence with an emphasis on conflicting theories of decreased vs. increased mitochondrial fat oxidation associated with lipid overload. Since different types of FFA may induce diverse metabolic responses in skeletal muscle cells, this review also focuses on cellular mechanisms underlying the different action of saturated and unsaturated FFA.

[Vitamin D during cancer treatment]. / Vitamin D pri lécbe nádorového onemocnení.

Recent knowledge on vitamin D has shown that its active form not only regulates calcium and phosphate metabolism but also has significant antimitotic and cell differentiation effects. It can inhibit proliferation, angiogenesis and metastatic potential in cancer tissue. Insufficient vitamin D plasma levels are found in 20- 60% of cancer patients at dia-gnosis. By many authors, vitamin D deficiency is associated with higher aggressivity of tumor and shorter survival of patients. Even in the absence of clinical studies showing benefit of supplementation on outcome, clear recommendations are currently available for treatment of vitamin D deficiency. Owing to the high prevalence of vitamin D insufficiency in cancer patients and significant risks of its further decrease after antitumor therapy, it should become standard of care to examine 25- hydroxyvitamin D serum levels and correct vitamin D insufficiency in cancer patients.

[Vitamin D -- remarks of known and overwiev of new facts]. / Vitamin D -- pripomínka známých a prehled méne známých skutecností

Vitamin D as one of liposolubile vitamins was related to children age and skeleton at the clinical practice until now. There is lot of new information considering rather more complicated connection of vitamin D into many functions of human body during last years. On the other hand we are able to measure the serum level of vitamin D, so we recognized the possibility of long term significantly low levels of vitamin D in tenths percent of population. This review shows actual information about relationship between vitamin D and organ systems and their disturbances. Long term low level of vitamin D potentiates cognitive deterioration in elderly, influences the mood up to depression appearance. The influence of vitamin D on immunity system and cancerogenesis appears to be of high importance too. From the seniors independence point of view the relationship between vitamin D and sarcopenia is very important especially in connection with osteoporosis prevention - the way how to reduce the danger of falls and osteoporotic fractures. Autoimmune diseases and diabetes mellitus are mentioned at the end of the review.