Cholesterol synthesis and degradation in normal rats fed a cholesterol-free diet with excess cystine

Adherence to aerobic training combined with high protein intake is associated with low blood pressure in Italian older adults: a cross-sectional study

BACKGROUND

Lifestyle habits have a key role in cardiometabolic health. The effects of combined aerobic training (AT) and high protein intake (HPI) on cardiometabolic parameters in older adults are not well established.

AIMS

To investigate the association of AT and HPI with blood pressure (BP), blood glucose, and total blood cholesterol levels in a sample of Italian older adults enrolled in the Longevity Check-up 7 + (Lookup 7 +) study.

METHODS

Lookup 7 + is an ongoing project started in June 2015 and conducted in unconventional settings (e.g., exhibitions, malls, health promotion campaigns) across Italy with the aim of fostering adoption of healthy lifestyles in the general population. For the present investigation, analyses were conducted in participants 65 + years and with body mass index values ≥ 18.5 kg/m2 (n = 3219). Systolic (SBP) and diastolic BP (DBP), blood glucose, and total blood cholesterol were measured. Protein intake was estimated using a 12-item food frequency questionnaire. HPI was operationalized as a daily protein intake ≥ 0.8 g/kg of body weight. AT was operationalized as the practice of running and/or swimming for 60 + minutes at least twice weekly during the previous year.

RESULTS

The mean age of the 3219 participants was 72.7 ± 5.7 years, and 55.2% were women. Adherence to AT combined with a HPI was negatively and independently associated with SPB (β: - 4.976; 95% confidence interval: - 9.8 to - 0.08). No other significant associations were observed.

DISCUSSION AND CONCLUSIONS

Our results indicate that AT combined with HPI was negatively associated with SBP in a large and relatively unselected sample of Italian older adults living in the community. These findings need confirmation by ad hoc designed studies.

Protein Intake Is Associated with Blood Pressure and Cholesterol Levels in Italian Older Adults: A Cross-Sectional Study

The present study was conducted to test the association between protein intake and blood pressure, glucose levels, and blood cholesterol in a large sample of Italian older adults. Longevity Check-up 7+ (Lookup 7+) is an ongoing project that started in June 2015. The project is conducted in unconventional settings (e.g., exhibitions, malls, health promotion campaigns) across Italy with the aim of fostering adoption of healthy lifestyles in the general population. For the present study, participants were eligible if they were 65+ years and provided written informed consent. Systolic (SBP) and diastolic blood pressure (DBP), and blood glucose and cholesterol levels were assessed. Protein intake was estimated using a 12-item food frequency questionnaire. Three-thousand four-hundred and four older adults were included in the study. The results of the linear regression showed an inverse association between protein intake (as a continuous variable) and DBP, and a positive correlation with blood cholesterol levels. The findings of the present study indicate that a high intake of protein was negatively associated with DBP and positively associated with total blood cholesterol levels in a large cohort of Italian older adults, after adjustment for numerous covariates.

Health Functions of Egg Protein

Egg protein is a remarkably abundant source of protein, with an amino acid score of 100 and the highest net protein utilization rate. However, there have been relatively fewer studies investigating the health benefits of egg protein. In this review, we have summarized the available information regarding the health benefits of egg proteins based on human studies. In particular, studies conducted on the characteristics of egg whites, as they are high in pure protein, have reported their various health functions, such as increases in muscle mass and strength enhancement, lowering of cholesterol, and visceral fat reduction. Moreover, to facilitate and encourage the use of egg white protein in future, we also discuss its health functions. These benefits were determined by developing an egg white hydrolysate and lactic-fermented egg whites, with the latter treatment simultaneously improving the egg flavor. The health benefits of the protein hydrolysates from the egg yolk (bone growth effect) and eggshell membrane (knee join pain-lowering effect) have been limited in animal studies. Therefore, the consumption of egg protein may contribute to the prevention of physical frailty and metabolic syndromes.

Cholesterol lowering effect of sulfur-containing amino acids added to a soybean protein diet in rats

The cholesterol-lowering action of soybean protein was studied with rats from the aspect of sulfur-containing amino acids using casein as a counterpart. Weanling rats were fed for 3 wk on a soybean protein isolate (SPI) or casein diet. Serum cholesterol levels did not differ between the two diet groups, but were lowered by supplementing methionine to a 10% SPI diet or cystine to an amino acid mixture diet, equivalent to a 10% SPI or to a 20% SPI diet. By adding methionine or cystine to a 10% SPI diet, cholesterol 7alpha-hydroxylase activity was elevated concomitantly with elevated hepatic glutathione (GSH) level, while hydroxyl methyl-glutalyl coenzyme A reductase activity was reduced by methionine, regardless of GSH levels. Excretion of fecal steroid was not significantly changed by addition of either amino acid, as expressed per body weight. These results indicate that the relative amount of methionine and cystine in a diet affected cholesterol metabolizing enzyme activity in a way not parallel to GSH concentration.

Effect of lupeol and lupeol linoleate on lipemic – hepatocellular aberrations in rats fed a high cholesterol diet

Cholesterol feeding has been often used to study the etiology of hypercholesterolaemia-related metabolic disturbances. The aim of the present study is to investigate the effects of a pentacyclic triterpene, lupeol, and its ester derivative on hepatic abnormalities associated with hypercholesterolemic rats. Hypercholesterolaemia was induced in male Wistar rats by feeding them with a high cholesterol diet (HCD) containing normal rat chow supplemented with 4% cholesterol and 1% cholic acid, for 30 days. Lupeol and lupeol linoleate were supplemented (50 mg/kg body wt/day) during the last 15 days. Increased hepatic lipid profile along with abnormalities in lipid-metabolizing enzyme activities were seen in hypercholesterolemic rats. An apparent increase in the expression of Acyl-CoA cholesterol acyltransferase mRNA was seen in HCD fed rats. The activities of hepatic marker enzymes, which serve as indices of cellular injury, were altered in HCD fed rats. Treatment with triterpenes significantly modulated the abnormalities induced by hypercholesterolaemia. Also, an increased (P >0.001) faecal excretion of cholesterol and bile acids were observed in lupeol and lupeol linoleate group when compared with HCD fed group. Therefore, it can be concluded that triterpenes treatment afforded substantial protection against the anomalies, which are manifested during the early stage of hypercholesterolemic atherogenesis.

Assessment of the safety of glutamine and other amino acids

Glutamine is used to supplement intravenous and enteral feeding. Although there have been many human studies of its efficacy, there have been very few studies with safety as a primary goal. This article analyzes the literature on the safety of glutamine and also examines the available information on high intakes of total protein and other amino acids, so that additional indicators of potentially adverse effects can be suggested. Four studies that specifically addressed glutamine safety were identified, from which it was concluded that glutamine is safe in adults and in preterm infants. However, the published studies of safety have not fully taken account of chronic consumption by healthy subjects of all age groups. To help identify potential undetected hazards of glutamine intake, the literature on adverse effects of high dietary intake of protein and other amino acids was examined. High protein is reputed to cause nausea, vomiting and ultimately death in adults, and has been shown to result in neurological damage in preterm infants. Individual amino acids cause a variety of adverse effects, some of them potentially fatal, but neurological effects were the most frequently observed. Because glutamine is metabolized to glutamate and ammonia, both of which have neurological effects, psychological and behavioral testing may be especially important.