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Biomedical subjects

M B Katan

Publications and source records attributed to M B Katan.

At least 109 records · Page 6Linked to original sources
PubMed1997

High-oil compared with low-fat, high-carbohydrate diets in the prevention of ischemic heart disease.

Reducing the intake of saturated fatty acids reduces the risk of coronary disease. This paper reviews the merits of two types of diets reduced in saturated fat. Low-fat, high-carbohydrate diets lower plasma low-density lipoprotein (LDL) but also lower high-density lipoprotein (HDL) concentrations and raise plasma very-low-density lipoprotein. The predicted net effect on coronary risk is zero. Weight loss with low-fat diets is modest and insufficient to offset the fall in HDL. Evidence for other beneficial effects of low-fat diets in incomplete. In contrast, diets low in saturated fat but high in unsaturated oils improve the ratio of HDL to LDL in plasma and thus reduce the predicted coronary risk. Recommendations to reduce total fat intake are therefore too imprecise; guidelines should aim specifically at saturated and probably also at trans fatty acids, whereas recommendations for restriction of cis-unsaturated fatty acids are not supported by firm scientific evidence.

Animals↗
PubMed1997

Prevalence of malnutrition in nonsurgical hospitalized patients and its association with disease complications.

The prevalence of malnutrition and its predictive value for the incidence of complications were determined in 155 patients hospitalized for internal or gastrointestinal diseases. At admission, 45% of the patients were malnourished according to the Subjective Global Assessment (physical examination plus questionnaire), 57% according to the Nutritional Risk Index [(1.5 x albumin) + (41.7 x present/usual weight)], and 62% according to the Maastricht Index [(20.68 - (0.24 x albumin) - (19.21 x transthyretin (prealbumin) - (1.86 x lymphocytes) - (0 04 x ideal weight)]. Crude odds ratios for the incidence of any complication in malnourished compared with well-nourished patients during hospitalization were 2.7 (95% CI: 1.4, 5.3) for the Subjective Global Assessment, 2.8 (1.5, 5.5) for the Nutritional Risk Index, and 3.1 (1.5, 6.4) for the Maastricht Index. Odds ratios were reduced to 1.7 (0.8, 3.6), 1.6 (0.7, 3.3), and 2.4 (1.1, 5.4), respectively, after a multivariate analysis that included disease category and disease severity. Because the confounding factors adjusted for are not only a measure of the severity of the disease but may also be influenced by malnutrition itself, the actual risk for complications due to malnutrition could be higher than the adjusted odds ratios. In conclusion, malnutrition was frequent in patients with gastrointestinal disease and other internal diseases at the time of admission. The severity of malnutrition in the patients predicted the occurrence of complications during their hospital stay and this association was not completely explained by confounding factors.

Adult↗
PubMed1997

Bacterial fermentation of fructooligosaccharides and resistant starch in patients with an ileal pouch-anal anastomosis.

Patients with large bowel disease may undergo ileal pouch-anal anastomosis, in which the colon is removed and part of the distal ileum is used to construct a pelvic reservoir. Competence of the ileal pouch to ferment carbohydrates is associated with the absence of pouchitis. However, the extent to which bacterial fermentation takes place and whether it is affected by diet are unclear. We investigated fermentation of two nondigestible carbohydrates, fructooligosaccharides and resistant starch, in 15 healthy patients with an ileal pouch by using a placebo-controlled crossover design (with glucose as the placebo). Apparent fermentability of fructooligosaccharides was 83%; that of resistant starch was 46%. Resistant starch increased fecal excretion of butyrate by 69% whereas fructooligosaccharides reduced excretion of amino acid-derived isobutyrate by 94% and of isovalerate by 77%. Fructooligosaccharides also significantly increased fecal weight (651 compared with 541 g/d) and breath-hydrogen excretion (286 compared with 85 ppm x h). Bacterial fermentation of nondigestible carbohydrates in pouches takes place to an appreciable extent and in a substrate-specific manner. The relation between such fermentation and inflammation of the pouch (pouchitis) deserves study.

Adult↗
PubMed1997

The cholesterol-raising factor from coffee beans.

Some coffee brewing techniques raise the serum concentration of total and low-density-lipoprotein cholesterol in humans, whereas others do not. The responsible factors are the diterpene lipids cafestol and kahweol, which make up about 1% (wt:wt) of coffee beans. Diterpenes are extracted by hot water but are retained by a paper filter. This explains why filtered coffee does not affect cholesterol, whereas Scandinavian "boiled," cafetiere, and Turkish coffees do. We describe the identification of the cholesterol-raising factors, their effects on blood levels of lipids and liver function enzymes, and their impact on public health, based on papers published up to December 1996.

Animals↗
PubMed1997

Trans fatty acids, lipoproteins, and coronary risk.

Most dietary fatty acids contain at least one double bond, which is usually in the cis configuration. However, biohydrogenation in the rumen of cows and sheep, or catalytic hydrogenation of vegetable oils in the food industries, will convert some of the cis double bonds to the trans configuration. Trans fatty acid intake in western Europe and North America probably ranges from 5 to 15 g/day. Major dietary sources are frying fats used in industrial food preparation, margarines, and other spreads. In the past, margarines contained up to 50% trans fatty acids; however, these are now being phased out. Trans fatty acids raise serum low density lipoprotein (LDL) cholesterol and lower high density lipoprotein (HDL) cholesterol in humans when substituted for cis unsaturated fatty acids in the diet. These effects may be mediated by the cholesteryl ester transfer protein. Trans fatty acids also increase lipoprotein (a) levels relative to other fatty acids. The effects of trans fatty acids on the risk profile for coronary heart disease are thus unfavorable, and labels of food products should state the trans fatty acid content.

Cholesterol, HDL↗
PubMed1997

Kinetics of the incorporation of dietary fatty acids into serum cholesteryl esters, erythrocyte membranes, and adipose tissue: an 18-month controlled study.

Tissue levels of n-3 fatty acids reflect dietary intake, but quantitative data about rate of incorporation and levels as a function of intake are scarce. We fed 58 men 0, 3, 6, or 9 g/d of fish oil for 12 months and monitored fatty acids in serum cholesteryl esters, erythrocytes, and subcutaneous fat during and after supplementation. Eicosapentaenoic acid (EPA) in cholesteryl esters plateaued after 4-8 weeks; the incorporation half-life was 4.8 days. Steady-state levels increased by 3.9 +/- 0.3 mass % points (+/- SE) for each extra gram of EPA eaten per day. Incorporation of docosahexaenoic acid (DHA) was erratic; plateau values were 1.1 +/- 0.1 mass % higher for every g/d ingested. Incorporation of EPA into erythrocyte membranes showed a half-life of 28 days; a steady state was reached after 180 days. Each g/d increased levels by 2.1 +/- 0.1 mass %. C22:5n-3 levels increased markedly. Changes in DHA were erratic and smaller. EPA levels in adipose tissue rose also; the change after 6 months was 67% of that after 12 months in gluteal and 75% in abdominal fat. After 12 months each gram per day caused an 0.11 +/- 0.01 mass % rise in gluteal fat for EPA, 0.53 +/- 0.07 for C22:5n-3, and 0.14 +/- 0.03 for DHA. Thus, different (n-3) fatty acids were incorporated with different efficiencies, possibly because of interconversions or different affinities of the enzymatic pathways involved. EPA levels in cholesteryl esters reflect intake over the past week or two, erythrocytes over the past month or two, and adipose tissue over a period of years. These findings may help in assessing the intake of (n-3) fatty acids in epidemiological studies.

Adipose Tissue↗
PubMed1996

Comparison of effect of cafetière and filtered coffee on serum concentrations of liver aminotransferases and lipids: six month randomised controlled trial.

OBJECTIVE: To study the effects of prolonged intake of cafetière coffee, which is rich in the diterpenes cafestol and kahweol, on serum aminotransferase and lipid concentrations. DESIGN: Randomised parallel controlled trial. SUBJECTS: 46 healthy men and women aged 19 to 69. INTERVENTION: Consumption of five to six strong cups (0.9 litres) a day of either cafetière (22 subjects) or filtered coffee (24 subjects) for 24 weeks. MAIN OUTCOME MEASURES: Mean changes in serum aminotransferase and lipid concentrations. RESULTS: Cafetière coffee raised alanine aminotransferase concentration by up to 80% above baseline values relative to filtered coffee. After 24 weeks the rise was still 45% (9 U/l (95% confidence interval 3 to 15 U/l), P = 0.007). Alanine aminotransferase concentration exceeded the upper limit of normal in eight of the 22 subjects drinking cafetière coffee, being twice the upper limit of normal in three of them. Cafetière coffee raised low density lipoprotein cholesterol concentrations by 9-14%. After 24 weeks the rise was 0.26 mmol/l (0.04 to 0.47 mmol/l) (P = 0.03) relative to filtered coffee. Triglyceride concentrations initially rose by 26% with cafetière coffee but returned close to baseline values within six months. All increases were reversible after the intervention was stopped. CONCLUSIONS: Daily consumption of five to six cups of strong cafetière coffee affects the integrity of liver cells as suggested by small increases in serum alanine aminotransferase concentration. The effect does not subside with prolonged intake. High intakes of coffee brews rich in cafestol and kahweol may thus be responsible for unexplained increases in this enzyme activity in apparently healthy subjects. Cafetière coffee also raises low density lipoprotein cholesterol concentration and thus the risk of coronary heart disease.

Adult↗
PubMed1996

Inhibition of gastrin-stimulated gastric acid secretion by medium-chain triglycerides and long-chain triglycerides in healthy young men.

Long-chain triglycerides inhibit gastric acid secretion, but the effect of medium-chain triglycerides in humans is unknown. We compared the effects of intraduodenally perfused saline, medium-chain and long-chain triglycerides on gastrin-stimulated gastric acid secretion and cholecystokinin release. Eight healthy male volunteers participated in this study. Gastrin-stimulated gastric acid output was 9.4 +/- 1.1 mmol/30 min during saline perfusion. It was suppressed by medium-chain triglycerides by 43 +/- 9% (P = 0.04 vs. saline) and by long-chain triglycerides by 74 +/- 6% (P = 0.0003 vs. saline). Thus medium-chain triglycerides inhibited gastrin-stimulated gastric acid secretion but less so than long-chain triglycerides. When compared to saline perfusion (73 +/- 6 pM x 30 min) integrated plasma cholecystokinin concentrations were significantly elevated by long-chain triglycerides (96 +/- 5 pM x 30 min, P < 0.004) but not by medium-chain triglycerides perfusion (65 +/- 7 pM x 30 min). We also investigated the role of cholecystokinin infusion on gastrin stimulated gastric acid secretion. Higher concentrations (191.4 +/- 4.5 pM x 30 min) of CCK than released in the long-chain triglycerides perfusion experiment, did not suppress gastric acid secretion. Thus, circulating cholecystokinin appears not responsible for the inhibition of gastrin-stimulated gastric acid secretion by dietary fat.

Adult↗
PubMed1996

Relation between intake of flavonoids and risk for coronary heart disease in male health professionals.

OBJECTIVE: Flavonols and flavones are subgroups of flavonoids and are found in tea, vegetables, fruits, and red wine. Because they have antioxidant properties, we investigated whether intake of these dietary compounds is associated with a lower risk for fatal and nonfatal coronary heart disease. DESIGN: Prospective cohort study. SETTING: United States. PATIENTS: 34,789 male health professionals, 40 to 75 years of age, who responded to a questionnaire in 1986. MEASUREMENTS: In 1986 and 1990, detailed, 131-item questionnaires were used to assess dietary intake of flavonols and flavones. RESULTS: Between 1986 and 1992, 496 patients received a new diagnosis of nonfatal myocardial infarction. The relative risk for nonfatal myocardial infarction was 1.08 (95% Cl, 0.81 to 1.43) for the highest (median, 40.0 mg/d) compared with the lowest (median, 7.1 mg/d) quintiles for intake of flavonols and flavones after adjustment for age, obesity, smoking, intake of vitamin E, intake of alcohol, diabetes, hypertension, hypercholesterolemia, and family history of coronary heart disease. Among the 4814 men who reported that they had previously had coronary heart disease, we found a modest but nonsignificant inverse association between intake of flavonols and flavones and subsequent coronary mortality rates (relative risk, 0.63 [Cl, 0.33 to 1.20] for the highest compared with the lowest quintile for intake of flavonoids). CONCLUSION: The data do not support a strong inverse association between intake of flavonoids and total coronary heart disease, but they do not exclude the possibility that flavonoids have a protective effect in men with established coronary heart disease.

Adult↗
PubMed1996

Absorption and disposition kinetics of the dietary antioxidant quercetin in man.

Quercetin is a dietary antioxidant that prevents oxidation of low-density lipoproteins in vitro by scavenging to free oxygen radicals. Its intake was inversely associated with coronary heart mortality in Dutch elderly men. However, data on absorption of quercetin in man are scarce and contradictory. We studied the time course of the plasma quercetin concentration in two subjects after ingestion of fried onions containing quercetin glucosides equivalent to 64 mg of quercetin aglycone. Peak plasma levels of 196 ng/ml were reached after 2.9 h, with a half-life of absorption of 0.87 h. The half-life of the distribution phase was 3.8 h, and of the subsequent elimination phase 16.8 h. After 48 h the plasma concentration was about 10 ng/ml. We conclude that quercetin glucosides from onions are absorbed and are eliminated slowly throughout the day. Thus, the dietary antioxidant quercetin could increase the antioxidant capacity of blood plasma.

Adult↗
PubMed1996

Partial conservation of the sn-2 position of dietary triglycerides in fasting plasma lipids in humans.

The authors investigated the effect of the position of fatty acids within dietary triglycerides on the composition of plasma lipids. Sixty volunteers consumed two diets of equal fatty acid compositions for 3 weeks each. In the palm oil diet 82% of palmitic acid was attached to the sn-1 and sn-3, and 18% to the sn-2 position of glycerol. In the diet rich in a palm oil analogue, Betapol, these figures were 35% and 65% respectively. Oleic and linoleic acid in palm oil were mainly in the sn-2 position, and in Betapol mainly in the sn-1 and sn-3 position. The proportion of palmitic acid in the 2 position of fasting plasma triglycerides was 10·2 g 100 g-1 on palm oil and 12·3 on Betapol; that of oleic acid was 46·dot 9 vs. 43·6 (P < 0·0001). Overall oleic acid content of triglycerides was 1·4 g 100 g-1 lower on Betapol than on palm oil (P = 0·002). Betapol increased palmitic and palmitoleic acid in cholesteryl esters by 1 g 100 g-1 (P < 0·0001) at the expense of oleic and linoleic acid. The positional configuration of dietary fatty acids has small but consistent effects on lipid metabolism that persist beyond fat absorption and chylomicron clearance.

Adult↗
PubMed1996

Chronic consumers of boiled coffee have elevated serum levels of lipoprotein(a).

OBJECTIVES: Lipoprotein(a) consists of an LDL-particle attached to apolipoprotein(a), which is made by the liver. Diterpenes present in boiled coffee raise serum levels of LDL cholesterol and of the liver enzyme alanine aminotransferase in man. We investigated the association between intake of boiled coffee and serum levels of lipoprotein(a). DESIGN, SETTING AND SUBJECTS: Healthy Norwegians 40-42 years of age, who habitually consumed five or more cups of boiled coffee per day (n = 150) were compared with matched filter coffee consumers (n = 159) in a cross-sectional study, as part of the Norwegian National Health Screening in 1992. RESULTS: The median lipoprotein(a) level was 13.0 mg dL-1 (10th and 90th percentile: 2.5 and 75.0 mg dL-1, respectively) on boiled and 7.9 mg dL-1 (10th and 90th percentile: 1.9 and 62.5 mg dL-1, respectively) on filter coffee (P = 0.048). Means +/- SE were 25.8 +/- 2.4 mg dL-1 and 19.6 +/- 2.0 mg dL-1, respectively (P = 0.04). Although not statistically significant, subjects consuming nine or more cups of coffee per day had higher lipoprotein(a) levels than those drinking five to eight cups per day in both coffee groups. CONCLUSION: Chronic consumers of unfiltered, boiled coffee have higher serum levels of lipoprotein(a) than filter coffee drinkers.

Adult↗
PubMed1996

Boiled coffee fails to raise serum cholesterol in hamsters and rats.

Boiled coffee contains the lipid compounds cafestol and kahweol, which raise cholesterol strongly in man. These lipids are retained by paper filters. In a search for an animal model for the effect of coffee lipids on serum cholesterol concentrations, we fed hamsters (Mesocricetus auratus) and rats on mash diets consisting of a purified base diet and either boiled water, unfiltered boiled coffee or filtered boiled coffee. After a feeding period of 8 weeks there was no statistically significant effect of unfiltered boiled coffee on serum total cholesterol and triacylglycerol concentrations in either the hamsters or the rats. The level of serum cholesterol did respond predictably to the addition of cholesterol and/or saturated fatty acids to the diet. The lack of effect of unfiltered boiled coffee in the hamsters and the rats, when compared with the previously reported activity in humans, could not be explained by dosage, duration of treatment, mode of administration or by insufficient statistical power. It is concluded that hamsters and rats are insensitive to unfiltered boiled coffee and thus are unsuitable models for investigating its hypercholesterolaemic effect.

Animals↗
PubMed1996

Red wine consumption does not affect oxidizability of low-density lipoproteins in volunteers.

Phenolic compounds in red wine may protect low-density lipoproteins (LDL) against oxidative modification, thereby reducing the risk of cardiovascular morbidity. However, in vivo data are scarce. We gave 13 healthy volunteers 550 mL red wine and another 11 volunteers white wine for 4 wk in a randomized double-blind trial. Interference by alcoholic components of wine was eliminated by reducing the alcohol content to 3.5% Red wine did not affect the susceptibility of LDL to Cu2+ -mediated oxidative modification [lag time before and after red wine drinking (chi +/- SD) 61.8 +/- 7.7 and 62.7 +/- 11.8 min, respectively; lag time before and after white wine drinking: 64.5 +/- 10.4 and 63.3 +/- 10.8 min, respectively]. Concentrations of the antioxidants urate, vitamin C, and glutathione in plasma and of vitamin E and ubiquinol-10 in LDL were also unchanged after either red or white wine consumption. The results of this study do not show a beneficial effect of red wine consumption on LDL oxidation.

Adult↗
PubMed1996

Urinary salicylate excretion in subjects eating a variety of diets shows that amounts of bioavailable salicylates in foods are low.

Intake of acetylsalicylic acid reduces the risk of cardiovascular disease and is associated with a decreased risk for colorectal cancer. Amounts of salicylates in foods are thus of interest, but data are scarce and controversial. We gave 58 mumol (10.5 mg) pure acetylsalicylic acid or 66 mumol (9.1 mg) salicylic acid to six volunteers and recovered 77-80% in 24-h urine samples. Thus, urinary excretion is a valid indicator for intake of free forms of (acetyl)salicylic acid. To estimate the bioavailable salicylate contents of diets, we subsequently studied salicylate excretion in 17 volunteers from 14 countries and four continents who ate a wide variety of self-selected diets. Median 24-h urinary salicylate excretion was 10 mumol (range: 6-12 mumol). Values increased with the fiber content of the diet (r = 0.73), suggesting that vegetable foods are the main sources of salicylates. However, amounts of salicylates in a variety of diets are evidently low and probably insufficient to affect disease risk.

Adult↗
PubMed1996

Modulation of inflammation and cytokine production by dietary (n-3) fatty acids.

The production of pro-inflammatory cytokines, such as interleukin-1 and tumor necrosis factor, is pivotal in the response to infection. However, overproduction of these cytokines might be detrimental. It has been suggested that (n-3) fatty acids suppress inflammation and ameliorate the course of infection by decreasing the production of pro-inflammatory cytokines. We here, review these effects. Use of (n-3) fatty acids induced moderate clinical improvements in rheumatoid arthritis, psoriasis and colitis, but not in systemic lupus erythematosus. Data on critically ill burn or postoperative cancer patients are still inconclusive. The (n-3) fatty acids markedly inhibited sterile inflammation in animal studies and improved survival in some experimental infections. T cell responses decreased in healthy volunteers but remained unchanged or increased in certain patient groups. The production of pro-inflammatory cytokines decreased in most human studies. The (n-3) fatty acids increased cytokine production capacity in mice. Differences in cytokine-producing cell types studied may account for these paradoxical responses in humans and mice. Although the increased cytokine production in mice is partly mediated by effects on prostaglandins, mechanisms of action in other species remain to be elucidated. The (n-3) fatty acids may be of moderate benefit in some chronic inflammatory diseases. Their therapeutic value and possible hazards in critically ill patients remain to be established.

Animals↗