Small intestinal protein infusion in humans: evidence for a location-specific gradient in intestinal feedback on food intake and GI peptide release.

BACKGROUND: Protein infusion in the small intestine results in intestinal brake activation: a negative feedback mechanism that may be mediated by the release of gastrointestinal peptides resulting in a reduction in food intake. It has been proposed that duodenum, jejunum and ileum may respond differently to infused proteins. OBJECTIVE: To investigate differences in ad libitum food intake, feelings of hunger and satiety and the systemic levels of cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), peptide YY (PYY), glucose and insulin after intraduodenal, intrajejunal and intraileal protein infusion. METHODS: Fourteen subjects (four male, mean age: 23±2.1 years, mean body mass index: 21.6±1.8 kg m-2) were intubated with a naso-ileal catheter in this double-blind, randomized, placebo-controlled crossover study. Test days (four in total, executed on consecutive days) started with the ingestion of a standardized breakfast, followed by the infusion of 15 g of protein in the duodenum, jejunum or ileum over a period of 60 min. Food intake was measured by offering an ad libitum meal and Visual Analogue Scale (VAS) scores were used to assess feelings of hunger and satiety. Blood samples were drawn at regular intervals for CCK, GLP-1, PYY, glucose and insulin analyses. RESULTS: Intraileal protein infusion decreased ad libitum food intake compared with both intraduodenal and placebo infusion (ileum: 628.5±63 kcal vs duodenum: 733.6±50 kcal, P<0.01 and placebo: 712.2±53 kcal, P<0.05). GLP-1 concentrations were increased after ileal infusion compared with jejunal and placebo infusion, whereas CCK concentrations were only increased after intraileal protein infusion compared with placebo. None of the treatments affected VAS scores for hunger and satiety nor plasma concentrations of PYY and glucose. CONCLUSIONS: Protein infusion into the ileum decreases food intake during the next meal compared with intraduodenal infusion, whereas it increases systemic levels of GLP-1 compared with protein infusion into the jejunum and placebo respectively.

Bidirectional associations between alcohol consumption and health-related quality of life amongst young and middle-aged women.

BACKGROUND: Evidence from cross-sectional studies has suggested a positive association between moderate alcohol consumption and health-related quality of life but prospective data remain scarce. OBJECTIVES: To examine the bidirectional relationships between alcohol consumption and health-related quality of life using a longitudinal study design. METHODS: A total of 92 448 participants of the Nurses' Health Study II reported their alcohol consumption (in 1991, 1995, 1999 and 2003) and health-related quality of life (in 1993, 1997 and 2001). Using generalized estimating equations, we modelled the physical and mental component summary (PCS and MCS) scores as a function of alcohol consumption 2 years earlier (n = 88 363) and vice versa (n = 84 621). RESULTS: Greater alcohol consumption was associated with better PCS scores 2 years later in a dose-response manner up to ~1 serving daily [mean difference (ß) = 0.67 ± 0.06 PCS units, for moderate versus infrequent drinkers]. After adjustment for previous PCS, a similar but attenuated pattern was observed (ß = 0.33 ± 0.07). Moderate alcohol consumption was not related to MCS, whereas moderate-to-heavy alcohol consumption was associated with lower MCS scores (ß = -0.34 ± 0.15). Higher PCS scores were associated with greater alcohol consumption 2 years later, also after adjustment for previous alcohol consumption (ß = 0.53 ± 0.05 g day(-1) ). MCS was not associated with alcohol consumption 2 years later. CONCLUSION: Amongst young and middle-aged women, moderate alcohol intake was associated with a small improvement in physical health-related quality of life 2 years later and vice versa. Moderate alcohol consumption was not associated with mental health-related quality of life in either direction.

Ileal brake activation: macronutrient-specific effects on eating behavior?

BACKGROUND: Activation of the ileal brake, by infusing lipid directly into the distal part of the small intestine, alters gastrointestinal (GI) motility and inhibits food intake. The ileal brake effect on eating behavior of the other macronutrients is currently unknown. OBJECTIVE: The objective of this study was to investigate the effects of ileal infusion of sucrose and casein on food intake, release of GI peptides, gastric emptying rate and small-bowel transit time with safflower oil as positive control. DESIGN: This randomized, single-blind, crossover study was performed in 13 healthy subjects (6 male; mean age 26.4±2.9 years; mean body mass index 22.8±0.4 kg m(-2)) who were intubated with a naso-ileal catheter. Thirty minutes after the intake of a standardized breakfast, participants received an ileal infusion, containing control ((C) saline), safflower oil ((HL) 51.7 kcal), low-dose casein ((LP) 17.2 kcal) or high-dose casein ((HP) 51.7 kcal), low-dose sucrose ((LC) 17.2 kcal) and high-dose sucrose ((HC) 51.7 kcal), over a period of 90 min. Food intake was determined during an ad libitum meal. Visual analogue score questionnaires for hunger and satiety and blood samples were collected at regular intervals. RESULTS: Ileal infusion of lipid, protein and carbohydrate resulted in a significant reduction in food intake compared with control (HL: 464.3±90.7 kcal, P<0.001; HP: 458.0±78.6 kcal, P<0.005; HC: 399.0±57.0 kcal, P<0.0001 vs control: 586.7±70.2 kcal, P<0.001, respectively). A reduction in energy intake was still apparent when the caloric amount of infused nutrients was added to the amount eaten during the ad libitum meal.Secretion of cholecystokinin and peptide YY but not of glucagon-like peptide-1 (7-36) was increased during ileal perfusion of fat, carbohydrates and protein. During ileal perfusion of all macronutrients, a delay in gastric emptying and intestinal transit was observed, but differences were not significant compared with control. CONCLUSION: Apart from lipids, also sucrose and casein reduce food intake on ileal infusion, thereby activating the ileal brake. In addition to food intake, also satiety and GI peptide secretion were affected.

Effect of moderate alcohol consumption on adipokines and insulin sensitivity in lean and overweight men: a diet intervention study.

OBJECTIVE: Moderate alcohol consumption is associated with a decreased risk of type II diabetes. This study investigates the effect of moderate alcohol consumption on adipokines and insulin sensitivity. SUBJECTS: Twenty healthy, lean (body mass index (BMI) 18.5-25 kg/m(2); n=11) or overweight (BMI>27 kg/m(2); n=9) men (18-25 years). METHODS: Three cans of beer (40 g alcohol) or alcohol-free beer daily during 3 weeks. RESULTS: Adiponectin and ghrelin concentrations increased (P<0.01) by 11 and 8%, while acylation-stimulating protein (ASP) concentrations decreased by 12% (P=0.04) after moderate alcohol consumption. Concentrations of leptin and resistin remained unchanged. Insulin sensitivity by an oral glucose tolerance test (OGTT) was not affected by moderate alcohol consumption, but 2 h glucose concentrations were lower (P=0.01) after beer (4.5+/-0.1 mmol/l) than alcohol-free beer (4.9+/-0.1 mmol/l). Both free fatty acids and glucagon concentrations showed a stronger increase (P<0.01) after 90 min during OGTT after beer than alcohol-free beer. Changes of adiponectin were positively correlated (r=0.69, P<0.001), and changes of leptin (r=-0.53, P=0.016) and ASP (r=-0.43, P=0.067) were negatively correlated with changes of insulin sensitivity index. All these results did not differ between lean and overweight men. CONCLUSIONS: Moderate alcohol consumption increased adiponectin and ghrelin, while it decreased ASP concentrations both in lean and overweight men. These changes are in line with the hypothesized improvement of insulin sensitivity, but did not affect insulin sensitivity within 3 weeks of moderate alcohol consumption.

Moderate alcohol consumption after a mental stressor attenuates the endocrine stress response.

Alcohol is often consumed to reduce tension and improve mood when exposed to stressful situations. Previous studies showed that moderate alcohol consumption may reduce stress when alcohol is consumed prior to a stressor, but data on the effect of alcohol consumption after a mental stressor is limited. Therefore, our objective was to study whether moderate alcohol consumption immediately after a mental stressor attenuates the stress response. Twenty-four healthy men (age 21-40 y, BMI 18-27 kg/m2) participated in a placebo-controlled trial. They randomly consumed 2 cans (660 mL, ∼26 g alcohol) of beer or alcohol-free beer immediately after a mental stressor (Stroop task and Trier Social Stress Test). Physiological and immunological stress response was measured by monitoring heart rate and repeated measures of the hypothalamic-pituitary-adrenal axis (HPA-axis), white blood cells and a set of cytokines. After a mental stressor, cortisol and adrenocorticotropic hormone (ACTH) concentrations were 100% and 176% more reduced at 60 min (P = 0.012 and P = 0.001, respectively) and 92% and 60% more reduced at 90 min (P < 0.001 and P = 0.056, respectively) after beer consumption as compared to alcohol-free beer consumption. Heart rate and dehydroepiandrosterone (DHEA) were not influenced by alcohol consumption. Plasma IL-8 concentrations remained lower during the stress recovery period after beer consumption than after alcohol-free beer consumption (P < 0.001). In conclusion, consumption of a moderate dose of alcohol after a mental stressor may facilitate recovery of the endocrine stress response as reflected by decreasing plasma ACTH and cortisol.

Alcohol.

Alcohol consumption affects overall mortality. Light to moderate alcohol consumption reduces the risk of coronary heart disease; epidemiological, physiological and genetic data show a causal relationship. Light to moderate drinking is also associated with a reduced risk of other vascular diseases and probably of type 2 diabetes. Mortality and disease risk increase at higher levels of alcohol consumption. A substantial portion of the benefit of moderate drinking is connected with the alcohol component. However, small differences in effects of various alcoholic beverages on minor risk factors may occur. Proposed protective mechanisms include improved vascular elasticity, anti-thrombotic and anti-inflammatory processes and most importantly, the stimulation of high-density lipoprotein-mediated processes such as reverse cholesterol transport and antioxidative effects.

Cholecystokinin regulates satiation independently of the abdominal vagal nerve in a pig model of total subdiaphragmatic vagotomy.

The vagal nerve and gut hormones CCK and GLP-1 play important roles in the control of food intake. However, it is not clear to what extent CCK and GLP-1 increase satiation by stimulating receptors located on abdominal vagal nerve endings or via receptors located elsewhere. This study aimed to further explore the relative contribution of the abdominal vagal nerve in mediating the satiating effects of endogenous CCK and GLP-1. Total subdiaphragmatic vagotomy or sham operation was combined with administration of CCK1 and GLP-1 receptor antagonists devazepide and exendin (9-39) in 12 pigs, applying an unbalanced Latin Square within-subject design. Furthermore, effects of vagotomy on preprandial and postprandial acetaminophen absorption, glucose, insulin, GLP-1 and CCK plasma concentrations were investigated. Ad libitum liquid meal intake (mean±SEM) was similar in sham and vagotomized pigs (4180±435 and 3760±810 g/meal). Intake increased by about 20% after blockade of CCK1 receptors, independently of the abdominal vagal nerve. Food intake did not increase after blockade of GLP-1 receptors. Blockade of CCK1 and GLP-1 receptors increased circulating CCK and GLP-1 concentrations in sham pigs only, suggesting the existence of a vagal reflex mechanism in the regulation of plasma CCK1 and GLP-1 concentrations. Vagotomy decreased acetaminophen absorption and changed glucose, insulin, CCK and GLP-1 concentrations indicating a delay in gastric emptying. Our data show that at liquid feeding, satiation is decreased effectively by pharmacological blockade of CCK1 receptors. We conclude that regulation of liquid meal intake appears to be primarily regulated by CCK1 receptors not located on abdominal vagal nerve endings.

Distribution of lecithin-retinol acyltransferase activity in different types of rat liver cells and subcellular fractions.

It is now well documented that lecithin-retinol acyltransferase (LRAT) is the physiologically important enzyme activity involved in the esterification of retinol in the liver. However, no information regarding the cellular distribution of this enzyme in the liver is presently available. This study characterizes the distribution of LRAT activity in the different types of rat liver cells. Purified preparations of isolated parenchymal, fat-storing, and Kupffer + endothelial cells were isolated from rat livers and the LRAT activity present in microsomes prepared from each of these cell fractions was determined. The fat-storing cells were found to contain the highest level of LRAT specific activity (383 +/- 54 pmol retinyl ester formed min-1.mg-1 versus 163 +/- 22 pmol retinyl ester formed min-1.mg-1 for whole liver microsomes). The level of LRAT specific activity in parenchymal cell microsomes (158 +/- 53 pmol retinyl ester formed min-1.mg-1) was very similar to LRAT levels in whole liver microsomes. The Kuppfer + endothelial cell microsome fractions were found to contain LRAT, at low levels of activity. These results indicate that the fat-storing cells are very enriched in LRAT but the parenchymal cells also posses significant levels of LRAT activity.

Nutritional skin care: health effects of micronutrients and fatty acids.

Human skin is continuously exposed to internal and external influences that may alter its condition and functioning. As a consequence, the skin may undergo alterations leading to photoaging, inflammation, immune dysfunction, imbalanced epidermal homeostasis, or other skin disorders. Modern nutritional science is developing new insights into the relation between food intake and health, and effects of food ingredients may prove to be biologically relevant for optimal skin condition. The objective of this review was to evaluate the present knowledge about the interrelation of nutrients and skin, particularly the photoprotective effects of nutrients, the influences of nutrients on cutaneous immune responses, and therapeutic actions of nutrients in skin disorders. The nutrients of focus were vitamins, carotenoids, and polyunsaturated fatty acids. Supplementation with these nutrients was shown to provide protection against ultraviolet light, although the sun-protection factor was relatively small compared with that of topical sunscreens. An increase in delayed-type hypersensitivity skin responses after supplementation with nutrients has proven beneficial, especially in elderly people, and may boost cell-mediated immunity. Dietary consumption of certain plants or fish oil is known to modulate the balance of lipid inflammatory mediators and, therefore, is valuable in the treatment of inflammatory skin disorders. It was concluded that nutritional factors exert promising actions on the skin, but information on the effects of low-to-moderate doses of nutrients consumed long term by healthy individuals is obviously lacking, as are data on direct effects on basal skin properties, including hydration, sebum production, and elasticity.

Endotoxin-induced liver injury in aged and subacutely hypervitaminotic A rats.

The plasma disappearance of endotoxin and endotoxin-induced hepatic injury were studied in two rat models: the aging rat and the subacutely hypervitaminotic A rat. The choice of these models was based on their respective association with a decreased or increased Kupffer cell endocytic activity. The half-life of endotoxin (E. coli O26: B6, phenol extracted) in plasma was significantly prolonged in aged rats as measured by both the Limulus assay (t1/2 = 2.1 +/- 0.1 h in 3-6-month-old, and 3.3 +/- 0.3 h in 24-36-month-old rats) and 51Cr-labeled endotoxin radioactivity assay (t1/2 = 5.3 +/- 0.3 h in 3-6-month old and 7.7 +/- 0.6 h in 24 36-month-old rats). In subacute hypervitaminosis A, the half-life of endotoxin was significantly decreased in the Limulus assay (t1/2 = 2.1 +/- 0.1 h in 3-6-month old and 1.4 +/- 0.2 h in subacutely hypervitaminotic A rats), but not in the radioactivity assay (t1/2 = 5.3 +/- 0.3 h in 3-6-month-old and 5.0 +/- 0.4 h in subacutely hypervitaminotic A rats). Hundred percent mortality was observed at a dose of 2 mg endotoxin/100 g body wt. in old rats, but not in young rats. Only 1 of 7 young subacutely hypervitaminotic A rats died following injection of this dose of endotoxin. The dose of endotoxin which caused only minimal parenchymal liver cell injury in young rats induced substantial parenchymal cell injury in old rats and subacutely hypervitaminotic A rats as determined by both histological and biochemical parameters. It is concluded that some basic characteristics of experimental animals, such as age and nutritional status, can dramatically influence the sensitivity to endotoxin and this is not necessarily correlated with the rate of endotoxin clearance.

Changes in postprandial lipoproteins of low and high density caused by moderate alcohol consumption with dinner.

We measured the effects of consumption of moderate amounts of beer, wine or spirits with evening dinner on plasma LDL and HDL levels as well as composition in 11 healthy middle-aged men. Forty grams of alcohol were consumed daily with dinner for a period of 3 weeks. Mineral water was used as a negative control. Dinner was served at 6 pm and blood samples were obtained at 1 h before and 3, 5, 9, and 13 h after the start of the meal. No differences were detected between the effects of the different alcohol-containing beverages. Plasma levels of triglycerides (TG), measured 1 h before dinner were very variable and higher than fasting values (means of 2.2 and 1.5 mM, respectively). Daily consumption of 40 g of alcohol with dinner resulted in increased postprandial plasma TG levels and decreased low density lipoprotein (LDL) cholesterol concentrations. These effects were transient and observed at 11 pm (TG) and 9 pm and 11 pm (LDL). In contrast, high density lipoproteins (HDL) were raised by alcohol intake at all time points analysed. HDL composition was changed by alcohol consumption, resulting in a raised HDL-cholesterol/apo A-I ratio at 5 pm and 9 pm. The observed alcohol-dependent effects on plasma HDL and LDL during the postprandial phase are considered anti-atherogenic and may contribute to the observed protection against coronary heart disease by moderate alcohol consumption.

Daily moderate alcohol consumption increases serum paraoxonase activity; a diet-controlled, randomised intervention study in middle-aged men.

Moderate alcohol consumption is associated with a reduced risk of coronary heart disease. Part of this inverse association may be explained by its effects on HDL. Paraoxonase, an HDL-associated enzyme, has been suggested to protect against LDL oxidation. We examined the effects of moderate consumption of red wine, beer and spirits in comparison with mineral water on paraoxonase activity in serum. In this diet-controlled, randomised, cross-over study 11 healthy middle-aged men consumed each of the beverages with evening dinner for 3 weeks. At the end of each 3 week period, blood samples were collected pre- and postprandially and after an overnight fast. Fasting paraoxonase activity was higher after intake of wine (P<0. 001), beer (P<0.001), and spirits (P<0.001) than after water consumption (149.4+/-111.1, 152.6+/-113.1, 152.8+/-116.5 and 143. 1+/-107.9 U/l serum), but did not differ significantly between the 3 alcoholic beverages. Similar effects were observed pre- and postprandially. The increases in paraoxonase activity were strongly correlated with coincident increases in concentrations of HDL-C and apo A-I (r=0.60, P<0.05 and r=0.70, P<0.05). These data suggest that increased serum paraoxonase may be one of the biological mechanisms underlying the reduced coronary heart disease risk in moderate alcohol consumers

Stimulation of tissue-type plasminogen activator synthesis by retinoids in cultured human endothelial cells and rat tissues in vivo.

Tissue-type plasminogen activator (t-PA) and its inhibitor, plasminogen activator inhibitor 1 (PAI-1), play an important role in regulating the fibrinolytic capacity of plasma. Both t-PA and PAI-1 are synthesized by the endothelium. We report that retinoic acid (vitamin A acid) and other retinoids rather specifically stimulate the production of t-PA by cultured human umbilical vein endothelial cells. Effective retinoids induced a dose-dependent (range: 0.01-50 microM) increase in the production of t-PA of maximally about six-fold, while simultaneously causing no or only a small increase (less than two-fold) of PAI-1. The effects on t-PA synthesis were apparent by 4-8 h, and reached maximal values after about 24-48 h of incubation with retinoid. The retinoid effect on t-PA production was accompanied by increased t-PA mRNA levels, without any parallel change in PAI-1 or GAPDH mRNA concentrations. The study also shows that modifications at the carboxyl group of retinoic acid are associated with a decrease in stimulatory potency. The stimulatory pathway appears to be identical for all retinoids but distinct from a pathway by which another strong inducer, sodium butyrate, induces t-PA synthesis in endothelial cells. The induction of t-PA by retinoids might involve protein kinase C (PKC) as judged by an experiment using a specific PKC inhibitor. The effect of retinoids on the fibrinolytic system in vivo was assessed by feeding rats with a vitamin A deficient diet or a diet with excess of vitamin A or other retinoids.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol, coagulation and fibrinolysis.

Despite the solid evidence for thrombosis playing a key role in coronary heart disease (CHD) mortality, identifying specific haemostatic risk factors for CHD has been difficult except for fibrinogen. Excessive alcohol consumption clearly affects platelet function. Moderate alcohol consumption may affect several haemostatic factors, including fibrinogen concentration, platelet aggregability and the fibrinolytic factors tissue-type plasminogen activator and plasminogen activator inhibitor. These changes support the hypothesis that moderate alcohol beneficially affects the haemostatic balance in a way that decreases the risk of CHD mortality.

Effect of moderate alcohol consumption on fibrinogen levels in healthy volunteers is discordant with effects on C-reactive protein.

In a diet-controlled, crossover trial with 10 middle-aged men and 9 postmenopausal women, baseline concentrations of fibrinogen influenced the magnitude of decrease of fibrinogen after moderate alcohol consumption. The mechanism of reduction is specific for fibrinogen and unrelated to a reduction in C-reactive protein.

Retinoid (vitamin A) metabolism.

OBJECTIVE AND CONCLUSION: An overview is given of our understanding of the uptake and metabolism of retinoids. The mechanisms underlying retinol uptake by organs and tissues are still unsettled. The retinol-binding proteins CRBP I and CRBP II appear to play an essential role in retinyl ester hydrolysis and formation and in retinoic acid formation.

Retinoid signalling during embryogenesis.

CONCLUSION: Retinoids are suspected to have multiple functions during embryogenesis, which are carried out via various different signal transduction pathways involving active retinoids and nuclear retinoid receptors. Research focuses on the identification of the retinoid signal transduction components involved, and on their specific functions during development. Recent findings in this field are discussed.

Moderate alcohol consumption reduces plasma C-reactive protein and fibrinogen levels; a randomized, diet-controlled intervention study.

OBJECTIVE: To evaluate the effect of moderate alcohol consumption on the acute phase proteins C-reactive protein and fibrinogen. DESIGN: Randomized, diet-controlled, cross-over study. SETTING: The study was performed at TNO Nutrition and Food Research, Zeist, The Netherlands. SUBJECTS: Ten middle-aged men and 10 postmenopausal women, all apparently healthy, non-smoking and moderate alcohol drinkers, were included. One women dropped out because of a treatment-unrelated cause. The remaining 19 subjects finished the experiment successfully. INTERVENTIONS: Men consumed four glasses and women consumed three glasses of beer or no-alcohol beer (control) with evening dinner during two successive periods of 3 weeks. The total diet was supplied to the subjects and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period to compensate for possible carry-over effects. RESULTS: Plasma C-reactive protein and fibrinogen levels were decreased by 35% (P=0.02) and 12.4% (P< or =0.001), respectively, after 3 weeks' consumption of beer, as compared to no-alcohol beer consumption. CONCLUSIONS: Moderate alcohol consumption significantly decreased plasma C-reactive protein and fibrinogen levels. An anti-inflammatory action of alcohol may help explain the link between moderate alcohol consumption and lower cardiovascular disease risk. SPONSORSHIP: Dutch Foundation for Alcohol Research (SAR).

Energy restriction, a useful intervention to retard human ageing? Results of a feasibility study.

OBJECTIVE: Energy restriction (ER) retards the ageing process in animal models. It is possible that ER has a similar effect in humans. As a first approach to look after the potential application of ER in man the feasibility of a moderately energy-restricted diet was studied. DESIGN: A controlled intervention study. SETTING: TNO Toxicology and Nutrition Institute. SUBJECTS: 24 middle-aged non-obese men, selected from men responding to advertisements in regional newspapers. INTERVENTIONS: After a run-in period subjects were divided into two groups, a control group (n = 8) and an ER group (n = 16). Groups were matched on age and body mass index. The effects of 10 weeks of moderate ER (80% of habitual energy intake) on body composition, general health (blood pressure, lipid profile, routine clinical chemistry and haematology), physical and mental performance, and feelings of hunger, satiety and state of mind were measured. RESULTS: Subjects in the ER group lost about 7.4 +/- 2.6 kg weight (P < 0.001). This weight loss concerned mainly loss of fat mass. Diastolic and systolic blood pressure decreased significantly within the ER group (P < 0.05 and P < 0.01 respectively). The increase in HDL-cholesterol level was significantly related to weight loss (P < 0.05). CONCLUSIONS: The results show beneficial effects of 10 weeks of moderate ER on blood pressure and lipid profile without adverse effects on physical and mental performance and feelings of hunger, satiety and mood.

Spreads enriched with three different levels of vegetable oil sterols and the degree of cholesterol lowering in normocholesterolaemic and mildly hypercholesterolaemic subjects.

OBJECTIVE: To investigate the dose-response relationship between cholesterol lowering and three different, relatively low intake levels of plant sterols (0.83, 1.61, 3.24 g/d) from spreads. To investigate the effects on lipid-soluble (pro)vitamins. DESIGN: A randomized double-blind placebo controlled balanced incomplete Latin square design using five spreads and four periods. The five study spreads included butter, a commercially available spread and three experimental spreads fortified with three different concentrations of plant sterols. SUBJECTS: One hundred apparently healthy normocholesterolaemic and mildly hypercholesterolaemic volunteers participated. INTERVENTIONS: Each subject consumed four spreads, each for a period of 3.5 week. RESULTS: Compared to the control spread, total cholesterol decreased by 0.26 (CI: 0.15-0.36), 0.31 (CI: 0.20-0.41) and 0.35 (CI: 0.25-0.46) mmol/L, for daily consumption of 0.83, 1.61 and 3.24 g plant sterols, respectively. For LDL-cholesterol these decreases were 0.20 (CI: 0.10-0.31), 0.26 (CI: 0.15-0.36) and 0.30 (CI: 0.20-0.41). Decreases in the LDL/HDL ratio were 0.13 (CI: 0.04-0.22), 0.16 (CI: 0.07-0.24) and 0.16 (CI: 0.07-0.24) units, respectively. Differences in cholesterol reductions between the plant sterol doses consumed were not statistically significant. Plasma vitamin K1 and 25-OH-vitamin D and lipid standardized plasma lycopene and alpha-tocopherol were not affected by consumption of plant sterol enriched spreads, but lipid standardized plasma (alpha + beta)-carotene concentrations were decreased by about 11 and 19% by daily consumption of 0.83 and 3.24 g plant sterols in spread, respectively. CONCLUSIONS: The three relatively low dosages of plant sterols had a significant cholesterol lowering effect ranging from 4.9-6.8%, 6.7-9.9% and 6.5-7.9%, for total, LDL-cholesterol and the LDL/HDL cholesterol ratio, respectively, without substantially affecting lipid soluble (pro)vitamins. No significant differences in cholesterol lowering effect between the three dosages of plant sterols could be detected. This study would support that consumption of about 1.6 g of plant sterols per day will beneficially affect plasma cholesterol concentrations without seriously affecting plasma carotenoid concentrations.