Els Siebelink

Effect of a high monounsaturated fatty acids diet and a Mediterranean diet on serum lipids and insulin sensitivity in adults with mild abdominal obesity

BACKGROUND AND AIMS Diets high in monounsaturated fatty acids (MUFA) such as a Mediterranean diet may reduce the risk of cardiovascular diseases by improving insulin sensitivity and serum lipids. Besides being high in MUFA, a Mediterranean diet also contains abundant plant foods, moderate wine and low amounts of meat and dairy products, which may also play a role. We compared the effects of a high MUFA-diet with a diet high in saturated fatty acids (SFA) and the additional effect of a Mediterranean diet on insulin sensitivity and serum lipids. METHODS AND RESULTS A randomized parallel controlled-feeding trial was performed, in 60 non-diabetics (40-65 y) with mild abdominal obesity. After a two week run-in diet high in SFA (19 energy-%), subjects were allocated to a high MUFA-diet (20 energy-%), a Mediterranean diet (MUFA 21 energy-%), or the high SFA-diet, for eight weeks. The high MUFA and the Mediterranean diet did not affect fasting insulin concentrations. The high MUFA-diet reduced total cholesterol (-0.41 mmol/L, 95% CI -0.74, -0.09) and LDL-cholesterol (-0.38 mmol/L, 95% CI -0.65, -0.11) compared with the high SFA-diet, but not triglyceride concentrations. The Mediterranean diet increased HDL-cholesterol concentrations (+0.09 mmol/L, 95% CI 0.0, 0.18) and reduced the ratio of total cholesterol/HDL-cholesterol (-0.39, 95% CI -0.62, -0.16) compared with the high MUFA-diet. CONCLUSION Replacing a high SFA-diet with a high MUFA or a Mediterranean diet did not affect insulin sensitivity, but improved serum lipids. The Mediterranean diet was most effective, it reduced total and LDL-cholesterol, and also increased HDL-cholesterol and reduced total cholesterol/HDL-cholesterol ratio.

Self-reported energy intake by FFQ compared with actual energy intake to maintain body weight in 516 adults

It is generally assumed that a FFQ is not suitable to estimate the absolute levels of individual energy intake. However, in epidemiological studies, reported nutrients by FFQ are often corrected for this intake. The objective of the present study was to assess how accurately participants report their energy intakes by FFQ. We compared reported energy intake with actual energy intake needed to maintain stable body weights during eleven controlled dietary trials. FFQ were developed to capture at least 90 % of energy intake. Participants, 342 women and 174 men, with a mean BMI of 22.8 (SD 3.1) kg/m2 filled out the FFQ just before the trials. Energy intakes during the trials were calculated from provided foods and reported free-food items, representing 90 and 10 % of energy intake, respectively. Mean reported energy intake was 97.5 (SD 12.7) % of actual energy intake during the trials; it was 98.9 (SD 15.2) % for women and 94.7 (SD 16.3) % for men (P = 0.004 for difference between sexes). Correlation coefficients between reported and actual energy intakes were 0.82 for all participants, 0.74 for women and 0.80 for men. Individual reported energy intake as a percentage of actual intake ranged from 56.3 to 159.6 % in women and from 43.8 to 151.0 % in men. In conclusion, the FFQ appeared to be accurate for estimating the mean level of energy intakes of these participants and for ranking them according to their intake. However, the large differences found on the individual level may affect the results of epidemiological studies in an unknown direction if nutrients are corrected for energy intakes reported by FFQ.

Protein status elicits compensatory changes in food intake and food preferences

Background: Protein is an indispensable component within the human diet. It is unclear, however, whether behavioral strategies exist to avoid shortages. Objective: The objective was to investigate the effect of a low protein status compared with a high protein status on food intake and food preferences. Design: We used a randomized crossover design that consisted of a 14-d fully controlled dietary intervention involving 37 subjects [mean ± SD age: 21 ± 2 y; BMI (in kg/m2): 21.9 ± 1.5] who consumed individualized, isoenergetic diets that were either low in protein [0.5 g protein · kg body weight (BW)−1 · d−1] or high in protein (2.0 g protein · kg BW−1 · d−1). The diets were followed by an ad libitum phase of 2.5 d, during which a large array of food items was available, and protein and energy intakes were measured. Results: We showed that in the ad libitum phase protein intake was 13% higher after the low-protein diet than after the high-protein diet (253 ± 70 compared with 225 ± 63 g, P < 0.001), whereas total energy intake was not different. The higher intake of protein was evident throughout the ad libitum phase of 2.5 d. In addition, after the low-protein diet, food preferences for savory high-protein foods were enhanced. Conclusions: After a protein deficit, food intake and food preferences show adaptive changes that suggest that compensatory mechanisms are induced to restore adequate protein status. This indicates that there are human behavioral strategies present to avoid protein shortage and that these involve selection of savory high-protein foods. This trial was registered with the Dutch Trial register at http://www.trialregister.nl as NTR2491.

Effect of a High Intake of Conjugated Linoleic Acid on Lipoprotein Levels in Healthy Human Subjects

Background Trans fatty acids are produced either by industrial hydrogenation or by biohydrogenation in the rumens of cows and sheep. Industrial trans fatty acids lower high-density lipoprotein (HDL) cholesterol, raise low-density lipoprotein (LDL) cholesterol, and increase the risk of coronary heart disease. The effects of trans fatty acids from ruminants are less clear. We investigated the effect on blood lipids of cis-9, trans-11 conjugated linoleic acid (CLA), a trans fatty acid largely restricted to ruminant fats. Methodology/Principal Findings Sixty-one healthy women and men were sequentially fed each of three diets for three weeks, in random order, for a total of nine weeks. Diets were identical except for 7% of energy (approximately 20 g/day), which was provided either by oleic acid, by industrial trans fatty acids, or by a mixture of 80% cis-9, trans-11 and 20% trans-10, cis-12 CLA. After the oleic acid diet, mean (± SD) serum LDL cholesterol was 2.68±0.62 mmol/L compared to 3.00±0.66 mmol/L after industrial trans fatty acids (p<0.001), and 2.92±0.70 mmol/L after CLA (p<0.001). Compared to oleic acid, HDL-cholesterol was 0.05±0.12 mmol/L lower after industrial trans fatty acids (p = 0.001) and 0.06±0.10 mmol/L lower after CLA (p<0.001). The total-to–HDL cholesterol ratio was 11.6% higher after industrial trans fatty acids (p<0.001) and 10.0% higher after CLA (p<0.001) relative to the oleic acid diet. Conclusions/Significance High intakes of an 80∶20 mixture of cis-9, trans-11 and trans-10, cis-12 CLA raise the total to HDL cholesterol ratio in healthy volunteers. The effect of CLA may be somewhat less than that of industrial trans fatty acids. Trial Registration ClinicalTrials.gov NCT00529828

Trans monounsaturated fatty acids and saturated fatty acids have similar effects on postprandial flow-mediated vasodilation

Objective: Several studies suggest that a fatty meal impairs flow-mediated vasodilation (FMD), a measure of endothelial function. We tested whether the impairment was greater for trans fats than for saturated fats. We did this because we previously showed that replacement of saturated fats by trans fats in a controlled diet decreased FMD after 4 weeks.Design: We fed 21 healthy men two different test meals with 0.9–1.0 g fat/kg body weight in random order: one rich in saturated fatty acids (Sat), mainly from palm kernel fat, and one rich in trans fatty acids (Trans) from partially hydrogenated soy bean oil. The study was performed in our metabolic ward. We had complete data for both diets of 21 men.Results: FMD increased from a fasting value of 2.3±2.0% of the baseline diameter to 3.0±1.7% after the Sat test meal (95% CI for change −0.33, 1.70) and from 2.7±2.3 to 3.1±2.0% after the Trans test meal (95% CI for change −0.57, 1.29). The increase after the Sat meal was 0.22 (−1.18–1.61) FMD% higher than after the Trans meal. Serum triacylglycerols increased by 0.46±0.36 mmol/l after the Sat test meal and by 0.68±0.59 mmol/l after the Trans test meal; a difference of 0.23 (0.07, 0.39) mmol/l. Serum HDL-cholesterol was hardly affected by the test meals. The activity of serum paraoxonase, an esterase bound to HDL, increased slightly after the two test meals but the difference between meals was not significant.Conclusion: FMD was not impaired and not different after test meals with saturated or trans fatty acids. Thus, differences in long-term effects of these fats are not caused by differences in acute effects on the vascular wall.

Partly Replacing Meat Protein with Soy Protein Alters Insulin Resistance and Blood Lipids in Postmenopausal Women with Abdominal Obesity

Increasing protein intake and soy consumption appear to be promising approaches to prevent metabolic syndrome (MetS). However, the effect of soy consumption on insulin resistance, glucose homeostasis, and other characteristics of MetS is not frequently studied in humans. We aimed to investigate the effects of a 4-wk, strictly controlled, weight-maintaining, moderately high-protein diet rich in soy on insulin sensitivity and other cardiometabolic risk factors. We performed a randomized crossover trial of 2 4-wk diet periods in 15 postmenopausal women with abdominal obesity to test diets with 22 energy percent (En%) protein, 27 En% fat, and 50 En% carbohydrate. One diet contained protein of mixed origin (mainly meat, dairy, and bread), and the other diet partly replaced meat with soy meat analogues and soy nuts containing 30 g/d soy protein. For our primary outcome, a frequently sampled intravenous glucose tolerance test (FSIGT) was performed at the end of both periods. Plasma total, LDL, and HDL cholesterol, triglycerides, glucose, insulin, and C-reactive protein were assessed, and blood pressure, arterial stiffness, and intrahepatic lipid content were measured at the start and end of both periods. Compared with the mixed-protein diet, the soy-protein diet resulted in greater insulin sensitivity [FSIGT: insulin sensitivity, 34 ± 29 vs. 22 ± 17 (mU/L)(-1) · min(-1), P = 0.048; disposition index, 4974 ± 2543 vs. 2899 ± 1878, P = 0.038; n = 11]. Total cholesterol was 4% lower after the soy-protein diet than after the mixed-protein diet (4.9 ± 0.7 vs. 5.1 ± 0.6 mmol/L, P = 0.001), and LDL cholesterol was 9% lower (2.9 ± 0.7 vs. 3.2 ± 0.6 mmol/L, P = 0.004; n = 15). Thus, partly replacing meat with soy in a moderately high-protein diet has clear advantages regarding insulin sensitivity and total and LDL cholesterol. Therefore, partly replacing meat products with soy products could be important in preventing MetS. This trial was registered at clinicaltrials.gov as NCT01694056.

Hidden Fat Facilitates Passive Overconsumption

Food intake regulation may be disturbed when sensory signals from foods are disconnected from their metabolic properties. Consumption of high-fat, energy-dense foods may stimulate passive overconsumption, because these foods do not provide sensory signals in accordance with the actual nutrient content. We examined the effects of perception of fat on energy intake in adults after overfeeding (Study 1) and on energy intake during a meal (Study 2). In study 1, 57 participants consumed 6 mandatory lunches differing in energy level (100, 200, and 300% of a standard lunch intake) and fat condition (visible fat and hidden fat). Ad libitum energy intake was measured during subsequent meals. In Study 2, 51 participants consumed 2 lunches that were high in visible or hidden fats. We measured ad libitum energy intake during lunch. In Study 1, the energy intake at dinner was 8% higher in the hidden fat condition than in the visible fat condition (P = 0.0046). A main effect was also found for the energy level of the lunch (P < 0.0001), with the highest intake following the 100% energy level and the lowest intake following the 300% energy level. In Study 2, the energy intake was 9% higher in the hidden fat condition than in the visible fat condition (P = 0.013). Perception of fat influences energy intake. In the presence of visible fats, energy intake was lower than in the presence of hidden fats, suggesting that hidden fats may contribute to overconsumption. Appropriate sensory signals may be important in preventing overconsumption.

Effect of a nutrient-enriched drink on dietary intake and nutritional status in institutionalised elderly

Objective:(1) To determine whether nutritional supplementation (energy and micronutrients) in institutionalised elderly has a positive effect on dietary intake and nutritional status. (2) To investigate whether individuals tend to compensate for the energy content of the intervention product by decreasing their habitual food consumption.Methods:A 24-week, randomised, double-blind, placebo-controlled, intervention trial in homes for the elderly (n=3), in nursing homes (n=3) and ‘mixed’ homes (n=3) in The Netherlands. Institutionalised elderly people (n=176) older than 60 years of age, with a body mass index ⩽30 kg/m2 and a Mini-Mental State Examination score of 10 points or higher, randomly received a nutrient-enriched drink or a placebo drink twice a day during 24 weeks in addition to their usual diet. Allocation to treatment took into account of sex, the Mini-Mental State Examination score and the plasma homocysteine level. Body weight and several nutrition-related analyses in fasting blood samples were measured in all participants. Data on dietary intake were collected in a subsample (n=66).Results:A significantly favourable effect (P<0.001) of the intervention drink was observed on vitamin intake, mineral intake and vitamin status in blood (for example, homocysteine decreased from 14.7 to 9.5 μmol/l in the intervention group as compared with that in the placebo group (17.2–15.9)). The difference in change in total energy intake between the two treatment groups was 0.8 MJ/day (P=0.166). Energy intake from food decreased in both groups to the same extent (−0.5 MJ/day). Therefore, this decrease cannot be considered as compensation for the energy content of the product.Conclusions:This group of institutionalised elderly people does not compensate for the energy content of a concentrated nutritional supplement. Therefore, this supplement is effective for counteracting the development of malnutrition in this population.

Effects of sodium and potassium supplementation on blood pressure and arterial stiffness: a fully controlled dietary intervention study

We performed a randomised, placebo-controlled, crossover study to examine the effects of sodium and potassium supplementation on blood pressure (BP) and arterial stiffness in untreated (pre)hypertensive individuals. During the study, subjects were on a fully controlled diet that was relatively low in sodium and potassium. After a 1-week run-in period, subjects received capsules with supplemental sodium (3 g d−1, equals 7.6 g d−1 of salt), supplemental potassium (3 g d−1) or placebo, for 4 weeks each, in random order. Fasting office BP, 24-h ambulatory BP and measures of arterial stiffness were assessed at baseline and every 4 weeks. Of 37 randomized subjects, 36 completed the study. They had a mean pre-treatment BP of 145/81 mm Hg and 69% had systolic BP ⩾140 mm Hg. Sodium excretion was increased by 98 mmol per 24 h and potassium excretion by 63 mmol per 24 h during active interventions, compared with placebo. During sodium supplementation, office BP was significantly increased by 7.5/3.3 mm Hg, 24-h BP by 7.5/2.7 mm Hg and central BP by 8.5/3.6 mm Hg. During potassium supplementation, 24-h BP was significantly reduced by 3.9/1.6 mm Hg and central pulse pressure by 2.9 mm Hg. Pulse wave velocity and augmentation index were not significantly affected by sodium or potassium supplementation. In conclusion, increasing the intake of sodium caused a substantial increase in BP in subjects with untreated elevated BP. Increased potassium intake, on top of a relatively low-sodium diet, had a beneficial effect on BP. Arterial stiffness did not materially change during 4-week interventions with sodium or potassium.

Identification of biomarkers for intake of protein from meat, dairy products and grains: a controlled dietary intervention study

In the present controlled, randomised, multiple cross-over dietary intervention study, we aimed to identify potential biomarkers for dietary protein from dairy products, meat and grain, which could be useful to estimate intake of these protein types in epidemiological studies. After 9 d run-in, thirty men and seventeen women (22 (SD 4) years) received three high-protein diets (aimed at approximately 18% of energy (en%)) in random order for 1 week each, with approximately 14 en% originating from either meat, dairy products or grain. We used a two-step approach to identify biomarkers in urine and plasma. With principal component discriminant analysis, we identified amino acids (AA) from the plasma or urinary AA profile that were distinctive between diets. Subsequently, after pooling total study data, we applied mixed models to estimate the predictive value of those AA for intake of protein types. A very good prediction could be made for the intake of meat protein by a regression model that included urinary carnosine, 1-methylhistidine and 3-methylhistidine (98% of variation in intake explained). Furthermore, for dietary grain protein, a model that included seven AA (plasma lysine, valine, threonine, α-aminobutyric acid, proline, ornithine and arginine) made a good prediction (75% of variation explained). We could not identify biomarkers for dairy protein intake. In conclusion, specific combinations of urinary and plasma AA may be potentially useful biomarkers for meat and grain protein intake, respectively. These findings need to be cross-validated in other dietary intervention studies.