Linda A J van Mierlo

Unilever, Londinium, England, United Kingdom

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Publications (8)45.4 Total impact

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    ABSTRACT: Data suggest that polyphenol-rich products may improve endothelial function and other cardiovascular health risk factors. Grape and wine contain high amounts of polyphenols, but effects of these polyphenols have hardly been investigated in isolation in randomized controlled studies. Our objective in this study was to test the chronic effect of polyphenol-rich solids derived from either a wine grape mix or grape seed on flow-mediated dilation (FMD). Blood pressure and other vascular function measures, platelet function, and blood lipids were secondary outcomes. Thirty-five healthy males were randomized in a double-blind, placebo-controlled crossover study consisting of three 2-wk intervention periods separated by 1-wk washout periods. The test products, containing 800 mg of polyphenols, were consumed as capsules. At the end of each intervention period, effects were measured after consumption of a low-fat breakfast (~751 kJ, 25% fat) and a high-fat lunch (~3136 kJ, 78% fat). After the low-fat breakfast, the treatments did not significantly affect FMD. The absolute difference after the wine grape solid treatment was -0.4% (95% CI = -1.8 to 0.9; P = 0.77) and after grape seed solids, 0.2% (95% CI = -1.2 to 1.5; P = 0.94) compared with after the placebo treatment. FMD effects after the high-fat lunch and effects on secondary outcomes also showed no consistent differences between both of the grape solids and placebo treatment. In conclusion, consumption of grape polyphenols has no major impact on FMD in healthy men. Future studies should address whether grape polyphenols can improve FMD and other cardiovascular health risk factors in populations with increased cardiovascular risk.
    Journal of Nutrition 10/2010; 140(10):1769-73. · 4.20 Impact Factor
  • Archives of internal medicine 09/2010; 170(16):1501-2. · 11.46 Impact Factor
  • L van Mierlo, A Greyling, P Zock, F Kok, M Geleijnse
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    ABSTRACT: Objective: Potassium intake is inversely related to blood pressure and cardiovascular disease risk, and intervention studies show that increasing potassium intake lowers blood pressure. We reviewed potassium intake data and estimated the potential impact of optimizing intakes on population blood pressure levels. Design and Method: We conducted a structured search of PubMed and national health authorities' websites and included representative national surveys conducted from 1990–2009 with a sample size >1,000 in which potassium intake was assessed in adults. The optimal potassium intake level was set at 4.7 gram (g) per day and we assumed a linear association between intake and systolic blood pressure, i.e. reduction of 1 mmHg per 0.6 g increase in intake. Results: We collected data from 21 countries spread across North America, Europe, Asia and Oceania. Average potassium intake in the countries included in our review ranged from 1.7 (in China) to 3.7 g per day (in Finland, the Netherlands and Poland). Based on data from United Kingdom, Finland and United States of America (representing different average population intakes), increasing potassium intake to 4.7 g per day can be estimated to reduce population systolic blood pressure in Western countries by 1.7–3.2 mmHg. This is in the same order of what can be predicted for a reduction in sodium intake from 9 to 5 g per day. Conclusions: Potassium intakes in the population are below optimal. Our data indicate that modifying intakes of potassium and sodium have similar potential for reducing population blood pressure levels. Both should be considered for dietary policies and measures aimed at improving public health.
    Journal of Hypertension 05/2010; 28:e240. · 4.22 Impact Factor
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    ABSTRACT: Dietary factors directly influence blood pressure (BP). The lactotripeptides (LTPs) IPP (isoleucine-proline-proline) and VPP (valine-proline-proline), formed by hydrolyzing dairy proteins, and potassium, a mineral mainly found in fruit, vegetables, and dairy products, are extensively studied for their BP-lowering effect. The efficacy of LTPs seems modest in whites compared with that in Asians. The objective was to study the effects of enzymatically produced LTPs alone or in combination with potassium on ambulatory BP in whites. Two multicenter, placebo-controlled, randomized, crossover studies were conducted; each consisted of two 4-wk intervention periods separated by a 4-wk washout period. In study 1, 69 subjects received 200 g/d of a dairy drink with 5.8 mg IPP and 4.4 mg VPP or placebo. In study 2, 93 subjects received 100 g/d of a dairy drink with 2.7 mg IPP, 1.9 mg VPP, and 350 mg added K or placebo. The subjects were randomly assigned according to their daytime ambulatory BP. Mean 24-h systolic and diastolic BP (baseline values-study 1: 137.1/81.6 mm Hg; study 2: 139.2/80.9 mm Hg) remained similar with no significant differences between treatments in either study (P > 0.10). Office BP decreased over the course of both studies (systolic BP > 5 mm Hg), but differences between interventions were not significant (P > 0.10). In both studies, nighttime BP dipped during all treatments (> or =15%) but was statistically more significant with placebo (P < 0.05). Sodium excretion increased significantly after consumption of LTPs and potassium compared with after placebo intervention (P = 0.01), but not after consumption of LTPs alone. The data do not support a BP-lowering effect of LTPs in whites.
    American Journal of Clinical Nutrition 12/2008; 89(2):617-23. · 6.50 Impact Factor
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    ABSTRACT: Milk-derived peptides with ACE-inhibiting properties may have antihypertensive effects in humans. We conducted a randomized double-blind placebo-controlled trial to examine the blood pressure lowering potential of 2 ACE-inhibiting lactotripeptides, ie, Isoleucine-Proline-Proline and Valine-Proline-Proline. We included 135 Dutch subjects with elevated systolic blood pressure who were otherwise healthy and who received no current antihypertensive treatment. After a 2-week run-in period on placebo, subjects randomly received a daily dose of 200 mL dairy drink with 14 mg lactotripeptides obtained by concentrating fermented milk, enzymatic hydrolysis, or chemical synthesis, or placebo for 8 weeks, followed by a 2-week wash-out. The primary outcome was 8-week change in office systolic blood pressure. Secondary outcomes were change in diastolic blood pressure, home blood pressure, 24-hour ambulatory blood pressure, plasma ACE-activity, and plasma angiotensin II. Blood pressure at baseline was on average 142/84 mm Hg. Lactotripeptides did not significantly change systolic blood pressure (P=0.46) or diastolic blood pressure (P=0.31) compared with placebo. The mean difference (95%-CI) in systolic blood pressure response between treatment and placebo was 2.8 mm Hg (-2.6;8.2) for concentrated fermented milk lactotripeptides, -0.5 mm Hg (-6.0;5.0) for enzymatic lactotripeptides, and 1.6 mm Hg (-3.9;6.9) for synthetic lactotripeptides. Treatment neither had a significant effect on secondary outcome measures. In conclusion, the present study does not support the hypothesis of a blood pressure lowering effect of the lactotripeptides Isoleucine-Proline-Proline and Valine-Proline-Proline.
    Hypertension 03/2008; 51(2):399-405. · 6.87 Impact Factor
  • Journal of Human Hypertension 02/2008; 22(1):54-6. · 2.82 Impact Factor
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    Angelika de Bree, Linda A van Mierlo, Richard Draijer
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    ABSTRACT: The effect of folic acid on endothelial function, a prognostic factor for cardiovascular diseases, is not well established. We calculated this effect in a meta-analysis of randomized, double-blind, placebo-controlled trials in humans. The objective of the study was to quantify the effect of folic acid on endothelial function, as measured with the use of flow-mediated dilatation (FMD). We conducted a meta-analysis of randomized, double-blind, placebo-controlled folic acid trials evaluating endothelial function. Trials were identified through MEDLINE (1966-15 Sept 2005), by hand-searching of references, and by contact with investigators for unpublished results. Two of us (AdB and RD) independently extracted trial data. A pooled estimate was calculated by using random-effects meta-analysis. Previously defined stratified analyses were conducted to explore the influence of study characteristics. Of 163 identified studies, 14 met inclusion criteria and provided data on 732 persons. Evidence for publication bias was not obvious. In the overall pooled estimate, folic acid improved FMD by 1.08 (95% CI: 0.57,1.59; P = 0.0005) percentage points over placebo. Of the study characteristics, only folic acid dose significantly influenced the outcome. Post hoc analysis, which should be interpreted with caution, seemed to indicate a dose-response effect: the change in FMD was -0.07 (95% CI: -0.37, 0.22) percentage points at doses between 400 and 800 microg/d, 1.37 (95% CI: 1.12, 1.54) percentage points at doses of 5000 microg/d, and 2.04 (95% CI: 1.43, 2.65) percentage points at doses of 10,000 microg/d. This study indicates that high doses of folic acid improve endothelial function, which could potentially reduce the risk of cardiovascular disease.
    American Journal of Clinical Nutrition 10/2007; 86(3):610-7. · 6.50 Impact Factor
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    ABSTRACT: Calcium plays a role in blood pressure (BP) regulation, but the importance of supplemental calcium intake for the prevention of hypertension is still debated. We conducted a meta-analysis of randomized controlled trials to determine the effect of calcium supplementation on BP. A systematic search for randomized trials of calcium supplementation and BP in non-pregnant subjects was performed in Medline from 1966 to June 2003. Seventy-one trials were identified, 40 of which met the criteria for meta-analysis (total of 2492 subjects). Two persons independently extracted data from original publications on changes in calcium intake and BP. In addition, data were collected on subjects' characteristics, that is, age, gender, initial BP and initial calcium intake. A random effects model was used to obtain the effect of calcium supplementation on BP, overall and in predefined population subgroups. Calcium supplementation (mean daily dose: 1200 mg) reduced systolic BP by -1.86 mm Hg (95% confidence interval: -2.91 to -0.81) and diastolic BP by -0.99 mm Hg (-1.61 to -0.37). In people with a relatively low calcium intake (< or =800 mg per day) somewhat larger BP estimates were obtained, that is, -2.63 (-4.03 to -1.24) for systolic BP and -1.30 (-2.13 to -0.47) for diastolic BP. Our study suggests that an adequate intake of calcium should be recommended for the prevention of hypertension. More research on BP in people with calcium-deficient diets is warranted.
    Journal of Human Hypertension 08/2006; 20(8):571-80. · 2.82 Impact Factor