Dietary Approaches to Stop Hypertension (DASH) diet: applicability and acceptability to a UK population.

BACKGROUND: The Dietary Approaches to Stop Hypertension (DASH) diet is widely promoted in the USA for the prevention and treatment of high blood pressure. It is high in fruit and vegetables, low-fat dairy and wholegrain foods and low in saturated fat and refined sugar. To our knowledge, the use of this dietary pattern has not been assessed in a free-living UK population. METHODS: The DASH diet was adapted to fit UK food preferences and portion sizes. Fourteen healthy subjects followed the adapted DASH diet for 30 days in which they self-selected all food and beverages. Dietary intake was assessed by 5-day food diaries completed before and towards the end of the study. Blood pressure was measured at the beginning and end of the study to assess compliance to the DASH style diet. RESULTS: The DASH diet was easily adapted to fit with UK food preferences. Furthermore, it was well tolerated and accepted by subjects. When on the DASH style diet, subjects reported consuming significantly (P < 0.01) more carbohydrate and protein and less total fat (5%, 6% and 9% total energy, respectively). Sodium intakes decreased by 860 mg day(-1) (P < 0.001). Systolic and diastolic blood pressure decreased significantly (P < 0.05) by 4.6 and 3.9 mmHg, respectively when on the DASH style diet. CONCLUSIONS: The DASH style diet was well accepted and was associated with a decrease in blood pressure in normotensive individuals and should be considered when giving dietary advice to people with elevated blood pressure in the UK.

Markers of de novo lipogenesis in adipose tissue: associations with small adipocytes and insulin sensitivity in humans.

AIMS/HYPOTHESIS: Previous studies have shown relationships between fatty acid ratios in adipose tissue triacylglycerol (TG), adipocyte size and measures of insulin sensitivity. We hypothesised that variations in adipose tissue de novo lipogenesis (DNL) in relation to adiposity might explain some of these observations. METHODS: In a cross-sectional study, subcutaneous abdominal adipose tissue biopsies from 59 people were examined in relation to fasting and post-glucose insulin sensitivity. Adipocyte size, TG fatty acid composition and mRNA expression of lipogenic genes were determined. RESULTS: We found strong positive relationships between adipose tissue TG content of the fatty acids myristic acid (14:0) and stearic acid (18:0) with insulin sensitivity (HOMA model) (p < 0.01 for each), and inverse relationships with adipocyte size (p < 0.01, p < 0.05, respectively). Variation in 18:0 content was the determinant of the adipose tissue TG 18:1 n-9/18:0 ratio, which correlated negatively with insulin sensitivity (p < 0.01), as observed previously. Adipose tissue 18:0 content correlated positively with the mRNA expression of lipogenic genes (e.g. FASN, p < 0.01). Lipogenic gene expression (a composite measure derived from principal components analysis) was inversely correlated with adipocyte cell size (p < 0.001). There was no relationship between dietary saturated fatty acid intake and adipose tissue 18:0 content. CONCLUSIONS/INTERPRETATION: Our data suggest a physiological mechanism whereby DNL is downregulated as adipocytes expand. Taken together with other data, they also suggest that hepatic and adipose tissue DNL are not regulated in parallel. We also confirm a strong relationship between small adipocytes and insulin sensitivity, which is independent of BMI.

Does the DASH diet lower blood pressure by altering peripheral vascular function?

We tested whether lowering of blood pressure (BP) on the dietary approaches to stop hypertension (DASH) diet was associated with changes in peripheral vascular function: endothelial function, assessed by flow-mediated vasodilatation (FMD) of the brachial artery, and subcutaneous adipose tissue blood flow (ATBF). We also assessed effects on heart rate variability (HRV) as a measure of autonomic control of the heart. We allocated 27 men and women to DASH diet and control groups. We measured FMD, ATBF and HRV on fasting and after ingestion of 75 g glucose, before and after 30 days on dietary intervention, aiming for weight maintenance. The control group did not change their diet. The DASH-diet group complied with the diet as shown by significant reductions in systolic (P<0.001) and diastolic (P=0.005) BP, and in plasma C-reactive protein (P<0.01), LDL-cholesterol (P<0.01) and apolipoprotein B (P=0.001), a novel finding. Body weight changed by <1 kg. There were no changes in the control group. We found no changes in FMD, or in ATBF, in the DASH-diet group, although heart rate fell (P<0.05). Glucose and insulin concentrations did not change. In this small-scale study, the DASH diet lowered BP independently of peripheral mechanisms.

Glycaemic responses in type 2 diabetic patients to various mixed meals taken at home.

Eight Type 2 diabetic patients ate and prepared five different meals at home, taking each meal on two separate occasions. They measured their blood glucose just before eating and 30, 60, 120, and 180 min after the meal. The meals varied in energy and dietary fibre content and in the ratio (by energy) of carbohydrate to fat. Total energy content of the meals had little effect on the postprandial glycaemic responses nor were the responses reduced by meals with high dietary fibre content. The ratio of carbohydrate to fat did not significantly affect postprandial glycaemic responses when meals were low in fibre. However, postprandial glycaemic responses were significantly greater in the meal with a high ratio of carbohydrate to fat, high in fibre and low in energy compared with those after the equicaloric meal low in carbohydrate to fat ratio and low in fibre (area under the curve 683 +/- 131 vs 306 +/- 55 mmol l-1 min-1, p < 0.05). Fat intake of 35% of energy may be compatible with improved postprandial blood glucose concentrations. Many meal combinations need to be studied in order to provide reliable information for diabetic patients. The method outlined proved producible (within patient coefficient of variation 13%), easy to perform and inexpensive.

Can life-styles of subjects with impaired glucose tolerance be changed? A feasibility study.

Thirty-one subjects with impaired glucose tolerance were randomly allocated to a group receiving advice to improve their diet and physical activity levels over 6 months (n = 23) or to a control group (n = 8). At 6 months, 18 of the 23 subjects receiving 'healthy living' advice were re-examined (five subjects had withdrawn). Fourteen of the 18 subjects showed an alteration in diet or an increase in exercise. The 18 subjects re-evaluated showed a reduction in systolic blood pressure (118 +/- 15 vs 124 +/- 15 mmHg, p less than 0.05) and decrease in total plasma cholesterol (4.5 +/- 1 vs 5.2 +/- 1 mmol l-1, p less than 0.01) and LDL-cholesterol levels (2.8 +/- 0.9 vs 3.2 +/- 0.9 mmol l-1, p less than 0.05). Plasma glucose levels were unchanged. One subject withdrew from the control group. At 6 months, the seven control subjects examined showed no significant change in metabolic parameters, with little measurable change in diet or exercise. At 2 years, 17 of the 23 'healthy living' subjects were reassessed. Nine of the subjects had continued to exercise or maintained a decreased weight compared to baseline. Fasting plasma glucose levels had increased (6.0 +/- 1.2 vs 5.5 +/- 0.6 mmol l-1, p less than 0.05), with the only continued improvement being a reduced LDL level (2.8 +/- 0.7 vs 3.1 +/- 0.9 mmol l-1, p less than 0.05). At 2 years, a similar proportion of the control group were taking regular exercise compared with the 'healthy living' group.(ABSTRACT TRUNCATED AT 250 WORDS)

'Healthy living' and sulphonylurea therapy have different effects on glucose tolerance and risk factors for vascular disease in subjects with impaired glucose tolerance.

This study was undertaken to determine whether impaired glucose tolerance and associated risk factors for cardiovascular disease can be improved with 'healthy living' by diet and exercise or with sulphonylurea therapy. Patients were recruited by screening subjects with either a family history of type II diabetes, previous gestational diabetes, or a previously raised plasma glucose (5.6-6.6 mmol/l). Impaired glucose tolerance was defined as hyperglycaemia on two separate tests, an achieved glucose level after a glucose infusion test above the 90th percentile of an age-matched normal population (> 9.3 mmol/l) or a fasting plasma glucose above the 95th percentile (> 5.6 mmol/l). Thirty-seven subjects with impaired glucose tolerance were entered into a randomized, prospective study for 6 months with allocations to healthy living or double blind to sulphonylurea (gliclazide 40 mg twice daily) or placebo tablets. The study took place in an out-patient setting, with three times weekly exercise sessions at a Sports Centre. After 6 months the placebo group showed no change in plasma glucose, cholesterol and blood pressure. The subjects receiving gliclazide showed improved glucose levels (mean fasting plasma glucose levels fell from 5.8 to 5.1 mmol/l, p < 0.05) but no significant change in plasma cholesterol or blood pressure. The healthy living group, after exclusion of four non-compliant subjects, showed no change in glucose levels, but a decreased systolic blood pressure (fall in mean from 124 to 116 mmHg, p < 0.05) and plasma cholesterol levels (fall in mean from 5.2 to 4.5 mmol/l, p < 0.01). with an increase in HDL:LDL ratio (rise in mean from 0.39 to 0.46, p < 0.05). Subjects with impaired glucose tolerance may benefit in different ways from gliclazide and healthy living. The metabolic responses to each therapy may help to decrease the risk of developing diabetes and cardiovascular disease.