Participants
Personal and lifestyle characteristics for the two treatment groups were similar at baseline (Table 1). Participants were mostly male and non-smokers; mean age was about 60 years. Most were overweight at baseline, which was unchanged at outcome: 82% in the hawthorn group and 90% in the placebo group had BMI over the target maximum for health (BMI ≥25) according the many authorities.11
Table 1 Personal and lifestyle characteristics of participants at baseline, including prescribed drug usage, according to treatment group.a
With regard to waist circumference, 56% and 63% of participants taking hawthorn and placebo respectively, were categorised as being at ‘substantial risk’ of coronary heart disease and diabetes (≥102 cm for men and 88 cm for women12) and a further 29% and 32%, respectively, were at ‘increased risk’ (≥94 cm for men and 80 cm for women12). Most participants were over target (0.95 for males and 0.85 for females) for waist to hip ratio (64% hawthorn, 65% placebo).13
Prescription drug treatment was similar between groups (Table 1). Low-dose insulin was equally distributed between groups (hawthorn n = 4, placebo n = 3). Mean hypoglycaemic drug use was 1.9 and 2.1 drugs per participant in the hawthorn and placebo groups, with use of 0, 1, 2, or 3 drugs by 15, 13, 9, and 2 participants in the hawthorn and 9, 21, 8, and 2 participants in the placebo group, respectively. Mean hypotensive drug use was 2.5 and 2.2 drugs per participant in the hawthorn and placebo groups, with use of 0, 1, 2, 3, or 4 drugs by 11, 13, 9, 4, and 2 participants in the hawthorn and 12, 16, 9, 2, and 1 participants in the placebo group, respectively. In the entire study group, 71% (n = 28 in both groups) used one or more hypotensive drugs. Statins, aspirin, clofibrates and digoxins were prescribed for 9, 8, 1, and 0 participants in the hawthorn and 6, 6, 3, and 1 in the placebo group respectively. During the study there were 11 changes in drug regime (six in the hawthorn and five in the placebo group): seven dosage increases, three new drug introductions, and one drug cessation.
Table 2 shows mean energy intake and percentage contributions to energy intake from protein, fat, carbohydrate, and alcohol as calculated by the DIETQ Food Frequency Questionnaire. Mean total fat intake was below the recommended level of 35% of total energy intake for patients with diabetes,14 except for seven participants on hawthorn and eight on placebo. Mean intake of energy from polyunsaturated fatty acids was well within the guidelines of <10% of total energy,14 except for one participant in the placebo group. However, mean intake of saturated fat on hawthorn and 18 on placebo were over target. Group mean values for energy contribution from monounsaturated fatty acids were close to the lower limit of the recommended 10–20% of total energy:14 12 participants on hawthorn and 11 on placebo had lower intakes. For sugar, group mean intakes were above recommendations: 30 participants on hawthorn and 29 on placebo had sugar intake greater than 10% of total energy.
Table 2 Mean daily nutrient intake implicated in maintenance of normal blood pressure.
The micronutrients tested for were chosen because of their involvement in countering raised blood pressure.15–21 There was no significant difference in intake of nutrients for men between the two groups and only vitamin E levels were significantly different between women in the two groups. Mean intakes according to group were generally above the reference nutrient levels.22 However, mean intake was greater than the reference nutrient intake for vitamin D for both groups. Mean intake of potassium was greater among men on hawthorn and women on placebo. Mean selenium intake was greater among men in both groups and copper intake was greater among women in the placebo group. Mean intake of vitamin E in men on hawthorn was lower than the recommended safe intake.22
Participants who did not reach daily target intakes included 71% of the study population with vitamin D intakes less than the reference nutrient intake, 48% for potassium, 46% for selenium, 35% for copper, 29% for iodine, 27% for vitamin A and vitamin E, 16% for magnesium, and 8% for folate. Participant intakes of iron, zinc, iodine, manganese, vitamins B1, B2, B3, and B6 fell below their targets for between 1 and 10% of the study population. All participants reached target intakes for B12, biotin and pantothenic acid. Only three participants in the study group met all dietary targets: 24 were below nutrient targets for 1–3 nutrients, 22 for 4–6, eight for 7–9, and three were below target for 10–12 micronutrients.
Dietary supplement use between the two treatment groups at baseline was similar. For the study population, 40.5% were taking dietary supplements (n = 15 hawthorn, n = 17 placebo). The most popular dietary supplements were omega-3 (29.0% study population), multi-nutrients (12.7%), and vitamin C (10.0%).
Outcome measures
No significant difference was found between groups on mean baseline values for blood pressure measurements or indices of glycaemic control (Table 3). The primary outcome measure of diastolic blood pressure showed a significant reduction of 2.6 mmHg in the hawthorn group compared with the placebo group (P = 0.035) (Figure 2). No significant difference was found between treatment responses for systolic blood pressure: a paired t-test of baseline versus outcome showed a non-significant (P = 0.096) decline of 3.6 mmHg in the hawthorn group. There was no significant outcome difference between groups in the indices of glycaemic control, that is, fasting glucose, glycated haemoglobin and fructosamine.
Figure 2 Change in blood pressure after 16 weeks of daily supplementation with hawthorn extract compared with placebo. Diastolic blood pressure was significantly reduced in the hawthorn group compared with the placebo group (P = 0.035).
Table 3 Mean values for blood pressure and indices of glycaemic control at baseline and outcome.
All mean values for liver and kidney function tests were normal for both groups at baseline and outcome, except γ-glutamyl transpeptidase which was 70 and 75 U/L at baseline and outcome respectively for the placebo group (normal range 12–58 U/l). Eight participants on hawthorn and nine on placebo had slightly raised levels at baseline; two participants in the placebo group had levels >250 U/l.
No significant difference was noted in total wellbeing score using Bradley's Well-being Questionnaire, or subscores of depression, anxiety, energy or positive wellbeing. Mean total scores at baseline were 50.5 (95% CI = 48.62 to 52.38) and 49.4 (95% CI = 47.68 to 51.12) for hawthorn and placebo groups respectively; at outcome these scores were 50.4 (95% CI = 48.51 to 52.29) and 50.6 (95% CI = 48.86 to 52.34) respectively. Minor health complaints at 16 weeks of treatment were reduced in both groups compared with baseline (Table 4).
Table 4 Number of participants at baseline and outcome with minor health complaints.a
Participants who finished the study were asked to guess whether they had been assigned to the treatment or placebo group. Eleven participants on hawthorn made correct guesses while none made an incorrect guess. Two participants in the placebo group guessed correctly and two participants guess incorrectly. The remainder did not know which group they had been assigned to.
