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Adherence to dietary recommendations linked to small improvement in weight, CHD risk factors
An increased intake of foods recommended for a heart-healthy diet was linked to small improvements in weight and CHD risk factors in patients with overweight, according to findings published in the Journal of the American College of Cardiology.
However, participants wanting to control their CHD risk factors by increasing their intake of fruits, vegetables, whole-grain cereals and functional foods such as nuts, fiber, soy protein found it difficult to do so even when provided weekly food provisions, researchers wrote.
“These data demonstrate the difficulty in effectively promoting fruit, vegetable and whole-grain cereals to the general population, using recommendations that, when followed, decrease risk factors for chronic disease,” David J.A. Jenkins, MD, professor and Canada Research Chair in Nutrition and Metabolism at the department of nutritional science at the University of Toronto, and colleagues wrote. “They indicate an urgent need for innovative approaches to support the implementation of current dietary advice.”
Researchers analyzed data from 919 participants (710 women; mean age, 45 years; mean BMI, 32.4 kg/m2) from Toronto with a BMI > 25 kg/m2. Families also participated if at least one member met the BMI requirement. The primary outcome was body weight change.
Participants were randomly assigned to one of three intervention groups or a control group between October 2005 and August 2009. All groups received Health Canada’s Food Guide, but nothing further was given to the control group.
One treatment group received weekly dietary guidance for the first month, then monthly for the next 5 months over the phone. One treatment group had weekly food provisions delivered for 6 months, which mirrored the advice given to the first group, but without the phone calls. The third group was given the dietary advice and weekly food provisions. Participants within the same family were asked to follow the treatment guidelines.
After 6 months, 685 participants (515 women) completed the study (75% retention rate). The retention rate was higher for participants who received food provisions (91%) compared with those who just received dietary advice (67%; P < .0001).
Researchers observed slight increases in the intake of vegetables (0.4 to 1.3 servings per day), fruit (0.3 to 1.1 servings per day) and whole-grain cereals (0 to 1 serving per day). The treatment group that received advice and food provisions showed a consistent increase in intake compared with the control group.
All treatment groups saw slight increases in fruit (0.8 servings per day), vegetable (0.9 servings per day) and whole-grain cereals (0.9 servings per day) vs. the control group. Functional food intake minimally increased among all groups, with the highest increase seen in the food delivery and advice group (6.5 g per day).
Small reductions were also seen in the cohort’s waist circumference (–1.4 cm; 95% CI, –1.9 to –0.9), body weight (–1 kg; 95% CI, –1.4 to –0.7) and BP (diastolic: –0.8 mm Hg; 95% CI, –1.3 to –0.4; mean arterial pressure: –0.7 mm Hg; 95% CI, –1.3 to –0.1). The control and individual test groups showed similar reductions: waist circumference (–1.1 to –1.9 cm), body weight (–0.8 to –1.2 kg) and BP (diastolic: –0.1 to –1 mm Hg; mean arterial pressure: 0 to –1.1 mm Hg). A significant reduction was noted within the control group for diastolic BP (–1 mm Hg; P = .002) and mean arterial BP (–0.9 mm Hg; P = .042).
Within-group differences in waist circumference and body weight were significant for all groups, but there were no significant differences between the groups for any of the outcomes, Jenkins and colleagues wrote.
At 18 months, the retention rate for the cohort was 65%. Participants who received food provisions had a retention rate of 81% vs. 57% who did not receive them. Small increases in vegetables (0.3 to 0.6 servings per day), fruit (0.4 to 0.6 servings per day) and whole-grain cereals (0 to 0.6 servings per day) were observed from the baseline, which were significant reductions from the 6-month data. Reductions in BMI, body weight and waist circumference were maintained.
“[An] ... interesting aspect is the ‘legacy effect’ of the nutritional intervention observed in this trial; benefits of the intervention on CVD risk factors extend beyond the finite period of active treatment,” Ramon Estruch, MD, PhD, from the department of internal medicine at the Hospital Clinic of Barcelona, Spain, and Emilio Ros, MD, PhD, from the lipid clinic, department of endocrinology and nutrition, Institut d’Investigacions Biomèdiques August Pi Sunyer, Hospital Clinic of Barcelona, wrote in a related editorial. “Small, shorter-term trials with outcomes on intermediate markers like that of Jenkins et al are also difficult but manageable, particularly if specific foods are delivered to participants in the active treatment group.” – by Darlene Dobkowski
Disclosure : Estruch reports no relevant financial disclosures. Jenkins reports financial ties with multiple food and pharmaceutical companies. Ros reports receiving nonfinancial support, grants and other fees from Aegerion, Akcea, Alexion, Amgen, the California Walnut Commission, Ferrer International, Merck Sharp & Dohme, Pfizer and Sanofi. Please see the full study for the other researchers’ relevant financial disclosures.
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This research had a very strong study design. As a randomized controlled trial, it was able to show cause and effect. The number of participants was high, and the researchers measured behaviors, which included the servings of the target foods, and conducted biochemical analyses.
The results of this study were disappointing. It would have been so encouraging to see meaningful changes in dietary habits, BMI, BP and biochemical measures with the intervention. As the researchers stated in the discussion, the results really show how difficult it is for people to make changes in their diets, even when the food is provided, and that we possibly need multilevel interventions and for longer, sustained periods of time. We may also need to add an individual level with more personalized interventions.
The foods that researchers added in the study were ones I would have picked. I would have added in olive oil, since there is moderately good evidence for its benefits. The DASH/Portfolio dietary patterns have strong evidence supporting them. I like the dietary pattern approach rather than a single-food approach.
An addition of exercise would have been my major recommendation. I realize that they wanted to focus on foods, but the addition of exercise may have improved the results for BP and blood fats.
The legacy effect was interesting and shows that, while the results of this study may not have been clinically significant, this type of intervention is heading in the right direction.
The interventions may need to be more robust or community-wide with messaging throughout the community, and individualized counseling may also be necessary. A lot of the counseling research shows that simply advising people on how to change is generally not effective. Internal motivation may be key.
It would be interesting to do some qualitative follow-up interviews with the participants on what their barriers were to eating more of the healthy foods. They may have done some of that in the advice groups, but I would like to see some of the details on the advice intervention. There may be some clues there on how that aspect of the intervention was designed and implemented.