Food may be medicine but it is not an easy one to give nor is it very effective
We here at Sensible Medicine love randomized trials, but they don't always answer important questions especially when Medicine leaves its area of expertise
Three facts: high blood pressure is one of the most important risks to good health and nutrition is a key component in causing and treating high blood pressure.
High blood pressure also disproportionately affects groups of people—especially susceptible are non-hispanic black individuals.
Since nutrition is causal, nutritional intervention might be a reasonable idea.
JAMA has published the results of the GoFresh randomized trial of a DASH-patterned grocery intervention in 180 individuals from a low-income neighborhood in Boston.
One group received 12 weeks of home-delivered DASH-patterned groceries designed in consultation with dieticians. The other group received a DASH brochure and $500 every four weeks intended for self-directed grocery shopping.
The primary outcome was a change in office-measured systolic BP at 3 months.
The trial had very strict entry criteria including being a self-identified African American or Black person, having a SBP of 120 to 150 mmHg and a diastolic BP less than 100 mmHg and living in a Boston neighborhood with poor access to grocery stores. You also could not be on a BP or diabetes medicine nor have an elevated HbA1c. The mean age and BP of trial participants were 48 years and 130 mm Hg.
The “Positive” Result
At 3 months, the mean SBP (primary outcome) changed by −5.7 mm Hg in the DASH group and −2.3 mm Hg in the self-directed group. The difference in changes, −3.4 mm Hg; 95% CI, −5.9 to −0.8 mm Hg; P = .009)
That’s the good news. The difference made it over the bar of statistical significance. The authors noted that the effect was greater in older people, which was true, but there were only 15 older people of 180.
The bad news was that nothing else good happened. After the 3-month intervention, the differences went away by 6 months. There were also no significant improvements in BMI or glucose control, and only modest effects on cholesterol.
To the authors credit, they present the screened to enrolled numbers. They screened 5500 people to enroll 180.
Comments
Both the authors and editorialist spent a great deal of effort on the components of the DASH intervention.
Two specific criticisms raised by the editorialist were that the authors used the older low-fat DASH diet but recent studies have suggested that the Mediterranean-style DASH diets higher in unsaturated fat or plant protein performed better. The trial intervention also did not include enough undersconsumed quality foods—such as minimally processed fruits, vegetables, nuts, seeds, legumes, whole grains, plant oils, plain yogurt, and fish.
Another problem was the $1100 per month cost of the intervention—which is about $1090 more than a generic BP pill.
Then there is the matter of how robust of an endpoint are two measures of office-based BP. Most recent BP trials use ambulatory BP.
The Bigger Issues
The AHA and Harvard supported the work. The trial looked like a huge effort performed by many motivated people. I don’t criticize any of the people involved.
But I wonder about the value in spending this much time and effort on such an intervention. You screen more than 5000 and with immense effort in 180 people you show that you can lower SBP by 3 mmHg for only 3 months.
I am not a policy expert but I can’t see how such a resource-intensive intervention could ever be scaled to large diverse populations. And if this was the prior, why should such a trial ever have been conducted?
While there are substantial disparities of health outcomes amongst poor and rich people in the US, I am not sure the medical establishment has the remedy.
Medicine excels when we treat individuals with problems. We are quite good at that. Medicine also has pills for high blood pressure that cost $4 per month. If SBP is your goal, that’s hard to beat.
In my opinion, the remedy for the substantial gaps in health outcomes in this country lie far upstream from modern medicine. I see the solutions as societal and political—not medical.
You may disagree. If so, please subscribe and leave a comment.
This is fine for someone with the time and means to eat that way. It is a privilege, and I say this as someone who is privileged. I also grew up in a state with a lot of food deserts. My husband’s small home town had a mom and pop type gas station store and a Dollar General as grocery options. The nearest true grocery store was 25 minutes away. People want to solve health issues with food…the very first thing to do is to address food deserts and access to healthy options. We are lucky that we live within 10 minutes of three major grocery retailers, a super Walmart and Target, and 20 minutes from a Whole Foods. We also have access to a farmer’s market in the warmer months. Eating well costs money, though. I understand why people take a pill instead.
You are correct, this study was not worth the time or money. Not because changing one's diet doesn't help, but for a number of other reasons.
1. They gave people access to healthy food for 3 months which worked to lower blood pressure, but then also measured BP at 6 months. Did the researchers expect that eating healthy for 3 months would continue to keep BP low? What if people only took a BP med for 3 months and then we checked their BP in 6 months?
2. Was there any education on healthy eating given? Then again, even if there was, if people lived in a food desert it wouldn't help. This is a more complex topic than a 3 month study could help. Were all the confounders accounted for (economic situation, access to healthy food, educational level, etc.)?
3. Any study that looks at making a diet change for only 3 months is useless. The long-term effects that come from changing one's diet happen because it is a permanent change. As a society, we have to make healthy food accessible (location, price).
I see studies every once in a while that seem to want to discredit the impact of diet on HTN and diabetes as well as other chronic diseases. They are poorly designed, such as this one. Many people who have embraced changes in their diet (and other lifestyle changes) have lived longer and healthier lives (my mother and her brother are 2 that I personally know).
Speaking of Lifestyle Medicine, it is more than just changing diet. It's making sure you have tools to handle stress, having enough sleep, exercising, having purpose and having a social network. All these things work together, along with diet, to make for a healthier life.