Tag Archives: DASH diet

Mediterranean Diet Helps Preserve Brain Function

Well, perhaps that’s a bit of an overstatement. Preserved brain function and the Mediterranean diet were  positively associated in a study involving Americans in Utah. This fits with prior observations that the Mediterranean diet prevents dementia.

Macadamia nuts

In the study at hand, the DASH diet (Dietary Approaches to Stop Hypertension) also protected the brain:

Higher levels of accordance [compliance] with both the DASH and Mediterranean dietary patterns were associated with consistently higher levels of cognitive function in elderly men and women over an 11-year period. Whole grains and nuts and legumes were positively associated with higher cognitive functions and may be core neuroprotective foods common to various healthy plant-centered diets around the globe.

See the American Journal of Clinical Nutrition for details.

Prevention of Weight Regain Is NOT Impossible

I often hear from the general public, and even my physician colleagues, that losing weight and keeping it off is a hopeless goal.  So, why try?

Because it’s not hopeless.

The March 12, 2008, edition of the Journal of the American Medical Association includes an article from the Weight Loss Maintenance Collaborative Research Group.  Researchers identified a group of 1,032 overweight or obese adults who lost at least 8.8 pounds (4 kg) during a 6-month weight loss program.  These adults had high blood pressure, blood lipid abnormalities, or both.  38% were African American and 63% were women.

Average weight of the group before losing weight was 213 pounds (96.7 kg).  The weight-loss program consisted of 20 weekly group sessions, exercise goal of 180 minutes per week (26 minutes per day, usually walking), reduced caloric intake, and adoption of the Dietary Approaches to Stop Hypertension eating pattern.  The goal rate of weight loss was 1 or 2 pounds per week (0.45 to 0.91 kg per week).  Study subjects were taught how to keep records of their caloric intake and physical activity.

Except for the weekly group sessions, this program is similar to the Advanced Mediterranean Diet.

So each of these folks lost at least 8.8 pounds on this program.  Researchers followed them over the next 30 months to see how much weight would be regained.  Average weight loss for the entire group actually was 19 pounds (8.6 kg).  As expected, many people did regain weight over the next 30 months, between 6 and 9 pounds on average.  Of course, some individuals lost much more weight initially, and didn’t gain any back.  Some regained all of the lost weight, plus extra.

Overall, 42% of participants “maintained at least 4 kg [8.8 pounds] of weight loss compared with entry weight…” over the 30 months of follow-up.  37% remained at least 5% below their initial weight.

The “5%” figure stands out, for me, because we see improvement in obesity-related medical problems with loss of just 5 to 10% of body weight.

The authors cite studies indicating that “each kilogram [2.2 pounds] of weight loss is associated with a decrease in systolic blood pressure of 1.0 to 2.4 mmHg and a reduction of incident diabetes of 16%.”

To summarize the weight changes:  Study participants weighed 213 pounds before the behavioral weight-loss program.  Average weight loss was 19 pounds, down to 194 pounds.  Average weight regain over 30 months was in the range of 6 to 9 pounds.  Participants were still pretty big, but 37% of them probably saw some improvement in their medical status.

A huge amount of effort went into this study, on the part of both researchers and study participants.  Nevertheless, average results are relatively modest.  Keep in mind, however, that the numbers are averages, and you are not average.  I’m sure some of the participants went from 220 pounds down to 150 pounds and stayed there.  That could be you.

Steve Parker, M.D.

Reference: Svetkey, Laura et al.  Comparison of Strategies for Sustaining Weight Loss: The Weigth Loss Maintenance Randomized Controlled Trial.  Journal of the American Medical Association, 299 (2008): 1,139-1,148.

Why Are Kidney Stones Increasingly Common?

MedPage Today on May 24, 2012, reported a substantial increase (70%) in the prevalence of kidney stones in the U.S. over the last two decades. Stone prevalence rose from 5.2% to 8.8% of the population.  Prevalence was based on the periodic National Health and Nutrition Examination Survey, which asked participants, “Have you ever had kidney stones?”

Stone prevalence began rising even earlier.  Again according to the third NHANES, prevalence increased from 3.8 percent in the period 1976 to 1980 to 5.2 percent in the years 1988 to 1994.

Older studies estimated that one in 10 men and one of every 20 women will have at least one painful stone by the age of 70.

What are kidney stones make of?  

Three out of four patients with kidney stones form calcium stones, most of which are composed primarily of calcium oxalate or, less often, calcium phosphate.  Pure uric acid stones are less than 10 percent of all stones.

Why the increased stone prevalence?  Does diet count?

Unfortunately, the article doesn’t offer any reasons or even speculation as to why kidney stones are more prevalent.  Kidney stones have a genetic component, but our genes have changed very little over just two decades.  I have to wonder if diet plays a role.

UpToDate.com reviewed diet as a risk factor for kidney stones.  Some quotes:

There are several dietary factors that may play an important role in many patients: fluid, calcium, oxalate, potassium, sodium, animal protein, phytate, sucrose, fructose, and vitamin C intake. Lower intake of fluid, calcium, potassium, and phytate and higher intake of sodium, animal protein, sucrose, fructose, and vitamin C are associated with an increased risk for calcium stone formation. The type of beverage may also influence the risk. The effect of calcium intake is paradoxical, with a decreased risk with increased dietary calcium and an increased or no change in risk with calcium supplements.

The combination of dietary factors may also have a significant impact upon stone risk. As an example, the Dietary Approaches to Stop Hypertension (DASH) diet is high in fruits and vegetables, moderate in low-fat dairy products, and low in animal protein. Based upon an analysis of three large cohorts, adherence to a DASH-style diet lowered the risk for kidney stones among men, older women, younger women, high body mass index (BMI) individuals, and low BMI individuals. Thus, the DASH diet is a reasonable option in the attempt to reduce the risk of stone recurrence.

Higher sucrose [table sugar] intake is associated with an increased risk of stone formation in younger and older women.
Standard advice to prevent initial and recurrent kidney stones is to avoid low urine output.  Do that by drinking plenty of fluid.
Although I pay about $400 a year for access to UpToDate, they offer free public access to some of the website.  Here’s the UpToDate poop sheet on kidney stones.
Extra credit:  Medical conditions that predispose to kidney stones include primary hyperparathyroidism, obesity, gout, diabetes, and medullary sponge kidney.

DASH Diet Reduces Risk of Heart Disease and Stroke in Women

U.S News and World Report recently ranked the DASH diet as the No.1 Healthiest Diet.  Today I partly explain why.

The Dietary Approaches to Stop Hypertension (DASH) diet has been shown to lower blood pressure.  Another study associated a DASH-style diet with lower incidence of heart attack and stroke.

The DASH diet is low in total and saturated fats and cholesterol, moderate in low-fat dairy products, high in fruits and vegetables, low in salt, low in sweetened beverages, moderate in whole grains, and low in animal protein but has substantial amounts of plant protein from nuts and legumes.

The DASH diet was designed as a healthy way of eating, not a weight-loss diet.  It is promoted by the National Heart, Lung, and Blood Institute for the prevention and treatment of high blood pressure.  It is also included as an example of a healthy diet in the 2005 Dietary Guidelines for Americans.  Yet many people still have never heard of it.

Researchers affiliated with multiple Boston and Atlanta institutions looked at the participants in the massive Nurses Health Study.  88,517 middle-aged women free of stroke, diabetes, and coronary heart disease were followed between 1980 to 2004.  They filled out food frequency questionnaires designed to assess average food intake over the preceding year.  The researchers constructed a DASH diet score and graded all the study participants in terms of adherence or conformity to the ideal DASH diet.

Over the course of the study, there were 2129 cases of nonfatal heart attack, 976 deaths from coronary heart disease, and 2317 strokes.  (If you read the original study, please note that some numerical errors were corrected in a later journal issue.)

Women with the highest adherence to the DASH Diet had 24% lower risk for coronary heart disease, compared with the women who had the lowest conformity.  Again comparing the same two groups for stroke, the high-adherence women had 18% less incidence of stroke.  There were clear trends for less coronary heart disease and stroke as adherence to the DASH diet increased.

Blood samples were analyzed for a subset of participants.  Higher DASH compliance was significantly associated with lower plasma levels of interleukin-6 and C-reactive protein.  These are markers for the inflammation felt to underlie atherosclerosis and cardiovascular disease.  You want to avoid high inflammatory markers.  The DASH diet scores in this study were not associated with serum lipid changes, although other DASH studies found lower LDL cholesterol and an undesirable reduction in HDL cholesterol.

The researchers examined causes of death in participants, yet did not report any association – positive, negative, or neutral – with DASH score.  I wonder why?  It’s possible that higher DASH scores were associated with higher overall death rates even though they had fewer heart attacks and strokes.  I imagine they also had access to cancer death statistics.  Why no mention?  Academicians are under pressure to publish research reports.  Are they saving the mortality and cancer data for future articles?  Abscence of all-cause mortality numbers is a major weakness of this study.

The DASH diet is similar in composition to the traditional Mediterranean diet.  The main differences are that the Mediterranean diet ignores salt intake, allows wine and other alcohol, and places more emphasis on olive oil and whole grains.  The Mediterranean diet has numerous supportive studies showing prolonged lifespan and less chronic disease: fewer heart attacks and strokes, less cancer, less dementia.  And very recently the Mediterranean diet was associated with a lower incidence of type 2 diabetes mellitus.

Steve Parker, M.D.


Fung, Teresa, et al.  Adherence to a DASH-Style Diet and Risk of Coronary Heart Disease and Stroke in Women.  Archives of Internal Medicine, 168 (2008): 713-720.

Your Guide to Lowering Your Blood Pressure with DASH, from the National Heart, Lung, and Blood Institute