High-Fiber Diet Tied to Lower CV Risk in Diabetes, Hypertension

Batya Swift Yasgur, MA, LSW

October 10, 2019

High-fiber diets can improve blood pressure, cholesterol level, and fasting glucose in patients with hypertension and type 2 diabetes mellitus (T2DM), a new study suggests.

Researchers studied 200 adults with T2DM and hypertension who increased their dietary intake of fiber over a 6-month period from the recommended dietary allowance for dietary fiber by 20% to 25%. Participants also adhered to a low-glycemic diet.

Those adhering to the dietary changes had a significant improvement in brachial-ankle pulse wave velocity (baPWV), systolic and diastolic hypertension, serum cholesterol, low-density-lipoprotein cholesterol, and fasting glucose.

"This study shall help clinicians all around the world to learn three important things," lead author Rohit Kapoor, MD, medical director, Care Well Heart and Super Specialty Hospital, Amritsar, India, told theheart.org | Medscape Cardiology.

"A high-fiber diet is important to be prescribed in cases of diabetes and hypertension for future cardiovascular disease prevention, and this type of diet, in combination with medical treatment, can improve dyslipidemia, pulse wave velocity, waist-to-hip ratio, and hypertension," he said.

Moreover, he added, "medical nutrition therapy and regular counseling sessions also hold a great importance in treating and preventing diabetes and hypertension."

The researchers' results were presented at the American College of Cardiology (ACC) Middle East Conference 2019 and the 10th Emirates Cardiac Society Conference.

"Limited" Knowledge

"Markers of subclinical cardiac injury are elevated in individuals with T2DM compared to healthy individuals," the authors write.

Low intake of protein, fiber, vitamins, and minerals and high intake of carbohydrate and fat are known to be associated with an elevated probability of having coronary artery disease, and increased consumption of dietary fiber is "widely recommended" to improve health, they note.

However, information regarding the relation between a high-fiber diet and CVD risk is "limited," and "comprehensive etiologic effects of dietary factors on cardio metabolic outcomes, their quantitative effects, and corresponding optimal intakes are not well established," they write.

The researchers therefore aimed to investigate whether dietary changes in patients with T2DM can control hypertension and associated risk factors.

The study tracked the fiber intake of 200 individuals (mean age, 49.8 ± 12.1 years) with hypertension and T2DM who were overweight, defined as a body mass index (BMI) above 26 kg/m2, over a 6-month period.

Participants received checkups at baseline, 3 months, and 6 months after initiating their dietary regimen, which consisted of a low-fat, high-fiber intervention.

Guidelines from the National Institute of Nutrition and the Indian Council of Medical Research recommend a daily fiber intake of 40 g/2000 kcal, and the study participants, whose caloric intake was 1200 kcal to 1500 kcal, had a daily fiber consumption of 24 g to 30 g.

Participants were guided in increasing their fiber intake up to 20% to 25% from the recommended allowances to be considered as consuming a "high-fiber diet."

The checkups evaluated participants' baPWV, lipid profile, fasting blood glucose, A1c, BMI, and waist-to-hip ratio.

Participants received behavioral and nutritional education, including information about portion sizes and recommendations for increasing the consumption of high-fiber vegetables, fruits, cereals, and legumes by certified dieticians who provided the information through regular counseling sessions and also used audiovisual aids to augment and reinforce the participants' understanding.

Fiber intake was tracked through a number of different channels. Patients were asked to send photographs of their meals on WhatsApp to the researcher, which not only helped to ascertain fiber intake but also to approximate portion sizes. In addition, participants received phone calls three times a week that served to ascertain their dietary recall.

Indirect Impact

The high-fiber diet was associated with significant improvements in several key markers of cardiovascular (CV) risk, Kapoor reported.

High-Fiber Diet and CV Risk Factors
Factor Percent Reduction P Value
Serum cholesterol 9 < .0001
Fasting glucose 28 .0017
A1c 15 .0001
Systolic blood pressure 15 .0068
Brachial-ankle pulse wave velocity 32 .0001
Waist-to-hip ratio 18 .0001

"The basic mechanism of fiber is to reduce overall cholesterol by binding with cholesterol particles in the digestive system and moving them out of the body before they are absorbed, thus indirectly, a [high]-fiber diet interferes with cholesterol absorption," he explained.

A high-fiber diet also "helps in early satiety and this help in reducing the diet portions and definitely lowering blood sugar," he said. Additionally, a high-fiber diet "keeps the gut healthy and [promotes] good evacuation."

Simple and Inexpensive

Commenting on the study for theheart.org | Medscape Cardiology, Richard Kovacs, MD, Q.E. and Sally Russell Professor of Cardiology at Indiana University (IU) School of Medicine and cardiology service line leader of IU Health, called the study "an important 'proof of concept' that a relatively simple dietary change — increased fiber intake — can have measurable effect on risk."

Kovacs, who is the president of the American College of Cardiology and was not involved with the study, noted that it "opens the door to larger studies that demonstrate a sustained benefit on hard CV outcomes in patients at risk."

The take-home message is that "diet can be an important and inexpensive risk reduction factor in South Asian patients at high risk for cardiovascular disease," he said.

The authors conclude that a high-fiber diet "has strong positive corroboration for cardiovascular risk reduction in patients with hypertension and type 2 diabetes."

The study was self-funded. Kapoor, his coauthors, and Kovacs have disclosed no relevant financial relationships.

American College of Cardiology (ACC) Middle East Conference 2019 and the 10th Emirates Cardiac Society Conference: Abstract P538. Presented October 3, 2019.

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