Vegan and vegetarian diets help lower HbA1c and cholesterol levels and improve other cardiometabolic risk factors in middle-aged, overweight people controlling their type 2 diabetes with medications, say authors of a literature review published online in Clinical Nutrition.
Effie Viguiliouka, MSc, with the Clinical Nutrition and Risk Factor Modification Center at St. Michael's Hospital in Toronto, Ontario, and colleagues, analyzed findings from nine randomized controlled trials involving 664 participants who were taking oral glucose-lowering drugs, insulin, lipid-lowering agents, and/or anti-hypertensive agents.They found that vegetarian diets compared with nonvegetarian diets improved the primary outcome of HbA1c by 0.29%.
While the HbA1c reduction may seem moderate, Cara Schrager, MPH, RD, CDE, of the Joslin Diabetes Center in Boston, Massachusetts, pointed out that the improvement is the same as the therapeutic threshold the US Food and Drug Administration uses when considering new medications for diabetes.
Schrager told Medscape Medical News that this level of reduction suggests that patients could consider moving toward a plant-based diet with primarily vegetables, fruits, whole grains, and legumes, perhaps even before they move to diabetes medications.
Vegetarian Diet Also Helped Reduce BMI
Other results included reductions in fasting glucose of 0.56 mmol/L; LDL-cholesterol (0.12 mmol/L); non-HDL-cholesterol (0.13 mmol/L); body weight (2.15 kg or 4 lbs, 12 oz); body mass index (BMI) (0.74 kg/m2), and waist circumference (2.86 cm) with the vegetarian compared with nonvegetarian diets.No significant differences were seen in blood pressure, fasting insulin, HDL-cholesterol, or triglycerides.Only diets that excluded meat and fish (from vegan [no animal products] to vegetarian diets that included eggs and dairy products) were considered vegetarian in the meta-analysis.The authors stress that the link between diabetes and heart disease is strong and well-established."Sixty to seventy percent of people who have type 2 diabetes die of heart disease," study coauthor Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine said in a press release."This study shows that the same simple prescription — eating a plant-based diet — can reduce our risk for heart problems and improve type 2 diabetes at the same time."
The researchers acknowledge, however, that the findings had a low-to-moderate confidence level and they encourage further study.
Findings Build on Body of Evidence: No Downside to a Plant-Based Diet
Katherine Zeratsky, a registered dietitian nutritionist (RDN) at the Mayo Clinic in Rochester, Minnesota, told Medscape Medical News that this new review adds to a body of evidence that indicates eating less red meat and more vegetables can benefit people with type 2 diabetes.
Many of the noted reductions in this study fit with what others have shown, she said.
"We know that weight in and of itself is a strong risk factor for diabetes — so it makes sense that a plant-based diet will have a large impact on health overall," she said, while countering that she wished the evidence "was stronger."