Low-carb vegan diet as effective as vegetarian approach for weight loss, glycemic control

When it comes to vegetarian versus vegan diets for diabetes, it’s a stalemate as far as weight loss and glycemic control go. However, with a lower environmental footprint, a vegan diet is better for the planet. These were the take-home message from a study published in the American Journal of Clinical Nutrition. Vegan diets differ from vegetarian diets because they don’t include meat-source products such as dairy and eggs, while vegetarian diets do. Studying a vegan versus vegetarian approach was of interest because of increasing popularity of bother diets, said Dr. David Jenkins, professor of nutrition science and medicine at the University of Toronto. He is lead author of a study which compared low-carbohydrate vegan to vegetarian diets in weight loss for diabetes. Read: Diets, the evidence and the media: we need a better solution to obesity In general, diets such as the Dietary Approaches to Stop Hypertension (DASH) and Mediterranean diets are commonly recommended in guidelines as healthy diets to reduce heart disease risk and for people with diabetes. They emphasize higher fruit and vegetable content and lower amounts of dairy foods and meat. “However, the higher fruit and vegetable content means they are not low in carbohydrates and may not suit those looking for a low carb diet,” he told the Medical Post in an interview. High meat diets such as the Atkins diets, and the low-carbohydrate versions such as “paleo” and “keto” diets have drawbacks. This is because their high red-meat and animal-based saturated fat content can be problematic in terms of many chronic diseases. Even too many eggs may be problematic because recent studies suggest they increases the risk for developing diabetes. As well, with climate change negatively impacting many agriculture regions and issues with high emissions, there will be a greater push for more environmentally friendly foods. Plant-based foods fit this because by being directly field to plate they have a small foot print, while red meats take at least a couple of years to get from farm to plate and are more resource intensive, he said. “For our study we developed a low-carbohydrate vegan version of an Atkins-type diet using foods that are high in plant proteins and unsaturated vegetable oils, such as canola,” Dr. Jenkins said. Both the vegan and vegetarian diets used in the study kept in-line with various dietary guidelines. Examples of the foods for the vegetarian arm included whole wheat bread (but no white breads); various select fruits and juices (but not apples, pears or berries); vegetables such as leafy greens, broccoli, cabbage, tomatoes and peppers (but not eggplant, okra or mushrooms). Many dairy products were allowed as were eggs, but not ice cream or cream. Lentils, which are high in protein, were included as were almonds as a protein source. Allowed fats and oils included margarine and corn oil, but not canola or olive oil. For the vegan diet, participants were given canola oil enriched bread, but no other breads were allowed. For carbohydrates they were allowed various bran products, barley, sweet potatoes and various beans (but not most rices or corn); low starch vegetables such as eggplant, okra, mushrooms, broccoli and others, but not potatoes or other starchy roots. Various popular plant-based meat products were allowed, as were several types of nuts and non-sweetened soy beverages. A total of 164 male and female adults with type 2 diabetes were randomized. At enrolment, participants were already taking a stable dose of oral antihyperglycemic agents for at least a month, were not on insulin therapy, and had glycated hemoglobin (HbA1c) values that were between 6.5% and 8.5%, and none had significant cardiovascular (CVD) or liver disease. They were randomized to either a low-carbohydrate vegan diet (83 subjects), or a vegetarian therapeutic diet (68 subjects), for three months. Both groups had an average BMI between 32 and 34, and were prescribed a diet at 60% of energy requirement for weight loss. Results showed there were significant differences in the macronutrient profiles between the two diets, with the vegan diet having 16% less available carbohydrate, 10% more fat and 5% more protein as a percentage of total calories, but was also low in calcium. Both groups had similar clinically relevant reductions in weight and waist circumference, down an average of 5.9 kg and 5.2 kg respectively. There were no changes in blood pressure medications or blood pressure, but both diets showed significant reductions in systolic blood pressure with an average drop of about 4.12 mmHg. “The association of change in weight with blood pressure change suggested that 40% of the systolic blood pressure reduction was related to weight loss achieved on both diets,” the study said. HbA1c fell dramatically on both diets, .99 and .88 respectively. The study concluded that “low-carbohydrate vegan diets or vegetarian diets without carbohydrate restrictions do not differ in their effectiveness for weight loss, glycemic control, or cardiovascular disease risk factor reduction in type 2 diabetes.” Calculations for greenhouse emissions based on self-reported dietary intake showed consistently reduced levels on the vegan diet and related to blood pressure and lipid reductions, said Dr. Jenkins. “The study is encouraging in that it seems to show that a vegetarian diet was as good as a vegan diet. (But) most patients would probably find it easier to follow a vegetarian diet with some of the added protein sources such as egg white, than a vegan diet,” said Dr. David Spence, a professor emeritus of neurology and clinical pharmacology at Western University. He was not involved in this study. Limitations included it was a relatively small study, covered only 12 weeks, and there was a loss to follow-up of about 16% in both arms of the study. He noted that a study from 2008 showed that for weight loss a Mediterranean diet was equal to a low-carb diet similar to the Atkins diet, and both were superior to a low-fat diet for weight loss. And the Mediterranean diet was better for insulin resistance. “Although it is not widely appreciated, the ‘good Mediterranean diet’ is a mainly vegetarian diet,” said Dr. Spence.

Low-carb vegan diet as effective as vegetarian approach for weight loss, glycemic control

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