Research pooled from nearly 100 studies has indicated that people who adhere to a vegan diet (ie, completely devoid of animal products) or a vegetarian diet (ie, devoid of meat, but may include dairy and eggs) are able to ward off some chronic diseases, such as cardiovascular disease, optimize glycemic control, and decrease their risk for cancer compared with those who consume omnivorous diets.
Vegan and vegetarian diets, or flexitarian diets — which are less reliant on animal protein than the standard US diet but do not completely exclude meat, fish, eggs, or dairy — may promote homeostasis and decrease inflammation by providing more fiber, antioxidants, and unsaturated fatty acids than the typical Western diet.
Inflammation and Obesity
Adipose tissue is a major producer of pro-inflammatory cytokines like interleukin (IL)-6, whose presence then triggers a rush of acute-phase reactants such as C-reactive protein (CRP) by the liver. This process develops into chronic low-grade inflammation that can increase a person’s chances of developing diabetes, cardiovascular disease, kidney disease, metabolic syndrome, and related complications.
Adopting a plant-based diet can improve markers of chronic low-grade inflammation that can lead to chronic disease and worsen existent chronic disease. A meta-analysis of 29 studies encompassing nearly 2700 participants found that initiation of a plant-based diet showed significant improvement in CRP, IL-6, and soluble intercellular adhesion molecule 1.
If we want to prevent these inflammatory disease states and their complications, the obvious response is to counsel patients to avoid excessive weight gain or to lose weight if obesity is their baseline. This can be tough for some patients, but it is nonetheless an important step in chronic disease prevention and management.
Plant-Based Diet for Type 2 Diabetes
According to a review of nine studies of patients living with type 2 diabetes who adhered to a plant-based diet, all but one found that this approach led to significantly lower A1c values than those seen in control groups. Six of the included studies reported that participants were able to decrease or discontinue medications for the management of diabetes. Researchers across all included studies also noted a decrease in total cholesterol, low-density lipoprotein cholesterol, and triglycerides, as well as increased weight loss in participants in each intervention group.
Such improvements are probably the result of the increase in fiber intake that occurs with a plant-based diet. A high-fiber diet is known to promote improved glucose and lipid metabolism as well as weight loss.
It is also worth noting that participants in the intervention groups also experienced improvements in depression and less chronic pain than did those in the control groups.
Plant-Based Diet for Chronic Kidney Disease (CKD)
Although the use of a plant-based diet in the prevention of CKD is well documented, adopting such diets for the treatment of CKD may intimidate both patients and practitioners owing to the high potassium and phosphorus content of many fruits and vegetables.
However, research indicates that the bioavailability of both potassium and phosphorus is lower in plant-based, whole foods than in preservatives and the highly processed food items that incorporate them. This makes a plant-based diet more viable than previously thought.
Diets rich in vegetables, whole grains, nuts, and legumes have been shown to decrease dietary acid load, both preventing and treating metabolic acidosis. Such diets have also been shown to decrease blood pressure and the risk for a decline in estimated glomerular filtration rate. This type of diet would also prioritize the unsaturated fatty acids and fiber-rich proteins such as avocados, beans, and nuts shown to improve dyslipidemia, which may occur alongside CKD.