By Naji M. Hamdan, M.D., cardiologist, Providence Heart and Vascular Institute and Terese Scollard, MBA, RD, LD, regional clinical nutrition manager, Providence Health & Services
Do a Google search for “plant-based diet” and what turns up is more than 6.5 million results on the subject. Even if you haven’t heard about it from Ellen DeGeneres, Glee’s Lea Michele, former President Bill Clinton or Oprah, chances are you’ve heard something. Popular books, such as “The China Study” and “Skinny Bitch,” and the documentaries “Food, Inc.” and “Forks Over Knives” have put the world on notice: eating green – making plant-based foods your primary source of nutrition – is neither fleeting nor faddish.
Today, an estimated 7.3 million Americans embrace a plant-based diet. But what is a plant-based diet? While it typically excludes meat, there are variations on this type of diet. All, however, put emphasis on fiber-rich foods that include fruits and vegetables, grains, nuts, beans and legumes. There are five basic categories:
- Lacto-vegetarian: Excludes meat, fish, poultry and eggs, and the foods that include them. Includes dairy products such as cheese, yogurt and butter.
- Lacto-ovo vegetarian: Excludes meat, fish and poultry. Includes eggs and dairy products.
- Ovo-vegetarian: Excludes meat, poultry, seafood and dairy products. Includes eggs.
- Vegan: Excludes meat, poultry, fish, eggs and dairy products – and all foods that contain any of these.
- Semi-vegetarian (flexitarian): A largely plant-based diet that includes, on occasion, meat, dairy, eggs, poultry and fish.
Advocates say that plant-based diets can prevent or reverse heart disease, diabetes, cancer and obesity. Researchers, however, don’t yet know if the heart benefits are derived from the diet or from some other factor related to a healthy lifestyle.
Medical research on the cardiovascular benefits of a plant-based diet is limited, but we do know that people following a plant-based diet are at lower risk for hypertension and heart disease. A study published in 2011 found that participants who ate a plant-based diet low in saturated fats and rich in vegetables, fruits, grains, nuts and soy proteins reduced their LDL cholesterol more than those who merely cut back on fat.
Medical experts are clear on the nutritional benefits of a balanced diet that includes meat. It’s less clear, however, what makes for an optimal plant-based diet. If you’re committed to or just trying any of the variations of a plant-based diet, listed above, you’ll want to consider the following:
- Nutrient deficiencies. People who follow a strict plant-based diet may be lacking in these key nutrients: vitamin B-12, calcium, iron, zinc, vitamin D, riboflavin, iodine and long-chain omega-3 fatty acids. Not all vegetarian food substitutes are fortified with proper nutrients. Become a vigilant food label reader, and choose fortified products over non-fortified.
- B-12 supplementation. Long-term vegans may be low in vitamin B-12 without being aware of it, because their diets are rich in folacin, which can mask the symptoms of a vitamin B-12 deficiency. Vegan diets should include B-12 supplements or B-12-fortified foods.
- Boosting protein. Your protein needs may be higher than the recommended dietary allowance if you are consuming hard-to-digest protein sources, such as legumes.
- Hidden eating disorders. If someone you know who follows a plant-based diet shows signs of an eating disorder, you may want to have a conversation about it. In some instances, individuals may use a plant-based diet as a socially acceptable excuse to limit food intake.
- Short-sightedness. Younger individuals – teenagers, for example – may think that cutting out dairy and animal protein foods is the only step they need to take to retool their diet. If you are the parent or friend of a teenager who has recently changed up his or her diet, take time to point out the importance of replacing missing nutrients with vegetarian-based substitutes.
- Special needs. Individuals who have diabetes or kidney disease or who are pregnant can benefit from the insight of a registered dietitian when attempting to transition to a plant-based diet.
If you’re debating whether to switch to a plant-based diet, remember that a diet containing all four of the traditional food groups – including moderate portions of meat, fish and poultry – can improve long-term heart health more than an overly restrictive diet.
If you’re interested in trying a plant-based diet but don’t quite know how to proceed, or if you’ve recently converted to a plant-based diet, nutritional counseling from a Providence Health & Services registered dietitian can help.