Is a plant-based diet the same thing as a vegetarian diet?
You’ve undoubtedly heard the term “plant-based diet” used in describing eating habits linked to heart health, cancer prevention and more. Some sources use the term to indicate a vegetarian diet. Yet not all the studies and recommendations about plant-based diets are actually referring to vegetarian eating.
At a recent heart health conference I attended, plant-based diets in their broader sense were the subject of several presentations, including one that received a lot of interest from media reaching health professionals and the public.
Let’s look at this study, which you may see reported somewhat differently by various sources, and see how it fits in the big picture of overall research on healthy eating patterns.
Just as vegetarian diets come in several forms, “plant-based diet” is an even bigger “umbrella” term. Vegetarian diets may include no animal products at all (vegan); other forms avoid meat but include dairy products (lacto-vegetarian), fish (pesco-vegetarian), or other animal foods. Plant-based diets encompass vegetarian diets and eating patterns that include modest amounts of poultry or red meat.
♦ As I use the term, plant-based diet means a diet that is mostly – but not necessarily exclusively – plant foods.
♦ This means the majority of your plate comes from vegetables, fruits, whole grains, “pulses” (dried beans and peas, including soy foods), nuts and seeds.
♦ You might also hear plant-based diets called semi-vegetarian, pro-vegetarian or plant-focused.
♦ In this sense, “diet” does not mean a set of rules and restrictions that you go on and go off. It means the pattern or overall habits that describe your eating over time. In fact, diet originally came from a word that means not just how you eat, but how you live.
The New Plant-Focused Eating Study
The conference I recently attended – the American Heart Association’s EPI/Lifestyle 2015 Scientific Sessions – focused on research in populations or otherwise translated to humans about improving heart health. A study on “pro-vegetarian diets” involved more than 450,000 European adults (in the EPIC cohort study) whose diets were scored to indicate proportion of animal versus plant foods.
A pro-vegetarian (“PVEG”) dietary score was created as the total of 12 components.
- Plant-based foods: people scored from 1 through 5 points for each of seven food groups: vegetables, fruit, dried beans and peas, grains, potatoes, nuts and olive oil. Each person’s consumption of a food group was compared to that of other people in the study; one point was given to people in the bottom fifth of consumption, and two, three, four or five points as consumption increased.
- Animal-based foods: people scored from 1 through 5 points for each of five food groups: meats/meat products, fish and other seafood, eggs, animal fats and dairy products. Here, people’s consumption of each group was again compared to that of others in the study, but (as representing a more plant-focused eating pattern), one point was given to the top consumers of a food group, with higher points indicating progressively less consumption.
- Total PVEG score ranging from 12 to 60 for each person was the sum of points for each of these 12 food groups.
- People were classified, based on this total score, into categories of how closely their eating habits fit a “pro-vegetarian” pattern: very low (<30), low (30-34), moderate (35-39), high (40-44) or very high (>45).
♦ Compared to people with lowest scores (least plant-focused eating habits), those with “moderately” pro-vegetarian diets had 12% lower risk of cardiovascular death.
♦ People whose diets were “high” or “very high” in PVEG score had 20% lower risk of cardiovascular death.
♦ Beyond a score of 40 – indicating that about 70 percent of foods were plant-based — there was a ceiling effect: Reducing animal-based foods even more was not linked to any further reduction in cardiovascular deaths.
Key Question: Was it the plant- versus animal-focus of eating habits? No single component of the score – such as vegetables or meat – accounted for the association with lower heart-related mortality. Comparisons were made after adjusting for calorie consumption, weight (based on body mass index), physical activity, educational level, and stratified by gender and age. Still, we can’t assume that some other factors weren’t involved, and this new study has not yet undergone the process of peer review for publication in a scientific journal.
Healthy Eating: What You Boost or Reduce?
This study’s PVEG scoring was trying to assess the relative proportion of people’s diets coming from plant foods versus animal-based foods. The findings fit compatibly with those of studies of vegetarian eating patterns, though looking through a different lens. Analysis of seven studies concluded that vegetarians had 29% lower heart disease mortality than those who more frequently ate meat. (Vegetarians included vegans, lacto-ovo-vegetarians and those who ate meat and fish less than once a week). And the Adventist Health Study 2 published after that showed 12% lower deaths from all causes among vegetarians (all types), and a trend not clear enough to be statistically significant for lower heart disease deaths.
When studies link vegetarian diets to lower risk of chronic disease, many people assume that the reason for the association is what is obviously avoided or reduced in vegetarian diets: meat and perhaps dairy products. As a group, however, vegetarians tend to have lifestyles that are healthy in many ways – they tend to exercise more, are less likely to smoke and are less likely to be obese, for example. So good quality studies of vegetarian eating patterns statistically adjust for the influence of factors like this as much as possible.
Yet as a group, vegetarian diets may differ from those of non-vegetarians beyond the avoidance of all or specific animal-based foods. For example, in the Adventist Health Study 2:
♦ Vegetarians didn’t only eat less meat, dairy and eggs; they also consumed less refined grains, sweets, snack foods and sugar-sweetened beverages like soda.
♦ Vegetarians ate more of various plant foods with important nutrients and phytochemicals (natural health-promoting compounds): fruits, vegetables, avocados, non-fried potatoes, whole grains, legumes, soyfoods, nuts and seeds. This resulted in higher intake of dietary fiber among vegetarians.
The new study linking heart health and pro-vegetarian diet score represents a net balance of plant foods and animal foods. Yet it doesn’t show the negative influence of excessive sweets, or protective potential of choosing a wide variety within vegetables selected, for example. Another study presented at the conference found that in the Nurses’ Health Study (after adjusting for obesity, physical activity, and family history of type 2 diabetes), an overall plant-based diet was associated with lower risk of type 2 diabetes. However, the association with lower diabetes risk was stronger when the plant-based diet had more of the healthy plant foods and less of plant foods like sweets, French fries, refined grains and sugar-sweetened soft drinks.
Key Question: Healthy Compared to What?
When you see studies linking a particular eating pattern with some aspect of health, be sure to ask: “Healthier than what?” Sadly, the average American diet still is low in vegetables, includes minimal beans and whole grains, and contains sugar well beyond recommended limits. It’s no surprise that a vegetarian diet is linked to better health than that. However, that does not mean that a diet without meat but filled with high-sodium processed foods and sweets is healthy. It also doesn’t mean a vegetarian diet necessarily leads to better health outcomes than a DASH, Mediterranean or other plant-focused eating pattern built around nutrient-rich foods. Perhaps it does, although regardless, it’s essential that an eating pattern is appropriate for individual needs (medical, genetic) and can be realistic and enjoyable as a long-term habit.
Several different scoring systems show eating habits that reflect principles linked in solid research with better health – lower risk of heart disease, cancer, and diabetes, and longer life.
Bottom Line: Multiple Choices Sum to Make Healthy Eating
Another study, this one of nearly 90,000 U.S. men and women that was also presented at the American Heart Association conference, provides an optimistic message: Making eating habits more healthful – as represented by improvement in any of several dietary scoring systems — was linked with significantly lower risk of cardiovascular disease, both in the short-term and long-term. These researchers concluded that even modest improvement in diet quality over time brings heart health benefits. As you decide how to go from a global “eat healthier” resolution to concrete steps that you are ready to implement, consider the plant- vs. animal-based food balance in your habits (as seen in the pro-vegetarian score). Whether some form of vegetarian diet is right for you, or whether you will simply move the needle to give plant foods a clear dominance, remember that it’s also important to look at the nutrition quality of the choices you make within that overall balance.
Focus on one doable step at a time.
In future Smart Bytes® posts, we’ll look at more of the specific choices you can make to create realistic eating habits that promote your good health. Sign up to receive Smart Bytes® by email so you don’t miss a thing! (Scroll up the sidebar)
The study in which plant-focused eating habits (more plant-based foods and fewer animal-based foods identified by PVEG score) was linked with fewer heart disease deaths found the maximal risk reduction reached with a diet that was 70% or more plant foods. Resources are abundant to help you figure out what that means in real food choices.
♦ The American Institute for Cancer Research’s approach to healthful eating, the New American Plate, specifically focuses on making plant foods at least two-thirds of your plate, offering tips and recipes.
♦ The federal MyPlate approach to eating is also an example of plant-focused eating. You’ll find more on each food category and a tracker to monitor how you’re doing.
Lassale, C. A Pro-Vegetarian Food Pattern and Cardiovascular Mortality in the Epic Study (Abstract 16). March 5, 2015; presentation, American Heart Association meeting, Baltimore, MD.
Huang, T et al. Cardiovascular disease mortality and cancer incidence in vegetarians: a meta-analysis and systematic review. Ann Nutr Metab. 2012; 60(4):233-40.
Orlich, MJ et al. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med. 2013 Jul 8;173(13):1230-8.
Orlich, MJ et al. Patterns of food consumption among vegetarians and non-vegetarians. Br J Nutr. 2014; 112(10):1644-53.
Rizzo, NS et al. Nutrient profiles of vegetarian and nonvegetarian dietary patterns. J Acad Nutr Diet. 2013 Dec;113(12):1610-9.
Satija, A et al. A Prospective Study of the Association Between Plant-Based Dietary Patterns and Incident Type 2 Diabetes in Women (Moderated Poster Abstract 14). Circulation. 2015;131:Suppl 1 AMP14
Sotos-Prieto, M et al. Changes in Diet Quality Scores and Risk of Cardiovascular Disease Among Us Men and Women (Abstract 18). March 5, 2015; presentation, American Heart Association meeting, Baltimore, MD.
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