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Adhering to a healthy vegetarian diet may help slash a person’s death risk later in life. Image credit: d3sign/Getty Images.
  • A new study finds that adhering to a healthy plant-based diet is associated with a lower risk of death from all causes and from cardiovascular disease among older people.
  • However, an unhealthy plant-based diet increases one’s risk of these conditions, the findings showed.
  • The study found no significant association between a mixed plant- and animal-based diet and a change in all-cause or specific cause mortality risk.
  • No meaningful connection between any plant-based diets and risk of death from cancer was observed in this study.

There are ethical and environmental reasons to switch to a more plant-centric diet, as well as a growing body of research suggesting such diets are better for our health. However, a full understanding of the long-term benefits of such diets takes time to establish.

A new study from Spain looks specifically at the effect of plant-based diets on longevity by assessing their impact on the incidence of all-cause death and deaths from cardiovascular disease (CVD) and cancer in older people.

The study is published in The Journal of Nutrition, Health, and Aging.

Using data from the European Eye Study (EUREYE), the authors of the new study investigated connections between three types of plant-based diets and mortality among 597 of its participants. Of this cohort from the Spanish province of Alicante, 54.3% were female and all were age 65 or older.

The researchers tracked the participants’ dietary habits via questionnaires, with information on deaths among the group from governmental records over a 12-year follow-up period.

The researchers categorized each person’s pro-vegetarian (PVG) diet into one of three categories:

  • hPVG, for “healthy pro-vegetarian” diet
  • uPVG, for “unhealthy pro-vegetarian” diet
  • gPVG, for “general pro-vegetarian” diet.

The healthy pro-vegetarian and unhealthy pro-vegetarian diet definitions were developed by A. Satija in 2016. The general pro-vegetarian diet was defined by M.A. Martínez-González in 2014.

The new study found that, compared to those with the lowest adherence, people who adhered moderately to the healthy pro-vegetarian diet experienced a 41% lower risk of all-cause mortality and a 53% lower risk of CVD mortality.

Underscoring that there is more to nutrition than simply whether it is plant-based or not, people who most closely followed an unhealthy pro-vegetarian diet had a 53% increased risk of all-cause death and a 110% increased risk of death from CVD.

Adherence to a general pro-vegetarian diet was not associated in this study with all-cause or a specific type of mortality. The study says this has also been reported in other research.

No association between any of the diets and the likelihood of dying from cancer was observed by the researchers.

Food-frequency questionnaires allowed participants to report their consumption of 131 food items in standard portions.

Menka Gupta, MD, IFMCP at NutraNourish, who was not involved in the study, explained what one might find in an healthy pro-vegetarian diet.

This type of eating, she said, “includes nutrient-dense plant foods such as green vegetables, fruits, plant-based proteins such as tofu and legumes, whole grains, nuts, and healthy oils such as olive oil and coconut oil. It eliminates processed foods, unhealthy fats, and deep-fried foods.”

An example of an healthy pro-vegetarian diet meal might be quinoa or brown rice with mixed vegetables, such as broccoli, spinach, and carrots with tofu or lentils and olive oil dressing.

“An [unhealthy pro-vegetarian] diet will include processed plant-based foods, high in refined grains and sugars along with unhealthy fats. A typical example would be someone eating a veggie burger with french fries and carbonated soda,” said Gupta.

“I’ve seen several vegetarians start their day with white toast and butter/ processed jam and fried potatoes. That would be another example,” she noted.

Julia R. Blank, MD, board-certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA, who was not involved in the study, also told us that:

“The unhealthy [pro-vegetarian] diet has a lot of processed food. It’s food that is depleted of the things that make a diet healthy.”

Blank said foods qualify as belonging to the unhealthy pro-vegetarian group for two reasons: How they are processed and how they are cooked.

For example, fried foods, she said, are typically cooked in unhealthy fats. Fruit juices are high in natural sugar and lack the fiber of whole fruits. Furthermore, many unhealthy pro-vegetarian foods contain high levels of sodium, which is associated with hypertension, stroke, and CVD.

“They’re pro-inflammatory, they increase blood sugar, increase the risk of diabetes. All of those, down the line, will have negative effects on the cardiovascular system,” said Blank of unhealthy pro-vegetarian dietary items.

“According to the study, a general pro-vegetarian diet emphasizes plant-based foods but also includes some animal-based foods,” Gupta explained.

“It scores plant foods positively and reverse scores animal foods. An example will be a chicken sandwich with salad,” she said.

Blank’s view of a general pro-vegetarian diet is that it is tied into “the idea […] that becoming a vegetarian is a process.”

She added: “I think that this is more of a reflection of what real diets are like rather than idealized diets. So I think this has more relevance to the way people live.”

The Mediterranean, DASH, and MIND diets generally start in the general pro-vegetarian category but can also be practiced as healthy pro-vegetarian diet, resulting in greater health benefits.

The lack of a dietary link to cancer may have to do with the specifics of this study, and not necessarily the absence of an association, suggested Blank. “You have to look at several things,” she said.

“While this was a large study, it wasn’t large enough. There weren’t so many cancer deaths — [just 58] — that they could reach statistical significance.”

“Number two is, if you think about what is the natural course of developing cancer, it’s a long-term process. There have to be many changes over an extended period of time,” Blank said, “for a study to be able to really catch that, you know, from cause to actual diagnosis. I don’t think that 12 years is a sufficient time.”

Nonetheless, there may well be a connection, since dietary choices can be related to inflammation over a long period of time.

Blank also noted other potential factors that could influence cancer risk, such as microplastics and pesticides found in food items, which do take a long time at the DNA level to create the changes that would later down the line lead to cancer.