Battle of the proteins: Sizing up plant- versus animal-based diets

14 Jul 2020 --- Research has taken the plant versus animal protein debate to center stage. Two separate investigations came to similar conclusions that incorporating more plant-based protein into the diet can decrease the risk for noncommunicable chronic diseases (NCDs) as well as overall mortality. Meanwhile, another study stresses it remains “nebulous” whether plant-based milk alternatives are as nutritionally adequate as cow’s milk.

Published in JAMA, the first study identified that higher plant protein intake was associated with reduced risk of overall mortality, with men and women experiencing 12 percent and 14 percent, respectively, lower mortality per 10 g/1000 kcal intake increment. 

The researchers noted “small but significant associations” between a higher intake of plant protein and cardiovascular disease (CVD)-related mortality. The most prominent inverse associations were observed for the replacement of egg protein and red meat protein with plant protein, particularly for plant protein derived from bread, cereal and pasta.

Click to EnlargeThe researchers noted “small but significant associations” between a higher intake of plant protein and CVD-related mortality.The cohort study encompassed 237,036 men and 179,068 women with 16 years of observation and nearly 78,000 deaths. The overall median ages of the study participants were above 62 years for men and women. 

Primary dietary sources for plant protein (mean percentages of total plant protein intake) included bread, cereal, and pasta (46 percent), nuts (4.5 percent), beans and legumes (8 percent) and other plant protein (42 percent). 

Meanwhile, primary dietary sources of animal protein were both fresh and processed red meat (31 percent), white meat including poultry, fish and processed white meat (31 percent), and other animal protein, such as dairy products (32 percent) and eggs (4 percent). 

Just 3 percent makes a world of difference
Replacement of 3 percent energy from various animal protein sources with plant protein was associated with 10 percent decreased overall mortality in both sexes. However, the study also showed that participants with higher plant protein intake were more likely to have diabetes.

Nevertheless, this group reported having an overall higher educational level, lower Body Mass Index (BMI) and total energy intake, as well as higher fiber, fruit and vegetable intake. Participants in the plant-based diet group were also more likely to be more physically active and use vitamin supplements and were less likely to be current smokers or report their health as poor or fair. 

Click to EnlargePlant-based diets rich in fruits, vegetables, grains and legumes showed reduced risks of various heart conditions.“Findings from this and previous studies provide evidence that dietary modifications in choice of protein sources may promote health and longevity. This study provides evidence for public health recommendations regarding dietary modifications in choice of protein sources that may promote health and longevity,” the study emphasizes.

Preparing for a growing elderly population
In a separate editorial published in the Journal of the American College of Nutrition, researchers raised their concerns about the looming growing elderly population worldwide. “The global population of adults 60 years old or older is expected to double from 841 million to 2 billion by 2050, presenting clear challenges for our health care system,” says study author Dr. Hana Kahleova, Director of Clinical Research for the Physicians Committee. “Fortunately, simple diet changes can go a long way in helping populations lead longer, healthier lives.”

Dr. Kahleova’s research team concluded that plant-based diets can reduce the risk of diseases such as Type 2 diabetes, cancer and heart disease by almost 50 percent as well as slash cardiometabolic-related deaths in the US by half.

The authors cite studies showing that plant-based diets rich in fruits, vegetables, grains and legumes:

• Reduce the risk of developing metabolic syndrome and type 2 diabetes by about 50 percent.

• Reduce the risk of coronary heart disease events by an estimated 40 percent.

• Reduce the risk of cerebral vascular disease events by 29 percent.

• Reduce the risk of developing Alzheimer’s disease by more than 50 percent.

• May reduce the risk of cognitive diseases such as Alzheimer’s disease by almost 50 percent.

The authors also note that these improvements in health will reduce health care costs caused by chronic diseases. According to the US Centers for Disease Control and Prevention, lifestyle-related chronic diseases are the leading cause of death and disability in the US, accounting for the majority of the nation’s annual US$3.5 trillion in health care spending.

Click to EnlargeThe third study warned that plant-based milk alternatives may not have enough calcium and protein as found in cow's milk.Got milk protein? Alternatives lacking nutrients
A third study found in the Nutrients journal casts a different light on plant-based protein, or rather, the lack of it found in plant-based beverages. It highlights that out of a total of 115 alternative milk products tested from Australian supermarkets, just over half were fortified, but only a third contained a similar calcium content to cow’s milk.

“Indiscriminate substitutions might reduce intakes of protein and micronutrients, particularly vitamin A, B2, B12, iodine and zinc. [It might also] lead to reductions of over 50 percent of the Australian Estimated Average Requirements for protein, zinc and calcium in the chosen dietary scenarios. To avoid unintended dietary outcomes, it is vital that consumers make pragmatic decisions regarding dietary replacements for cow’s milk,” the study reads.

Along these lines, NutritionInsight learned from researchers earlier this year that not all plant-based dietary patterns are healthy. Moreover, UK-based lobby group Action on Salt flagged that plant-based meals often contain “shocking” amounts of salt and saturated fat amid calls for clearer marketing and labeling of plant-based meat alternatives. 

Edited by Anni Schleicher

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