Live longer with more plant-based protein

People often misinterpret that "plant-based" descriptor as meaning "vegetarian" or even "vegan".

Nothing could be further from the truth.

The Mediterranean Diet does not cut out all animal proteins or even all land animal proteins (as opposed to water-living animal sources of protein like fish or shellfish).

The Mediterranean Diet is "plant-based" in that the foods that make up a Mediterranean Diet are largely from plants - not all from plants.

Practically speaking this means that those following a Mediterranean Diet limit their land-animal protein, eat more fish and shellfish, and eat more vegetarian meals [read: plant protein]. (Here's more information on what foods are in a Mediterranean Diet.)

This long term, observational study performed in Japan compares protein intake from plant or animal sources with risk of death from certain causes (JAMA Intern Med doi:10.1001/jamainternmed.2019.2806)

This particular study made use of data gathered through the Japan Public Health Center-based study, which began enrolling participants between the ages of 40 and 59 in 1990. Three years later another ~78,000 people were added to the study from locales other than those in the original cohort. At the start of the study and every 5 years thereafter, the participants responded to dietary and lifestyle questionnaires, while the researchers were able to track the participants' deaths and their causes through Japan's centralized health records.

For this study the authors excluded from their analysis anyone with a history of cancer, stroke, heart disease, kidney disease, or unrealistic caloric intake, leaving almost 71,000 people's records to be analyzed.

Given their interest in the source of protein in the participants' diets, the authors used the participants' food frequency questionnaires to estimate each participants' protein intake from animal versus plant sources, then correlated that intake with the number of deaths from various causes that occurred over the total of over 20 years of follow-up.

In their analysis the researchers took into account a number of variables, from the total number of calories a participant consumed, to the number of calories consumed from the different types of fat in an individual's diet, to Body Mass Index, smoking status, coffee or green tea consumption, carbohydrate intake, and more.

Somewhat surprisingly, they found that "Higher total and animal protein intake was not associated with risk of overall mortality or cause-specific mortality."

Let me spell that out for you again: eating more protein from animal sources did not increase the risk of dying from any cause in general or from any particular cause.

On the other hand, higher intake of protein from plant sources meant a lower risk of death from any cause: compared to those in the lowest fifth of intake, those who ate the most plant-sourced protein (in the highest fifth of intake) were 13% less likely to die of any cause. Similarly, risk of death from cardiovascular disease in particular was 27% lower for those at the highest 20% of plant protein intake. That said, consuming more plant protein didn't seem to be associated with a lower risk of death from cancer.

The authors modelled the effects of replacing animal proteins - specifically proteins from red meats - with plant-based proteins. They found that replacing just 3% of calories from red meat with the same number of calories from plant-based protein meant:

• 34% lower risk of death from all causes
• 39% lower risk of death from cancer, and
• 42% lower risk of death.

Further, and more significantly, replacing 3 ounces of processed meats (such as sausage or deli meats) with the same amount of plant proteins meant:

• 46% lower risk of death from all causes and
• 50% lower risk of death from cancer.

What this means for you

This is another study that only shows association - that those eating more plant-based protein lived longer than those eating more land-animal-based protein. This doesn't mean that eating less red or land-animal protein caused people to live longer.

In other words, this association does not mean that eating less animal-based or even red meat protein had a direct effect on how long a participant lived: this analysis only shows that people who ate [this] tended to also die [of that]. Nor does this mean that you should go vegan [defined as consuming no animal products whatsoever] or even vegetarian [defined as consuming perhaps no land animal meats like chicken or beef, perhaps no land animal products like cheese or eggs, etc.].

What this does mean is that too much red or processed meat is bad for you. Keep your intake of unprocessed red meat (lean beef or pork; no, pork is NOT 'the other white meat') to a 3-4 ounce serving once every couple of weeks, while saving processed red meats like bacon or sausage to an occasional (once every few months) treat.

We also know that fish and shellfish are great for you: have them as your dinner protein about 3 times per week, with the rest of meals divided between mostly vegetarian, then lean poultry, then lean beef and pork. You can still eat great food while still protecting your health: you just have to be mindful of how you choose your meals.

First posted: September 4, 2019