Why plant protein is better for you than meat protein
The source of your protein is as important as the portion size, a new study has found.
And if you're getting too much of your protein from meat, you may be setting yourself up for trouble down the track.
While multiple studies have analysed the ratio of protein to carbs and fat, few have looked at the sources of protein and their effect on human health and longevity.
The new study, the largest of its kind, has examined plant and animal sources of protein, and has found that not all are created equal.
The researchers from Massachusetts General Hospital looked at the health data of nearly 132,000 people since the 1980s. The data included information about their diet as well as how much and what types of proteins they consumed.
They then looked at health outcomes of the participants and, after adjusting for other diet and lifestyle factors, found that high intake of animal proteins (meat, eggs, dairy) was associated with a greater risk of premature death than when the protein intake came from plant sources (breads, cereals, pasta, beans, nuts and legumes).
"Overall, our findings support the importance of the sources of dietary protein for long-term health outcomes," said co-author Mingyang Song in a statement.
"While previous studies have primarily focused on the overall amount of protein intake – which is important – from a broad dietary perspective, the particular foods that people consume to get protein are equally important.
"Our findings also have public health implications and can help refine current dietary recommendations about protein intake, in light of the fact that it is not only the amount of protein but the specific food sources that is critical for long-term health."
There was however a caveat to the findings. The increased risk among meat eaters disappeared among those who had a healthy lifestyle – they had to also drink alcohol or smoke, be sedentary, obese or underweight.
This, the authors discovered when they looked closer, was due to the fact that those with "unhealthy" lifestyles tended to consume more processed forms of animal protein and red meat, whereas the healthier ones got theirs from fish or poultry.
"We suspect the different sources of animal protein between the two groups may contribute to the stronger results in the unhealthy lifestyle group," Song said.
"Our findings suggest that people should consider eating more plant proteins than animal proteins, and when they do choose among sources of animal protein, fish and chicken are probably better choices."
Melbourne-based dietitian, Melanie McGrice said the authors "hit the nail on the head" and added that lifestyle factors and dietary choices often go hand in hand.
"It's not necessarily that red meat intake increases mortality, but the other foods with the red meat," MCGrice says. "A common example is 'steak and chips'. 'Steak and chips' is a much more common term than 'steak and salad'. Conversely, who eats chips as a side to their lentil pattie?"
Regardless, she says upping our intake of plants and plant-based protein while reducing the amount of meat we eat is better for everyone.
"As a dietitian, I'd really like to see people serving smaller portion sizes of red meat though. 100-150g 3-4 times per week is adequate to meet nutrition requirements. And aim for at least two vegetarian meals each week."