We’ve all heard the news – diets high in animal protein significantly increase the risk of cancer.

The protein craze

It might seem surprising, considering we’re in the midst of a low carb, high protein frenzy, with high protein foods popping up all over the health food section. What’s more, we’re constantly being told how protein helps us lose weight, build muscle and feel fuller – just think of the Atkins, Dukan and Paleo diets. It’s easy to get the impression the more the better – no wonder evidence to the contrary prompted lively debate.

How much protein is high protein?

What’s a high protein diet anyway? Some researchers define it as getting at least 20% of your daily calories from protein. Just to put that in context, until 2002 the US government recommended daily protein consumption of 10% – 11%. It was then decided, based on no credible evidence, that it was safe to consume protein up to 35% total daily calories, without adverse health effects. Never mind that most nutritionists estimate protein needs between 10% and 20% of total daily calorie consumption. Perhaps it’s now time to revise our recommendations closer to the low end of that scale – as recent studies seems to confirm.

Why we need protein  

Protein is a nutrient vital for growth and repair. It’s needed to give our body structure and support, for hormones and antibodies – but too much is not a good thing:

Too much of a good thing

A diet high in protein can overload our liver’s capacity to function properly. This results in a toxic, disease-friendly environment in the body.

Many high protein foods, especially the ones from animal sources, contain excessive amounts of saturated fats – a major risk factor for heart attacks and stroke.

Protein controls the growth hormone IGF-1, which not only promotes the growth of healthy cells (in early life), but also hastens the aging process and encourages the growth of cancer cells (in later life). Too much protein puts the body in overdrive and accelerates the reproduction of cells.

On overdrive

The last point is the focus of the latest research implicating a connection with cancer. But as the researchers point out, it’s important to understand that there’s a distinction between animal protein and plant protein. Simply put – animal protein increases IGF-1 and plant protein doesn’t. It’s no coincidence that the people in these studies consumed two thirds of their protein from animal sources such as meat, chicken, eggs, fish and dairy.

Bottom line

So what’s the bottom line when it comes to optimal protein intake? Children, teenagers, pregnant and breastfeeding women need a little more, but for the rest of us it seems that the original recommendation of 10 to 11 percent is about right. Some evidence even indicates that when it comes to cancer protection and overall health no more than 5% should come from animal sources. Plant protein like beans, legumes, nuts, seeds, soy products (tofu and tempeh), quinoa and hemp should make up the rest.