We know foods that are just as harmful as smoking

It is well known that smoking significantly damages health. In relation to the promotion of cancer development, it is stated that smokers have up to a four-fold higher risk of dying from cancer than non-smokers. Similar evaluations are conducted in nutrition, where a range of factors increasing cancer risk are monitored—such as the known negative impact of trans fats, lack of fiber, excess sugars and xenobiotics, or consumption of ultra-processed foods.

An extensive study [1] provided interesting information, in which scientists observed a significant sample of people over two decades. It was found that the consumption of a diet rich in animal proteins increased the probability of dying from cancer fourfold compared to those consuming low amounts of proteins. It is important to add that the resulting values refer to the middle-aged population.

This discovery is crucial primarily because it offers some resolution to debates on the topic of optimal protein intake in the diet. Health agencies, headed by WHO, typically recommend protein intake at 0.8 g / 1 kg of body weight. However, this amount relates to the safe intake, meaning the amount that should cover the protein needs for the vast majority of the adult population. The issue with this calculation is that it includes minimal, not optimal, needs and does not apply to parts of the population that demonstrably require more proteins (such as pregnant women, athletes, children, seniors...). Therefore, another approach to calculating protein intake is presented, in relation to their energy representation in the daily diet:

A) A low-protein diet is considered as protein intake up to 10% of the total energy intake (including proteins of both plant and animal origin).

B) A diet with moderate protein intake is defined as protein ratio between 10 and 19 energy percent.

C) A diet with high protein content exceeds 20% of their energy representation.

The study monitored over 6,000 adults over the age of 50, whose dietary protein was around 16% (approximately two-thirds accounted for animal proteins, which corresponds to the average in Western eating habits). Even though it was a diet with a moderate protein intake, the results were indeed surprising.

Besides finding that higher protein consumption in middle age significantly increases mortality, the study pointed out several other interesting facts:

1. In the studied sample, there was also a multiple-fold higher probability of dying from diabetes due to higher protein intake. 

2. Plant proteins apparently do not have the same effects on mortality as animal proteins (suggesting that animal proteins are the main culprit).

3. Higher intake of animal proteins is essentially as risky a factor as smoking.

However, the study focused on the impact of protein intake on health in the middle-aged population. It is necessary to add that recommendations for reducing the amount of protein do not apply to everyone. A good example is the generation of seniors. After 65 years of age, the production of the growth hormone IGF-1 significantly decreases, leading to muscle mass loss and a decrease in bone density. Therefore, it appears that a slightly higher protein intake in this population segment is beneficial, as it reduces susceptibility to certain diseases.

For studies on the effects of diet on health to have meaning, it is necessary to know how to translate their results into practice, that is, onto an actual plate. In the context of protein intake, it is important to learn how to calculate the correct amount.

Examples of foods with approximate protein content [2]:

In the context of the presented study, the health-safe amount of proteins in the daily diet of a middle-aged person appears to be up to 10 energy percent. This means that an individual weighing 80 kg with an energy expenditure of around 2500 kcal per day would need to ensure approximately 60 g of proteins. With three meals a day, this entails 20 g of proteins on each plate.

What does this imply for those interested in potentially changing their diet?

At least two challenges:

1. Reduce the proportion of animal proteins in favor of plant proteins,

2. Decrease the volume of commonly used protein sources, such as meat, dairy products, and eggs, which are concentrated protein sources.

In practice, this means primarily monitoring portion sizes and simultaneously realizing that the real problem today is not a lack of proteins, but rather their excess. In the following recipe example, a 70 g portion of chicken corresponds to approximately a quarter of an entire thigh...

An interesting aspect of the study’s results is undoubtedly that even a small change in reducing protein intake from a moderate to low level decreased the probability of premature death by 21 percent.