Lifestyle

Protein: Myths and Facts

Protein: Mythen & Fakten

There are many myths and claims about protein that have become stubbornly entrenched in our minds and opinions. The sources of these come, for example, from poorly conducted studies, personal convictions or simply misinformation/false assertions that unfortunately become entrenched as beliefs.

Let’s bring a little light into the darkness :).

The basics

Protein is derived from the Greek word proteios for “fundamental” and “primary”, based on protos for “first, foremost” or “paramount”.

This consists of individual amino acids which in turn are divided into essential, semi-essential and non-essential amino acids.

Essential amino acids

  • Quantity: 9
  • These must be taken in through food, as the body cannot produce them itself.
  • These include: Histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine

Semi-essential amino acids

  • Quantity: 2
  • These are essential under certain circumstances (e.g. stress, illness), as the body is then unable to produce them in sufficient quantities.
  • Examples: Arginine, histidine (in children)

Non-essential amino acids

  • Quantity: 11
  • The body can produce these itself.
  • These include: Alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, tyrosine, ornithine

Protein is the most important of the three macronutrients and we often eat far too little of it in relation to the other two (fats and carbohydrates).

If we look at our body composition, it consists of approx:

  • 50-65% from water
  • 16-20% from protein
  • 10-30% from fat
  • 5-6% from minerals
  • 1-2 % from carbohydrates

As you can see, protein is the 2nd most abundant nutrient in our body after water. And for good reason, because protein fulfills numerous important functions in your body:

  • Structure formation (e.g. in muscles, skin and hair)
  • Enzymes for biochemical reactions
  • Hormones to regulate bodily functions
  • Strengthening the immune defense/immune system
  • Transport of nutrients and oxygen

The most common protein myths

Myth 1: A high protein intake damages the kidneys.

It is often claimed that a high protein intake puts a strain on the kidneys and damages them in the long term. This assumption is based on the fact that protein breakdown products are excreted via the kidneys. In healthy people, however, there is no evidence that an increased protein intake, which needs to be defined, has a negative impact on kidney function.

Fact:
Numerous studies show that a “higher” protein intake is safe for people without existing kidney disease.

A one-year crossover study from Antonio et al. (2016) investigated the effects of a very high protein intake of 4.4 g/kg/day in strength-trained men. No harmful effects on kidney function were found, suggesting that even extremely high protein intakes in healthy, trained people have no negative effects on the kidneys.

It is important to note that these are trained men and that this high amount of protein was consumed over a year.

The meta-analysis by Martin et al. (2005) analyzed various studies and came to the conclusion that there is insufficient evidence to justify restricting protein intake in healthy adults to maintain kidney function. The authors emphasized that a protein intake of up to 2.4 g/kg/day has no negative effects on kidney function.

According to the (EFSA, 2012), the safe upper limit is up to 2.2 g/kg/day and is also considered safe for kidney function in the long term.

These studies all relate to people with healthy kidneys.
People with already impaired kidney function should discuss their protein consumption with a doctor. Depending on the type and severity of the kidney disease, this can be between 0.6g and 1.2g per kilogram of body weight.

Myth 2: 0.8g of protein per kilogram of body weight is enough to cover your daily protein requirement.

The German Nutrition Society (DGE) recommends a daily protein intake of 0.8g per kilogram of body weight for healthy adults. According to the DGE, this amount is sufficient to cover the general requirement.

As already shown above (Myth1), this corresponds to approximately the same recommended amount of protein as for people with kidney disease, which varies depending on the stage of the disease and the individual situation.

So no difference between “sick” and healthy people?

Fact:
Several studies and meta-analyses show that a daily protein intake of 0.8g per kilogram of body weight is insufficient for maintaining or building muscle mass. Especially for active people or older adults.

A meta-analysis in the British Journal of Sports Medicine (2018) examined the influence of protein supplementation on muscle mass and strength during strength training. The results showed that a protein intake of around 1.6 g/kg/day is optimal for muscle building. This indicates that the recommended intake of 0.8 g/kg/day is not sufficient to effectively maintain or build muscle mass.

The review article from the Journal of the International Society of Sports Nutrition (2017) argues that the current recommended protein intake of 0.8 g/kg/day is insufficient for active individuals. An intake of 1.4 to 2.0 g/kg/day is suggested to maintain and build muscle mass, especially with regular training.

The study in the American Journal of Clinical Nutrition (2015) examined the relationship between protein intake and muscle mass in older adults. The results indicated that a higher protein intake than the recommended amount of 0.8g is also necessary here in order to prevent age-related muscle loss.

The current recommended protein intake of 0.8 g/kg/day according to the DGE is based on the minimum required to maintain nitrogen balance and prevent muscle loss. For people who want to build or maintain muscle, especially those who train regularly or are older, scientific findings show that a protein intake of at least 1.4 to 2.0 g/kg/day is beneficial.

Myth 3: Plant proteins are equal to or even better than animal proteins.

Spoiler: A very emotional topic for vegetarians, vegans and carnivores.

Fact:
Animal proteins, including whey protein (whey), are considered superior to plant proteins from several scientific perspectives.

  1. Amino acid profile
  • Animal proteins contain all essential amino acids in optimal quantities, whereas plant proteins are often incomplete and may lack certain amino acids such as methionine, cysteine or tryptophan.
  • Whey protein, for example, is particularly rich in leucine, an amino acid that effectively stimulates muscle protein synthesis.
  1. Biological value and digestibility
  • The biological value (BW) of animal proteins is higher. For example, meat has a BW of 84, while beans only reach 60.
  • The Protein Digestibility Corrected Amino Acid Score (PDCAAS) also shows a higher quality of animal proteins (e.g. beef: 92; beans: 41).
  1. Fast absorption and effectiveness
  • Whey protein is quickly digested and absorbed, which is particularly beneficial for muscle recovery after training.
  • Studies show that whey protein can stimulate muscle protein synthesis by up to 68%, compared to 31% for casein.
  1. Comparison with plant proteins
  • Plant proteins can achieve a complete amino acid profile by combining different sources (e.g. rice and beans), but their bioavailability remains lower. And also the extra calories that are added by this combination to increase the amount of protein should be considered, depending on the goal.
  • Soy protein is an exception with comparable effectiveness to whey protein in terms of muscle building. The individual tolerance and quality of soy should be taken into account here.

It can be said that animal protein offers a “better all-round package” for muscle building and recovery due to its complete amino acid profile, higher bioavailability and rapid digestibility. However, plant proteins are also effective if they are combined or come from high-quality sources such as “good” soy. Vegans in particular should make sure that they consume enough plant-based protein sources and supplement accordingly if necessary to avoid nutrient deficiencies.

Myth 4: More protein automatically leads to more muscle mass

Fact:
Although protein is a crucial building block for muscle growth, excessive intake without appropriate training does not lead to additional muscle growth. A systematic review by Morton et al. (2018) shows that the combination of adequate protein intake and strength training is crucial for muscle growth. Without the mechanical stimulus of training, excess protein is not converted into muscle mass, but can be used as an energy source or converted into fat. Therefore, a balance between protein consumption and physical activity is essential.

Myth 5: Protein shakes are necessary for building muscle

Fact:
Many people believe that protein shakes are essential for building muscle. In fact, they are a very practical and simple way of supplying the body with more protein to cover the daily protein requirement. Especially around (strength) training. However, they are not absolutely necessary.
A balanced diet with protein-rich foods such as meat, fish, eggs, pulses and dairy products also covers the requirement. Studies show that natural protein sources such as meat, fish or dairy products have similar effects on muscle protein synthesis as supplements. Basically, it is important to spread your protein intake over the entire day (over meals) as this enables optimal protein synthesis.

Myth 6: Protein should be consumed directly after training

Fact:
The concept of the “anabolic window” states that protein should be consumed immediately after exercise to maximize muscle growth. However, a meta-analysis of 43 studies found no strong correlation between immediate protein intake and muscle growth or strength. More important, as mentioned in Myth 5, is the total daily protein intake and its even distribution throughout the day. Nevertheless, the prompt intake of protein after training can be beneficial, especially if no meal follows for a longer period of time.

Myth 7: A high protein intake leads to bone loss

Fact:
Earlier assumptions that a high protein intake increases calcium excretion and thus impairs bone health have been refuted by more recent research. Recent studies show that a high-protein diet increases intestinal calcium absorption and is associated with higher bone density. A meta-analysis of studies on milk-based proteins found no evidence that animal proteins have a negative impact on bone health. Rather, adequate protein intake in combination with calcium and vitamin D can promote bone health.

In this context, it is also claimed that an increased protein intake has a negative effect on the acid-base balance. This is often referred to as “hyperacidity”.

The human body has efficient mechanisms to regulate the acid-base balance. According to current research, there is no convincing evidence for healthy people that a high daily protein intake (approx. 2g +/- protein per kg body weight) as part of a varied diet leads to harmful acidification of the body.
Although it is undisputed that a protein-rich diet produces more acid, which is visible in more acidic urine and increased acid excretion, the body’s own buffer systems (respiration, kidney function and, if necessary, the bones as a buffer) generally absorb this load effectively. The blood pH homeostasis remains intact so that no chronic acidosis develops. Consequential damage such as osteoporosis or kidney damage due to “hyperacidity” has not been confirmed in controlled long-term studies.

Myth 8: Older people need less protein

Fact:
It is often assumed that the need for protein decreases with age. However, the need actually increases to maintain muscle mass and function and to counteract age-related muscle loss (sarcopenia). Studies recommend that older adults consume more protein than younger adults to support muscle health. A regular protein intake with each meal, with breaks of three to four hours, is recommended to best support protein synthesis.
Recommended amounts vary depending on the source and individual health conditions, but are generally between 1.0 and 1.2 grams of protein per kilogram of body weight per day for people aged 65 and over. If weight training is practiced, which is recommended, the amount should be increased slightly.

Myth 9: Protein leads to weight gain

Fact:
A widespread myth is that a high protein intake automatically leads to weight gain. This assumption often results from confusing muscle gain with fat gain. In fact, protein is an extremely satiating macronutrient that increases the thermic effect of food (TEF). This means that the body has to expend more energy to digest and metabolize protein than fats or carbohydrates.

Scientific studies show that an increased protein intake can even support fat loss, especially when combined with a calorie deficit and strength training. A meta-analysis from 2021 showed that high-protein diets led to significantly higher fat loss while largely preserving muscle mass. Another study by Longland et al. (2016) showed that people who followed a high-protein diet were able to build muscle mass despite a calorie deficit.

Conclusion

Protein is far more than just a building block for muscles – it is an essential component of a healthy diet that supports numerous bodily functions. Common myths about protein are often scientifically debunked and based on misconceptions or outdated information. You can easily optimize your fitness and health by consciously choosing high-quality protein sources and the right individual amount.

Whether building muscle, losing weight or maintaining muscle mass in old age – protein plays a central role in every phase of life. Make sure you adapt your protein intake to your individual needs and leave the myths behind you. With sound knowledge and evidence-based approaches, you can get the most out of your training and diet!

Sources:

  1. Antonio et al. (2016)
  2. Martin et al. (2005)
  3. EFSA (2012)
  4. Morton et al. (2018)
    • Titel: “A systematic review, meta-analysis, and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.”
    • Quelle: British Journal of Sports Medicine
  5. American Journal of Clinical Nutrition (2015)
  6. Journal of the International Society of Sports Nutrition (2017)
  7. Meta-Analyse (2021)
  8. Longland et al. (2016)
    • Titel: “Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gains and fat mass loss.”
    • Quelle: American Journal of Clinical Nutrition
  9. Meta-analysis on bone health
    • Titel: “Effects of dietary protein on bone health: a systematic review and meta-analysis.”
    • Quelle: Osteoporosis International