When I upped my powdered hydrolysed collagen intake to a whopping 40 grams a day (that’s 4 table spoons), a friend told me I was crazy and heading for severe kidney damage!

WHAT!! Renal Failure I thought?!! Really? I panicked and went straight to Dr. Google (as you do) to get some answers.

Well what I found was plenty of collagen ‘experts’ out there (health gurus, pseudo doctors, celebrities, even suburban housewives) none of who really addressed my question – does taking too much hydrolysed collagen damage your kidneys? I suspect because they have got no idea themselves.

So that inspired (well scared) me into embarking on a quest to find the scientific evidence and  ultimately the truth.

I put in the hours, trawled through the bowels of PubMed and Google Scholar, and after months of painstaking research, I found the unequivocal answer to my question. 

So, “does taking hydrolysed Collagen powder damage your kidneys?"

Well, based on all the literary evidence, the short and simple answer is NO!

To put it straight, there is no evidence that taking even extremely high daily doses of Collagen over long periods of time will have any negative impact on healthy kidneys.

 And how did I come to this conclusion I hear you ask. Well, read on.

 But first. we need to understand two things, - just exactly what is hydrolysed collagen and what is the function of the kidneys.

 

How is Hydrolysed Collagen Made?

Hydrolysed collagen is also called collagen hydrolysate, collagen peptide, hydrolysedgelatine or gelatinehydrolysate.

This research article published in Journal Of Applied Sciences describes Collagen as:

‘not a uniform substance, but rather a family of protein. It is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. For food or nutritional purpose, collagen is broken down into gelatine, which can be broken down further into hydrolysed collagen. Hydrolysed collagen is a polypeptide composite made by further hydrolysis of denatured collagen or gelatin and the molecular weights are within the range approximately 500 to 25000 Da. In hydrolysate, the molecular mass and the size of the molecules have been deliberately decreased by hydrolysis part of peptide bonds of the gelatine molecules. This will make the hydrolysed collagen dissolve in cold water and does not gel anymore but still has surface active properties. The processes involved in processing hydrolysed collagen are demineralisation, extraction of collagen to gelatine, enzymatic hydrolysis to obtain hydrolysed collagen, ion exchange, filtration, evaporation, sterilisation and finally drying’.

The process is shown in the following diagrams:

  

1. Process for production of hydrolysed collagen using combined method

2.Process for production of hydrolysed collagen using commercial gelatine as raw material

The enzymatic hydrolysis process yields improved functional and nutritional benefits in contrast to heat denaturation or native applications.[2]

When administered orally, hydrolysed collagen reaches the small intestine where it is absorbed into the blood stream, both in the form of small collagen peptides and free amino acids.[3] Through the network of blood vessels, these collagen peptides and free amino acids are then distributed in the human body, reaching the target tissue of their bioactivity, e.g. skin, bone or cartilage, they deliver a messaging signal to the local cells positively influencing its function, and in particular to the skin, where it has been proven they can remain up to 14 days.

As functional foods, collagen peptides have been shown to exhibit important physiological functions with a positive impact on health. Numerous studies have shown an improvement in skin elasticity, the recovery of lost cartilage tissue, reduced activity-related joint pain, strengthened tendons and ligaments, increased lean body mass in elderly men and premenopausal women, increased bone mineral density in postmenopausal women, and activate protection against UVA radiation.

 

What Is The Function of Our Kidneys?

Basically, your kidneys filter waste compounds, excess nutrients and liquids out of the bloodstream, to produce urine. About 20% of the blood your heart pumps through your body goes to the kidneys. In an adult, the kidneys may filter around 180 litres of blood every single day.

A test which measures how well the kidneys filter blood and remove waste is the Glomerular Filtration Rate (GFR). It’s really a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the tiny filters in the kidneys that filter waste from the blood. Kidneys can acutely increase the GFR, or the rate of filtration of the blood. They do this in response to dietary protein intake[4], and the lack of this compensation in some forms of kidney damage are a reason protein intake is controlled for in kidney disease management.

Some say that your kidneys need to work hard to clear the metabolites of protein from your body, leading to increased strain on the kidneys. At the center of the controversy is the theory that habitual consumption of dietary protein in excess of recommended amounts promotes chronic renal disease through increased glomerular pressure and hyperfiltration.

Now, Hydrolysed Collagen can contain up to 97% protein, so I needed to explore this further and find out where this theory came from.

 

The Brenner Hypothesis

Perhaps the most consistently cited reference with regard to the potentially harmful effects of dietary protein intake on renal function is that of Brenner et al. [5]. In brief, the Brenner Hypothesis states that situations associated with increased glomerular filtration and glomerular pressure cause renal injury, ultimately compromise renal function, and potentially increase the risk for or progression of renal disease. Brenner proposed that habitual consumption of excessive dietary protein negatively impacted kidney function by a sustained increased in glomerular pressure and renal hyperfiltration.

Since the majority of scientific evidence cited by the authors was generated from animal models and patients with co-existing renal disease, extension of this relationship to healthy individuals with normal renal function is inappropriate. Indeed, a relationship between increased glomerular pressure or hyperfiltration and the onset or progression of renal disease in healthy individuals has not been clearly documented in the scientific literature. Rather, findings from numerous studies suggest otherwise, such as this study on Dietary protein intake and renal function [6] published in 2005 in the Journal of Nutrition and Metabolism in London which found:

‘no significant evidence for a detrimental effect of high protein intakes on kidney function in healthy persons after centuries of a high protein Western diet'.

The author of the study goes on to say:

‘Although high protein diets cause changes in renal function (i.e., increased GFR) and several related endocrine factors that may be harmful to individuals with renal disease, there is not sufficient research to extend these findings to healthy individuals with normal renal function at this time’.

The study concludes that:

‘the literature lacks significant research demonstrating a link between protein intake and the initiation or progression of renal disease in healthy individuals. More importantly, evidence suggests that protein-induced changes in renal function are likely a normal adaptive mechanism well within the functional limits of a healthy kidney. There is not sufficient proof to warrant public health directives aimed at restricting dietary protein intake in healthy adults for the purpose of preserving renal function’.

In another clinical study, examining the effect on renal function (creatinine clearance and inulin clearance) from changes in chronic dietary protein intake in healthy male subjects [7] further backs up these findings and ‘fails to show an effect of changes in chronic protein intake on glomerular filtration rate (GFR)’.

Further evidence comes from this study [8] conducted by the Institute of Physical Education and Kinesiotherapy, Free University of Brussels, Belgium who investigated body-builders and other well-trained athletes with high and medium protein intake in order to find evidence that high protein intake by athletes has no harmful consequences on renal function.

The authors of the study found that:

‘When looking at active male athletes and measuring urinary creatinine, albumin, and urea, no significant changes were seen in dosage ranges of 1.28-2.8g/kg bodyweight’. It appears that protein intake under 2.8 g.kg does not impair renal function in well-trained athletes as indicated by the measures of renal function used in this study'.

And this study [9] in 2011 conducted to investigate whether dietary protein is associated with impaired renal function suggests:

‘higher protein intake is not associated with impaired renal function among postmenopausal women’.

In May 2014, the first ever meta-analysis was performed to investigate the effects of High Protein diets on outcomes of renal function in subjects without Chronic Kidney Disease [10] and concluded that:

‘high protein diets were associated with increased GFR, serum urea, urinary calcium excretion, and serum concentrations of uric acid. Most of these changes could be interpreted as physiological adaptive mechanism induced by high protein diet without any clinical relevance’. 

And this study [11] conducted as far back as 1983 concludes that:        

‘The capacity of the kidney to increase its level of function with protein intake suggests a renal function reserve’. ie; Instead of being a pathophysiological reaction, high protein-induced changes in kidney function such as the increase in GFR might as well represent a physiological adaptation process.

Also, the authors of this study [12], published in 2016, and conducted to determine the effects of a high protein diet on healthy resistance-trained men over a one-year period concludes:

‘Our investigation discovered that, in resistance-trained men that consumed a high protein diet (~2.51-3.32 g/kg/d) for one year, there were no harmful effects on measures of blood lipids as well as liver and kidney function. In addition, despite the total increase in energy intake during the high protein phase, subjects did not experience an increase in fat mass’.

And finally, the most recent evidence comes from this meta study [13] published in November 2018 in the Journal of Nutrition. Researchers analysed data from 28 papers dating from 1975 to 2016, examining the effects of a low/normal protein intake versus higher protein diets on GFR in health individuals. The scientific trials included data from 1358 participants and concluded that High Protein diet intakes do not adversely influence kidney function on GFR in healthy adults.

The participants in these trials included those who were healthy, obese, or had type 2 diabetes and/or high blood pressure. None of the participants were diagnosed with chronic kidney disease and all consumed either a high, moderate or low-protein diet.

A high-protein diet included either 1.5 grams of protein per kilogram of bodyweight per day, at least 20% of total caloric intake coming from protein or at least 100 grams of protein per day.

Stuart Phillips, a professor of kinesiology at McMaster University, who oversaw the study says: " there's just no evidence to support this hypothesis in fact, the evidence shows the contrary is true: higher protein increases, not decreases, kidney function,"

"While there is a mountain of evidence showing the benefits of higher protein consumption, some people are still afraid it could cause kidney damage" says Michaela Devries-Aboud, lead author of the study and assistant professor of kinesiology at the University of Waterloo, who conducted the analysis as a postdoctoral fellow at McMaster.

"With these findings, we have shown that a higher protein diet is safe. In fact, it should be viewed as an important tool for muscle health across an entire lifespan."

According to Phillips, "Protein causing kidney damage just lacks any support. I think we can put this concept to rest”.

 

So, Just How Much Protein Can We Have and still be Safe?  

Well, the International Society of Sports Nutrition [14] comments that:

'Despite a plethora of studies demonstrating safety, much concern still exists surrounding the clinical implications of consuming increased amounts of protein, particularly on renal and hepatic health. The majority of these concerns stem from renal failure patients and educational dogma that has not been rewritten as evidence mounts to the contrary. Certainly, it is clear that people in renal failure benefit from protein-restricted diets, but extending this pathophysiology to otherwise healthy exercise-trained individuals who are not clinically compromised is inappropriate. Published reviews on this topic consistently report that an increased intake of protein by competitive athletes and active individuals provides no indication of hepato-renal harm or damage. This is supported by a recent commentary which referenced recent reports from the World Health Organisation where they indicated a lack of evidence linking a high protein diet to renal disease. Likewise, the panel charged with establishing reference nutrient values for Australia and New Zealand also stated there was no published evidence that elevated intakes of protein exerted any negative impact on kidney function in athletes or in general'.

Recently, Antonio and colleagues published a series of original investigations that prescribed extremely high amounts of protein (~3.4–4.4 g/kg/day) and have consistently reported no harmful effects [15],[16],[17],[18]. The first study in 2014 had resistance-trained individuals consume an extremely high protein diet (4.4 g/kg/day) for eight weeks and reported no change in adverse outcomes. A follow-up investigation required participants to ingest up to 3.4 g/kg/day of protein for eight weeks while following a prescribed resistance training program and reported no changes in any of the blood parameters commonly used to assess clinical health (e.g., there was no effect on kidney or liver function). Their next study employed a crossover study design in twelve healthy resistance-trained men in which each participant was tested before and after for body composition as well as blood-markers of health and performance. In one eight-week block, participants followed their normal (habitual) diet (2.6 g/kg/day) and in the other eight-week block, participants were prescribed to ingest greater than 3.0 g/kg/day resulting in an average protein intake of 2.9 g/kg/day over the entire 16-week study. No changes in body composition were reported, and importantly, no clinical side effects were observed throughout the study. Finally, the same group of authors published a one-year crossover study in fourteen healthy resistance-trained men. When prescribed to a high protein diet, the participants were instructed to ingest 3 g/kg/day and achieved an average intake of 3.3 g/kg/day and when following their normal diet they consumed 2.5 g/kg/day. This investigation showed that the chronic consumption of a high protein diet (i.e., for 1 year) had no harmful effects on kidney or liver function. Furthermore, there were no alterations in clinical markers of metabolism and blood lipids.

The key points from the research are:

• Multiple review articles indicate that no controlled scientific evidence exists indicating that increased intakes of protein pose any health risks in healthy, exercising individuals.
• Statements by large regulatory bodies have also indicated that concerns about one’s health secondary to ingesting high amounts of protein are unfounded.
• A series of controlled investigations spanning up to one year in duration utilising protein intakes of up to 2.5–3.3 g/kg/day in healthy resistance-trained individuals consistently indicate that increased intakes of protein exert no harmful effect on blood lipids or markers of kidney and liver function.

 So, the verdict’s in.

In adults without established kidney disease, these studies suggest that eating more dietary protein causes an increase in GFR, serum urea, and urinary calcium excretion. However, it does not cause an increase in urinary albumin excretion, which is the most sensitive marker of kidney damage. These changes can be interpreted as normal physiological adaptive mechanisms induced by eating more protein.

This conclusion is shared by the World Health Organisation in their official report published in 2002 on PROTEIN AND AMINO ACID REQUIREMENTS IN HUMAN NUTRITION [19] where they state on page 231 that 

"the most widely quoted potential problem (of a high protein diet) relate to renal function and damage, but the evidence for such claims in otherwise healthy individuals does not stand up to scrutiny’.

 

So Does Hydrolysed Collagen Act Differently on the Kidneys?

I mean is hydrolysed collagen safe? And how much can I take and for how long?

Well most hydrolysed collagen’s are around 90% protein however percentage and purity varies with brand so make sure you read the label. This one [20] contains one of the highest protein content on the market and is 97% protein on a dry weight basis. Its purity is second to none.

So what do the clinical studies tell us?

Well here are some studies specifically using hydrolysed collagen.

This recent study[21] conducted in May 2019 was to determine the maximum level of dietary collagen peptides that can be incorporated in the Western pattern diet while maintaining its indispensable amino acid balance.

The study suggests that the effective amounts of functional collagen peptides (2.5 to 15 g per day) observed in the literature are below the maximum level of collagen that may be incorporated in the standard American diet.

But more over, this study[22] published back in 2011 in order to define the oral chronic toxicity of collagen in rats found:

'No evidence of significant adverse effect or health risk was indicated from the chronic toxicity assessment of hydrolysed collagen up to the diet concentration of 18%, estimated to be 8.586 g/kg·bw/day for females and 6.658 g/kg·bw/day for males. The study results provide an experimental basis for hydrolysed collagen to be safely used as ingredients of functional foods or pharmaceuticals’.

So, to put these results into a human perspective, a woman weighing lets say 60 kg could, according to this study, take 515g of collagen and a man of 80 kg could theoretically take 532g (that’s over half a kilo for each) every day for 2 years and have no toxic effects in the body.

These 2 studies[23],[24] affirm the fore-mentioned evidence that collagen appears to be safe in rodents given extremely high doses of collagen over extended periods.

So to Sum Up.

The overwhelming evidence proves that eating a high protein diet or supplementing with even extremely high doses of collagen hydrolysate does not harm the kidneys in healthy people. Although some people still theorise that dramatically increasing protein intake in a short timespan may lead to adverse effects on the kidneys, the evidence to support this is lacking.