The Rise in Popularity of High Protein Diets and the Possible Implications on Kidney Health

Introduction

In 2018, High protein diets for example Dukan, Atkins, The South Beach, Paleo and Ketogenic are becoming increasingly popular. The general public relates these diets to a healthy lifestyle choice. A High protein diet is one that includes protein in excess of Dietary Reference Intake recommendations for a person without kidney disease (0.8g/kg/day) (Poortmans and Dellieux, 2000). There are various tests that can be used to detect kidney function. The most used test in the healthcare industry is to find the GFR (Glomerular Filtration Rate) of the individual. This is determined by first finding the creatinine levels which is a waste product found in muscle tissues in the body. When this is found the GFR level can then be calculated using this value as well as factors such as age, gender and race. In Ireland the most used method for detecting and measuring CKD (Chronic Kidney Disease) is to perform a five stage system test based on the individuals GFR levels over a period of time. The higher the stage goes the more severe the disease is.(HSE, 2018) In this study we try to find the correlation between high protein diets and the implications that could possibly be an outcome on kidney health.

The increase and popularity of protein diets

In recent years high protein diets have risen significantly in popularity. Proteins are essential nutrients, which are vital structural components of body tissues, for example muscle, hair and nails. Many individuals have now made a conscious choice to increase their protein consumption, and Nielsen has reported that 55% of households would regard high protein as an important attribute when buying food for their households (Nielsen, 2018).

Due to protein being a vital component of the human body, it has major health benefits, which are the causes for high protein diets significant rise in popularity (Du, 2018). One of the prime benefits being that in studies where high protein diets have been consumed, it has been concluded that high protein diets are effective in promoting fat loss and therefore helping to maintain, or achieve a healthy weight ((Phillips, 2006), (Blachier et al, 2018), (Murphy et al, 2013), (Oh and No, 2018)). One of the reasons proteins helps individuals who consume it in high amounts lose weight is because tends to have satiety enhancing effects (Du, 2018).

Protein is very popular amongst individuals who are also trying to increase their muscle mass. Protein promotes muscle growth because the building blocks of protein are amino acids, which help with cellular function and muscle repair. Therefore, if not enough protein is present in the diet, then there will not be an adequate supply of amino acids available for muscle metabolism and ongoing anabolism (Leal, 2018). Many studies have consistently showcased these findings that high protein diets lead to increased muscle mass ((Phillips, 2006), (Kadey, 2018)). In addition to this, high protein diets have been said to be advantageous for individuals hoping to increase their muscle strength (Kadey, 2018), and that these diets may improve training adaptations to exercise training (Antonio et al , 2016).

Pros and Cons of high protein diet

A High protein diet is one that includes protein in excess of Dietary Reference intake recommendations for a person without kidney disease (0.8g/kg/day). (Poortmans and Dellieux, 2000) An RDA is a general recommendation which doesn’t take many things into account calories, carbohydrate intake, biological sex, age, how active we are, how eco-friendly the protein sources intake is. Glomerular filtration rate is the most accurate overall measure of kidney function as recognised by the NFK Disease Outcome Quality Initiative. Fad diets have been known to influence high protein diets for weight loss. Only recently high protein diets have been compared to low protein diets for health reasons. High protein weight loss diets have existed in U.S. for years. Apart from their weight loss purpose there is a serious reason for concern as these High Protein diets clinically altar renal function. (Friedman, 2004). An Omni Trial study carried out in America states” high in protein diets can cause glomerular hyperfiltration, a potentially maladaptive response which may accelerate the progression of the disease”. Healthy participants involved in the Omni trial which replaces partial carbohydrates with protein had no kidney disease/problems prior to the trial. Participants keeping consistent weight followed 3 diets for 6 week periods with a 2-4-week washout period. The three diets consisted of carbohydrates, protein or unsaturated fats. Dietary protein making up to 15% of the carbohydrate and unsaturated fat diet or 25% protein of energy intake. Serum creatinine was recorded after each 6 week period. The protein diet when compared to the carbohydrate diet and unsaturated fat diet showed an increase in cystatin C-based Glomerular filtration. To conclude the Omni trial, Glomerular filtration rate increased following the High protein diet but there is uncertainty to whether high protein diets can lead to kidney disease in the long term. (Bernstein, Treyzon and Li, 2018) A high protein diet can be determined as follows: the total amount of protein, the percent of total calories as protein and the amount of protein(g) per kg of body weight. The Brenner hypothesis is the most cited reference in this topic. The hypothesis proposes that “the sustained rise in glomerular filtration rate due to a high consumption of protein is detrimental to kidney function accelerating a potential rise in renal disease”. (Tipton, 2011) In the UK, the normal intake of protein is 16% of energy intake for a sedentary adult which is around 64-88g/day at energy balance for both men and women. There is no one general consensus to state what a high protein diet is but it is referred to as a ‘protein-enriched’ in food industry for over 20% of protein from energy. (Johnstone, 2012) Long term clinical trials should be carried out to test increased protein diets in healthy subjects to determine how effective a high protein diet is and what the consequences are over a long period of time.

Detecting kidney health and causes of poor kidney health

The kidneys are a two bean-shaped organ that is found in vertebrates which is located on the right and left of the abdominal cavity. The kidneys have many functions, the most important being the removal of waste, toxins, sodium and water from the body. (NIDDK, 2018)

Recently in the past few years people have become more aware of kidney health as the incidence of CKD (chronic kidney disease) has doubled; especially among older individuals. This could possibly be because of the increasing prevalence of conditions such as diabetes and hypertension in recent years which is seen to damage the delicate blood vessels of the kidneys. (Liu H, 2010) One in ten American adults is now living with some degree of CKD, and kidney disease is the ninth leading cause of death in the United States (NKUDIC, 2012) According to research done by (Stack et al, 2014) they were able to determine the overall prevalence of CKD in the Irish health system. They concluded that the prevalence of CKD in the Irish health system was 11.8% in addition to the rate of 4.5% in the general population. There was a higher prevalence of CKD in women than in men. (12.6% women versus 10.9% men). Another study which was done in the UK also discussed the prevalence of CKD and found that the prevalence of low excretory kidney function was 5.2% (Sutton et al, 2015)

There are many tests today in the healthcare industry that can be used to test the kidneys. Blood tests, Imaging tests, kidney biopsy and urine tests are various assessments used on kidneys. The most effective and widely used method would be detecting GFR in the blood. As mentioned in the introduction the most used method for detecting and measuring CKD (Chronic Kidney Disease) in Ireland is to perform a five stage system test based on the individuals GFR levels over a three month period. The higher the stage goes the more severe the disease is. (HSE, 2018) The levels of creatinine which is a waste product in muscles is found in the blood and then this can be used to calculate GFR (Glomerular Filtration Rate) along with the individual’s sex, gender and age.

A study done in Australia by (M Ludlow et al,2014) assessed local GP’S on whether they were following correct current guidelines when detecting and managing the kidneys. They recommended similar tests as explained above such as serum creatinine test, urine albumin creatinine ratio. They also were able to identify key indicators of increased risk of CKD such as hypertension, smoking and family history of kidney failure.

Research done by (Sutton et al,2015) on the methods used in economic evaluations of chronic kidney disease used results of 2,671 papers that were identified in which 21 were included in the final review. Eighteen studies focused on proteinuria which is the presence of protein in the urine which in turn rises GFR. Three evaluated glomerular filtration rate testing and one included both tests.

Why protein is needed in the diet

Protein is essential in the diet. It assists with body growth and repair of cells. Without protein the body wouldn’t be able to function to its full capacity.

According to the British Nutrition Foundation , the recommended amount of protein is 0.75g per kilogram bodyweight per day. This recommendation varies for each individual depending on sex and age. Protein requirement is increased for women who are pregnant or are lactating(British Nutrition Foundation,2016).

In order for athletes to excel at their chosen sport the need for protein in the diet is vital. To prevent muscle damage, an athletes protein intake would be larger amount than an ordinary individual. An athletes protein intake should be in the range of 10-15% of their total dietary intake (Urdampilleta et al, 2014). An excess of 2g of protein can be damaging to the athletes performance.

The National Kidney Foundation (2018) explains that the more protein digested the more the kidneys have to filter which puts stress on them. Diets with high protein content can be damaging to an individual’s health. High protein content is associated with the increase of Glomerular Hypofiltration, ( Friedman et al, 2010).

Discussion

With a protein enriched diet, evidenced based research and trials carried out show an increase in Glomerular filtration rates in addition to a high protein diet. Creatinine clearance is the measure of glomerular filtration rate. From reviewing this argument, it is shown to be a controversial topic as although a high protein diet is seen to increase GFR there is no evidence based data to state that the kidneys will suffer renal damage in addition to a high protein dietary lifestyle. Although a rise Glomerular filtration rate increases stress on the kidneys to filter more fluid which in long term may degrade kidney health. After extensive research regarding this particular field we conclude, that in order to accurate evidence based data to state the whether the effect of high protein influences kidney health. Long term research/trials must be conducted on this topic to support the hypothesis.

Conclusion

In conclusion to the argument ‘The Rise in popularity of high protein diets and the possible implications on kidney health’, there is no scientific evidence to prove high protein damages the kidney over short periods of time, but research shows that high protein does have an effect on GFR which in long term trials may result in damaging outcomes.

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