Does Pea Protein Cause Kidney Stones?

It is unclear if pea protein causes kidney stones. However, a high protein diet based on animal sources is linked to increased kidney stone risk (1). 

Despite there being a lot of debate amongst scientific researchers regarding the safety of plant based protein for those with a risk of developing kidney stones. At present the answer to "is pea protein is safe?" for those with a risk of developing kidney stones is, there is no evidence of it being dangerous (2). It is believed, those without any underlining illness are able to safely consume pea protein without worrying about kidney health and the development of kidney stones.

There are four types of kidney stone which have different causes. Therefore, the type of kidney stone someone has will determine both their treatment and the changes required to their diet.

Some scientific evidence indicates pea protein may actually benefit those with low kidney function and provide some protection against developing kidney stones. This is due to containing high levels of the amino acid arginine. Arginine has been found to lower blood pressure (3).

What Is Pea Protein?

Pea protein comes from yellow split peas. It is often used as plant based protein powder to help increase daily protein intake. Protein is a vital macronutrient used to restore cells, and help in the growth and repair of muscles, skin, bones, organs, hair and nails (4).

Pea protein powder can be used to increase daily protein intake, assist with athletic performance, muscle and strength development. Further to this, studies have shown increased protein intake can help suppress cravings and help with weight loss (5).

Pea protein powder is amongst the most popular plant-based proteins due to the fact it is hypoallergenic and has a protein content which is comparable to whey protein.

What Are Kidney Stones?

Kidney stones can vary in size from being as small as a grain of sand to as large as a golf ball (6). There are primarily four types of kidney stone, they are calcium oxalate stones, struvite stones, uric acid stones and cysteine stones.

However, the most common type of kidney stone is a calcium stone which is composed of calcium oxalate and calcium phosphate. Approximately 70-80% of kidney stones are calcium stones (7).

Unfortunately, kidney stones are very painful and can be difficult to pass. Those who have suffered from kidney stones once are likely to have them again. Studies have shown about 50% of kidney stone sufferers go on to develop another within seven years if preventive measures are not put in place (8).

Types Of Kidney Stones And How They Are Treated

Cystine stones are rare and they are caused by genetic disorders, but hydration as well as taking medication to moderate Ph levels in urine is used to help prevent kidney stones (9).

Struvite stones tend to form following a bacterial infection which has caused a change in the urine’s Ph level. Medication can be used to regulate Ph and ammonia levels which in turn aids dissolving hte stones (9). Women are more likely to get struvite stones, whilst men are more likely to get uric acid or calcium oxalate stones (7).

Uric acid kidney stones form when a patient’s urine becomes too acidic. This prevents uric acid from dissolving. The result is it crystallises and produces stones. Medication can be used to neutralise acidic urine. Patients are also advised to consume less animal protein (10). This is because uric acid is a by-product of protein metabolism.

Calcium oxalate kidney stones are the most common type of kidney stones. People who suffer with calcium oxalate kidney stones are advised to reduce their consumption of foods high in oxalate. These foods include nuts, chocolate and potatoes.

What Causes Kidney Stones To Form?

Kidney stones form when chemicals within an individual's urine become concentrated enough to form crystals (12). As these crystals grow larger, they can travel to the urinary tract and get stuck blocking the flow of urine. This can be extremely painful. Dehydration is also a key factor in causing any type of kidney stone to form. For those who have previously suffered from a kidney stone, drinking 2 litres of fluid a day can greatly reduce the likelihood of a reoccurrence by almost 50% (13).

Research has found approximately 15-20% of patients with uric acid stones have a history of gout (14). Gout is an arthritic condition which is often linked to metabolic conditions and the over consumption of food rich in purine. Diets rich in animal protein have a higher risk of uric acid stones due to animal protein having a high purine content.

How Does Protein Effect The Kidneys?

Studies have shown animal protein increases urinary excretion of oxalate, a compound which combines with calcium and other compounds to form kidney stones (8). Particularly, foods which are high in protein and low in carbohydrate can increase kidney stone risk. This also reduces the body’s capacity to absorb calcium (11). Calcium binds with oxalate in the intestine; reducing the amount excreted by the kidneys into the urine. With lower oxalate levels in the urine there is less opportunity for it to bind with calcium and create crystals which can turn into kidney stones (13).

Another concern with high protein diets, is some studies have linked a high protein diet to increasing the levels of acid on the kidneys. High levels of acidity around the kidneys can increase the likelihood of kidney stones forming (15).

Is Pea Protein Bad For Kidneys?

'The National Institute of Diabetes and Digestive and Kidney Diseases' advise those with CKD and those susceptible to kidney stones to limit the amount of animal protein in their diet (16).

They also recommend a plant based protein source as a good alternative for those wanting to take a protein supplement. When your body stores an excess of oxalate this can result in kidney stones forming. Pea protein powder is low in oxalate and high in protein, making it a great option for those who suffer with kidney stones.

Studies into the health benefits of pea protein powder have found it can assist the body in flushing away any excess uric acid the body has stored. Research has found too much uric acid can lead to kidney stones developing (14). Pea protein powder has also been found to lower blood pressure. This has led to some to believe pea protein could be used as a potential chronic kidney disease treatment (10). However, so far studies have only been done on lab rats so more research is needed in this regard to determine how human subjects would react.

Ways To Reduce The Probability Of Kidney Stones

1) Hydration is key. By staying hydrated the chemicals in the urine will be diluted. Experts believe drinking 2 litres of water per day can reduce kidney stone risk by 50%. Previous suffers of kidney stones should drink 2.5 litres of water to prevent a future reoccurrence (13).

2) Calcium rich foods are beneficial as they bind with the oxalate in the intestine; reducing the amount which is excreted by the kidneys into the urine. Lower oxalate levels in the urine mean there is a lower probability for it to bind with calcium and from crystals which can turn into kidney stones (13).

3) Try to avoid foods which are rich in oxalate, such as nuts, chocolate, tea, spinach and potatoes (9).

4) If you consume animal protein try to limit your daily intake. Red meat, eggs, seafood, and poultry are know to increase uric acid levels which can lead to kidney stones forming (14).

Research Has Not Linked Pea Protein With Kidney Stones

In individuals with chronic kidney disease, a high protein diet based on animal protein sources has been shown to accelerate renal deterioration (2). However, protein still remains a very important macronutrient because of how vital it’s is to support our bodies to grow and repair.

There is very little research to show the effect of plant-based protein upon the body and whether it too is connected to the formation of kidney stones. Recent studies have found pea protein could be used as a potential chronic kidney disease treatment due to its ability to lower blood pressure. Further research has found pea protein is able to aid the body in flushing away any excess uric acid the body has stored, which could make pea protein beneficial for those who suffer from kidney stones. If you are in any doubt as to whether you should take pea protein or require help choosing the best pea protein powder for you, it is important to consult with a medical professional.