A Gene That Can Impact Kidney Stone Formation (CASR)

Drink More Water 

Regardless of variant, it is recommended that everyone drink a sufficient amount of water per day. This amount can vary; men are recommended to drink about 3 liters (approximately 13 cups) of water per day, while non-pregnant women are recommended to drink about 2.2 liters (approximately 9 cups) [R]. 

Drinking a sufficient amount of water can help dilute calcium oxalate and sodium in the urine, as well as help remove these salts from the body. Both urine dilution and regular excretion of salts can reduce the risk of kidney stone formation [R].

Water can help dilute urine and flush salts from the body. Although everyone should be drinking the recommended amount of water daily, carriers of CASR risk variants should be especially careful to drink this recommended amount, in order to reduce risk of kidney stone formation.

Get a Routine Urinalysis Done

It is a good idea for individuals carrying risk variants of CASR to occasionally visit their family doctor in order to complete a routine urinalysis, or urine test. A urinalysis can determine whether urine contains high levels of calcium crystals — an early warning sign of kidney stone formation [R]. 

Limit Oxalate Intake

Oxalate is a compound found in cooked spinach, rhubarb, rice bran, potato skins, and navy beans. Individuals with variants that may predispose them to kidney stones should limit their intake of foods containing oxalate [R, R].

Consume Healthy Amounts of Calcium

Paradoxically, too little calcium can also increase kidney stone formation. When eaten in healthy amounts, calcium can bind oxalate in the stomach and intestines, and calcium oxalate can be excreted in stool. However, when calcium is eaten in low amounts, there is not enough calcium present in the stomach and intestines to bind oxalate. In this case, non-bound oxalate is instead transferred to the kidneys, ureters, and bladder, where it can combine with (reabsorbed) calcium in urine to form kidney stones [R, R, R, R, R]. 

Regardless of CASR variant, consuming the recommended amount of 1000 mg to 1200 mg of calcium per day can help avoid both excess calcium levels and low calcium levels in the body. Calcium supplements can often result in excess calcium intake; therefore, it is best to stick to dietary sources of this mineral. Dietary sources of calcium include dairy products, green leafy vegetables, soy products, and nuts [R, R]. 

Calcium can combine with oxalate to form calcium oxalate salt, a component of the most common types of kidney stones. Carriers of CASR risk variants should consume the recommended amount of calcium and limit their intake of oxalate to reduce their risk of developing kidney stones.

Limit Vitamin C Intake

Vitamin C can be converted to oxalate in the body, thus further increasing the risk of calcium oxalate stone formation. Therefore, carriers of CASR risk variants are recommended to limit their intake of vitamin C from supplements to 1000 mg per day [R].

Foods that are rich in vitamin C, and should thus be eaten in moderation by individuals that carry risk variants, include citrus fruits (such as oranges), melons (such as cantaloupe), broccoli, peppers, and tomatoes [R].

Reduce Sodium Intake

A diet high in salt (sodium) can similarly increase the risk of kidney stone development. Although the mechanism is unclear, it is possible that high levels of sodium in the body require more water to be reabsorbed in the kidneys. This can ultimately result in urine that is concentrated with calcium [R]. 

It is recommended that individuals carrying risk variants of CASR limit their intake of foods that are high in sodium, such as smoked or cured meat, salted nuts, salted beans, and frozen entrees [R]. 

Consume Less Animal Protein

Animal protein can make your urine more acidic, which can aid in the formation of calcium oxalate kidney stones (as well as other types of kidney stones) [R, R]. 

It is important to note that protein is an essential nutrient. Therefore, individuals that are carriers of CASR risk variants should limit their intake of foods that contain animal proteins, while simultaneously increasing their intake of foods that contain plant proteins [R]. 

Specifically, carriers should limit animal products rich in animal protein, such as beef, chicken, eggs, and milk. They should instead consume more plant products rich in plant protein, such as legumes (e.g., lentils), soy products, and nuts. Interestingly, many plant products that are high in protein, such as soy products and nuts, are also good sources of calcium (as described above) [R]. 

Carriers of CASR risk variants are recommended to limit vitamin C and sodium intake. They are also recommended to increase their intake of plant proteins, while simultaneously decreasing their intake of animal proteins.

Vitamin D 

Vitamin D has been shown to aid the intestines in absorbing calcium from food. Individuals carrying CASR risk variants may benefit from 800 to 1000 individual units (IU) of vitamin D per day from supplements, if they are not getting enough sunlight [R].