Recent research suggests that a low oxalate diet may help reduce the risk of developing kidney stones. However, other research suggests that not only a low-oxalate diet but a high-calcium diet are equally important for preventing kidney stones. So first let’s know what are kidney stones.
What is kidney stone?
Kidney stones which are also known as ‘renal calculi’, ‘nephrolithiasis’ or ‘urolithiasis’, is the disease of the kidneys and ureters in which small or large stones form inside the kidney. These stones or hard deposits are mainly made up of salts and minerals which are present in urine.
Most of these stones pass out of the body without the help of a doctor. But sometimes they get stuck in the urinary tract and block the flow of urine which causes pain. Kidney stones can be as small as a grain of sand or as large as a golf ball.
Calcium oxalate is the most common type of kidney stone. It is formed when calcium mixes with oxalate present in urine.
Kidney stones can cause severe pain in the upper back. Apart from this, the following symptoms can also be a symptom signalling towards kidney stone –
- Blood in urine
- Fever and chills
- Foul smell of urine
- Burning feeling while urinating.
What is oxalate?
Oxalate, also known as oxalic acid – is an organic compound found in plants. It is mainly found in leafy vegetables, fruits, nuts and seeds. Our body can make oxalate on its own (endogenous synthesis) or get it from food. Apart from this, vitamin C can be metabolised inside the body and converted into oxalate.
Disadvantages of High Oxalate consumption
A high oxalate diet can be harmful to the body due to the following reasons:
Oxalate can reduce mineral absorption –
Research suggests that oxalate can bind with minerals in the gut and prevent the body from absorbing them. Therefore an excess amount of oxalate can lead to a deficiency of minerals in the body. For example, spinach is high in calcium and oxalate, but oxalate prevents calcium from being absorbed into the body. Similarly, eating a fiber-rich diet and oxalate together can further hinder the absorption of nutrients.
According to some other research, even though the absorption of calcium from spinach is reduced, but consuming milk and spinach together does not affect the absorption of calcium from milk. It is important to remember that only a small number of minerals bind to oxalate.
Excess of oxalate can lead to kidney stones –
Normally, both calcium and a small amount of oxalate are present in the urine. Both these minerals are soluble and do not cause any problems in the body. However, sometimes these minerals turn into crystals and cause kidney stones, especially when the oxalate content is high and the urine volume is low.
However, small stones often do not cause any problems and are passed out on their own through urine. But large stones can cause severe pain and blood in the urine while passing through the urinary tract. About 80% of kidney stones are made up of calcium oxalate. For this reason, people who have kidney stone problems, doctors ask them to consume low-oxalate foods.
Some experts, however, believe that a high oxalate diet may not be a major cause of kidney stones. This is because our body too produces oxalate of its own. Most urologists, now recommend eating a low-oxalate diet (less than 50 milligrams per day) only to those people who have high levels of oxalate in their urine. Therefore, it is important to have periodic tests for accurate detection of oxalate in urine. So that the amount of oxalate in the diet can be increased or decreased.
What is low oxalate diet?
Low oxalate diet means consuming such food items which have the low oxalate content. In fact, inside the body, oxalate can combine with minerals (calcium and iron) to form other types of compounds, including calcium oxalate and iron oxalate.
These compounds are mostly in the colon, kidney and urinary tract. Most people excrete oxalate through faeces or urine. However, there are some individuals whose bodies are unable to excrete oxalate – so in them it causes kidney stones or other diseases.
Purpose of Low Oxalate diet
The purpose of a low oxalate diet is to limit the amount of oxalate the body consumes daily. Low oxalate diets are generally applicable to individuals who suffer from kidney stones or have a history of kidney stones or increased levels of oxalic acid.
A low-oxalate diet is the one in which less than 100-50 milligrams of oxalate is consumed per day. However, the amount may vary from person to person. Therefore, eat oxalate-rich diet according to the doctor or dietician.
Merits of Low Oxalate diet
Following are the benefits of adopting a low-oxalate diet.
Assists in case of Kidney stones –
Low oxalate diet can prevent kidney stone formation. Excess amounts of oxalic in the body form crystals with calcium. These crystals get stuck in the kidney or our urinary tract and cause kidney stones.
Helpful in cystic fibrosis-
A low oxalate diet may reduce the risk of cystic fibrosis complications. Cystic fibrosis (CF) is a genetic disorder that damages various organs such as the lungs, pancreas, liver, kidneys and intestines. This disease makes sticky mucus in the organs and infects them.
Controls under-active thyroid –
When there is excess oxalate in the body, it accumulates in various tissues and in the thyroid. This excess oxalate binds to hormones released by the thyroid and forms crystals. This crystal reduces the activity of the thyroid gland, leading to weight gain, fatigue, high cholesterol level, menstrual problems, etc. Therefore, a low oxalate diet can be beneficial for treating under-active thyroid.
Benefits in Controlling Spectrum Symptoms –
Researchers have found that a low-oxalic diet may help control symptoms across the spectrum. Autism spectrum disorder is a serious mental illness that affects the nervous system.
Demerits of Low Oxalate diet
The low oxalate diet restricts a wide variety of foods, including green leafy vegetables, nuts, seeds and starches.
For example, spinach is high in oxalate, as well as a great source of iron, fiber, vitamin A, calcium and magnesium. Therefore, by adopting a low oxalate diet, you will have to remove spinach from your diet.
Similarly, beets also contain high amounts of oxalate and are packed with nutrients like folate, potassium and manganese.
Green vegetables, beans and nuts are nutritious foods that are rich in protein. But due to the restriction of oxalate diet, you are not able to take these nutrients from your diet, and due to which there is a lack of protein in the body.
Protein deficiency can have many negative effects, including weakened immunity, weakness, anaemia and stunted growth.
Therefore, if you follow a low-oxalate diet, you will need to ensure that your diet meets your nutritional needs.
How to control oxalate in urine?
The amount of oxalate in urine can be controlled in the following ways-
- Eat a low oxalate diet – Eat foods that contain small amounts of oxalate. Below is a list of low oxalate diets.
- Boil oxalate vegetables before eating- Boil foods that are high in oxalates before consuming them. This is because boiling reduces the amount of oxalate.
- Increase the amount of calcium in your diet – A small amount of calcium in your diet can increase your chances of forming a kidney stone (calcium oxalate). Calcium helps bind oxalate in the intestines. A diet rich in calcium helps reduce the amount of oxalate your body absorbs, which reduces the chances of getting stones. According to experts, people suffering from kidney stones are advised to take less than 100 -50 mg of oxalate per day and calcium up to 1000-1200 mg/day. However, scientists need to do more research on this point.
- Limit the amount of Vitamin C – High doses of vitamin C can increase the amount of oxalate in your urine, which increases your risk of kidney stone formation. If you are taking a vitamin C supplement, do not take more than 500 mg of vitamin C daily.
- Drink more fluids – Drink plenty of fluids especially water. Your target should be 10-12 glasses a day. At least 5-6 glasses of water should be drunk. In addition to water, you can also consider drinking lemonade. Research suggests that lemon water may be helpful in reducing the risk of calcium oxalate stone formation. However, excessive amounts of lemon can be harmful.
- Eat the right amount of protein daily – Eating too many protein-rich foods can lead to stone formation. Therefore, eat only good proteins in limited quantity and not consume protein powder.
- Reduce the amount of sodium in your diet – An overdose of sodium can also cause high oxalates in the urine. So control the amount of salt.