The Low-Oxalate Diet Isn't For Everyone, Experts Say. Here's What to Know.
When a particular eating plan becomes super popular all of a sudden, it's worth looking at with skeptical eyes. After all, plenty of diets that started out as legitimate, expert-backed plans designed to address specific health issues or medical conditions have become twisted into little more than lose-weight-quick schemes, then mass marketed to people, many of whom never needed to change their eating in the first place.
Lately, there's been an increasing buzz around low-oxalate diets. This particular eating plan is often recommended for people who struggle with kidney stones, says Keri Gans, MS, RD, author of "The Small Change Diet." And it's great for people who are prone to the painful condition, which occurs when hard deposits made of minerals and salts form inside the kidneys.
But the low-oxalate diet isn't meant to be a weight-loss plan — nor is it meant to be a panacea for anyone looking to add more nutrients to their diet. We asked experts for more info about what the low-oxalate diet involves and how to know if it's the right eating plan for you. Here's what they had to say.
What is a low-oxalate diet?
As the name would indicate, this eating plan is meant to be low in oxalate, which is a compound found in certain foods and produced in small amounts by your body, says Sonya Angelone, RD, a spokeswoman for the Academy of Nutrition and Dietetics. "The breakdown of vitamin C in our bodies also produces oxalates," she adds.
Oxalate is found naturally in many vegetables, nuts, fruits, and grains, says Deborah Cohen, RDN, an associate professor in the Department of Clinical and Preventive Nutrition Sciences at Rutgers University. Cohen says that you pee out almost all oxalic acid (which mixes with other minerals to form oxalate) you come into contact with. Kidney stones form when oxalates bind to calcium as they leave the body.
A low-oxalate diet is designed to help minimize your interactions with oxalates. "Some suggest that reducing the amount of oxalate one consumes can decrease the risk [of kidney stones]," Cohen says.
"However," she adds, "it's important to note that the development of kidney stones is multifactorial." For example, getting too little calcium or being dehydrated can also increase your risk of developing kidney stones, the National Kidney Foundation states. So a low-oxalate diet alone may not be the only preventive step worth taking, which is why it's advised to speak with a doctor before trying it.
Who is the low-oxalate diet for?
While some people online tout this type of diet as a cure-all for "inflammation," that's not a proven outcome. It's strictly for people who've had a history of calcium oxalate kidney stones. "Typically, the main reason for going on a low-oxalate diet is either to help decrease the risk for kidney stones — only, though, if you have a history of high oxalate levels and kidney stones — or to help lower high oxalate levels during a kidney stone attack," Gans says.
But the diet may not be a fit for everyone who's had a kidney stone. While calcium oxalate stones are the most common type, kidney stones can be made up of other substances, in which case a low-oxalate diet may not help.
And even if you do have calcium oxalate stones, there may be a different way of reducing the risk of them coming back. "Since calcium can bind with oxalates so they do not reach your kidney and contribute to kidney stones, eating enough calcium in your diet may be just as effective as decreasing the oxalates in your diet," Cohen says.
All that to say: it's essential to talk to a doctor before adopting this diet.
What foods can you eat — and which should you avoid — on a low-oxalate diet?
"Oxalates don't have a taste, so you won't know if you are eating a food high in oxalates," Angelone says. "It is important to learn which foods are high in oxalates and which have very little." You'll generally want to avoid the following foods on a low-oxalate diet:
- Swiss chard
- Beet greens
- Sweet potato
- Soy milk
- Most grains and legumes
- Sesame seeds
- Dark chocolate
- Some berries, like raspberries
"Be careful with smoothies that contain these items," Angelone warns. Smoothies can pack in a ton of high-oxalate foods in a small cup that can be consumed quickly, so it's worth being cautious.
What are the risks of a low-oxalate diet?
In general, there aren't specific health risks to going on a low-oxalate diet, Cohen says. However, you run the risk of missing out on certain nutrients, she adds. "Any type of diet that restricts certain foods can lead to nutrient deficiencies, and high-oxalate foods tend to be high in important nutrients," she says.
Another limitation of the low-oxalate diet? It can be tough to follow. "There is no unique characteristic of those foods that are high in oxalates," Cohen says. Meaning, there isn't really a common theme in high-oxalate foods that you can follow easily. It can take a lot of studying up to make sure you stay on track.
What to know before trying a low-oxalate diet
Again, there are a lot of factors that can go into whether you develop kidney stones, including genetics and how much water you drink, reports the World Journal of Nephrology. So just going on a low-oxalate diet may not get rid of your risk of kidney stones, Cohen says.
Again, talk to your doctor before starting this diet to make sure it's the right step for you — and to learn what else you should be doing instead of or alongside the eating plan. Cohen, for instance, suggests doing the following to minimize your risk of kidney stones, either in addition to a low-oxalate diet or before trying the restrictive eating plan:
- Drink more water. The US National Academies of Sciences, Engineering, and Medicine recommends that women aim to have 11.5 cups of fluids a day and men strive for 15.5 cups. But Cohen says you can tell how hydrated you are by looking at your urine. When it's clear or pale yellow, you're in good shape.
- Have more calcium. "Calcium binds to oxalates in the GI tract and helps to prevent their absorption," Cohen says.
- Limit your sodium intake. Strive for less than 2,300 milligrams a day, which is the amount recommended by most health organizations, including the American Heart Association (AHA).
- Watch your vitamin C supplements. Too much vitamin C can increase the amount of oxalic acid in your body, raising your risk of kidney stones, Cohen points out. She recommends sticking at or below your recommended daily intake — which means staying away from supplements that contain mega doses, sometimes over 1,000 percent your recommended daily intake.
- Cook high-oxalate vegetables well. "Boiling is one method to decrease the oxalate content," Cohen says. "However, this can also decrease the vitamin content of the vegetable."
Not to sound like a broken record, but if you're interested in going on a low-oxalate diet, Gans emphasizes the importance of talking to your doctor first: "There's no reason to start this diet if your oxalate levels are normal and you're not in any risk for kidney stones."