Eating almonds — on a regular basis and in high quantities — can increase your risk of forming kidney stones.
However, this answer might be slightly misleading! Because while almonds can raise the risk of developing calcium oxalate stones, they do not influence the formation of other types of kidney stones [1, 2]
In this case, it will be more accurate to say that eating almonds can increase the risk of developing only calcium oxalate stones, the most common type.
This is especially true if you have had the same type of stones before; because the recurrence rate for calcium oxalate kidney stones is about 50% in the following 10 years [3, 4, 5, 6].
In the rest of the article, we will discuss how exactly almond consumption influences the development of calcium oxalate stones and what to do about it.
Almonds and Calcium Oxalate Stones
The reason that almonds are associated with an increased risk of calcium oxalate stones is that they are rather high in oxalate, a naturally-occurring compound found in many foods [7, 8].
According to WebMD; one ounce of almonds, or approximately 22 kernels, contains roughly 120 milligrams of oxalates.
Note: People with a high risk of developing calcium oxalate stones are usually advised to limit their daily oxalate intake to 50 mg [9, 10].
It is now clear that since almonds are high in oxalate they can raise the risk of developing calcium oxalate stones, especially when eaten in high quantities. That certainly applies to other oxalate-rich foods.
For instance, spinach. This leafy green vegetable is extremely high in oxalate; therefore, usually not recommended to those who are prone to developing calcium oxalate stones.
In fact, when eaten in the same amount, spinach provides more oxalate than almonds. But, some studies suggest that oxalate taken from nuts (including almonds and cashews) is better absorbed in the body compared to many other foods high in oxalate [11, 12].
Another factor that might be making almonds riskier is that many people consume almonds every day as a snack. On the other hand, spinach or rhubarb (both of them are extremely high in oxalate) tend to be eaten occasionally and seasonally.
How Do Calcium Oxalate Stones Form?
If the urine contains high levels of oxalate and too little liquid, oxalate and calcium can bind together and form calcium oxalate crystals. These crystals can then clump together, forming kidney stones.
In other words; the higher oxalate and calcium in your urine and the lower fluid that can dilute these substances, the more chance these substances can stick together and form calcium-oxalate kidney stones.
For these reasons, people who are at risk for calcium oxalate stones are recommended to drink plenty of fluid (mostly water) and limit the amount of oxalate they consume.
So if you constantly eat almonds or other oxalate-rich foods in high quantities and consume too little fluid, then you are increasing your risk of forming calcium oxalate stones.
Calcium Is Necessary
You might be thinking that reducing your calcium intake is good for preventing calcium-oxalate stones; after all, calcium-oxalate kidney stones are made of both calcium and oxalate.
However, healthcare professionals who specialise in kidney stones advise doing the opposite.
They say that to help prevent the development of calcium oxalate stones, an adequate amount of dietary calcium needs to be eaten per day; and if possible, calcium and oxalate-containing foods should be consumed at the same time [13, 14, 15, 16].
This is because when oxalate-containing foods are eaten together with calcium-containing foods, calcium and oxalate will most likely bind together in the intestines instead of in the kidneys and leave the body in faeces. This, in turn, reduces the likelihood of developing kidney stones.
The above-given information tells us that eating almonds together with a calcium-rich food or beverage may help counteract the stone-causing effects of almonds.
Does Eating Almonds Risky For You?
Almonds provide a range of essential nutrients; therefore, can contribute to your health in many ways. However, if you eat too many almonds on a regular basis, you might be increasing your risk of developing calcium oxalate stones due to almonds’ high levels of oxalate.
Note that everyone — whether he/she has risk factors or not — can develop calcium oxalate stones. However, certain factors make some people more susceptible to this type of kidney stone. Here are some of them …
- Being a man. Men are more likely to form kidney stones than women [17, 18].
- Having too much oxalate in the urine.
- Having gone through calcium-oxalate stones before.
- Being obese or overweight. Obesity is a risk factor for kidney stones [19].
- Drinking an insufficient amount of fluid, mostly water [20].
- Having a family member with a history of kidney stones. Your genetics may increase your risk of forming kidney stones [21, 22].
- Having certain medical conditions. Some medical conditions can cause your urine to have high levels of stone-causing substances.
- Eating a diet rich in sodium, sugar and protein.
- Frequently performing sweating activities such as saunas, hot yoga and strenuous exercise or living in a hot environment. These factors increase sweating thus decreasing urine production, which can lead to kidney stones.
So, if you have some of these risk factors, plus eat almonds on a regular basis, then yes, eating almonds may be risky for you in regards to developing calcium-oxalate stones.
Should You Avoid Almonds To Prevent Kidney Stones?
If your urine oxalate levels are too high or you have had calcium oxalate stones before, then it is best for you to either completely avoid or limit the consumption of high oxalate foods, such as almonds.
Healthcare providers usually recommend eating no more than 50 mg of oxalate daily to people at risk for calcium oxalate stones. But, eating a handful of almonds means you are ingesting approximately 120 mg of oxalate.
Moreover, if you consume salted almonds, you might be increasing the stone risk even more. Because salt can cause more calcium to be absorbed in the kidneys [15, 23].
In addition to these, if you do not drink enough water, almonds may cause you to develop calcium oxalate stones.
Consider working with your physician or a dietitian who specialises in kidney stone prevention to determine whether it is safe for you to consume almonds.
Conclusion
In this article, we investigated the potential effect of almond consumption on kidney stones and concluded that since almonds are high in oxalate they can raise the risk of forming calcium oxalate stones.
Please note that because almond milk is made of raw almonds, drinking almond milk in excessive amounts may also increase the risk of developing calcium oxalate kidney stones.
If you are prone to developing this type of stone, but at the same time love eating almonds, hearing the fact that almonds can bring on kidney stones may upset you.
However, you shouldn’t forget that you may enjoy eating almonds and other foods high in oxalate with a carefully planned diet. But, this should be determined by your doctor or a dietitian who specialises in a kidney stone diet.
Please discuss with your health care provider what you should and shouldn’t eat to keep kidney stones at bay. By doing so, you can prevent or significantly reduce the risk of kidney stones which can be quite painful.
