Cashews aren’t dangerous for most people, but they do have a few properties that can cause real problems in specific situations. At 157 calories per ounce (just 18 nuts), they’re calorie-dense and easy to overeat. They’re also higher in saturated fat than other popular nuts, contain compounds that interfere with mineral absorption, and rank among the highest-oxalate foods you can eat. Whether any of this matters depends on how many you’re eating and what health conditions you’re managing.
They’re Easy to Overeat
A single serving of cashews is about 18 nuts, which fits in the palm of your hand. That small handful contains 157 calories. Most people eat far more than one serving in a sitting, especially when snacking from a large container. Two or three handfuls and you’ve consumed 300 to 500 calories before registering that you’ve eaten much at all.
Cashews also contain more saturated fat than almonds or walnuts, which are both higher in the unsaturated fats typically recommended for heart health. They deliver slightly less protein per ounce too: about 5.2 grams compared to 6 grams in almonds. None of this makes cashews inherently fattening, but the combination of high calorie density, moderate protein, and a flavor that encourages mindless snacking means they can quietly push your daily intake higher than you intended. Salted or honey-roasted varieties make this worse by adding sodium and sugar on top of the existing calorie load.
Oxalate Content and Kidney Stones
Cashews are classified as a very high-oxalate food. One ounce contains about 49 milligrams of oxalate, which is higher than walnuts (31 mg), peanuts (27 mg), and pistachios (14 mg). Only almonds rank higher among common nuts, at 122 mg per ounce.
Oxalates bind with calcium in your body to form crystals. In most people, these pass through without issue. But if you’re prone to calcium-oxalate kidney stones, which are the most common type, regularly eating high-oxalate foods increases your risk. Pairing cashews with calcium-rich foods like milk or yogurt can help, because the calcium binds to oxalate in your digestive tract before it reaches your kidneys. If you’ve had kidney stones before, cashews are one of the foods worth paying attention to.
Digestive Problems for Some People
Cashews are high in FODMAPs, a group of short-chain carbohydrates that ferment in the gut and draw extra water into the intestines. For people with irritable bowel syndrome, this can trigger bloating, gas, cramping, and diarrhea. Cashews and pistachios are the two nuts most commonly flagged as problematic on a low-FODMAP diet.
If you don’t have IBS or a sensitive gut, the FODMAP content in cashews probably won’t bother you. But if you’ve noticed that cashews consistently leave you feeling bloated or uncomfortable, this is likely the reason. Almonds, walnuts, and pecans are generally better tolerated.
Phytic Acid Reduces Mineral Absorption
Like most nuts and seeds, cashews contain phytic acid, a compound that binds to minerals in your digestive tract and prevents your body from absorbing them. The minerals most affected are zinc, iron, and calcium. This doesn’t mean eating cashews depletes your mineral stores. It means that the iron and zinc present in the cashews themselves, and in other foods you eat at the same meal, won’t be fully absorbed.
For people eating a varied diet with plenty of mineral sources, this is a minor issue. It becomes more relevant if you rely heavily on plant-based foods for your iron and zinc, since plant sources are already less bioavailable than animal sources. Soaking raw cashews in water for several hours before eating or cooking with them breaks down some of the phytic acid and improves mineral availability. Roasting has a similar, though smaller, effect.
Cashew Allergies Can Be Severe
Cashew allergy is a tree nut allergy, and it’s more common than many people realize. Research from the American Academy of Allergy, Asthma & Immunology found that nearly 1.5% of 12-month-old infants tested positive for cashew allergy. Reactions can range from mild hives to full anaphylaxis, and cashew allergies tend to persist into adulthood rather than being outgrown.
Cashews belong to the same botanical family as poison ivy and mangoes. The shells contain urushiol, the same oily compound that causes the rash from poison ivy. This is why you never see cashews sold in their shells the way you’d buy pistachios or walnuts. The urushiol is concentrated in the shell and the liquid surrounding it, not in the nut itself. By the time cashews reach store shelves, they’ve been steamed or roasted to remove the shell and neutralize any residual irritant. Workers who process cashews, however, face significant skin irritation from handling the shells.
Aflatoxin Risk Is Low
Some nuts are susceptible to mold contamination that produces aflatoxins, a group of compounds that are toxic to the liver and classified as carcinogenic with long-term exposure. Cashews are sometimes lumped into this concern, but testing data from the Canadian Food Inspection Agency found no detectable aflatoxin levels in cashew products. Peanuts and certain other nuts carry a higher practical risk. Proper storage in a cool, dry place keeps mold risk minimal.
How Much Is Too Much
One ounce per day, roughly 18 cashews, is the commonly cited amount that lets you benefit from the nutrients (copper, magnesium, healthy fats) without running into calorie or oxalate problems. Going beyond that occasionally is fine for most people, but making it a daily habit can add up. Choosing raw or dry-roasted unsalted cashews over fried or flavored varieties cuts out unnecessary sodium and added fat. If you’re watching your weight, measuring out a serving rather than eating from the bag makes a real difference.