Peanut butter is a staple in most homes, and there’s a good reason why. It’s tasty, filling, and versatile. You can spread it on toast, add it to smoothies, or eat it straight from the jar with a spoon (we’ve all been there!). But what if that creamy treat is hiding something harmful? Research shows that peanut butter can sometimes contain a dangerous substance called aflatoxin – a type of mold that grows on peanuts. This isn’t just a minor issue – it can cause serious health problems if you eat too much of it. Let’s talk about how to spot this problem and what to do if you notice something’s wrong with your peanut butter.
What is aflatoxin and why is it dangerous
Aflatoxin is a type of mold that grows on peanuts when they’re stored in warm, moist conditions. You can’t always see it, which makes it extra sneaky. Peanuts are more likely to have this problem because they grow underground in humid places. When peanuts get turned into peanut butter, the aflatoxin doesn’t just disappear – it can stay in the final product. If you eat too much of this mold over time, it can harm your body, especially your liver and brain.
What makes aflatoxin so concerning is its potential to affect your nervous system. According to Dr. Becky Campbell, “mycotoxins can be harmful to all systems of the body, especially our neurological system.” In high amounts, this toxin can cause problems like feeling tired all the time, trouble focusing, feeling down, and in very rare cases, it might even be linked to more serious brain conditions. While most store-bought peanut butter in the US is tested for aflatoxin levels, it’s still good to know what to look for.
Unusual smell or taste means throw it away
The first and most obvious sign that your peanut butter might have gone bad is a strange smell or taste. Fresh peanut butter should smell nutty and pleasant. If you open your jar and get a whiff of something sour, bitter, or just “off,” that’s a big red flag. The same goes for taste – if your peanut butter tastes weird in any way, don’t keep eating it. Trust your senses! They’re designed to help you avoid things that might make you sick. Even if the peanut butter looks normal, an off smell or taste is your body’s way of warning you.
Another warning sign is if your peanut butter tastes strangely bitter. Natural peanut butter can have a slight bitterness, but it shouldn’t be unpleasant. If you notice an unusually bitter or sour taste, this could be a sign that the oils in the peanut butter have gone rancid, or worse, that there’s mold growth including potential aflatoxin contamination. Don’t take chances with your health – if your peanut butter doesn’t taste right, it’s safer to throw it away and get a new jar than to risk eating something that could make you sick.
Weird color changes or visible mold
Visual changes in your peanut butter are another clear sign that something’s not right. Normal peanut butter should be a consistent tan or light brown color throughout. If you see any strange discoloration – like dark spots, green or blue-ish areas, or white fuzzy patches – that’s definitely mold, and you should throw the whole jar away immediately. Don’t try to scoop around the moldy parts! Mold can spread invisible “roots” throughout food even if you can’t see them, and some types of mold produce harmful toxins.
Sometimes the changes aren’t as obvious as visible mold. You might notice that your peanut butter has darkened significantly or developed an unusual sheen on the surface. While natural peanut butter will have oil separation (that’s normal), any significant change in color or texture could indicate that the fats in the peanut butter have oxidized or that other chemical changes have occurred. A 2022 study found that many peanut butter samples contained mycotoxins, with some exceeding the maximum allowed levels. When in doubt, it’s better to be safe than sorry – toss it out and get a fresh jar.
Unusual stomach issues after eating
Pay attention to how your body feels after eating peanut butter. If you often get a stomach ache, feel bloated, or have digestive problems after having peanut butter, this could be your body trying to tell you something. While some of these symptoms might just be from the high fat content (peanut butter is pretty rich), they could also be signs that something’s wrong with the peanut butter itself. If you notice these symptoms consistently after eating from the same jar, it might be contaminated with mold or bacteria.
Other symptoms to watch for include nausea, vomiting, or diarrhea shortly after eating peanut butter. These are your body’s way of trying to get rid of something it thinks is harmful. While these could also be signs of a peanut allergy (if you’ve never had one before), they might also indicate food poisoning from contaminated peanut butter. According to nutrition expert Gillean Barkyoumb, “Eating too much of anything can give you a stomach ache,” but consistent problems after eating peanut butter specifically could be a warning sign of contamination or sensitivity. Don’t ignore what your body is telling you.
Signs of an expired jar
Always check the expiration date on your peanut butter jar. While peanut butter has a pretty long shelf life (usually 6-9 months unopened, or 2-3 months after opening), it doesn’t last forever. If the date has passed, be extra careful about checking for the other signs we’ve talked about. Even if the peanut butter looks and smells fine, the oils can go rancid over time. Rancid oils don’t just taste bad – they can cause stomach upset and aren’t good for your health in the long run.
Another sign that your peanut butter jar might be past its prime is excessive oil separation or an unusually dry, hard texture. While some separation is normal in natural peanut butter (just stir it back in), extreme separation or changes in texture can indicate that the peanut butter has degraded. Exposure to heat, light, and air speeds up the process of oils going rancid. For best quality, store your peanut butter in a cool, dark place, and consider keeping natural peanut butter (the kind with just peanuts and salt) in the refrigerator after opening. This can help prevent both rancidity and potential mold growth.
How to choose safer peanut butter
Not all peanut butter is created equal when it comes to aflatoxin risk. To reduce your chances of getting a contaminated jar, buy peanut butter from well-known brands that follow strict testing standards. The Food and Drug Administration (FDA) regulates aflatoxin levels in peanut products in the United States, so sticking with established brands is generally safer. Smaller, unregulated brands or homemade peanut butter might have higher risks, as they may not test for aflatoxins as rigorously.
Looking at the ingredients list can also help you choose safer peanut butter. The best options are those with minimal ingredients – ideally just peanuts and maybe a little salt. As nutrition expert Marysa Cardwell advises, “Buy peanut butter with only a little bit of salt and avoid ones with more than three ingredients.” Additionally, peanut butter grown closer to the US tends to have lower aflatoxin levels. Some natural food stores also carry brands that specifically test for and advertise low aflatoxin levels, which might be worth considering if you eat peanut butter regularly or give it to children, who can be more sensitive to toxins.
Proper storage matters a lot
How you store your peanut butter makes a big difference in keeping it safe. Once you open a jar, bacteria and mold can start to grow if you’re not careful. Always use clean utensils when scooping out peanut butter – never lick the knife and then dip it back in the jar! This introduces bacteria from your mouth into the peanut butter. Keep the rim of the jar clean too, as dried peanut butter bits around the edge can grow mold that can spread to the rest of the jar.
Temperature and light also affect peanut butter quality and safety. Store unopened jars in a cool, dark pantry away from heat sources like your stove or sunny windows. Heat speeds up oil rancidity and creates better conditions for mold growth. For natural peanut butter without preservatives, consider keeping it in the refrigerator after opening, especially in warm, humid climates. While this might make it harder to spread, you can let it sit out for 15 minutes before using it, and proper storage will extend its shelf life and reduce the risk of contamination.
Alternatives if you’re concerned
If you’re worried about aflatoxins in peanut butter but still want that creamy, nutty goodness in your life, you have options! Other nut and seed butters like almond butter, cashew butter, or sunflower seed butter make great alternatives. These are less likely to have aflatoxin issues because the nuts grow on trees rather than underground. Each has its own unique taste and nutrition profile, but they can be used just like peanut butter in most recipes. Sunflower seed butter is a good choice for people with nut allergies too.
If you really love peanut butter and don’t want to switch, consider brands that use Valencia peanuts, which are grown in drier conditions and tend to have lower aflatoxin levels. Some companies also use special processing techniques to reduce aflatoxin content. Another option is to make your own peanut butter using roasted peanuts, as the roasting process can reduce aflatoxin levels. However, homemade peanut butter won’t last as long as store-bought versions, so make smaller batches and keep them in the refrigerator. Rotating between different nut butters is also a good strategy – variety in your diet is always a smart move.
Peanut butter can be a healthy, delicious part of your diet when it’s fresh and properly stored. But it’s important to be aware of the potential risks, especially from mold like aflatoxin. By knowing what warning signs to look for and taking simple steps to choose and store your peanut butter safely, you can enjoy your favorite spread without worry. Remember – your health is worth more than an iffy jar of peanut butter, so when in doubt, throw it out!
