PEANUTS: What Happens to Your KIDNEYS When You Eat Them

Right now, somewhere in your kitchen, there's probably a jar of peanut butter with a few knife marks on the surface, or a bag of roasted peanuts clipped shut, sitting next to the coffee maker. You grab a handful without thinking. It feels like the most innocent snack in the house. But over the next few hours, that handful is going to be taken apart piece by piece inside your body. And some of what's left will travel straight to your kidneys, waiting in line to be filtered. So let's follow that handful from the first bite to the tiny filters inside your kidneys. Stay with me until the end, because I'm going to show you three things. First, why the phosphorus in peanuts plays by completely different rules than the phosphorus in a can of cola. Second, what the salt on game day peanuts quietly does to the one real advantage peanuts have. And third, the mistake almost everyone makes with the peanut butter jar, which has nothing to do with the peanuts themselves. Let's start with a detail most people get wrong. A peanut isn't really a nut. It's a legume, from the same family as beans, peas and lentils. And legumes store their minerals in a very particular way. Hold on to that, because it comes back in a few minutes. The journey begins with your teeth. Chewing breaks open the tiny cells that hold the peanuts' fat, protein and minerals. In the stomach, acid and enzymes start on the protein, while the fat slows everything down. That's why a small handful of peanuts keeps you full A full longer than a handful of crackers. In your small intestine, bile breaks the fat into smaller droplets and enzymes cut the protein into amino acids. This is where the minerals get released. Phosphorus, potassium, and magnesium. At the same time, the fiber in peanuts, about 2 grams in a small handful, moves along slowly. Think of it as a natural break. It keeps the flow into your bloodstream steady instead of rushing in. Whatever gets through your intestine enters your blood. And here's a number that puts your kidneys in perspective. Every minute, roughly a fifth of all the blood your heart pumps goes straight to them. Over a day, they filter around 50 gallons of fluid out of your blood. So what exactly is arriving? One ounce of dry roasted peanuts, about 28 grams, is roughly what fits in the palm of your hand. That ounce carries about 100 milligrams of phosphorus and around 185 milligrams of potassium. It also brings about 50 milligrams of magnesium and close to 7 grams of protein. Is that a lot? An ounce of almonds has a bit more phosphorus, around 135 milligrams, and more potassium too. An ounce of pistachios lands near 300 milligrams of potassium, much higher than peanuts. So peanuts sit right in the middle of the pack. Inside each kidney there are around a million microscopic filters called nephrons. Each one works like a tiny strainer attached to a long winding tube. The strainer lets water, salts and minerals out of the blood. Then the tube takes back whatever your body still needs and sends the rest out in your urine. Extra phosphorus? Healthy nephrons simply let it go. The trouble starts when the filters lose capacity. Phosphorus builds up in the blood and over time it can pull calcium out of the bones and help stiffen your blood vessels. Your body fights back with hormones that push the kidneys harder, which is extra effort for filters already struggling. And here's what almost nobody knows. Not all phosphorus is absorbed the same way. Remember that peanuts are legumes. Legumes and seeds store most of their phosphorus locked inside a compound called phytic acid. Your body doesn't make much of the enzyme needed to break that lock open, so a good part of the phosphorus in peanuts simply passes through your gut and leaves without ever reaching your blood. Estimates vary, but from plant foods like this your body often absorbs only around half. If you had no idea your body leaves part of the phosphorus in peanuts behind, hit like so more people get to see this. It helps the channel more than you'd think. Now compare that with a can of cola, because this is where peanuts and soda part ways. Many colas list phosphoric acid in the ingredients. That's phosphorus added by the factory, with nothing locking it up. Your intestine absorbs it almost completely, often estimated at around 90% or more. The same goes for phosphate additives in many processed meats and frozen meals. On an American label, they show up by name. Look for the letters POS in the ingredient list. Phosphoric acid. Sodium phosphate. Disodium phosphate. So that's the first thing I promised you. Two foods can show a similar number of milligrams, and your kidneys still end up seeing very different amounts. So, is there real science behind this? Or is it just a nice theory? Let me show you one study that tested it directly in people. It was published in 2011 in a journal of the American Society of Nephrology. Researchers took nine adults with moderate to advanced kidney disease Each person spent one week eating a vegetarian diet, built on grains and soy, and another week eating a diet based on meat and dairy. On paper, both diets had a similar amount of phosphorus. After the vegetarian week, the level of phosphorus in their blood was lower, so was the hormone the body releases when phosphorus starts piling up. That fits exactly with what we just saw about phytic acid. Plant phosphorus seems to reach the blood in smaller amounts Now, for the honest part, because this channel doesn't skip it, only 8 of the 9 people finished both weeks. One week per diet is very short. And this study looked at whole diets, not peanuts specifically. Not every measurement confirmed the effect either. The phosphorus in their urine was lower on the vegetarian week, but that difference wasn't statistically clear. So keep this number in mind. About 100 mg of phosphorus per ounce of peanuts is what the label suggests. But your body may only keep around half of it. We'll come back to it at the very end. Peanuts do bring something good, too. Large observational studies have linked regular nut and peanut eating with lower rates of heart disease. That's an association, not proof, because people who eat nuts every day may also move more or smoke less. Still, there's a reasonable mechanism. The magnesium in peanuts helps your blood vessels relax. And relaxed vessels mean steadier blood pressure. That matters, because high blood pressure is one of the leading causes of kidney disease in this country. If you're new here, subscribe. Every week I take one everyday food from the American kitchen and follow it all the way to your kidneys. Just like this. Now back to that blood pressure benefit, because there's a catch. And it's sitting on the outside of the peanut. One ounce of plain dry roasted peanuts has almost no sodium, just a couple of milligrams. The salted version of that same ounce has around 230 milligrams. On the Nutrition Facts label, look at the line that says sodium and the percent daily value next to it. 230 milligrams is about 10% of the daily limit of 2,300. If you want to turn sodium into salt, multiply by two and a half. Picture a hypothetical example. Robert is 64, and every Sunday he watches the game on television with a bowl of salted peanuts. Over three hours he goes back for four or five handfuls. That's around a thousand milligrams of sodium, close to half his daily limit, before the wings and the chips even arrive. And that's the second thing I promised. All that sodium pulls water into the blood, raises the pressure inside the vessels, and makes those tiny filters work harder. The one real advantage peanuts have, their gentle effect on blood pressure, gets cancelled out by what's stuck to the shell. And unlike the plant phosphorus, sodium doesn't come with a lock. Your body absorbs almost all of it. Now let's open that jar of peanut butter, because this is where the third mistake lives. The label serving is two tablespoons, about 32 grams. That serving has roughly 100 milligrams of phosphorus and close to 180 milligrams of potassium, very similar to an ounce of peanuts. Salted brands usually add between 100 and 150 milligrams of sodium per serving. It varies a lot by brand. The mistake almost nobody notices is the spoon. You scoop it with a knife, you lick the spoon, you spread a thick layer on a bagel. A heaping tablespoon can easily hold twice as much as a level one. So what you think is one serving is often two, sometimes three. Try this once. Measure two level tablespoons, put them on a plate, and look at them. That's roughly the size of a ping pong ball. It looks smaller than you'd expect. The second thing in the jar is everything that isn't peanuts. Turn it around and read the ingredient list. The simplest versions say peanuts and maybe salt. Many popular brands add sugar and hydrogenated oil, so the jar never needs stirring. And the reduced fat versions are a classic trap. They often replace some of the peanuts with sugar and fillers, so you get less of the good part. One quick myth while we're here. Some people avoid peanuts because they've heard protein overloads the kidneys. For adults with healthy kidneys, the protein in a handful of peanuts is not a concern. So, in practice, what do you do with all of this? If your kidneys are healthy, here's a simple approach. First, keep peanuts to about one ounce a day, the amount that fits in your palm. Pour it into a small bowl, not straight from the bag. Second, choose unsalted or lightly salted peanuts. If you love the salty taste, mix half-salted and half-unsalted, and your tongue will barely notice. Third, measure your peanut butter for one week, two level tablespoons at most, until your eye learns what a real serving looks like. And pick a jar where the ingredient list is just peanuts, or peanuts and salt. Fourth, keep an eye on the company Peanuts Keep. A handful of peanuts with an apple is a very different snack from a handful of salted peanuts with a large cola. Tell me in the comments, are you a salted peanut person or did you already switch to unsalted? This next part is for anyone who needs to be extra careful. Maybe it's you or someone you love. If you have advanced chronic kidney disease or you're on dialysis, phosphorus and potassium are no longer just numbers on a label. Your kidneys can't clear them the way they used to and peanuts and peanut butter often show up on the lists of foods to limit. Whether you can eat them how much and how often depends on your stage and on your lab results. That's a decision for your nephrologist or your renal dietitian, not for a general video like this one. The same goes for protein. Your care team sets that number, and it's different before and during dialysis. Some blood pressure and heart medications make your body hold on to potassium. If you take one, talk to your doctor before adding more potassium-rich foods. And please, never stop or change a medication on your own because of something you heard in a video. If you've had kidney stones, especially calcium oxalate stones, know that peanuts and peanut butter contain a moderate amount of oxalate. It's worth asking your doctor or dietician how they fit into your plan. And if you live with gout, peanuts aren't among the highest purine foods. Still, if your doctor gave you a specific plan, that plan comes first. Let's go back to the number I asked you to keep in mind, about 100 milligrams of phosphorus per ounce, with your body keeping only around half. Now set that next to the sodium, the 230 milligrams of sodium on a salted ounce. Your body absorbs nearly every last bit of it, so the part of the peanut people worry about most is partly left behind in your gut, and the part nobody thinks about, the salt on the shell, goes straight through to your kidneys. Before this video you probably saw peanuts as either a health food or a fatty snack, and the peanut butter spoon as just a spoon. Now you know the peanut is a legume that locks away part of its own phosphorus, you know the cola next to it doesn't play by the same rules, and you know the real decisions happen If this changed the way you look at the peanut jar, leave a like. in the salt shaker Share this video with someone and in the size of that spoon. who eats peanuts by the handful while watching the game, because they'll want to hear this. Subscribe and turn on notifications so you don't miss the next food we follow through your body. And tell me in the comments which food in your pantry you want me to break down next. Right here on the screen, you'll find another video from our Nuts series waiting for you.