Beetroot is widely considered a healthy food, but it does come with a handful of side effects worth knowing about. Most are harmless and temporary, like a startling change in urine color. Others, like digestive discomfort or interactions with blood pressure, matter more depending on your health history. Here’s what to expect.
Red or Pink Urine (Beeturia)
The most common and most alarming side effect of eating beetroot is harmless: your urine or stool turns red or pink. This is called beeturia, and it happens in roughly 10% to 14% of the general population. The color comes from a family of pigments called betacyanins, which pass through your digestive system and, in some people, get absorbed into the bloodstream and filtered out through the kidneys.
Whether you experience beeturia depends largely on what’s happening in your gut. The pigments are broken down by stomach acid and bacteria in the intestines, so people with lower stomach acidity or faster digestion are more likely to see the color change. Iron deficiency plays a significant role too. In people with pernicious anemia, the rate of beeturia jumps to about 45%, likely because the gut absorbs more of the pigment when it’s working harder to pull in iron.
The discoloration can also show up in stool, sometimes making it look dark or tarry. If you’ve recently eaten beets, this is almost certainly the cause. But if you haven’t, dark stool can signal internal bleeding, so it’s worth paying attention to what you’ve eaten before worrying.
Digestive Symptoms
Beetroot contains fructans, a type of short-chain carbohydrate that the human body struggles to digest. Only about 5% to 15% of fructans are absorbed in the small intestine. The rest travel to the large intestine, where gut bacteria ferment them and produce gas. Fructans also draw extra water into the intestine, which can trigger bloating, cramping, and diarrhea.
For most people, this causes mild or no symptoms. But if you have irritable bowel syndrome, the effect can be much more noticeable. An estimated 24% of people with IBS are sensitive to fructans specifically, and beetroot is one of the higher-fructan foods. In clinical practice, restricting fructans and similar fermentable carbohydrates (collectively known as FODMAPs) has been shown to reduce symptoms in IBS patients. If you notice that beets consistently cause gas, bloating, or loose stools, fructan sensitivity is the likely explanation.
Blood Pressure Effects
Beetroot is rich in dietary nitrate, which your body converts into nitric oxide, a molecule that relaxes and widens blood vessels. This is the reason beetroot juice is popular among athletes and people looking to lower blood pressure naturally. But if your blood pressure is already on the lower side, or you’re taking medication to reduce it, the added drop can become a problem.
Symptoms of blood pressure falling too low include lightheadedness, dizziness, and headache. In clinical studies testing beetroot juice, participants have reported brief headaches after drinking nitrate-rich beet juice. These effects are typically mild and short-lived, but they’re worth watching for if you drink beet juice regularly or in large amounts. Doses used in studies generally range from 70 to 140 mL (about a quarter to a half cup) of juice per day.
The interaction becomes more serious if you take certain medications. Drugs prescribed for chest pain, like nitroglycerin and other nitrate-based heart medications, work through the same nitric oxide pathway. Combining them with a high-nitrate food like beetroot can cause a dangerous drop in blood pressure. The same applies to medications for erectile dysfunction, which amplify the blood pressure-lowering effects of nitric oxide donors. If you take either type of medication, the combination with concentrated beetroot juice is worth discussing with your prescriber.
Oxalates and Kidney Stone Risk
Beetroot is a high-oxalate food, containing roughly 870 mg of oxalate per 100 grams. Oxalates are naturally occurring compounds found in many plants, and in most people they pass through the body without issue. But in people prone to calcium oxalate kidney stones (the most common type), a high-oxalate diet can increase the risk of new stones forming. The oxalate binds with calcium in the kidneys and crystallizes.
If you’ve had kidney stones before, or if you have existing kidney disease, limiting high-oxalate foods like beetroot is a standard dietary recommendation. For everyone else, the oxalate content of beets eaten in normal amounts isn’t a practical concern. Drinking plenty of water and eating calcium-rich foods at the same meal (which binds oxalate in the gut before it reaches the kidneys) both help reduce risk.
Effects on Mineral Absorption
There’s a longstanding belief among nutritionists that the oxalates in beetroot block absorption of iron and calcium from other foods in the same meal. The calcium concern has some basis: oxalate does bind calcium in the gut, reducing how much your body absorbs. This is relevant if you’re relying on a beet-heavy meal as a calcium source, but it’s unlikely to matter in the context of a varied diet.
The iron story is more nuanced than commonly assumed. Research examining actual absorption rates found that iron uptake from beetroot itself is quite good, despite its oxalate content. This appears to be because beetroot also contains citric acid and vitamin C, both of which promote iron absorption and offset the oxalate. The same isn’t true of beetroot greens (the leafy tops), which are high in polyphenols that do inhibit iron uptake. So the root and the leaves behave quite differently when it comes to mineral availability.
How Much Is Too Much
There’s no established upper limit for beetroot intake, and beet juice in amounts up to 140 mL daily has been used safely in studies lasting several weeks. The concern with very large amounts centers on the cumulative oxalate load and the potential for low calcium levels, though these effects haven’t been documented in otherwise healthy people eating normal food quantities.
For most people, a serving of roasted beets or a small glass of beet juice causes no problems at all. The side effects that do occur tend to be dose-dependent: more beet juice means more nitrate (and a bigger blood pressure drop), more oxalate, and more fructans reaching the gut. Starting with smaller amounts and increasing gradually is a practical way to see how your body responds, especially if you have IBS, low blood pressure, or a history of kidney stones.