What should not be eaten with onions?
Jun 20, 2025
Source: Cainiu Health
Dr. Yu Yongchao
Introduction
Onions are generally not suitable to be consumed with certain foods and medications. Foods that should not be eaten with onions include honey, kelp, fish, shrimp, and soybeans. Medications that may interact with onions include Glibenclamide Tablets, Warfarin Sodium Tablets, Digoxin Tablets, Nifedipine Sustained-Release Tablets, and Clopidogrel Tablets. In daily diet, ingredients should be reasonably combined, and onions should be consumed separately from these foods and medications to avoid simultaneous intake.
Generally speaking, onions are not suitable to be consumed together with foods such as honey, kelp, fish, shrimp, and soybeans. They also should not be taken with medications including glibenclamide tablets, warfarin sodium tablets, digoxin tablets, nifedipine sustained-release tablets, and clopidogrel tablets. Detailed explanations are as follows:
I. Foods
1. Honey: Honey is rich in various sugars and enzymes, while onions contain plant alkaloids and sulfides. When consumed together, the enzymes in honey may chemically react with substances in onions, producing irritants in the gastrointestinal tract. This can affect digestive function and may cause discomfort symptoms such as diarrhea and abdominal pain, harming gastrointestinal health.
2. Kelp: Kelp is rich in minerals such as iodine and calcium. The oxalic acid in onions can combine with calcium in kelp to form calcium oxalate precipitate. This precipitate not only reduces calcium absorption and utilization from food, but long-term excessive consumption may also increase the risk of developing stones, which is detrimental to health.
3. Fish: Fish is rich in high-quality protein and various trace elements. The allyl sulfide in onions can degrade thiamine (vitamin B1) in fish, leading to vitamin B1 deficiency. Vitamin B1 deficiency can interfere with normal body metabolism, reduce the nutritional value of food, and may also cause problems such as neuritis.
4. Shrimp: Shrimp contains abundant nutrients such as protein and calcium, while onions contain significant amounts of tannic acid. Tannic acid can combine with calcium in shrimp to form indigestible substances. Additionally, their combination may produce substances harmful to the human body, affecting health and possibly causing food poisoning symptoms.
5. Soybeans: Soybeans are rich in nutrients such as protein, calcium, and phosphorus. Onions contain large amounts of oxalic acid. Oxalic acid combines with calcium in soybeans to form calcium oxalate, making it difficult for the human body to absorb and utilize the calcium. This reduces the nutritional value of the food and may increase the likelihood of developing stones.
II. Medications
1. Glibenclamide Tablets: Sulfonylurea antidiabetic drugs lower blood glucose by stimulating pancreatic β cells to secrete insulin. Onions themselves have a certain blood sugar-lowering effect. If taken together with sulfonylurea antidiabetic drugs like glibenclamide tablets, the hypoglycemic effects may accumulate, causing excessive lowering of blood sugar and resulting in symptoms such as dizziness, palpitations, cold sweats, and in severe cases, hypoglycemic coma, which can harm health.
2. Warfarin Sodium Tablets: Warfarin sodium is a coumarin oral anticoagulant that exerts anticoagulant effects by inhibiting the synthesis of vitamin K-dependent coagulation factors. Onions contain large amounts of vitamin K, which can antagonize the anticoagulant effect of warfarin sodium, reducing its efficacy, increasing the risk of thrombosis, and possibly causing serious consequences such as cardiovascular and cerebrovascular blockages, which is unfavorable for controlling the patient's condition.
3. Digoxin Tablets: Digoxin is a cardiac glycoside drug commonly used to treat heart failure and certain arrhythmias. The dietary fiber and certain components in onions can affect gastrointestinal absorption of the drug, leading to unstable blood concentrations. This not only makes it difficult to achieve the desired therapeutic effect but may also cause adverse reactions such as nausea, vomiting, and arrhythmias due to abnormal drug concentrations.
4. Nifedipine Sustained-Release Tablets: Nifedipine sustained-release tablets are commonly used to treat hypertension and angina by blocking calcium ion influx, dilating blood vessels, lowering blood pressure, and relieving angina. Onions have vasodilatory and blood pressure-lowering effects. Taking them together with nifedipine sustained-release tablets may cause excessive vasodilation, leading to excessively low blood pressure and symptoms such as dizziness, fatigue, or even fainting, which can be harmful to the body.
5. Clopidogrel Tablets: Clopidogrel is a platelet aggregation inhibitor used to prevent thrombosis. The sulfides in onions also have anti-platelet aggregation effects. Combining the two enhances the antiplatelet effect and increases the risk of bleeding, which may result in symptoms such as nosebleeds, gum bleeding, skin bruising, or even gastrointestinal bleeding, posing a serious threat to the patient's health.
In daily diets, ingredients should be reasonably combined. When consuming onions, try to avoid eating them simultaneously with the above-mentioned foods and medications. Those taking medications or suffering from chronic diseases are advised to consult a doctor or nutritionist to adjust their dietary plans accordingly.
