But can vegetables like onions actually help regulate your blood sugar levels? Do onions, in particular, have any other health benefits for people with diabetes?
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Here, learn how you can eat onions to lower blood sugar, and other onion benefits.
Nutrition Content of Onions
Before we dive into onions' effect on blood sugar, we should know a bit about their nutrient content.
1 Cup Sliced Onions
Can Onions Lower Blood Sugar?
If you're looking for ways to lower blood sugar, incorporating more low-carb veggies like onions into your diet may help. Onions have a low glycemic index (GI) of 15, which is helpful for people with diabetes, per Glycemic-Index.
Examples of other low-GI vegetables include: leafy greens, raw carrots, kidney beans, chickpeas and lentils, per the Mayo Clinic.
While there isn't much current research surrounding blood sugar-regulation and onions, there are a few older studies that draw some possible links between the two.
In particular, one older October 2014 review in Nutrition mentions that sulfur compounds found in onions, (namely S-methylcysteine and the flavonoid quercetin) may be responsible for the vegetable's hypoglycemic effect.
The review also mentions that, in clinical trials, people with diabetes experienced blood sugar-lowering effects after eating onion slices.
Keep in mind, though, that more research is needed in order to determine these connections. Always talk to your doctor before trying at-home remedies to regulate blood sugar.
Can You Use Onion Extract to Lower Blood Sugar?
Onion extract is made from the juices of an onion and can be used in cooking, similar to onion powder. There is limited research to suggest that onion extract is beneficial for lowering blood sugar. However, the above Nutrition study mentions that onion extract could have a small hypoglycemic effect by stabilizing the process of glycolysis (breaking down glucose).
Another small study on rats found that onion powder may be protective against high blood sugar due to diabetes, according to a July-August 2020 article in the Avicenna Journal of Phytomedicine. However, these study findings can't necessarily be extended to humans.
Other Benefits of Onions
Besides possibly helping with blood sugar, there are some other health benefits of onions that are worth noting. These include:
1. They May Help Reduce InflammationSome Evidence
Onions are chock-full of nutritious antioxidants and vitamins that can help reduce levels of inflammation throughout the body. Per the Cleveland Clinic, they contain about 25 different flavonoids, a type of antioxidant that's helpful in warding off disease.
One flavonoid, called quercetin, offers heart-healthy benefits and can help fight obesity and metabolic syndrome, along with high blood pressure and cholesterol, per the Cleveland Clinic.
Red onions, in particular, have health benefits because of their anthocyanin content. Anthocyanins are antioxidants that give red onions their purple-reddish color. So when you're cooking with red onions, try to keep as much of the vegetable with the coloring as possible to reap the benefits, per the Cleveland Clinic.
2. They Can Help Support a Healthy GutSome Evidence
While onions can be a trigger for people with irritable bowel syndrome (IBS) — causing gas, bloating and occasional diarrhea — they can be beneficial in other instances due to their prebiotic content, per UMass Chan Medical School.
Prebiotics serve as "food" for the good bacteria in your gut, helping them to grow and thrive, per the Mayo Clinic.
Onions are a sufficient source of prebiotics and fiber, but they may be better digested and offer more benefits for your digestive system when cooked, per the Cleveland Clinic.
Eating onions could be part of a healthy diet that helps reduce your risk of certain cancers. In fact, a small October 2019 study in Asia-Pacific Journal of Oncology found that eating allium vegetables (i.e., onions) is associated with a reduced risk of colorectal cancer.
And according to the Cleveland Clinic, eating a diet rich in onions may also help reduce your risk of other cancers, including bladder cancer and stomach cancer.
Keep in mind, though, that this does not mean eating onions alone will prevent or cure cancer.
Especially for older adults, eating onions or drinking onion tea may help support good bone health, per the Cleveland Clinic.
In fact, one February 2016 study in Food & Function found that middle-age and postmenopausal people who drank 3 ounces of onion juice every day for eight weeks had mildly improved bone mineral density. The study authors conclude that drinking onion juice could be recommended to help treat bone-related disorders like osteoporosis.
So if you want to reap onion water benefits or onion tea benefits, try making it yourself at home.
How to Make Onion Tea at Home
- Wash and cut half an onion and five slices of ginger
- Put the onion into a teapot (optional: add five slices of ginger and some green tea leaves).
- Pour boiling water into the pot and allow the tea to steep for three to four minutes.
- Strain and enjoy.
Tips for Adding Onions to Your Diet
While the research is not solid on whether onions can lower your blood sugar, they are a low-calorie, low-glycemic, non-starchy food, which can be helpful for people with diabetes.
A few ways to incorporate onions into your diet include:
- Slicing raw onions to add to sandwiches or salads
- Grilling or roasting onion slices to add to a meal
- Dicing or sautéeing them with peppers as a side dish or topping
- Turning them into a relish to add to dishes
- Pack more onions into existing recipes — especially for soups, chilis and stews — to add more volume (and fiber) without much increase in carbs or calories
How Much Onion Should You Eat per Day?
The American Diabetes Association recommends eating at least three to five servings of non-starchy vegetables, such as onions, per day, where one serving is equal to one-half cup cooked or 1 cup raw.
If you're eating more than 1 cup cooked or 2 cups of raw onions at a meal, and you're counting carbs to control blood sugar, you may need to count those servings towards your total carb intake for that meal. For example, 2 cups of raw sliced onions would count as about 20 grams of carbs.
Other Tips for Regulating Your Blood Sugar
There are many different things you can do at home to manage high blood sugar, per the Centers for Disease Control and Prevention (CDC):
- Get regular exercise
- Take your medicine as instructed
- Follow your diabetes meal plan, prioritizing fruits and veggies along with foods lower in calories, saturated fat, trans fat, sugar and salt (see your doctor or a registered dietitian if you need more guidance)
- Stick to a regular eating schedule and don't skip meals
- Limit alcohol
- Check your blood sugar as directed by your doctor, and take note of what makes your levels go up or down
- Talk to your doctor about adjusting your insulin dose
When to See a Doctor About Your Blood Sugar
If you check your blood glucose level and it's consistently too high (above 240 mg/dL), per the Mayo Clinic, call your doctor to discuss whether you need to make changes to your medication plan.
While there isn't a lot of research showing onions' role in regulating blood sugar, they are a low-glycemic food and contain sulfur compounds, which could have a blood sugar-lowering effect.
On top of that, onions contain healthy antioxidants that can help reduce your risk of disease.
If you're unsure about whether you should incorporate onions into your diet to help manage your blood sugar, talk to your doctor or a registered dietitian. They can help you come up with a diabetes diet plan and suggest other blood sugar-regulating foods.
- Avicenna Journal of Phytomedicine: "The effects of onion (Allium cepa L.) dried by different heat treatments on plasma lipid profile and fasting blood glucose level in diabetic rats"
- USDA: "Onions, raw"
- Glycemic-Index: "Onion (fresh)"
- Nutrition: "Spice plant Allium cepa: dietary supplement for treatment of type 2 diabetes mellitus"
- Asia-Pacific Journal of Oncology: "Allium vegetables are associated with reduced risk of colorectal cancer: A hospital-based matched case-control study in China"
- Cleveland Clinic: "Stop the Tears: Why Onions Are Good for You"
- Food & Function: "Consumption of onion juice modulates oxidative stress and attenuates the risk of bone disorders in middle-aged and post-menopausal healthy subjects"
- UMass Chan Medical School: "Prebiotics: what, where, and how to get them"
- Mayo Clinic: "What are probiotics and prebiotics?"
- Journal of Food and Drug Analysis: "Systematic study on active compounds as antibacterial and antibiofilm agent in aging onions"
- CDC: "Manage Blood Sugar"
- American Diabetes Association: "Non-starchy Vegetables"
- Mount Sinai: "Sulfur Information"
- Mayo Clinic: "Hyperglycemia in Diabetes"
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