Onions have been used in food for more than 3,000 years, and the vegetable was one of the earliest plants to be cultivated. Yet, many people do not realize that nutritional values that are associated with onions, particularly when it comes to red onions nutritional benefits.
In fact, many people assume that red and white onions are essentially the same, or that the only difference between these two types of onion is their taste.
That isn’t true though, and red onions are a valuable and healthy addition to any kitchen. In fact, they offer more health benefits than white onions and they are a good way to add variety to your meals.
Additionally, red onion can make a tasty addition to food and is easy to include in the diet, even for people who don’t particularly like the taste. Onions also have the benefit of being exceptionally easy to store and transport.
Red Onion Nutrition Facts
Nutritionally, red onions are a low calorie food, where most of the calories (90%) are from carbs. In contrast, red onions aren’t a good source of the macronutrients protein or fat. On average, a large onion has 63 calories, 2 grams of fiber and 6.5 grams of sugar (1), so they are easily included in most diet types.
The carb count does mean that you have to be careful of red (and white) onions if you are following a low-carb diet. However, with enough planning, they could still easily be included.
Onions are also a low glycemic index (GI) food, with a GI rating of 10 (2). Even though onions are mostly used as an ingredient, this low GI is still relevant for reducing blood sugar spikes – making onions particularly relevant for anyone with diabetes.
As a general rule, red onions are fairly low in nutrients. However, they can be a key source of a few important compounds, including vitamin B6 and vitamin C. Both of these vitamins are important to human health.
Additionally, red onions do have a fairly high level of chromium. This is a trace mineral that has been positively associated with control of glucose levels.
This can make consumption of red onion particularly important for people who have problems with glucose control.
People who eat foods low in chromium can sometimes suffer from chromium deficiency, although the condition is rare (3). This has multiple possible consequences, including potentially impairing control of blood sugar, and increasing the risk of type 2 diabetes as well as cardiovascular disease.
There are even some indications that a high level of chromium deficiency may act to make weight loss significantly more challenging. Nevertheless, chromium is only significant for weight loss if you are deficient – if you’re not, it’s unlikely to do much (4).
The biggest nutritional difference between red and white onions is their colors.
The red coloration comes from a group of compounds called anthocyanins. Anthocyanins are pigment compounds and are responsible for blue, purple and red pigmentation in plants. They are also a prominent type of flavonoid.
While flavonoids are challenging to study, but at the same time, they offer considerable potential for human health (5,6). One issue with the compounds is that they are relatively unstable, which makes them difficult to isolate and to purify.
Nevertheless, there is enough evidence to suggest that they can improve health (7).
This is a key reason that getting anthocyanins through food, such as from red onions, is so important (8). Consuming a range of food colors is also important, as the various compounds have their own specific impacts on health.
Another significant flavonoid present in red onions is quercetin, which is a highly effective antioxidant, helping to reverse many of the damaging impacts that can be caused by free radicals (9). For that matter, other plant-based compounds in red onions also have an antioxidant role (10).
Antioxidants have been linked to significant health benefits, particularly as free radical activity is associated with some of the negative elements of aging (11). There are many different foods and compounds that have some degree of antioxidant activity, but the antioxidant levels of red onions are especially significant (12).
What’s more, getting a variety of different antioxidants from the diet may be the best way to take advantage of all the benefits antioxidants provide. For example, this includes options like tart cherry juice, pomegranate and blueberries.
Quercetin itself is also a key focus of research into red onions and may play a role in many of the observed health benefits (13). For example, animal research suggests that this compound may decrease inflammation markers (14).
Another key area to consider is allicin in onions. This compound one of the reasons why raw onions offer significant health benefits and allicin has antimicrobial properties.
Red Onion Research
Traditional medicine has also involved the use of red onion in combating gastrointestinal issues, suggesting that the compounds in the vegetable may help with stomach issues (16).
Recent research has also focused on the role that red onion may play in the treatment of type I and type II diabetes, including improvements to insulin sensitivity and glucose tolerance (17).
One study considered the outcome of red onion supplementation on people with each type of diabetes. The study found that red onion was able to produce hypoglycemic effects, meaning that red onion may be an effective supplement for the management of diabetes (18).
The flavonoids in red onions have been strongly linked to a number of substantial health benefits. This includes a reduction in the risk of cardiovascular disease as well as some types of cancer (19).
Likewise, there has been considerable evidence that red onion extracts have antimicrobial properties (20), which suggests that red onion may help the immune system. This has important implications in our busy and stressful modern environment where our immune system is often strained and it can be easy to get sick.
The chemicals in red onions have also been associated with an antimutagenic action. This term refers to the ability to limit the occurrence of mutations. This provides the compounds with the ability to reduce the risk of cancer (21). Indeed, some research into red onions suggests that they can help stop cancer cells from multiplying (22).
Researchers have suggested that foods containing flavonoids may be a novel strategy for preventing cancer within the population (23).
As the prevalence of cancer continues to increase and the disease remains challenging to combat, any approach that can help to reduce the risk of cancer is certainly worth trying.
This strategy has significant benefits, particularly as red onions and other foods containing flavonoids are so widely available.
Red onions are particularly relevant to this discussion because they do contain a significant amount of flavonoids (24).
Red Onion Storage and Preparation
Research into red onion hasn’t been extensive and most studies have either considered the compounds individually or have looked at red onion as part of an overall diet. As a result, there is no reliable information about the optimal amount of red onion to have each day.
However, a good place to start would be having half a red onion per day (or every other day, if you like). Doing so within your diet should be fairly easy, especially as red onions are a common ingredient in many recipes.
Furthermore, there is a range of different ways that red onions can be consumed, including raw in salads and sandwiches, as well as cooked in many of the dishes that white onion is used in.
In most cases, you can simply do a 1-to-1 replacement, substituting in red onions instead of white ones.
This can create some different tastes in food, but this isn’t necessarily a bad thing. Sometimes variations in flavor can make food seem much more interesting, and it is certainly worthwhile when red onions offer significant health benefits.
For people who don’t like the way that red onions taste, or don’t like raw onions, one good trick is to include it in meals that have rich red sauces. Budget Bytes also offers details about how to make pickled red onions for anyone who enjoys pickled vegetables.
When it comes to working with red onions, one of the most important aspects is ensuring the greatest health benefits. A key way of doing this is to be careful in peeling onions. In red onions, most of the flavonoids are located in the outer layer of the onion.
Excessive peeling can significantly reduce the amount of flavonoids present, which in turn reduces the health benefits.
Like most produce, it is important to pick healthy onions. For red onions, this involves choosing onions that are round, with dry outer skins and that look like they are clean.
Onions should be avoided if they are sprouting, have any indications of mold, have dark patches or have soft spots, these factors are an indication that the onion is decaying.
If you choose onions that show no signs of decay, then they will last longer and be fresher when they are used.
Finally, red onions should be stored in a dark and well-ventilated area, and kept away from sources of heat. A dark cool cupboard is usually a good choice.
After all, you want to keep them in a good condition so you can enjoy them.
- Like white onions, red onions contain many natural chemicals and offer significant potential health benefits
- The red in red onions comes from anthocyanins, which is an important class of flavonoids for promoting human health
- Red onion has antioxidant activities and may play a role in treating diabetes, in addition to potential anti-cancer effects