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Important Red Onion Nutrition Facts You Need to Know

Red Onion Nutrition

Onions and red onions are the world’s favourite vegetables, along with tomatoes. Among the other onion cultivars, red onion is widely available in India. Red onion nutrition facts suggest that it is full of antioxidants. Let’s look at red onion calories and other nutrition in onion and see what red onions are best for.

Important – Always add the outermost dark purple layer of the red onion, and do not discard it. Readout why?

Red onions – the most common vegetable in the world

Firstly, red onions are the oldest and most widely consumed vegetable globally, along with tomatoes.

Red onion is usually supplemented as a vegetable ingredient in most cuisines worldwide. However, onions may be eaten raw in salads or made into juice.

Red onions are staples for almost every kitchen cook. But can these humble plants provide any health benefits for your meals? Most experts say yes, they do. Onions of all kinds (including white and red onions) are excellent sources of beta-carotene, vitamin A, vitamin C, vitamin D, and copper. Onion contains various phytochemicals that promote different health functions.

Red onion calories

As per IFCT, 100 grams of onion have around 48 kcal calories. The onions referred to by IFCT are medium or large-size red onions. Small red onions have approximately 56 kcal calories in every 100-gram edible portion. Read the complete red onion nutrition facts below.

Health benefits from red onion nutrition facts

a. The best home remedy herbal medicine

Admittedly, most Indian households use red onion as herbal medicine to relieve or prevent several common diseases such as fevers, coughs, asthma, and bronchitis.

b. Contains Flavanols

Red onions have naturally the highest levels of flavanols among other cultivars [PMID: 30996417]. Regular consumption of red onions has been shown to reduce the risk of several diseases [PMID: 25212303].

When evaluating the red onion nutrition facts, it is observed that the outmost layer of the red onion bulb has the highest density of antioxidant compounds. Additionally, the antioxidant content decreases towards the inner layers [PMID: 30996417]. Unfortunately, most of us discard it with the shell cover. It is essential to consume the outer bulb of onion in order to get maximum red onion nutrition.

c. Anti-cancer properties

Red onions, along with other cultivars, also contain high content of phenolic compounds. These phenolic compounds have antiproliferative and anti-cancer effects. The phenolic compound in all onions increases with storage more than in fresh onions. Interestingly, the total phenolic content in red onions stored for up to 3 months is higher among other cultivars [PMID: 29567221]. 

d. Reduces body fat

Animal studies have observed that onion peel extracts from the outer layer rich in Quercetin have helped change the body composition in rats. This finding hints at a beneficial role of the onion or its peel extract for humans [PMID: 27087901].

e. Promotes reproductive system health

Onion has been known to Indians as a mood enhancer for ages. Researchers also have observed that onion or onion juice may enhance fertility and sperm count in the male reproduction system [].

f. Promotes eye health

The antioxidant properties in red onion may also protect the eyes from harmful radiation and avoid the risk of cataracts [PMID: 25212303].

g. Protects DNA damage

Red onion nutrition shows it contains antioxidants, which can protect your DNA from damage by free radicals. These free radicals are caused by things like pollution, cigarette smoke, stress, and alcohol.

h. Promotes healthy heart

Those who eat red onions regularly may get many dietary phytochemicals. Phytochemicals are suggested to be the major bioactive compounds contributing to reduced risk for the development of cardiovascular disease [PMID: 15506817].

Red onion contains Quercetin which may reduce fat deposits in arteries. Several studies suggest that red onion or its dried powder may reduce the arteriosclerosis risk due to its anti-atherogenic effect [PMID: 25212303].

i. Regulates blood pressure

It’s well-known that eating onions is good for your health, but did you know that eating them can also lower your blood pressure? 

Quercetin has been shown to reduce your risk of cardiac arrest and improve blood circulation, so it’s not just another antioxidant that you’re eating – onion could be a powerful artery-clogging herb.

j. Promotes healthy skin

The quercetin content of onion is also known to prevent melanin formation, which is the main reason for darker skin. Hence it may be said that eating red onions or applying them to the skin may be helpful as a whitening agent []

Red onions in your cuisine

Depending on how you prepare your onions, they can either add or take away from the flavour of your dish. Chopping brings the natural flavour out of the onion.  

If you puree or chop the onions, you’ll receive a more robust onion flavour than if you use the onions whole. Either way, you’re sure to please everyone at the dinner table. Moreover, researchers have found that chopping, cooking in the heat, refrigeration, or frying the red onions does not significantly reduce the antioxidants such as flavanols or anthocyanin [PMID: 30996417].

Red onion nutrition facts compared with males and females RDA

Let’s see how much nutrition males or females got when they consumed red onion of 100 grams in their diet.

Serving size – 100 gm of red onion medium or large.

Calories in red onion

a. Water – 85.76 gm.

b. Calories in red onion are 48.01 kCal; as much as 2.40 % of male DRI of 2000 kCal. Further, it can attain 3.20 % of female DRI of 1500 kCal.

c. Protein forms 12.50 % of the calories

d. Carbs form 79.65 % of the calories in red onion.

e. Fats form 4.50 % of the calories.

Macros in red onion

a. Protein in red onion – 1.50 gm, particularly 2.00 % of male DRI of 75 gm. Therefore, it can complete 2.67 % of female DRI of 56.25 gm. To clarify, protein DRI is 15% of calories.

b. Carbs in red onion – 9.56 gm, therefore, is 3.48 % of male DRI of 275 gm. Thus, it can achieve 4.64 % of female DRI of 206.25 gm. In general, the carbohydrates DRI is 55% of calories.

c. Fats in red onion – 0.24 gm, notably 0.36 % of male DRI of 66.67 gm. As a result, a woman gets 0.48 % of female DRI of 50.00 gm. Fats DRI is 30% of calories.

d. The Fibre in red onion – 2.45 gm, thus is 6.45 % of male DRI of 38 gm. On the other hand, females get 9.80 % of female DRI of 25 gm.

e. Soluble Fibre – 0.53 gm, particularly 5.30 % of male DRI of 10 gm. Additionally, females will get 5.38 % of female DRI of 9.86 gm.

f. Total Free Sugar – 5.88 gm, which is not only 9.80 % of male DRI of 60 gm but also 11.76 % of female DRI of 50 gm.

Vitamins in red onion

a. Vitamin A – 0.09 mcg, as much as 0.01 % of male DRI of 900 mcg. Furthermore, women can get 0.01 % of female DRI of 700 mcg.

b. Thiamine (Vitamin B1) – 0.04 mg, particularly 3.33 % of the daily requirement of males of 1.2 mg. Subsequently, females will get 3.64 % of female DRI of 1.1 mg.

c. Riboflavin (Vitamin B2) – 0.01 mg, therefore, is 0.77 % of male DRI of 1.3 mg. Besides, women also get 0.91 % of female DRI of 1.1 mg.

d. Niacin (Vitamin B3) – 0.34 mg, notably 2.13 % of male DRI of 16 mg and 2.43 % of female DRI of 14 mg.

e. Pyridoxine (Vitamin B6) – 0.10 mg, thus is 7.69 % of DRI of 1.3 mg for males and females.

f. Biotin (Vitamin B7) – 2.61 mcg, therefore, is 8.70 % of DRI of 30 mcg for males and females.

g. Total Folate (Vitamin B9) – 28.88 mcg, as much as 7.22 % of DRI of 400 mcg for males and females.

h. Cobalamin (Vitamin B12) – 0.00 mcg, particularly 0.00 % of DRI of 2.4 mcg for males and females

i. L-ascorbic acid (Vitamin C) – 6.69 mg, therefore, is 7.43 % of male DRI of 90 mg. Further, it is 8.92 % of female DRI of 75 mg.

j. Calciferol (Vitamin D) – 0.73 mcg, notably 14.60 % of DRI of 5 mcg for males and females.

k. Alpha-tocopherol (Vitamin E) – 0.05 mg, thus is 0.33 % of DRI of 15 mg for males and females.

l. Vitamin K – 4.50 mcg, as much as 3.75 % of male DRI of 120 mcg and 5.00 % of female DRI of 90 mcg.

Minerals in red onion

a. Calcium – 21.03 mg, particularly 2.10 % of DRI of 1000 mg for males and females.

b. Phosphorus – 32.34 mg, therefore, is 4.62 % of DRI of 700 mg for males and females.

c. Iron – 0.43 mg, notably 5.38 % of male DRI of 8 mg and 2.39 % of female DRI of 18 mg.

d. Magnesium – 17.96 mg, thus is 4.49 % of male DRI of 400 mg and 5.79 % of female DRI of 310 mg.

e. Copper – 110.00 mcg, as much as 12.22 % of DRI of 900 mcg for males and females.

f. Manganese – 0.24 mg, particularly 10.43 % of male DRI of 2.3 mg and 13.33 % of female DRI of 1.8 mg.

g. Molybdenum – 0.00 mcg, therefore, is 0.00 % of DRI of 45 mcg for males and females.

h. Zinc – 0.35 mg, notably 3.18 % of male DRI of 11 mg. At the same time, women get 4.38 % of female DRI of 8 mg.

i. Chromium – 3.00 mcg, thus is 8.57 % of male DRI of 35 mcg. Besides, women too get 12.00 % of female DRI of 25 mcg.

j. Selenium – 0.35 mcg, as much as 0.64 % of DRI of 55 mcg for males and females.

k. Cholesterol – 0.00 mg,

l. Potassium – 171.00 mg, as much as 3.64 % of DRI of 4700 mg for males and females.

m. Sodium – 5.50 mg, particularly 0.37 % of DRI of 1500 mg for males and females.

n. Omega 3 – 6.63 mg, therefore, is 1.11 % of DRI of 600 mg for males and females,

o. Omega 6 – 100.00 mg, not only 16.67 % of DRI of 600 mg for males and females.


Values of RDA are for a healthy adult aged between 19 to 50 years, and energy requirements may change as per gender, age, and physical activities. Nutritional values of red onions are approximate and may have variance. There is also a variety of small red onions in the market.

Nutritionist & Dietician
Hello everyone, I am Nutritionist Smriti Indarapu, a Post Graduate Diploma holder in Nutrition and Dietetics, practicing nutrition for the last 10 years. The journey started when we were having our family... Read full bio

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