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Onion vs. Garlic — Health Impact and Nutrition Comparison

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Article author photo Ani Harutyunyan by Ani Harutyunyan | Last updated on April 18, 2023
Medically reviewed by Elen Khachatrian Article author photo Elen Khachatrian
Onion
vs
Garlic

Summary

Garlic is denser in nutrients, providing more carbs and protein. Garlic contains ten times more vitamin B6 and four times more vitamin C, while onion has higher amounts of folate. Garlic is a better source of minerals, including iron, phosphorus, potassium, zinc, calcium, magnesium, and especially copper

Introduction

Garlic and onion are different vegetables with important nutrient content. This article will discuss their differences regarding the nutritional profile and health impact.  

Garlic is a bulbous flowering plant widely used as a flavoring and medicine in different dishes. It is a well-known flavoring in Chinese cuisine. 

Onion is a famous blub vegetable cultivated worldwide, usually in regions with a moderate climate and well-drained soils. Onion is commonly used as a flavoring for sandwiches, salads, soups, and other dishes. It can be consumed alone, in grilled, roasted, deep-fried, or caramelized forms.   

As the classification indicates, garlic and onion are two species from the same genus - Allium

Actual differences

Although both are close relatives, garlic and onion, differ in taste, smell, and appearance

An onion is a yellow, red, or white globe-shaped bulb. The bulb consists of multilayered leaves that store all the essential nutrients for the plant. 

Garlic is a bulbous vegetable too, but the garlic bulb holds approximately 20 white cloves instead of leaves. Garlic is covered with thin, membrane-like skin, while onion has a thick peel

Onions have a wide range of flavors: tangy or umami, sour or sweet, soft or crisp. Garlic has a unique taste: when it is raw, it can be described as a spicy flavor, but when it is cooked, it turns out to be nutty. 

Crushed garlic smells pungent, while onion has a sulfurous odor with a metallic nuance

Nutrition 

In the infographics below, you can find information about the nutritional composition of 100g servings of onion and garlic

The average serving size for these vegetables is one cup, chopped, equalling 160g for onion and 136g for garlic

Macronutrients

Garlic is much denser in nutrients than onion. Onion contains 89% of water, 9% of carbs, and 2% of other nutrients, while garlic has 59% of water, 33% of carbohydrates, 6% of protein, and 2% of other nutrients

Macronutrient Comparison

Macronutrient breakdown side-by-side comparison
Onion
1
:
4
Garlic
Contains more Water +52.1%
Contains more Protein +478.2%
Contains more Fats +400%
Contains more Carbs +254%
Contains more Other +328.6%
9% 89%
Protein: 1.1 g
Fats: 0.1 g
Carbs: 9.34 g
Water: 89.11 g
Other: 0.35 g
6% 33% 59%
Protein: 6.36 g
Fats: 0.5 g
Carbs: 33.06 g
Water: 58.58 g
Other: 1.5 g
Contains more Water +52.1%
Contains more Protein +478.2%
Contains more Fats +400%
Contains more Carbs +254%
Contains more Other +328.6%
 

Calories

Onion is classified as a low-calorie food, while garlic lies in the medium-calorie food list. 

Garlic is significantly higher in calories, containing 109 more calories per every 100g. In each 100g, onion contains 40 calories, while garlic provides 149 calories

Carbohydrates

Garlic is 23.4g higher in net carbs than onion in every 100g serving, while onion contains 1.3g of fructose that lacks in garlic, resulting in onion being sweeter than garlic.

100g serving size of onion contains 9.3g of carbs, 82% of which are net carbs and 16% - dietary fiber, while the exact size of garlic provides 33.1g of carbs, 94% of which are net carbs and 6% - dietary fiber

Onion and garlic are good sources of dietary fiber. Both of them are especially rich in soluble fiber

Protein

Garlic is six times higher in protein, containing 6.4g per 100g, while onion has 1.1g. It is known that most garlic proteins act as immune system-modulating agents. However, their identities and structures have not been described yet (1). 

Fats

Garlic and onion contain less than one gram of fat per 100g. Hence, the fat content can be neglected. 

Most of the fats present in onions are saturated. Garlic contains primarily polyunsaturated fats. 

Fat Type Comparison

Fat type breakdown side-by-side comparison
Onion
2
:
1
Garlic
Contains less Saturated Fat -52.8%
Contains more Monounsaturated Fat +18.2%
Contains more Polyunsaturated fat +1364.7%
58% 18% 24%
Saturated Fat: 0.042 g
Monounsaturated Fat: 0.013 g
Polyunsaturated fat: 0.017 g
26% 3% 71%
Saturated Fat: 0.089 g
Monounsaturated Fat: 0.011 g
Polyunsaturated fat: 0.249 g
Contains less Saturated Fat -52.8%
Contains more Monounsaturated Fat +18.2%
Contains more Polyunsaturated fat +1364.7%
 

Vitamins

Garlic is higher in most vitamins, containing ten times more vitamin B6, nearly four times more vitamin C, and overall more vitamins B1, B2, B3, B5, E, A, and K.

Onion has more than six times more vitamin B9 /folate/ than garlic.

Vitamin Comparison

Vitamin comparison score is based on the number of vitamins by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.
Onion
1
:
9
Garlic
Contains more Folate +533.3%
Contains more Vitamin A +350%
Contains more Vitamin E +300%
Contains more Vitamin C +321.6%
Contains more Vitamin B1 +334.8%
Contains more Vitamin B2 +307.4%
Contains more Vitamin B3 +503.4%
Contains more Vitamin B5 +384.6%
Contains more Vitamin B6 +929.2%
Contains more Vitamin K +325%
Vitamin A Vitamin E Vitamin D Vitamin C Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Folate Vitamin B12 Vitamin K 1% 1% 0% 25% 12% 7% 3% 8% 28% 15% 0% 1%
Vitamin A Vitamin E Vitamin D Vitamin C Vitamin B1 Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Folate Vitamin B12 Vitamin K 1% 2% 0% 105% 50% 26% 14% 36% 285% 3% 0% 5%
Contains more Folate +533.3%
Contains more Vitamin A +350%
Contains more Vitamin E +300%
Contains more Vitamin C +321.6%
Contains more Vitamin B1 +334.8%
Contains more Vitamin B2 +307.4%
Contains more Vitamin B3 +503.4%
Contains more Vitamin B5 +384.6%
Contains more Vitamin B6 +929.2%
Contains more Vitamin K +325%
 

Minerals

Garlic is the winner in this section as well. It is significantly higher in most minerals: iron, phosphorus, potassium, zinc, magnesium, calcium, and copper. Garlic covers 100% of the DV for copper

Onion contains less sodium.  

Mineral Comparison

Mineral comparison score is based on the number of minerals by which one or the other food is richer. The "coverage" charts below show how much of the daily needs can be covered by 300 grams of the food.
Onion
1
:
9
Garlic
Contains less Sodium -76.5%
Contains more Calcium +687%
Contains more Iron +709.5%
Contains more Magnesium +150%
Contains more Phosphorus +427.6%
Contains more Potassium +174.7%
Contains more Zinc +582.4%
Contains more Copper +666.7%
Contains more Manganese +1196.1%
Contains more Selenium +2740%
Calcium Iron Magnesium Phosphorus Potassium Sodium Zinc Copper Manganese Selenium 7% 8% 8% 13% 13% 1% 5% 14% 17% 3%
Calcium Iron Magnesium Phosphorus Potassium Sodium Zinc Copper Manganese Selenium 55% 64% 18% 66% 36% 3% 32% 100% 219% 78%
Contains less Sodium -76.5%
Contains more Calcium +687%
Contains more Iron +709.5%
Contains more Magnesium +150%
Contains more Phosphorus +427.6%
Contains more Potassium +174.7%
Contains more Zinc +582.4%
Contains more Copper +666.7%
Contains more Manganese +1196.1%
Contains more Selenium +2740%

Glycemic index 

Onion has an average GI of 15, fitting into the list of low-glycemic index foods. For more information, you can read this in-depth article: onion nutrition

Garlic's average glycemic index equals 30, considering it a low-glycemic index food. However, garlic has a higher glycemic index than onion. 

You can also look at our glycemic index chart page for more information about other foods' glycemic indexes. 

Health impact

Cardiovascular health

Garlic and onion contain different compounds that help maintain cardiovascular health. 

Onions produce a wide range of antioxidants - compounds that help fight oxidative stress and prevent damage to the organism. Quercetin is one of the antioxidants abundant in onions. It may benefit in lowering high blood pressure (2). Research shows that using onion extracts can notably decrease systolic blood pressure due to their quercetin content (3). Another study indicates that high amounts of red onions may lower LDL cholesterol concentrations (4). 

Garlic reduces total blood cholesterol levels. It lowers LDL and total cholesterol concentrations by 10-15% (5) (6). However, garlic has a significant effect on LDL (bad) cholesterol levels rather than HDL cholesterol levels (7) (8). 

Antioxidants

Onion and garlic are excellent sources of antioxidants. Onion contains different types of flavonoids - plant antioxidants that may benefit the human organism. 

Anthocyanins are one of those flavonoids. They are abundant in red onions because they are plant pigments that give onion its color. Anthocyanins can inhibit cell proliferation in cancer pathogenesis and prevent diabetes (9) (10). 

Garlic consumption leads to a higher concentration of antioxidant enzymes in the human organism. It contains antioxidants having anti-inflammatory effects (11). Garlic can reduce the risk of dementia and Alzheimer's disease (12). 

Bone Health

Garlic and onion benefit from increasing bone density and supporting bone health. However, this impact is due to the different mechanisms and chemicals these vegetables provide. 

Garlic increases estrogen levels in postmenopausal women's blood. This leads to a lower risk of fractures and higher bone density (13) (14). 

Some studies show that high onion consumption results in a lower risk of hip fracture and higher bone density (15) (16). 

Digestive Health

Section reviewed by gastroenterologist Arpi Gasparyan Article author photo Arpi Gasparyan

Garlic and onion are not the best choices for people with IBS, as they are high in FODMAPs and may trigger the symptoms. They may cause bloating, gases, and abdominal pain in people without IBS too.

Garlic and onion may also trigger heartburn in some individuals (17) (18).

Article author photo Ani Harutyunyan
Education: General Medicine at YSMU
Last updated: April 18, 2023
Medically reviewed by Elen Khachatrian

Infographic

Onion vs Garlic infographic
Infographic link

Comparison summary table

Pay attention to the rightmost column. It displays the amounts side by side, giving a clearer understanding of the difference.
Onion Garlic
Lower in Sodium ok
Lower in Saturated Fat ok
Lower in Glycemic Index ok
Lower in price ok
Lower in Sugar ok
Rich in minerals ok
Rich in vitamins ok
Lower in Cholesterol Equal

All nutrients comparison - raw data values

Nutrient Onion Garlic Opinion
Net carbs 7.64g 30.96g Garlic
Protein 1.1g 6.36g Garlic
Fats 0.1g 0.5g Garlic
Carbs 9.34g 33.06g Garlic
Calories 40kcal 149kcal Garlic
Fructose 1.29g Onion
Sugar 4.24g 1g Garlic
Fiber 1.7g 2.1g Garlic
Calcium 23mg 181mg Garlic
Iron 0.21mg 1.7mg Garlic
Magnesium 10mg 25mg Garlic
Phosphorus 29mg 153mg Garlic
Potassium 146mg 401mg Garlic
Sodium 4mg 17mg Onion
Zinc 0.17mg 1.16mg Garlic
Copper 0.039mg 0.299mg Garlic
Manganese 0.129mg 1.672mg Garlic
Selenium 0.5µg 14.2µg Garlic
Vitamin A 2IU 9IU Garlic
Vitamin E 0.02mg 0.08mg Garlic
Vitamin C 7.4mg 31.2mg Garlic
Vitamin B1 0.046mg 0.2mg Garlic
Vitamin B2 0.027mg 0.11mg Garlic
Vitamin B3 0.116mg 0.7mg Garlic
Vitamin B5 0.123mg 0.596mg Garlic
Vitamin B6 0.12mg 1.235mg Garlic
Folate 19µg 3µg Onion
Vitamin K 0.4µg 1.7µg Garlic
Tryptophan 0.014mg 0.066mg Garlic
Threonine 0.021mg 0.157mg Garlic
Isoleucine 0.014mg 0.217mg Garlic
Leucine 0.025mg 0.308mg Garlic
Lysine 0.039mg 0.273mg Garlic
Methionine 0.002mg 0.076mg Garlic
Phenylalanine 0.025mg 0.183mg Garlic
Valine 0.021mg 0.291mg Garlic
Histidine 0.014mg 0.113mg Garlic
Saturated Fat 0.042g 0.089g Onion
Monounsaturated Fat 0.013g 0.011g Onion
Polyunsaturated fat 0.017g 0.249g Garlic

Which food is preferable for your diet?

ok
ok
is better in case of low diet
Onion Garlic
Low Fats diet ok
Low Carbs diet ok
Low Calories diet ok
Low Glycemic Index diet ok

People also compare

Vitamins & Minerals Daily Need Coverage Score

The summary scores indicate the extent to which this food can fulfill your daily vitamin and mineral requirements if you consume 3 servings, consisting of 100 grams of each (an approximation of 3 serving sizes).
Vitamins Daily Need Coverage Score
8%
Onion
43%
Garlic
Minerals Daily Need Coverage Score
8%
Onion
67%
Garlic

Comparison summary

Which food contains less Sodium?
Onion
Onion contains less Sodium (difference - 13mg)
Which food is lower in Saturated Fat?
Onion
Onion is lower in Saturated Fat (difference - 0.047g)
Which food is lower in glycemic index?
Onion
Onion is lower in glycemic index (difference - 15)
Which food is cheaper?
Onion
Onion is cheaper (difference - $0.4)
Which food is lower in Sugar?
Garlic
Garlic is lower in Sugar (difference - 3.24g)
Which food is richer in minerals?
Garlic
Garlic is relatively richer in minerals
Which food is richer in vitamins?
Garlic
Garlic is relatively richer in vitamins
Which food contains less Cholesterol?
?
The foods are relatively equal in Cholesterol (0 mg)

References

All the values for which the sources are not specified explicitly are taken from FDA’s Food Central. The exact link to the food presented on this page can be found below.

  1. Onion - https://fdc.nal.usda.gov/fdc-app.html#/food-details/170000/nutrients
  2. Garlic - https://fdc.nal.usda.gov/fdc-app.html#/food-details/169230/nutrients

All the Daily Values are presented for males aged 31-50, for 2000-calorie diets.

Data provided by FoodStruct.com should be considered and used as information only. Please consult your physician before beginning any diet.