Onion vs. Garlic — Health Impact and Nutrition Comparison

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

Protein: 1.1 g

Fats: 0.1 g

Carbs: 9.34 g

Water: 89.11 g

Other: 0.35 g

Garlic

4

Protein: 6.36 g

Fats: 0.5 g

Carbs: 33.06 g

Water: 58.58 g

Other: 1.5 g

Contains more WaterWater

+52.1%

Contains more ProteinProtein	+478.2%
Contains more FatsFats	+400%
Contains more CarbsCarbs	+254%
Contains more OtherOther	+328.6%

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

Saturated Fat: Sat. Fat 0.042 g

Monounsaturated Fat: Mono. Fat 0.013 g

Polyunsaturated fat: Poly. Fat 0.017 g

Garlic

1

Saturated Fat: Sat. Fat 0.089 g

Monounsaturated Fat: Mono. Fat 0.011 g

Polyunsaturated fat: Poly. Fat 0.249 g

Contains less Sat. FatSaturated Fat	-52.8%
Contains more Mono. FatMonounsaturated Fat	+18.2%

Contains more Poly. FatPolyunsaturated 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

Garlic

10

Contains more FolateFolate

+533.3%

Contains more Vitamin CVitamin C	+321.6%
Contains more Vitamin AVitamin A	+350%
Contains more Vitamin E Vitamin E	+300%
Contains more Vitamin B1Vitamin B1	+334.8%
Contains more Vitamin B2Vitamin B2	+307.4%
Contains more Vitamin B3Vitamin B3	+503.4%
Contains more Vitamin B5Vitamin B5	+384.6%
Contains more Vitamin B6Vitamin B6	+929.2%
Contains more Vitamin KVitamin K	+325%
Contains more CholineCholine	+280.3%

~equal in Vitamin D ~0µg

~equal in Vitamin B12 ~0µg

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

Garlic

9

Contains less SodiumSodium

-76.5%

Contains more MagnesiumMagnesium	+150%
Contains more CalciumCalcium	+687%
Contains more PotassiumPotassium	+174.7%
Contains more IronIron	+709.5%
Contains more CopperCopper	+666.7%
Contains more ZincZinc	+582.4%
Contains more PhosphorusPhosphorus	+427.6%
Contains more ManganeseManganese	+1196.1%
Contains more SeleniumSelenium	+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. 

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

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).