Turnip vs. Onion — Health Impact and Nutrition Comparison

Calories

Turnips and onions are low-calorie foods because they are non-sweet vegetables. However, onions are higher in calories than turnips, providing 40 calories per 100g, while turnips have 28 calories.

Carbs

Both onions and turnips are low in carbs. However, in terms of carbs, onions are higher compared to turnips. They provide 3g more carbs.

Turnips are lower in net carbs: 100g has 4.6g of net carbs, while the same amount of onions contains 7.6g.

Protein

Turnips and onions are plant food products. Hence, they do not provide much protein. Still, onions are higher in proteins than turnips.

Vitamins

The two vegetables are rich in different vitamins.

Turnips are an excellent source of vitamin C: they are approximately three times higher in vitamin C (21mg per 100g) than Onions (7.4mg per 100g).

Onions are richer in vitamins B1, B6, and K, while turnips provide more vitamins B3, B5, and E.

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.

Turnip

5

Onion

5

Contains more Vitamin CVitamin C	+183.8%
Contains more Vitamin EVitamin E	+50%
Contains more Vitamin B3Vitamin B3	+244.8%
Contains more Vitamin B5Vitamin B5	+62.6%
Contains more CholineCholine	+82%

Contains more Vitamin AVitamin A	+∞%
Contains more Vitamin B1Vitamin B1	+15%
Contains more Vitamin B6Vitamin B6	+33.3%
Contains more Vitamin KVitamin K	+300%
Contains more FolateFolate	+26.7%

~equal in Vitamin D ~0µg

~equal in Vitamin B2 ~0.027mg

~equal in Vitamin B12 ~0µg

Minerals

Turnips are the champions in this section. They are higher in calcium, iron, potassium, zinc, and copper.

Turnips are more than two times higher in copper than onions.

You can check these two vegetables' mineral compositions in the chart below.

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.

Turnip

6

Onion

1

Contains more CalciumCalcium	+30.4%
Contains more PotassiumPotassium	+30.8%
Contains more IronIron	+42.9%
Contains more CopperCopper	+117.9%
Contains more ZincZinc	+58.8%
Contains more SeleniumSelenium	+40%

Contains less SodiumSodium

-94%

~equal in Magnesium ~10mg

~equal in Phosphorus ~29mg

~equal in Manganese ~0.129mg

Glycemic Index

The glycemic index of onions is equal to 15, while turnips have a glycemic index equal to 73. 

Onions are considered a low-GI food, whereas turnips are high-GI food.

Cancer

Turnips and Onions contain different plant compounds with anticancer properties.

Turnips have chemicals called glucosinates. They are a group of bioactive compounds with antioxidant capacities that help reduce oxidative stress-reducing cancer risk (3) (4). A higher intake of glucosinates is linked with a reduced risk of colon, rectal, and lung cancers (5) (6) (7).

The anticancer properties of Onions are mostly linked with sulfur-containing compounds. For instance, onion provides onionin A, a sulfur-containing chemical that decreases tumor development and inhibits the spread of lung and ovarian cancers (8) (9).

Diabetes

Both these vegetables have anti-diabetic effects connected with the different chemicals they provide.

Turnips help maintain blood glucose levels by lowering glucose production in the liver and reducing the absorption of carbs (10) (11).

Onions possess anti-diabetic effects by producing quercetin, an antioxidant that helps control blood sugar regulation (12).

Protection Against Bacteria 

Both Onions and Turnips are involved in antibacterial activities.

Turnips glucosinates can turn into isothyocianates that inhibit bacterial and microbial growth (13). These compounds are effective against harmful bacteria such as E.Coli and S. Aureus (14) (15).

Onion extracts inhibit Vibrio cholerae and Helicobacter pylori (16) (17).

Cardiovascular Health

Section reviewed by cardiologist Astghik Grigoryan

Turnips and onions both offer protective benefits when it comes to cardiovascular risk and atherosclerosis, although they work through different mechanisms.

Turnips are rich in fiber, antioxidants (like vitamin C), and minerals such as potassium. Fiber helps to reduce levels of LDL ("bad" cholesterol), a major contributor to atherosclerosis. By lowering LDL cholesterol, turnips can help prevent the buildup of plaque in the arteries, reducing the risk of atherosclerosis and related cardiovascular events (18). Additionally, the potassium content in turnips helps regulate blood pressure, further reducing cardiovascular risk.

Onions contain flavonoids, particularly quercetin, which possess antioxidant and anti-inflammatory properties. These compounds help reduce inflammation and oxidative stress in the body, which are key drivers of atherosclerosis. By combating inflammation and oxidative damage, onions may help prevent the development and progression of atherosclerotic plaques in the arteries. Furthermore, certain sulfur compounds found in onions have been linked to improvements in cholesterol levels and blood vessel function, further reducing cardiovascular risk (19).

According to this study, both onions and turnips contain less than 35 mcg of vitamin K per serving. Warfarin users need consistent daily vitamin K levels, so eating these foods in normal portions is unlikely to significantly affect their INR levels (20).

In summary, both turnips and onions can contribute to reducing cardiovascular risk and preventing atherosclerosis through various mechanisms, including their antioxidant content, ability to reduce inflammation, and effects on cholesterol and blood pressure levels. Incorporating both of these vegetables into a balanced diet rich in fruits, vegetables, whole grains, and lean proteins can support overall heart health and reduce the risk of cardiovascular disease.