Onions have a poor iron content. Only onion greens are rich in iron.
Health benefits of iron
Iron is vital for good health. First, iron is a key component of hemoglobin; a protein of red blood cells that transfers oxygen from the lungs to the tissues.
Also, iron is vital for muscle metabolism, healthy connective tissue, energy metabolism, cellular functioning, physical growth, neurological development, and the synthesis of some hormones, amino acids, and collagen.[1,2]
Iron deficiency is the most common nutritional deficiency worldwide, though! It may lead to serious side effects, such as gastrointestinal disturbances, impaired cognition, weakened immune function, fatigue, and low body temperature. Moreover, iron deficiency during pregnancy may increase the risk of premature delivery, and miscarriage.
How much iron do we need a day?
The recommended daily intake of iron is 18 mg for women of reproductive age, and 27 mg for pregnant women.
Adult men and women older than 51 years require only 8 mg of iron a day.
As women require high dosages of iron, they may have a hard time to meet their daily needs from food. They may benefit from taking a dietary supplement. You’ll find a wide variety of iron supplements on iHerb.
What’s the iron content of onions?
Onions are poor in iron. They have between 0.15 mg and 0.28 mg of iron per 100g. The iron content depends on the onion variety.
White onions have the lowest iron content. Yellow and red onions are much richer in iron. They contain almost twice as much iron, as compared to white onions.
Onion greens have the highest iron content, though. They contain approximately 1.5 mg of iron per 100g!
Does cooking affect the iron content of onions?
The cooking method doesn’t significantly affect the iron content of food. Iron and other minerals aren’t as much vulnerable to heat as vitamins.
Above all, you better use iron pots and pans to cook onions and other foods high in iron. Iron cookware can increase the iron content and iron bioavailability of food.[6,7,8]
You can find a wide variety of iron pots and other cookware on Amazon.
Is iron in onions bioavailable?
We absorb only a small percentage of iron of onions, though. Actually, all plant-based foods have a low iron bioavailability. It’s estimated that we absorb only 5-12% of iron from plants.
In contrast, we absorb up to 18% of iron from animal-based foods.
We could increase the absorption of iron, eating foods high in vitamin C. Vitamin C enhances iron absorption!
Also, animal-based foods, like meat, poultry, and seafood, enhance iron absorption.
On the other hand, better avoid consuming whole-grains and beans with foods high in iron. Phytates and polyphenols in these foods may inhibit iron absorption. High amounts of calcium might reduce the bioavailability of iron as well.
Other foods high in iron
Common foods high in iron are meat, poultry, fish, eggs, whole grains, seeds (e.g. pumpkin seeds), nuts, legumes, as well as certain fruits and vegetables.
Potatoes, chocolate, beans, spinach, cabbage, and kale are only a few common plant-based foods high in iron.
Certain fruit juices, such as prune and raspberry juices, are excellent dietary sources of iron as well. Their regular consumption could help us meet our daily needs.
Health benefits of onions
Onions have many health benefits, due to their superior antioxidant content. For instance, they’re particularly high in flavonoids, quercetin, and phenolic compounds.[9,10]
The outer layers of onions have the highest antioxidant content. Don’t discard them.
Onions have potent antioxidant, anti-inflammatory properties, anticancer, anti-diabetic, and antihypertensive properties. In fact, onions may reduce elevated LDL-cholesterol, boost the immune system and protect the heart.[12,13,14]
Also, onions (and garlic) help absorb the nutrients of other foods! For instance, onion consumption enhances the bioavailability of minerals, like iron and zinc. Onions are particularly high in sulfur-containing amino acids, which seem to promote mineral absorption.
Moreover, onions, as part of a well-balanced diet, could help you lose weight. They might help regulate blood sugar levels. Also, they’re low in calories, sugars and carbs. In addition, onions have a high fiber content, providing a great satiating effect.