Which Legumes Have the Most Iron?

Legumes are a whole food that many people rely on for nutrition, including minerals like iron, calcium, magnesium, and potassium.

Which legumes have the most iron?

See the table below for a more visual comparison of these five commonly eaten types of legumes:

NCCDB data (retrieved from Cronometer)

Depending on several factors, people have different requirements for the amount of iron they should consume in their diet.

The RDA for iron is 8 mg per day for men of all ages and post-menopausal women, while pre-menopausal, menstruating women have a higher need for dietary iron — the RDA for this group is about 18 mg per day.

So a single ½ cup serving of cooked lentils or raw peanuts would supply about 41% of the RDA for a man or post-menopausal woman, and 18% for a pre-menopausal woman.

However, when attempting to boost your iron status, you have to keep in mind that there are several factors that limit the absorption of iron in legumes.

According to a study entitled, “Bioavailability of minerals in legumes,”

“The mineral content of legumes is generally high, but the bioavailability is poor due to the presence of phytate, which is the main inhibitor of Fe and Zn absorption.

Some legumes also contain considerable amounts of Fe-binding polyphenols inhibiting Fe absorption.”

Phytate and iron-binding polyphenols can be reduced, however, by proper preparation of the legumes, such as soaking, cooking at high temperatures (I.e., boiling or pressure cooking), and fermenting.

Once phytate and polyphenols are sufficiently reduced, it stands to reason that the iron in the legumes would be better absorbed by the body.

The study concluded,

“Fe and Zn absorption has been shown to be low from legume-based diets.

It has also been demonstrated that nutritional Fe deficiency reaches its greatest prevalence in populations subsisting on cereal- and legume-based diets.

However, in a balanced diet containing animal protein, a high intake of legumes is not considered a risk in terms of mineral supply.”

Thus, in order to get sufficient bioavailable iron in your diet, you will most likely need to eat some animal foods — such as red meat, organs such as beef liver and spleen, mussels, and oysters.

Relying solely on legumes or grains for minerals will likely leave you deficient after a period of time.

Another study examined several different types of legumes—soybeans, black beans, lentils, mung beans, and split peas—and found that only 0.84-1.91% of the iron present in the legumes was actually absorbed by the body, even when those beans were prepared and served as a soup.

The conclusion of this study was that “these five commonly eaten legumes are all poor sources of dietary iron.”

Once again, the takeaway seems to be that you should not rely solely on legumes as a source of iron, but they are probably fine to include in a balanced diet that has ample iron-rich animal foods.

See the table below for a more visual comparison of these six commonly eaten types of legumes:

NCCDB data (retrieved from Cronometer)

This paper describes that just as with iron and other minerals, not all of the calcium present in the legumes is actually absorbed by the body.

Several factors impact the bioavailability of calcium in the foods we eat.

For example, consuming dietary fat in your meal reduces the absorption of calcium, while consuming protein and phosphorus in the meal enhances absorption.

Phytic acid, which is present in large amounts in most legumes, also inhibits the absorption of calcium.

Oxalic acid has the same effect, which is why spinach is a poor source of calcium (only about 5% of the calcium in the spinach is absorbed).

It’s estimated that 30-35% of the calcium in milk and milk products is absorbed, which is similar to soybeans.

See the table below for a comparison between five different types of legumes and how many total carbs and fiber each type contains:

NCCDB data (retrieved from Cronometer)

This means that out of the 20.4 total grams of carbs that ½ cup of black beans has, 7.5 grams is fiber.

Fiber is a type of carbohydrate that is not fully digested and is instead fermented by bacteria in the colon.

Practically speaking, this slows down the digestion of the food you eat and theoretically allows for a slower, more controlled release of glucose into your bloodstream.

This doesn’t necessarily make you lose weight, but it can aid with blood sugar regulation and insulin sensitivity.

See the table below for a comparison between five different types of legumes and how many total calories they have, along with a breakdown of the percentage of those total calories that come from protein, carbs, and fat:

NCCDB data (retrieved from Cronometer)

It’s important to pay attention to the percentage of total calories that come from protein.

Dr. Ted Naiman, author of The P:E Diet, argues that protein is used mainly as a building block within the body, and calories from pure protein don’t contribute to unhealthy weight gain.

Calories from carbs and fat, on the other hand, are either burned by the body as energy or stored as potential energy, which makes them more likely to lead to fat gain if you’re consistently eating in a caloric surplus.

This means that if you’re concerned about regulating your caloric intake to lose weight, you need to mainly reduce the calories from carbs and fat — NOT calories from protein.

Lentils, for example, provide a good portion of their calories from protein (27%), while peanuts have a lower proportion of protein.

Thus, not only are peanuts extremely calorie-dense (414 calories per ½ cup serving), the bulk of those calories are non-protein calories.

This doesn’t lead automatically to weight gain — that depends on how many overall calories you’re consuming and how much you burn on a daily basis.

But consistently tending towards protein in your diet and limiting calories from carbs and fat will make it easier for you to lose or maintain weight in the long run.

How much legumes you can eat per day depends on multiple factors — your daily caloric needs, your weight and body fat percentage, your activity levels, and the other foods you’re including in your diet.

Everyone has a unique level of calories they should consume (based on their weight and body fat percentage), depending on what their goals are.

If your goal is to lose weight, for example, you will need to consume fewer calories than you burn.

In that case, you would do well to gravitate towards legumes that are lower in overall calories and higher in protein — so more lentils and fewer peanuts, for example.

Another consideration for how many legumes you should eat is whether or not you have health conditions that worsen when you eat legumes.

For example, some compounds in legumes could exacerbate symptoms in people who have autoimmune diseases.