How to Eat More Spinach: Benefits, Iron Facts and Risks

Quick answer (TL;DR): Spinach is low in calories (about 23 per 100 g raw) and rich in vitamin K, folate and lutein. Its iron (about 2.7 mg per 100 g raw) is poorly absorbed, so it will not cure anaemia on its own. Light cooking lowers oxalate but also lowers vitamin C and folate, so a mix of raw and lightly cooked is sensible. Ask a doctor first if you have kidney stones or take warfarin.

Originally published: July 4, 2016 | Last updated: October 29, 2026

What nutrients are in spinach?

These are USDA reference values for the raw leaves. One cup of raw leaves weighs about 30 g, so a single serving is a small fraction of the 100 g column.

It is also a good source of vitamin A (as beta-carotene), and lutein and zeaxanthin are pigments found in the eye. Leafy greens are one part of an eye-friendly diet, not a protection by themselves.

Is spinach a magic cure for anaemia?

From my community health work, I often hear that it has a lot of iron and cures anaemia. It does contain iron, but it is not a cure, for two reasons.

• Plant iron is absorbed poorly. The US National Institutes of Health says the body absorbs about 15 to 35 percent of the iron in meat, fish and poultry (heme iron), but only about 2 to 20 percent of the iron in plant foods (non-heme iron). It also contains oxalate, which binds minerals and makes iron and calcium harder to absorb.
• Anaemia has several causes. Low iron is common, but a lack of folate or vitamin B12, blood loss and some long-term illnesses can also cause anaemia. Eating spinach will not fix those.

You can help your body use plant iron. Vitamin C (a squeeze of lemon, guava, tomato or a pepper) in the same meal improves absorption of non-heme iron, while tea, coffee, calcium and phytates (in legumes and whole grains) can reduce it. Meat, fish, liver, lentils and iron-fortified foods are better sources of iron.

If you feel constantly tired or weak, look pale or are short of breath, see a health worker or doctor for a blood test. Do not treat anaemia with leafy greens alone, and do not start iron tablets without advice. This matters even more in pregnancy and for adolescent girls, who need more iron.

Does cooking spinach for longer make it more nutritious?

From my community health work, I also hear that the longer it is cooked, the more nutrition it gives. This is not true. Cooking does help in some ways, but long cooking mostly loses nutrients.

• Oxalate falls: in a Japanese food-science study, boiling chopped leaves for 2 minutes removed about 72 percent of its oxalic acid and 58 percent of its nitrate, while keeping about 79 percent of its lutein. This can help people who are prone to kidney stones.
• Vitamin C and folate fall: the same research found that boiling lost between 36 and 73 percent of its vitamin C, depending on the conditions. Folate is also water-soluble and leaches into the cooking water.
• Beta-carotene from cooked leaves is generally easier for the body to absorb, especially with a little oil.

So the best approach is short cooking, not long cooking: a minute or two of steaming or stir-frying, or wilting leaves in a hot dish. If you have had kidney stones, boil briefly and throw away the water. Eating spinach both raw and lightly cooked over the week gives the broadest benefit. For other ways to eat more greens, see our post on eating more fruits and vegetables.

Does eating too much spinach cause hormone problems?

From my community health work, I also hear that too much of it upsets the hormones. I could not find good evidence that normal food amounts do this. There are two things people may be thinking of:

• Thyroid: the leaves contain small amounts of goitrogens, which can reduce iodine uptake, but they are much weaker than in cruciferous vegetables such as kale. This is a concern mainly for people who already have thyroid disease and eat very large amounts of raw leaves every day. Cooking and getting enough iodine (for example from iodized salt) reduce the concern. If you have a thyroid condition, ask your doctor.
• Plant oestrogens (phytoestrogens): these plant compounds are found in many foods. Research on them is mixed, and normal diets are generally considered safe.

The real reasons to avoid eating huge amounts are different: oxalate (kidney stones) and vitamin K (warfarin), described below.

What are easy ways to eat more spinach?

• Smoothies: a handful blends into mango, banana or berries. Keep the amount modest if you are prone to kidney stones, because raw leaves in large amounts are high in oxalate.
• Eggs: stir chopped leaves into an omelette or scrambled eggs.
• Quick stir-fry: cook with garlic in a little oil for a couple of minutes and finish with lemon juice, which also helps iron absorption.
• Salad: baby spinach works raw with nuts, fruit and a light dressing.
• Dal, soup or pasta: add at the end of cooking so the heat just wilts it.
• Mix your greens: palong shak, red amaranth (lal shak), Malabar spinach (pui shak) and others give variety. See our nutrition tips for more ideas.

Who should be careful with spinach?

• Calcium-oxalate kidney stones: it is among the highest-oxalate foods. If you have had stones, ask your doctor or a dietitian how much is right for you, and consider brief boiling with the water discarded.
• Warfarin: it is very high in vitamin K, which affects how warfarin works. Do not suddenly eat much more or much less. Keep your intake steady and tell your doctor.
• Thyroid disease: ask your doctor if you eat large amounts of raw leaves daily.
• Iron overload conditions (such as hemochromatosis): ask your doctor before relying on iron-rich foods or supplements.
• Allergy: get urgent medical help for swelling of the face or throat, or difficulty breathing, after eating any food.

Frequently Asked Questions

Is raw or cooked spinach healthier?

Both have advantages. Raw spinach keeps more vitamin C and folate. Light cooking lowers oxalate and may make beta-carotene easier to absorb. Eating it both ways across the week is sensible.

Can spinach cure anaemia?

No. Spinach contains iron, but plant iron is absorbed poorly, and anaemia can have causes other than low iron. See a health worker or doctor for a blood test and proper treatment.

Does too much spinach cause hormone problems?

There is no good evidence that normal food amounts upset hormones. People with thyroid disease who eat very large amounts of raw leaves should ask their doctor. Oxalate and vitamin K are the more important cautions.

Can spinach cause kidney stones?

Spinach is high in oxalate, which can contribute to calcium-oxalate stones in people who are prone to them. If you have had kidney stones, ask your doctor how much to eat. Most people with no history of stones do not need to avoid it.

Sources

• NIH Office of Dietary Supplements: Iron fact sheet for health professionals
• Food Science and Technology Research: cooking conditions for oxalate, nitrate and lutein in spinach
• McGill Office for Science and Society: spinach and iron
• Healthline: kale versus spinach, including oxalate and goitrogens
• Raw spinach nutrient values (USDA FoodData Central data)

General information only, not medical, healthcare, or psychological advice. Check current medical guidelines with a certified physician or licensed healthcare provider before acting on anything published here. Never disregard professional medical advice or delay seeking it because of something you read on this site.