Is Spinach High in Histamine? Spinach and Oxalates Explained

Spinach is one of the few vegetables that appears on almost every list of foods to avoid with histamine intolerance, and unlike some foods on those lists, there is good reason for it. Spinach does contain a fair amount of histamine. It is also one of the richest common sources of oxalates, natural compounds that matter for people prone to kidney stones. Spinach and oxalates often come up together online, sometimes with confusing claims that one causes the other’s symptoms. This guide separates what is known from what is speculation.

The short version is this. Spinach is high in histamine and is usually avoided during a low histamine elimination diet. Its oxalate content is a separate issue, mainly relevant to kidney stones, and cooking affects the two very differently.

How much histamine is in spinach

A 2021 review in Nutrients pooled published measurements of amines in foods commonly excluded from low histamine diets. For spinach, based on 18 samples, the average histamine content was about 32 mg per kg, with a range of roughly 9 to 70 mg per kg. That is far higher than fresh tomato in the same review, which averaged about 2.5 mg per kg, and similar to aubergine at about 39 mg per kg. The review also cites research showing that histamine in spinach rose during refrigerated storage, which was linked to bacterial growth.

Spinach also contains other amines, such as spermidine, which may add to the load on the enzymes that break down histamine. On our histamine intolerance food list, spinach is rated High. Unlike foods such as citrus or strawberries, which are avoided mainly because of a suspected liberator effect, spinach is avoided because it actually contains histamine.

Histamine levels in vegetables vary with freshness, storage and growing conditions. Spinach is delicate and wilts quickly, so bagged leaves that have been in the fridge for days are likely to contain more than freshly picked leaves. Even so, the average levels mean spinach is best left out during the elimination phase.

What oxalates are

Oxalates (oxalic acid and its salts) are natural compounds found in many plants. Spinach, rhubarb, beetroot leaves, Swiss chard, almonds, cocoa and some other foods are particularly rich in them. In the gut, oxalates bind to calcium and other minerals. Some oxalate is absorbed and leaves the body in urine.

For most people, dietary oxalate is not a problem. The main recognised concern is kidney stones. Calcium oxalate stones are the most common type, and people who have had them are often advised to watch their intake of very high oxalate foods, to drink plenty of fluids, and to include enough calcium with meals, because calcium binds oxalate in the gut. If you have had kidney stones, your doctor or dietitian can give you advice tailored to the type of stone you had.

Oxalates can also reduce the absorption of calcium and iron from the same food. This is why spinach, despite containing calcium and iron, is not a particularly good source of either.

Is there a link between oxalates and histamine?

You may read that oxalates cause histamine release, that “oxalate sensitivity” causes the same symptoms as histamine intolerance, or that most high oxalate foods are also high in histamine. These claims are not well supported.

• Different foods. Some foods are high in both, such as spinach. Many are not. Almonds, beetroot, sweet potatoes and rhubarb are high in oxalate but are not considered high histamine foods. Aged cheese, wine and cured meat are high in histamine but low in oxalate.
• No recognised oxalate sensitivity syndrome. Outside kidney stones and some rare medical conditions, there is no established diagnosis of oxalate sensitivity with symptoms like fatigue, joint pain or skin reactions. These ideas are popular online but are not backed by good research. People with bowel conditions such as Crohn’s disease, or who have had gastric bypass surgery, can absorb more oxalate and should get medical advice about it. Large daily raw spinach smoothies or juices can also deliver a very high oxalate load.
• “Oxalate dumping”. Some websites warn that cutting oxalates suddenly releases stored oxalate and makes symptoms worse. There is no good scientific evidence for this.

So if spinach causes histamine-type symptoms, such as flushing, headache, itching or a blocked nose, its histamine content is the most likely explanation. Oxalate matters mainly if you are prone to kidney stones.

Cooking affects oxalate but not histamine

This is the most practical difference between the two. Oxalates dissolve in water, so boiling spinach and throwing away the water removes a large share of them. Histamine is heat stable, so cooking does not remove histamine that is already in the leaves.

• A 2005 study in the Journal of Agricultural and Food Chemistry by Chai and Liebman found that boiling reduced the soluble oxalate in vegetables by roughly 30% to 87%, while steaming reduced it by 5% to 53%.
• A 2018 study in Food Science and Technology Research found that boiling spinach at 100°C for two minutes removed about two thirds of its oxalic acid while keeping most of its lutein.

Boiling does not help with histamine. Some histamine may leach into the cooking water, but this has not been measured well, and you cannot rely on it. If you react to spinach because of histamine, cooked spinach is still likely to be a problem.

Other reasons spinach might disagree with you

Histamine and oxalates are not the only possibilities.

• Fibre and gut sensitivity. Large amounts of raw leafy greens can cause bloating or loose stools in some people, especially those with irritable bowel syndrome.
• Allergy. Spinach allergy is uncommon but possible, and can cause hives, swelling or mouth itching. Allergy testing can help if reactions are clear and consistent.
• Food safety. Bagged salad leaves have been linked to food poisoning outbreaks. Wash leaves and use them before their date.
• Interactions with medicines. Spinach is rich in vitamin K. If you take warfarin, sudden large changes in how much spinach and other leafy greens you eat can affect your blood clotting. Keep your intake steady and talk to your doctor before making big changes.

Leafy greens to eat instead

You do not need to give up leafy greens. Several are rated low in histamine and are lower in oxalate than spinach.

If you are prone to kidney stones, choose lettuce, kale, cabbage and bok choy rather than chard or beetroot leaves. If your main concern is histamine, all of the low rated greens above can replace spinach.

Swapping spinach in recipes

• Smoothies. Use kale or a handful of lettuce instead of spinach. Our low histamine smoothie recipes use these greens.
• Pasta and risotto. Stir in chopped kale or shredded cabbage at the end of cooking.
• Curries and stews. Kale or Swiss chard holds up well to simmering.
• Salads. Use lamb’s lettuce or little gem for a soft leaf.
• Omelettes and frittatas. Use courgette, kale or fresh herbs. Cook eggs through, as our article on the egg white liberator claim explains.
• Pesto and green sauces. Basil, parsley and rocket work well. See our low histamine sauces and condiments guide.

Fresh, frozen and canned spinach

Frozen spinach is usually blanched before freezing, which removes some oxalate. Freezing also stops further changes during storage, so frozen spinach is unlikely to gain more histamine in your freezer. It does not remove histamine that formed before freezing, though, and there is little data comparing histamine in frozen and fresh spinach. Canned spinach has been cooked and stored for a long time and is best avoided on a low histamine diet. Creamed spinach and spinach dips often add aged cheese, so they are higher again.

Buying and storing leafy greens

Whichever greens you choose, freshness makes a difference.

• Buy whole heads of lettuce or bunches of kale rather than pre-cut bags where possible. Cut leaves spoil faster.
• Check bags for slimy or yellowing leaves, and avoid them.
• Store greens in the fridge wrapped loosely in a clean cloth or paper towel, and use them within a few days.
• Wash leaves just before using them, not before storing.
• If you buy more than you can use, blanch kale or chard briefly and freeze it in portions.

Hidden spinach in ready meals and restaurants

Spinach turns up in more dishes than you might expect: saag curries, spanakopita, lasagne, stuffed pasta such as ravioli and cannelloni, green smoothies and juices, quiches, veggie burgers and “green” wraps. When eating out, ask whether a dish contains spinach, and look out for it in vegetarian options especially. Many of these dishes also contain aged cheese, which adds its own histamine.

Can you ever eat spinach again?

Some people with histamine intolerance find they can manage small amounts of very fresh spinach after the elimination phase, especially on days when the rest of their diet is simple. Because spinach contains histamine itself, it is usually one of the later foods to test. Our low histamine elimination diet plan explains the order of reintroduction.

1. Wait until your symptoms have been settled for a couple of weeks.
2. Buy fresh spinach and use it the same day, rather than a bag that has been open for several days.
3. Try a small portion, cooked or raw, with an otherwise simple, low histamine meal.
4. Note any symptoms over the next day in a histamine food diary, and repeat once more before deciding.
5. If you are prone to kidney stones, boil it and discard the water, and follow your doctor’s advice on oxalate.

If spinach clearly causes symptoms, there is no nutritional reason you need it. Other vegetables provide the same nutrients.

Replacing the nutrients in spinach

Spinach is often praised for iron, folate, vitamin K, vitamin A and magnesium. Here is where to find them on a low histamine diet.

• Iron. Fresh beef and lamb provide well-absorbed iron. Plant sources include oats, quinoa, pumpkin seeds and kale. Eating vitamin C-rich vegetables such as peppers or broccoli with plant sources helps absorption.
• Folate. Broccoli, asparagus, Brussels sprouts, cabbage and lettuce.
• Vitamin K. Kale, broccoli, cabbage, lettuce and other green vegetables.
• Vitamin A. Carrots, sweet potatoes, butternut squash, kale and red peppers.
• Magnesium. Pumpkin seeds, oats, quinoa, buckwheat and potatoes. Our article on magnesium for histamine intolerance has more detail.

Spinach, eggplant and other high histamine vegetables

Spinach is not the only vegetable with notable histamine. In the same Nutrients review, aubergine (eggplant) averaged even higher, and tomato is commonly avoided for other reasons. A widely cited review of histamine intolerance in The American Journal of Clinical Nutrition also lists spinach and tomatoes among foods frequently linked with symptoms. Our guide to tomatoes and histamine explains why tomato is a different case from spinach. For a wider view of foods to leave out at first, see high histamine foods to avoid.

Most other vegetables are rated low when fresh, including courgette, cucumber, carrots, broccoli, cauliflower, cabbage, peppers, green beans and root vegetables. That leaves plenty of choice.

Why spinach gets mixed up with so many claims

Spinach has a reputation as a superfood, and that makes the advice to avoid it feel surprising. It also means a lot of content online tries to explain reactions to spinach with whatever theory is popular at the time, whether that is histamine, oxalates, lectins or “detox” reactions. The simplest explanation is usually the right one. Spinach is a nutritious vegetable for most people, but it contains enough histamine to be a problem for some people with histamine intolerance, and enough oxalate to be a concern for people prone to kidney stones. Neither of these makes spinach harmful for everyone, and neither requires complicated theories to understand.

If you are unsure what is behind your symptoms, the most useful step is a short, well-planned elimination diet followed by careful reintroduction, with notes. That gives you real information about your own body, rather than guesses based on lists.

When to see a doctor

Call emergency services straight away if you or someone else has swelling of the lips, tongue or throat, difficulty breathing or wheezing, a hoarse voice, feeling faint or collapse after eating. These are signs of anaphylaxis, which needs an adrenaline (epinephrine) injection and urgent care.

Get urgent medical advice if you have severe pain in your side or back that comes in waves, blood in your urine, fever with urinary symptoms, or vomiting with severe pain, as these can be signs of a kidney stone or infection. See your doctor if you have had kidney stones before and want advice on oxalate, if you take warfarin and want to change how many leafy greens you eat, or if your symptoms do not improve on a low histamine diet. Do not stop or change prescribed medicines because of diet changes without medical advice.

Spinach questions answered

Is spinach high in histamine?

Yes. Published measurements show spinach contains much more histamine on average than most vegetables, and levels can rise during storage. It is usually avoided during a low histamine elimination diet.

Does cooking spinach reduce histamine?

No. Histamine is heat stable, so cooking does not reliably remove it. Boiling does remove a large share of the oxalate in spinach, which matters for people prone to kidney stones.

Are oxalates linked to histamine intolerance?

There is no good evidence that oxalates cause histamine release or histamine-like symptoms. Spinach happens to be high in both. Oxalate mainly matters for people prone to calcium oxalate kidney stones.

Is oxalate dumping real?

“Oxalate dumping” is a popular online idea that cutting oxalates suddenly makes symptoms worse. There is no good scientific evidence for it. If you need to change your oxalate intake for kidney stones, follow your doctor’s or dietitian’s advice.

What can I use instead of spinach?

Lettuce, rocket, kale, cabbage, bok choy and lamb’s lettuce are all rated low in histamine and work in salads, smoothies and cooked dishes. Kale, cabbage and bok choy are also lower in oxalate.

Is baby spinach lower in histamine?

There is no good evidence that baby spinach is lower in histamine than mature spinach. Freshness matters more than leaf size. Bagged baby spinach that has been stored for days may be higher, not lower.

Medical disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement regimen.