Oxalates, Salicylates, Histamine, and Sulfur. Oh My!

By: Liz Schau, CHHC

Average reading time: 4.5 minutes

In the world of thyroid nutrition, there is much emphasis on identifying food sensitivities. Things like gluten, dairy, soy, and egg sensitivities are commonplace and well-covered in the literature. But there are other types of food sensitivities we may not yet be aware of: the sensitivity to certain natural chemical substances found in food. Please know, we’re not sharing this information to overwhelm you, but it’s good for thyroid patients to be aware of. Say you’re following a dietary template like Paleo or AIP and not seeing results; these are additional rocks you can look under with the help of a holistic or integrative nutritionist.

When we think of “chemicals”, we often assume them all to be man-made, but plant and animal products also contain naturally occurring chemicals that can affect how our gut, immune systems, and hormones function. In my work over the last several years, I find that many clients are sensitive to these naturally occurring “chemicals” including oxalates, salicylates, histamine, and sulfur/thiols. Often, because a person has Leaky Gut Syndrome, impaired liver or kidney function, nutrient deficiencies, common genetic mutations, or lack of intrinsic enzyme production, they are unable to tolerate them. Let’s break these down so you can start to identify if they are in fact a problem for you.


Calcium oxalate is a mineral found solely in plant foods (as well as in bits of animal products we usually don’t eat, such as the bones or shells). Oxalates are the most acidic organic acid found in bodily fluids and, commercially, are even used to remove rust from car radiators (yikes!). Oxalates act differently than traditional food allergens because they can literally build-up in your system and get stored in the tissues. Oxalates also bind with minerals such as magnesium, potassium, and other dietary sources of calcium, making them unavailable for absorption.

In a healthy person, oxalate-degrading bacteria in the gut—specifically Oxalobacter formigenes and Lactobacillus—consume oxalates and digest them so that they do not end up in human tissues. A round (or more) of antibiotics that kills healthy gut flora, a stressful life event, a nutrient deficiency, gene mutations or pre-existing kidney or liver problems may also make eliminating oxalates impossible.

Because oxalates build up in the tissues, you may not notice side effects until your “bucket” is overflowing. Common oxalate sensitivity symptoms include pain (localized or widespread) specifically in the joints and muscles or any damaged tissues, kidney problems (kidney stones are the biggest one), G.I. distress or impaired gut function, urinary tract infections, recurrent candidiasis, bone loss or tooth enamel weakening, and mineral deficiencies. Oxalates can also deposit themselves on the surface of the thyroid itself, contributing to cysts.

Chocolate, spinach, nuts and seeds (chia, hemp), white potatoes, quinoa, buckwheat, soy, celery, olives, rhubarb, sweet potatoes, and beets are common high oxalate foods. If you suspect oxalates are a problem for you, keep in mind, you do want to reduce your intake very gradually because once you lower your intake a phenomenon called “dumping” will occur which is where oxalates will begin to rapidly exit the tissues, which can cause increased symptoms.



Salicylates are naturally occurring acids found in plant foods (and negligible amounts in animal foods) and they act as natural pesticides to protect plants. Interestingly enough, conventional plants that are sprayed with pesticides are reported to be lower in salicylates than their organic counterparts. This is due to the fact that pesticides kill bugs for the plant, so the plant doesn’t have to produce as much salicylic acid. (However, organic food is still preferable). Because of this and other factors, the salicylate content of foods can vary batch to batch. Factors affecting salicylate content include the season, the specific part of the plant that was tested, the ripeness, and if and how the food was cooked, or if it was left raw. Salicylates are also found in health and beauty products under various names, like methyl salicylate, salicylic acid, and essential oils or mint extracts, as well as aspirin.

Like oxalates, salicylates operate like a “bucket”. Once a person’s salicylate load becomes very high, they will begin to get allergic inflammatory reactions. These reactions can include seasonal allergies, recurrent yeast infections, sudden facial flushing, throat swelling, mood swings, asthma, IBS, or eczema outbreaks. If you have sluggish liver function, salicylate sensitivity is common because salicylates are broken down by phases 1 and 2 liver detoxification.

A low salicylate diet is pretty restrictive and the foods highest in this chemical include tomatoes, chilies and peppers, winter squashes, broccoli, eggplant, corn, spinach and other dark leafy greens, most herbs and spices, most fruits, and seaweed. Unlike oxalates, you can begin to lower your salicylate load immediately if you suspect you are sensitive.


Histamine is a neurotransmitter naturally produced by the body. It controls bodily functions like immune response, mood, sleep, and even helps to secrete gastric juices. Histamine is also present in many foods we eat. So a person may produce too much histamine as well as be eating a diet high in histamine without knowing it—both of which can cause symptoms. The body is also supposed to produce adequate levels of DAO, an enzyme that breaks down histamine, but due to gene mutations, gut dysfunction, nutrient deficiencies, and stress, people can lack adequate levels.

Foods highest in histamine include fermented foods, aged or cured foods (chocolate, yeast, alcohol, canned foods, meats, condiments, yogurt and cheese, bone broth), tomatoes, spinach, mushrooms, legumes, papaya, pineapple, strawberries, bananas, egg whites, and nuts. There are also foods considered “histamine liberators”, which are not high in histamine themselves but do contribute to your overall histamine load, including citrus, black tea, coffee, and other caffeinated drinks.

Going low-histamine can be done immediately. Additionally, adding in histamine-degrading and anti-inflammatory supplements also often help.


Sulfur is a mineral found in foods and soil. It’s also is a vital mineral for farming, animals, and people. Many people, however, are intolerant of high-sulfur foods and products due to gene mutations, nutrient deficiencies, or exposure to toxins (such as mercury). Thiols are the free form of sulfur and easily absorbed. Meat, for example, is high in sulfur but is the “bound” form, which is not as easily absorbed; cruciferous vegetables, on the other hand, are high in thiols, which are easily absorbed.

Sulfur molecules also help to produce glutathione, which is the body’s main antioxidant. Like many other food intolerances, sulfur can cause cravings for foods high in thiols, as well as a temporary “high” from eating these foods because it can stimulate norepinephrine responses. I have also observed that people with chronic fatigue often benefit from a low-sulfur diet.

Foods highest in sulfur include cruciferous vegetables, dairy, eggs, legumes, coffee, chocolate, maple, onions and other alliums, quinoa, sesame, and spinach. If you suspect you are sensitive to sulfur, you can eliminate it immediately. There are also supplements that help with processing sulfur. Additionally, check your beauty and hygiene products for any added sulfur ingredients.

Going Forward

As with any food sensitivity, it often requires a process of elimination. I suggest taking any food group you suspect you are sensitive to out of your diet for at least 4 weeks (with the exception of oxalates, which should be reduced gradually). Then reintroduce several times a day for about 3–4 days. Keep a log to note what you ate and any additional symptoms that pop up. Or better yet, use this handy food sensitivity tracker.

If you notice that you are sensitive to a class of these food chemicals, you may want to keep them out, or at a low level indefinitely. However, as mentioned above, there are supplements that can be strategically added in to help you process them better, or to lessen the side effects if you do overfill your bucket. In the big picture, eliminating any foods you are sensitive to will certainly help improve the status of your hormone, immune, and gut function.



About the Author

Liz Schau is a Certified Holistic Health Coach and Intuitive who specializes in nutrition and mind-body strategies for thyroid and autoimmune conditions. She is the former Wellness Coach for the renowned NYTimes bestselling author Amy Myers, M.D. and was trained by Dr. Myers in functional medicine approaches to autoimmune and thyroid diseases. She is also the former Nutritional Health Coach for Natural Grocers by Vitamin Cottage. She was diagnosed with Hashimoto’s Disease in 2007 and was able to put it into unmedicated remission in 2009. She can be found at