I wrote here on sulfur intolerance, or the phenomenon of seeing to be sensitive to any foods or supplements containing sulfur. I wrote here on how in many cases, SIBO producing H2S gas can be a compensatory mechanism for inability to convert sulfur to the usable form for detoxification, and thus producing an alternative source.
There’s more to sulfur than just detoxification, though—it’s a very important element, and even those who are sensitive can’t completely avoid it. There are also many reasons why we might be depleted… and this may be part of the reason for recurrent dysbiosis (imbalance in the gut microbiome) and leaky gut.
Why Sulfur Is Critical
By weight, sulfur ranks as the eighth most abundant element in the human body. It’s found in two of the main amino acid building blocks in the body: one of which is essential (methionine) and the other is conditionally essential (cysteine).
Disulfide bonds (bonds between two sulfur molecules) are what give skin, hair, and fingernails their strength. Sulfur is a primary component of glycosaminoglycans (GAGs) which form the scaffolding for collagen, and everything made of collagen—including the lining of the intestines. Adequate sulfur is therefore necessary for maintaining the intestinal barrier.
Additionally, sulfur combines with cholesterol, in the skin and in the liver, to form cholesterol sulfate. This forms part of bile, and aids in fat digestion. It also helps to keep the microbial population in the intestines in check, as sulfur is inherently antibacterial, antifungal, and even anti-parasitic.
When a cell finds itself unable to produce adequate ATP (the body’s energy currency) via its mitochondria due to lack of oxygen, the mitochondria trigger production of H2S (hydrogen sulfide) gas. This in turn increases the efficiency of ATP production.
H2S does more than just this, though, even though increasing ATP production is pretty huge; it’s also considered a “gasotransmitter,” sending signals in a wide range of systems throughout the body.
Why We’re Sulfur Deficient
Sulfur is abundant in animal products as well as a variety of vegetable sources. Anyone who eats a non-restrictive whole food diet should, in theory, get plenty of it.
Processed carbohydrate sources, however, are especially deficient, and this increasingly forms the backbone of the Standard American Diet.
Many also avoid animal products, for a variety of reasons, which eliminates that major source.
Vegetable sources of sulfur don’t contain the amounts that they once did. This mostly has to do with soil depletion due to modern industrial farming practices.
We used to get around 10% of our sulfur from our water supply. Many of us these days, in an effort to avoid all the other water contaminants, are drinking distilled or Reverse Osmosis water, which eliminates minerals and electrolytes along with the toxins—so that eliminates the water source of sulfur too.
Finally, we can also produce cholesterol sulfate, an abundant source of sulfur, in our skin via sunlight exposure. Those of us who don’t get enough sun exposure or slather ourselves in sunscreen whenever we do may be missing even this source.
Sulfa Drug Sensitivity vs Sulfite Sensitivity vs Sulfur Intolerance
Many people believe that they are allergic to sulfur due to allergic reactions to sulfa drugs. This is not a reaction to sulfur, however, but to a compound called sulfonamide, which then gets attached to proteins in the body. Some people’s immune systems flag this complex as foreign, leading to a true allergy—but it’s not an allergy to sulfur itself.
A sulfite sensitivity usually presents like an allergic response. This is due to an inability to convert sulfites into sulfates, which is mediated by an enzyme called sulfite oxidase (SUOX). This can be due to a genetic mutation, a deficiency in molybdenum, the necessary cofactor for SUOX, or a heavy metal toxicity.
Sulfates are the usable form. These should not cause a problem—but your body still has to do the work to make it (unless you absorb it though your skin, via Epsom salt baths, which are magnesium sulfate).
Sulfur Intolerance May Imply Sulfur Deficiency
As I wrote here, at least those with H2S SIBO are generally sulfur intolerant—i.e. they feel worse when they consume foods or supplements high in sulfur. But the bacterial overgrowth may be providing a necessary gasotransmitter for the body’s continued function, since the SUOX enzyme isn’t converting food and supplement sources of sulfur to the usable form.
Also, as mentioned above, a cell in distress (or an anaerobic cell, one that thrives without oxygen) uses sulfur as an alternative source to produce sufficient ATP. This is particularly interesting with respect to SIBO, as most of the bacteria involved are anaerobes—even those that don’t specifically produce excessive amounts of H2S primarily. This implies that other forms of SIBO too may actually thrive on sulfur. (I am indebted to Dr Kathleen Janel for this insight!)
It’s possible that sulfur intolerance is due to SUOX under-functioning, or due to CBS (Cystathione beta synthase) over-functioning, which is the common manifestation of that genetic mutation, or both. A CBS speed-up mutation will potentially overwhelm even a normally functioning SUOX. This can lead to too many sulfites (generally an allergic symptom presentation) and/or too much ammonia secondary to the CBS activity, which typically looks like confusion, fatigue, weakness, poor appetite, nausea, and back or abdominal pain.
Either way, there’s too much sulfur in one part of the pathway, and too little where it counts: in the sulfate form.
If this is you, the long-term solution isn’t to avoid sulfur completely; it’s to first correct the problem if it isn’t genetic (such as heavy metals or SIBO or molybdenum deficiency), quench any excess ammonia with chlorophyll (leafy greens, or a tincture version), and then slowly re-feed the sulfur pathways even with minute amounts of sulfur, as tolerated.