The third most abundant mineral in the body after calcium and phosphorus, sulfur (which has the chemical symbol S) is defined more specifically as a trace-element or macro-element: it generally represents 0.3% of bodyweight. It is also classified as essential, in that we are unable to produce it ourselves. (1). Sulfur plays a major role in the body’s biological processes, and is thus a prime compound.
Located in a number of body tissues, it forms part of the composition of keratin in the skin, hair and nails and chondroitin sulphate in joint cartilage. Truly ubiquitous, it also forms part of the structure of sulfur-containing amino acids (such as methionine and cysteine), the building blocks of proteins, as well of that of vitamins B1 and B8. And the ultimate proof of its importance is that it plays a role in no fewer than 400 different enzymatic reactions.
Despite its many qualities, sulfur suffers from a somewhat tarnished image, primarily because sulfur dioxide, the gas produced when sulfur is burned, gives rise to the infamous sulfites of the agro-food industry, much-criticised for their allergenic nature (2). It’s also because once it’s reduced to a powder and burned, it gives off toxic, foul-smelling fumes which are diverted for military purposes.
However, it’s important to distinguish this from the sulfur provided naturally by the diet, which remains essential for meeting our physiological needs (3). Even though health authorities have not established a daily reference intake for sulfur, WHO experts agree on nutritional recommendations of 13mg sulfur-containing amino acids per kilo a day for adults (4).
Present at trace levels in all foods, sulfur is found at higher levels in certain foodstuffs (5). So here, at last, is the sulfur top 10!
A staple of Asian cuisine, long-grain rice contains approximately 35mg of sulfur per 100g. Like all grains, it contains sulfur-containing amino acids (methionine and cysteine), which pulses mostly lack. That’s why vegetarians eat them together to reform complete proteins!
Part of the Alliaceae family, onions contain sulfur in the form of particular compounds called allyl sulfides (6-7). However, it’s only when they’re cut, that they really become active (and, by the way, make us cry).
While all varieties of onion contain a tiny amount, red onions are a little in front with close to 50mg of sulfur per 100g.
Slightly ahead of onions comes garlic with almost 64mg of sulfur per 100g. There’s significant scientific interest in this little bulb because of its content in alliin which when crushed, is converted into allicin, a valuable sulfur-containing compound (8).
Containing all the essential amino acids, eggs provide a sizeable amount of sulfur with 125mg per 100g! A great alternative to meat, particularly for vegetarians.
Make sure to eat the yolk too, as it contains more of the methionine/cysteine combo, weight for weight, than the white (9).
That smell of broccoli when it’s cooking? Once again, that’s sulfur! With a considerable 140mg per 100g, this cruciferous vegetable more than holds its own in the sulfur stakes. Its content of the much-studied sulfur-containing compounds glucosinolates, makes this a constantly ‘high-profile’ vegetable (10). Lightly steam the florets till tender so as not to lose their value.
It’s worth noting that all the other members of the Brassica family (such as cauliflower, Brussels sprouts, turnips and radishes) also acquit themselves well in terms of sulfur content.
Rich in vitamins (A, C, B1, B2, B9 and E), as well as minerals and fibre, the pumpkin seed is certainly no slouch when it comes to sulfur with a very decent 146mg per 100g, like most oilseeds (nuts, sesame seeds, peanuts …).
Add a handful to your bread or muffin dough to add crunch and nutrition!
Not crazy about offal? That’s a shame, because with a considerable 199mg per 100g, calves’ liver is one of the most sulfur-rich foods, with an excellent nutritional profile to boot. The more adventurous among you could also try kidneys or hearts, for a bit of variety …
A rib steak is often a more popular choice than offal. Which is interesting, as beef is neck-and-neck with calves’ liver when it comes to sulfur content with almost 200mg per 100g.
That doesn’t mean you should eat it to excess: according to the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) you should not exceed 500g of red meat a week(11).
The ultimate lean fish, cod is in silver medal position when it comes to providing sulfur with 260mg per 100g. Very low in calories, it also contains vitamin B12, iodine and selenium (12).
Take care, however, with salt cod: though it’s essentially the same fish, its salted, dried flesh can significantly raise your sodium levels.
Whether crustaceans or shellfish,seafood comes in at first place. While there are few available studies on their sulfur content, it seems that certain species such as lobster, crab and clams, have almost 500mg per 100g. An excellent reason to treat yourself to a seafood platter from time to time!
To go further ... have you heard about methyl-sulfonyl-methane, or MSM? This natural form of organic sulfur is a precursor of mucopolysaccharides, key substances for joint health (like chondroitin, glucosamine and hyaluronic acid) (13-14).
Present at trace levels in many foods, and abundant in the milk of mammals, MSM has been available as a dietary supplement since the 1990s. However, there are significant differences in how it is manufactured, which directly affects it purity and safety.
So if you want to take an MSM supplement, make sure you choose one where the molecules are isolated without crystallisation to protect yourself from heavy metals and other contaminants (try, for example, the product OptiMSM®, the purest MSM supplement on the market, produced using heat distillation only, with no controversial solvents).
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