L-selenomethionine (selenium) supplement: immunity, etc.

Selenium is a natural selenium supplement with optimal efficacy and bioavailability. Its organic form (selenomethionine) obtained from yeast extracts offers superior absorption than classic inorganic selenium supplements.

Essential to life, this trace-element plays a role in, amongst others, fighting oxidative stress, supporting normal immune function and maintaining healthy hair and nails. It thus remains a weapon of choice during periods of fatigue and convalescence.

What is selenomethionine?

Selenomethionine is the most abundant form of selenium in our diet. It’s primarily found in plant-source foods (grains, soya, brewer’s yeast …). When grown in selenium-rich soil, plants are able to capture this mineral and metabolise it into organic derivatives (1).

Chemically, selenomethionine corresponds to the selenium analogue of methionine, one of the 22 proteinogenic amino acids. In other words, methionine shares the same molecular formula as selenomethionine, but its sulphur atom is replaced by a selenium atom. This biochemical proximity means selenomethionine is able to integrate certain proteins in the body called selenoproteins. In this form, it can be durably stored in tissues, particularly muscle tissue, and released as necessary to meet the body’s needs.

The replacement of methionine by selenomethionine in the protein structure does not cause any notable change in function, and may even present some advantages. For example, compared with sulphur, selenium may offer additional protection against oxidative processes(3). In addition, during photochemical reactions, the carbon-selenium bond is more easily broken than the carbon-sulphur one: selenomethionine thus reacts better to the energy of ultraviolet light (4).

What’s the best form of selenomethionine?

First of all, it’s worth noting that organic selenium chelated with amino acids (such as selenomethionine or selenocysteine) is is better assimilated than inorganic selenium salts (such as selenite or selenium sulphide) (5). Selenomethionine displays an average absorption rate of around 90%, compared with 50%-60% for inorganic forms.

To be fully bioassimilated, a selenium supplementat needs to contain a form naturally ingested through food. The L isomer of selenomethionine, better-known as L-selenomethionine, is the form most commonly found in our diet (6). Perfectly-adapted to human metabolism, it offers superior bioavailability and produces a rapid increase in blood selenium levels(7).

What are the benefits of selenium?

According to EFSA-approved claims, selenium helps to:

• maintain normal immune system function: several studies have demonstrated the role played by selenoproteins in the activation, proliferation and differentiation of immune cells, as well as in modulating immunity(8);
• protect cells against oxidative stress: as a cofactor of glutathione peroxidase, a redox enzyme, selenium supports the neutralisation of free radicals that attack cell membranes (9). Conversely, a lack of selenium may exacerbate the toxicity of by-products of redox reactions;
• maintain normal thyroid function: the thyroid is the organ with the highest selenium content in the body. This trace-element regulates thyroid hormone production, specifically triiodothyronine (T3) (10) ;
• support normal spermatogenesis: selenium is particularly involved in the metabolism of testosterone and in sperm motility (11) ;
• maintain healthy hair and nails: as a result of its antioxidant properties, selenium helps to make the hair stronger and shinier (12), and the nails beautiful and glossy.