Thermogenesis: the holy grail of fat loss
Thermogenesis, i.e. the oxidation (burning) of fat within fat cells for the creation of heat is the holy grail of obesity research.
Normally fat is stored in white adipose tissue (white fat cells) and it is burned in muscles, organs etc. However, brown fat cells have an increased number of mitochondria and actually oxidise fat themselves, with heat being the outcome of this oxidation.
Mitochondria are the parts of the cell where energy is primarily produced, and an increased number of them in a fat cell make the cell appear more brown, hence the name "brown adipocyte". Normal fat storing cells on the other hand are white, simply because they mainly contain one huge oil droplet and very few mitochondria.
A high level of a protein called UCP1 is a marker of increased mitochondria, brown fat cells and fat burning in fat cells / thermogenesis.
The last few years a new type of fat cell emerged: the beige fat cell. Beige fat cells are white fat cells which become brown due to the continuous stimulation by cold, exercise, strict dieting and various other causes.
Since the discovery of brown and beige fat cells, more and more natural chemicals are discovered that can turn white fat cells into brown fat cells. This process is called "adipocyte browning".
Thymol: a model of thermogenesis
In a recent study, thymol, a thyme essential oil component, has been now found to "brown" white adipocytes. Thymol is so effective in this process, that scientists want to use it as a model of adipocyte browning.
Indeed thymol was found to stimulate literally all the important "browning proteins" in fat cells: PPAR-gamma, PPAR-delta, AMPK, hormone sensitive lipase / HSL, perilipin, PGC-1α, beta3-adrenoreceptors, and more importantly, UCP1. To those initiated in adipocyte biology, these names sound like the "who is who" of adipocyte browning and fat burning.
This makes thymol a model of thermogenesis, to which all other thermogenic chemicals may be compared.
A potential food additive for the prevention of obesity
Thymol is already used in foods as it is contained in the herbs thyme and oregano. In addition to it's newly discovered thermogenic property, it is also a powerful disinfectant, antifungal and antibacterial.
But most importantly, thymol has a nice smell which adds a unique flavour to several dishes, especially meat, pasta, potato, fish, chicken etc. Thyme and oregano have been used for millennia in the preparation of food (in countries like Greece thyme and oregano and used almost every day), so it makes sense to add those herbs now to your recipes to reap it's health and culinary benefits.
Furthermore, thymol can be used as "a potentially promising food additive for the prevention of obesity", as the authors of this study conclude. Quite a few food products, skin products and mouthwashes already contain thymol, mainly for it's aromatic or disinfectant properties, but in the future we may see increased usage of this herbal extract in both foods and skin products. However, I do not foresee any thymol-rich fat-busting cosmetic products coming to the market anytime soon, for a very obvious reason: nobody wants to smell like meat marinade...
Although healthful in small quantities, isolated thymol and essential oils of oregano/thyme are quite harsh chemicals, so never take them internally or apply them on skin undiluted and never use those products, even diluted, without supervision by a healthcare practitioner.
- Paper: Monoterpene phenolic compound thymol promotes browning of 3T3-L1 adipocytes.
- Abstract: PURPOSE: Appearance of brown-like adipocytes within white adipose tissue depots (browning) is associated with improved metabolic phenotypes, and thus a wide variety of dietary agents that contribute to browning of white adipocytes are being studied. The aim of this study was to assess the browning effect of thymol, a dietary monoterpene phenolic compound, in 3T3-L1 white adipocytes. METHODS: Thymol-induced fat browning was investigated by determining expression levels of brown fat-specific genes and proteins by real-time RT-PCR and immunoblot analysis, respectively. Moreover, the molecular mechanism underlying the fat-browning effect of thymol was investigated by determining expression levels of key players responsible for browning in the presence of kinase inhibitors. RESULTS: Thymol promoted mitochondrial biogenesis and enhanced expression of a core set of brown fat-specific markers as well as increased protein levels of PPARγ, PPARδ, pAMPK, pACC, HSL, PLIN, CPT1, ACO, PGC-1α, and UCP1, suggesting its possible role in browning of white adipocytes, augmentation of lipolysis, fat oxidation, and thermogenesis, and reduction of lipogenesis. Increased expression of UCP1 and other brown fat-specific markers by thymol was tightly coordinated with activation of β3-AR as well as AMPK, PKA, and p38 MAPK. CONCLUSION: Our findings suggest that 3T3-L1 is a potential cell model for screening browning agents. Thymol plays multiple modulatory roles in the form of inducing the brown-like phenotype as well as enhancing lipid metabolism. Thus, thymol may be explored as a potentially promising food additive for prevention of obesity.