**1. Introduction**

Carotenoids are tetraterpenoid molecules, which play an important role in the photosynthesis of bacteria, algae, fungi and plants. However, these molecules may have other not always clear roles because they could be synthesised in fruit chromoplasts or in plant roots, which are not involved in light-dependent energy conversion. In animals and humans, who can get carotenoids only with food, these molecules have an additional functionality, for example, in the retina they facilitate filtration of light with different wavelengths.

Apart from light-harvesting and antioxidant activities, carotenoids can modulate lipid phase transition in cellular membranes, which affects their fluidity, polarity and, consequently, their functional properties [1, 2]. In contrast to membrane biology,

the role of carotenoids in non-membrane lipid structures, such as lipid droplets or circulating lipoproteins, remains unclear. Only one property of these molecules is well documented, that they are hydrophobic antioxidants and can effectively protect lipoproteins and other lipids from free radical oxidation, which typically occurs in different pathological conditions [3, 4].

In this paper, based on our observations, we suggest that carotenoids may have another biological role. By creating thermodynamically favourable complexes with lipids, they can work as "thermal antennas" facilitating thermal energy absorption and conductivity, increase heat storage and heat retaining capacity and distribution within the lipid matrix of cellular and tissue structures. The reduction of lipid viscosity by carotenoids not only improves the control of thermogenesis but also increases oxygen solubility in lipid extra- and intra-cellular structures and boosts plasma lipoprotein oxygen transport, activation of mitochondria and tissue respiration.
