21 Carotenoids as Anti-obesity Supplements
543
Inflammation at the central level is largely suspected to be involved in obesity aetiologia via modulation of energy homeostasis (both at food intake and energy expenditure level) (Guillemot-Legris and Muccioli 2017). Indeed, the control of energy
homeostasis is finely tuned by nervous and endocrine mechanisms that cooperate
to maintain the balance between caloric intake and energy expenditure (Derghal
et al. 2017; Morton et al. 2006). In this respect, the central nervous system (CNS)
continuously monitors modifications in hormones (insulin, leptin, and ghrelin) or
metabolic parameters (i.e., blood glucose or free fatty acids levels) and elicits adaptive
responses like food intake (Derghal et al. 2017; Morton et al. 2006). Among the brain
regions involved in this regulation, the hypothalamus plays a pivotal role through
specific neuronal networks (Derghal et al. 2017; Morton et al. 2006; Berthoud 2002;
Schneeberger et al. 2014). Particularly, leptin is crucial to maintain both normal body
weight and feeding behavior by action in the different regions of the hypothalamus as
arcuate, paraventricular, or ventromedial nuclei as well as the lateral hypothalamus.
More particularly, this peripheral signal is detected by hypothalamic arcuate neurons
expressing the anorexigenic peptide POMC or the orexigenic peptides Neuropeptide
Y (NPY)/Agouti-related peptide (AgRP). These neurons project to melanocortin 3
and 4 receptor-expressing neurons located in hypothalamus and other brain structures (Morton et al. 2006; Mounien et al. 2005). Together these neurons are called
the melanocortin pathway and regulate feeding behavior, energy expenditure, and
glucose homeostasis through activation of the autonomic nervous system and higher
brain structures (Derghal et al. 2017; Morton et al. 2006; Berthoud 2002). A defect
in the communication between brain and peripheral organs can affect fat gain and
then lead to metabolic syndrome.
Obesity leads to increased inflammatory factors and immune cells in peripheral tissues and in brain regions that are essential for maintaining energy balance
(Guillemot-Legris and Muccioli 2017). In fact, the production of inflammatory
cytokines by adipose tissue and the accumulation of astrocytes and microglia (the
resident immune cells of the brain) in the hypothalamus can interfere with leptin
signaling and then can contribute to hyperphagia as well as many other obesity-related
diseases (Derghal et al. 2017; Morton et al. 2006). In this context, the endocrine function of the adipose tissue is essential to maintain a normal weight and the regulation
of energy homeostasis.
Several strategies have been proposed to fight obesity, including pharmacological
approaches, limitation of fat and sugar consumption, promotion of physical activity,
and consumption of fruits and vegetables. Indeed plant-based food is classically associated with weight management not only due to its macronutrient composition, but
also to the presence of micronutrients, such as carotenoids. Those molecules correspond to a large family of C40 lipophilic pigments produced by plants, fungi, and
bacteria (von Lintig 2010). Carotenoids can be divided into two groups according
to their chemical structure: carotenes, which are hydrocarbons, and xanthophylls,
which also contain oxygen and therefore are less apolar than carotenes. More than
600 different molecules have been identified, of which 50 can be found in human
diet, and of which only about 10 are present in significant amounts in human plasma
(Paetau et al. 1998). Carotenoids containing an unsubstituted β-ionone ring are
543
Inflammation at the central level is largely suspected to be involved in obesity aetiologia via modulation of energy homeostasis (both at food intake and energy expenditure level) (Guillemot-Legris and Muccioli 2017). Indeed, the control of energy
homeostasis is finely tuned by nervous and endocrine mechanisms that cooperate
to maintain the balance between caloric intake and energy expenditure (Derghal
et al. 2017; Morton et al. 2006). In this respect, the central nervous system (CNS)
continuously monitors modifications in hormones (insulin, leptin, and ghrelin) or
metabolic parameters (i.e., blood glucose or free fatty acids levels) and elicits adaptive
responses like food intake (Derghal et al. 2017; Morton et al. 2006). Among the brain
regions involved in this regulation, the hypothalamus plays a pivotal role through
specific neuronal networks (Derghal et al. 2017; Morton et al. 2006; Berthoud 2002;
Schneeberger et al. 2014). Particularly, leptin is crucial to maintain both normal body
weight and feeding behavior by action in the different regions of the hypothalamus as
arcuate, paraventricular, or ventromedial nuclei as well as the lateral hypothalamus.
More particularly, this peripheral signal is detected by hypothalamic arcuate neurons
expressing the anorexigenic peptide POMC or the orexigenic peptides Neuropeptide
Y (NPY)/Agouti-related peptide (AgRP). These neurons project to melanocortin 3
and 4 receptor-expressing neurons located in hypothalamus and other brain structures (Morton et al. 2006; Mounien et al. 2005). Together these neurons are called
the melanocortin pathway and regulate feeding behavior, energy expenditure, and
glucose homeostasis through activation of the autonomic nervous system and higher
brain structures (Derghal et al. 2017; Morton et al. 2006; Berthoud 2002). A defect
in the communication between brain and peripheral organs can affect fat gain and
then lead to metabolic syndrome.
Obesity leads to increased inflammatory factors and immune cells in peripheral tissues and in brain regions that are essential for maintaining energy balance
(Guillemot-Legris and Muccioli 2017). In fact, the production of inflammatory
cytokines by adipose tissue and the accumulation of astrocytes and microglia (the
resident immune cells of the brain) in the hypothalamus can interfere with leptin
signaling and then can contribute to hyperphagia as well as many other obesity-related
diseases (Derghal et al. 2017; Morton et al. 2006). In this context, the endocrine function of the adipose tissue is essential to maintain a normal weight and the regulation
of energy homeostasis.
Several strategies have been proposed to fight obesity, including pharmacological
approaches, limitation of fat and sugar consumption, promotion of physical activity,
and consumption of fruits and vegetables. Indeed plant-based food is classically associated with weight management not only due to its macronutrient composition, but
also to the presence of micronutrients, such as carotenoids. Those molecules correspond to a large family of C40 lipophilic pigments produced by plants, fungi, and
bacteria (von Lintig 2010). Carotenoids can be divided into two groups according
to their chemical structure: carotenes, which are hydrocarbons, and xanthophylls,
which also contain oxygen and therefore are less apolar than carotenes. More than
600 different molecules have been identified, of which 50 can be found in human
diet, and of which only about 10 are present in significant amounts in human plasma
(Paetau et al. 1998). Carotenoids containing an unsubstituted β-ionone ring are