Obesity is a clinical condition, the prevalence of which has increased significantly in recent decades in Western countries and, later, worldwide. Obesity has been defined as a pandemic and one of the main health problems of all time. The prevalence of overweight in children is over 25%, while in adults it is more than 50%; this prevalence is associated with the extreme changes in diet occurring in western countries. That can be summarized as an increase in the consumption of non-nutritional carbohydrates, in particular sugary drinks that have led to an increase in the rate of chronic diseases related to obesity, such as diabetes and cardiovascular disease. There are multiple molecular mechanisms that link obesity to its complications such as type 2 diabetes mellitus, hypertension, hypercholesterolemia, atherosclerosis, non-alcoholic fatty liver disease, among others. However, inflammation is a common feature that has been implicated in the pathophysiology of many disorders associated with obesity. Perturbed lipid metabolism is a common feature of obesity, leading to dyslipidemia and resulting in elevated plasma concentrations of triglycerides, VLDL and LDL and subnormal HDL levels, a phenotype associated with accelerated atherosclerosis and high cardiovascular risk.
The consequence of the metabolic syndrome of obesity is in part associated with alterations in adipose tissue; however, it is not the only one involved, among other participating tissues such as the liver. Insulin resistance is one of the most common alterations on obesity and is closely linked to diseases such as type 2 diabetes, atherosclerosis, hypertension, among others. The definition of resistance to insulin implies a lower sensitivity of insulin by cells and changes in glucose metabolism. In obesity and type 2 diabetes there is a decrease in insulin-stimulated glucose transport and metabolic alterations of fat tissue. The complex pathogenesis of obesity indicates the need for different intervention strategies to tackle this problem. Herbal supplements and weight loss diet therapies are among the most common modes of complementary and alternative medicine. As an alternative treatment of obesity and its complications, in the market there are a variety of natural products that includes medicinal plants, both as pure and extracted compounds. Different plants contain a large variety of different components with different anti-obesity effects on the body metabolism and on the oxidation of fats, and for this reason they have been studied and reported as useful in the treatment of obesity, diabetes and other chronic diseases .
The most studied plant for its wide range of effects including anti-obesity and antioxidant properties is tea (Camellia sinensis). Dozens of studies have shown its beneficial effects on obesity. Several mechanisms of anti-obesity action have been reported for tea, including inhibition of pancreatic lipase (Grove et al., 2012; Yuda et al., 2012), activity of appetite suppression (Moon et al., 2007 ; Wolfram et al., 2006), down-regulation of adipogenesis (Lu et al., 2012), thermogenesis (Hursel et al., 2011) and lipid metabolism. On the other hand, Park et al. (2011) reported that tea extract attenuates fatty liver by reducing lipogenesis and improving conditions of hepatic oxidative stress in ob/ob mice. In addition, treatment with green tea polyphenols administered to male fat Wistar rats reduced total serum concentrations of cholesterol, LDL and triglycerides compared to obese controls at any dose tested (Tian et al., 2013).
St John’s wort (Hypericum perforatum) is a perennial herbaceous plant, native to Europe and Asia, and subsequently introduced in America, where it has been naturalized. H. perforatum is traditionally used for its health benefits associated with its sedative potential in alterations such as depression, anxiety and neuralgia, among others (Newall et al., 1996). Several studies report that H. perforatum has an anti-obesity activity. An anti-obesity action mechanism reported for H. perforatum is the amount of serotonin present in neurons and which inhibits the absorption of serotonin. This increase in serotonin levels reduces food intake and suppresses appetite. Furthermore, H. perforatum has shown activity against the complications associated with obesity. Husain et al. (2011) reported that the hydroalcoholic extract of H. perforatum (50%) significantly inhibited the increase in plasma glucose (85%) and insulin (89%) caused by fructose feeding and 200 mg / kg of this extract significantly reduced plasma glucose (29%), insulin (12%) total cholesterol level (16%) and triglyceride levels (18%), compared to the fructose-fed control group.
Common beans (Phaseolus vulgaris) are considered an important source of protein in Latin American countries. For this reason it is an important grain legume that includes 50% of consumption worldwide (Broughton et al., 2003). In a recent study, Zhu et al. reported that consumption of common beans in mice reduced body weight by reducing plasma leptin concentrations (Zhu et al., 2012). Although the differences between the final body weights between the groups were not statistically significant. In clinical studies, Celleno et al. (2007) reported that a dietary supplement containing 445 mg of P. vulgaris extract, after 30 days of treatment, in subjects with a carbohydrate diet, from 2000 to 2200 calories, had significant reductions in body weight (4%) , fat mass (10%) and waist / hip circumference (3 / 1.3%, respectively) with respect to the baseline. Of the anti-obesity mechanisms reported for P. vulgaris, the inhibitory action reported on α-amylase by active components is well known. These same substances also have an anti-inflammatory effect on experimental models of obese mice.
Rosemary (Rosmarinus officinalis), evergreen perennial shrub of the Labiatae family, is cultivated in many parts of the world and widely used as a spice, food supplement and for cosmetic applications (Aguilar et al., 2008; Harach et al., 2010). Several studies report the effect of R. officinalis to promote weight loss. Harach et al. (2010) experimented with leaf extracts administered for 50 days at 200 mg/kg body weight in mice fed a high-fat diet, which induced a significant reduction in weight and increase in fat mass (64 and 57%, respectively). The main anti-obesity activity reported for rosemary is that it increases the excretion of faecal fat without decreasing food intake. On clinical trials, Labban et al. (2014) reported that 10g/day of rosemary leaf powder for 4 weeks in men and women aged 20 to 57 years, significantly reduced fasting serum glucose (18%), total cholesterol (34%), the concentration of LDL (34%), triglycerides (29%) and malondialdehyde (36%) compared to baseline. These results suggest that rosemary is a good natural alternative to obesity and its metabolic abnormalities.
Grapefruit (Citrus paradisi) was discovered for the first time in the forests of the Caribbean island, in Barbados. The fruit is a natural hybrid of pomelo and orange. Although grapefruits are traditionally used to lose weight, there are only a few studies related to this activity. On the other hand, in a clinical trial, Fujioka et al. (2006) reported an anti-obesity effect of fresh grapefruit, grapefruit juice and grapefruit capsules in obese patients with diagnosed metabolic syndrome. Ninety-one humans were included in 4 groups: placebo (placebo capsules and 207 ml of apple juice), group 2: (grapefruit capsules with 207 ml of apple juice), group 3 (237 ml of grapefruit juice with placebo capsule), and group 4 (half a fresh grapefruit with a placebo capsule) three times a day before each meal. After twelve weeks of treatment, group 4 had the highest effect with a decrease of 1.6 kg, followed by group 3 and group 2 with 1.5 and 1.1 kg respectively.
Pomegranate (Punica granatum), in particular its fruits, has a vast history of ethnomedics and is a phytochemical reservoir of medicinal value. Biological studies on pomegranate juice have shown antidiabetic effects. This activity is attributed to the high antioxidant capacity of the pomegranate, which can be attributed to its high content of polyphenols. On obesity research, Lei et al. (2007) reported that treatment with pomegranate leaf extracts (400 and 800 mg / kg / day) for 5 weeks, in obese mice fed with a high lipid diet, significantly decreased weight (12 and 20% respectively ), the energy supply (14 and 30%, respectively) and the adipose panniculus. In clinical studies, Mirmiran et al. (2010) reported that the consumption of pomegranate seed oil (400 mg) twice a day, for 4 weeks by hyperlipidemic subjects, diagnosed according to the definition of the National Cholesterol Education Program, reduced the total concentration of serum triglycerides (20 %) compared to baseline values. Furthermore, more detailed molecular / cellular studies on humans are needed to relate the potential anti-obesity of the fruit as a common consumption by the population.
So we are not alone in the fight against obesity and all the potential problems that come with it. Mother Nature’s help is always there, supporting us in the journey of our knowledge.
- edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
Lu C et al. PloS One. 2012; 7:e38332.
Bose M et al. J Nutr. 2008; 138:1677–83.
Celleno L et al. Int J Med Sci. 2007; 4:45.
Dow CA et al. Metabolism. 2012; 61:1026–35.
Dulloo AG et al. Int J Obes. 2010; 34:S4–S17.
Shamki AW et al. J Cell Plant Sci. 2012; 3:17–21.
Bustanji Yet al. J Med Plants Res. 2010; 4:2235–42.
Cunha CA et al. Mediators Inflamm. 2013; 2013:1–8.
Husain GM et al. ISRN Pharmacology. 2011; 2011:1–7.
Vroegrijk IO et al. Food Chem Toxicol. 2011; 49:1426–30.
Viuda-Martos M et al. Compr Rev Food Sci F. 2010; 9:635–54.
Boden G. Curr Opin Endocrinol Diabetes Obes. 2011; 18(2):139.
Hasani-Ranjbar S et al. J Diabetes Metab Disord. 2013; 12(1):28.