The Opuntia genus, known for its resilience in arid and semi-arid climates, presents a promising avenue for managing obesity and related metabolic complications. While Mexico boasts the highest diversity of wild Opuntia species, these cacti are globally distributed, with extracts demonstrating beneficial properties in preventing and treating certain metabolic disorders. This review aims to synthesize current knowledge regarding Opuntia ficus-indica (nopal or prickly pear) and other species like O. streptacantha and O. robusta, focusing on their impact on obesity and associated health issues.
Opuntia spp.: A Botanical Overview
Opuntia plants, belonging to the Cactaceae family, are characterized by their ability to thrive in challenging environmental conditions, given their capacity to grow in arid and semi-arid zones. They are distinguished by globose stems adorned with thorns, known as cladodes, which are flat, oval, fleshy segments bearing spikes (glochids). The genus is further recognized by its unique pear-shaped fruits, commonly called prickly pears. With over 250 species, opuntioid cacti are predominantly found in the Americas, with additional presence in Asia, Africa, Oceania, and parts of the Mediterranean. Opuntia fruits are widely consumed, and the plant's derivatives are utilized in pharmaceutical, food, and cosmetic industries, highlighting their significant economic value. Recognizing its minimal water requirements and substantial productivity, Opuntia serves as a viable option for animal feed, suggesting its potential contribution to agricultural development.
The Health-Promoting Power of Opuntia
For generations, folk medicine has documented the health benefits of the Opuntia genus, a tradition that remains relevant in many indigenous communities. These benefits are largely attributed to the plant's antioxidant and anti-inflammatory properties, stemming from its rich content of bioactive compounds like phenolic compounds, betalains, phytosterols, polysaccharides, and vitamins. All parts of the Opuntia plant, including roots, cladodes, seeds, fruits, and juice, contain phytochemicals like phenolic acids, pigments, and antioxidants, although their concentrations vary depending on the variety and plant part. The soil and geographical area of cultivation significantly influence the content of these bioactive compounds, making the chemical profile highly variable and dependent on climatic conditions.
Research Methodology
A comprehensive bibliographic search was conducted in the PubMed medical database up to May 2023, employing various combinations of keywords such as obesity, obesity management, body weight, anti-obesity agents, weight loss, overweight, metabolic syndrome, Opuntia, and cactus. The search was limited to original articles written in English. From the initial collection, 19 studies were selected based on the evaluation of their titles, abstracts, and full texts.
Effects of Opuntia spp. in In Vivo Models
Opuntia ficus-indica stands out as the most extensively studied cactus species in in vivo experimental models. These studies have utilized either genetic obese animal models or diet-induced obesity models.
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Genetic Obesity Models
Morán-Ramos et al. (2012) explored the effects of Opuntia ficus-indica cladodes on Zucker (fa/fa) rats, a genetic obesity model. Rats were fed either a control diet or a diet supplemented with dehydrated Opuntia ficus-indica cladode extract (4% fiber) for seven weeks. While no changes in weight gain were observed, the Opuntia ficus-indica-treated group showed a slight increase in daily food intake.
Diet-Induced Obesity Models
A substantial body of research has focused on the effects of cladode extracts from Opuntia ficus-indica in murine models characterized by high-fat diet-induced obesity. These studies involved diets providing fat in the range of 30-60% of energy or a cafeteria diet.
Aboura et al. (2019) investigated the impact of an aqueous extract of Opuntia ficus-indica cladodes on mice fed a high-fat diet (60% energy from fat), with or without 1% Opuntia ficus-indica cladode infusion in their drinking water for six weeks. The infusion contained 6.99 mg of polyphenols/100 mL. Mice on the high-fat diet exhibited significant increases in body and adipose tissue weight compared to those on a standard diet. However, supplementation with Opuntia ficus-indica infusion partially prevented obesity, as evidenced by lower values for both parameters. The infusion also completely prevented the high-fat diet-induced increase in gene expression of leptin and pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in adipose tissue.
Sánchez-Tapia et al. (2017) explored the potential of Opuntia ficus-indica supplementation to mitigate the metabolic consequences of obesity by modifying gut microbiota and preventing metabolic endotoxemia in rats subjected to a high-fat high-sucrose diet. Rats were fed either a standard diet or a high-fat-sucrose diet (45% energy from fat and 5% sucrose in drinking water) for the first seven months. Rats on the obesogenic diet for eight months showed significantly higher body weight. Supplementation with Opuntia ficus-indica prevented the increases in glucose and insulin serum levels, as well as serum triglyceride, total-cholesterol, LDL-cholesterol, and leptin levels induced by the high-fat feeding. Gut microbiota analysis revealed that the control group exhibited the highest diversity, while the obesogenic diet group had the lowest. Opuntia ficus-indica supplementation increased the abundance of Bacteroidetes relative to Firmicutes and prevented the reduction in intestinal mucus layer thickness and intestinal occludin-1 protein caused by the obesogenic diet, suggesting an improvement in intestinal permeability. Additionally, Opuntia ficus-indica supplementation reduced the expression of leptin, NADPH oxidase (Nox), Tnf-α, and amyloid precursor protein (App) genes in adipose tissue.
Héliès-Toussaint et al. (2020) analyzed the effects of a cladode extract from Opuntia ficus-indica on Sprague-Dawley rats fed a high-fat diet (30% energy from fat), with or without 0.5 w/w of the extract for eight weeks. Rats supplemented with Opuntia ficus-indica exhibited a significantly reduced body mass gain compared to those on the non-supplemented high-fat diet. Supplementation also led to a reduction in abdominal fat weight, serum glucose, insulin levels, and serum triglyceride levels, although these changes did not reach statistical significance. The Opuntia ficus-indica-supplemented group showed an increased amount of triglycerides in feces, which may contribute to the reduction in body weight.
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Urquiza-Martínez et al. (2020) investigated hypothalamic function by introducing Opuntia ficus-indica flour in either a standard diet or a high-fat diet. C57Bl/6J mice were divided into two groups, receiving either a standard diet or a high-fat diet (60% energy from fat) for twelve weeks. The cactus flour normalized body weight when administered with the high-fat diet, primarily due to the reduction observed in epididymal and retroperitoneal adipose tissues. Opuntia ficus-indica flour also improved glucose metabolism control and reduced activated microglial density in the hypothalamus.
Chekkal et al. (2020) assessed the impact of Opuntia ficus-indica cladodes on obesity and dyslipidemia in rats using a cafeteria diet (CD; 50% hyperlipidic diet + 50% junk food), supplemented or not with Opuntia ficus-indica cladode extract (OFI group; 50 g/100 g diet), for 30 days. Opuntia ficus-indica extract prompted a reduction in both body weight and adipose tissue weight. A decrease in food intake was also observed in rats fed the CD supplemented with Opuntia ficus-indica extract. The treated group showed a mitigation in serum glucose and insulin levels, decreased glycated hemoglobin and homeostasis model assessment of insulin resistance (HOMA-IR index), and a reduction in serum total cholesterol level. Serum triglycerides and very-low-density lipoprotein-triglycerides (VLDL-triglycerides) levels also decreased. The authors observed a significant decline in lipid peroxidation and an improvement in the enzymatic activity of paraoxonase 1 (PON-1) in the Opuntia ficus-indica-treated group.
Clinical Investigations of Opuntia ficus-indica
A 3-month clinical investigation demonstrated that cactus (Opuntia ficus-indica) fiber promotes weight loss. This double-blind, randomized, placebo-controlled, crossover study involved healthy subjects over approximately 45 days. Participants received either cactus fiber or a placebo, taking two tablets thrice daily with main meals. All subjects were provided with standardized meals containing 35% of daily energy needs from fat. The cactus fiber group exhibited increased fecal fat excretion compared to the placebo group.
The results of the study suggest that cactus fiber aids in reducing body weight by binding to dietary fat and increasing its excretion, thereby reducing the amount of dietary fat available for absorption.
Cactus Water: A Refreshing Hydration Beverage
Cactus water, derived from the prickly pear cactus, is emerging as a plant-based hydration beverage packed with electrolytes, antioxidants, vitamins, and minerals. It offers a natural, fruity alternative to plain water and coconut water, supporting hydration, skin health, weight regulation, and energy levels.
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Hydration and Electrolyte Balance
Cactus water is a natural source of five essential electrolytes and taurine, an amino acid that aids in muscle repair and building after exercise.
Antioxidant Protection
Prickly pear cactus water is rich in antioxidants that neutralize free radicals, preventing cellular damage and promoting overall wellness.
Anti-Inflammatory Properties
The anti-inflammatory electrolytes and antioxidants in cactus water help soothe inflammation and promote faster recovery, particularly after exercise.
Skin Health
Cactus water hydrates the skin from within, improving elasticity, preventing dryness, and supporting metabolic functions that impact skin health. Vitamins C and E in cactus water support collagen production, brighten skin tone, and protect against sun damage.
Digestive Health
Prickly pear is a source of fiber, essential for healthy digestion and regulating blood sugar and cholesterol levels.
Hangover Relief
Cactus water can alleviate hangover symptoms due to its antioxidants and hydration benefits, supporting liver recovery.
Nutritional Profile of Prickly Pear
Prickly pears are a good source of dietary fiber, magnesium, vitamin C, potassium, and calcium. They contain both soluble and insoluble fiber, essential for healthy digestion.
Potential Health Benefits
Prickly pear consumption may decrease fasting blood sugar levels in both healthy adults and those with type 2 diabetes. The antioxidant compounds in prickly pear may protect against inflammation and oxidative stress that can damage the liver.
Culinary Uses of Prickly Pear
Prickly pear fruits and nopales (cactus pads) are used in various dishes, including Mexican egg dishes, salads, tacos, soups, cocktails, juices, and jams.
Preparation of Prickly Pear
Proper preparation is essential to remove the glochids (prickles) from the exterior of prickly pears. Wearing gloves and using tongs, the glochids can be scraped off or singed off over a gas stove.
Prickly Pear and Weight Loss
Prickly pear consumption may lead to reductions in body fat, cholesterol levels, and blood pressure. The fiber in prickly pears binds to dietary fat, reducing its absorption and promoting satiety.
Anti-Inflammatory Properties of Prickly Pear
Cactus pear may help prevent and reduce inflammation, with studies showing reductions in inflammatory markers and increased antioxidant levels in subjects who consumed cactus pear fruit pulp.