Table 1.

General characteristics of the assessed diets

Type of diet	Characteristics	Components
Mediterranean diet (MD) [54]	Plant-based diet originating around the Mediterranean Sea’s olive-producing regions	Olive oil as the main source of fat, cereals, vegetables, fruit, grains and legumes in abundance, seafood (frequently), moderate consumption of poultry, dairy products, nuts and alcohol, low intake of red meat, sugar, and juices
Plant-based diet [55]	Group of diets ranging from vegan to semi-vegetarian	High consumption of fiber, β-carotene, vitamin A, lutein, zeaxanthin, and vitamin C
Very low-calorie diets (VLCD) [56]	400–500 kcal per day administered in an effort to induce rapid weight loss	Meal replacement products that contain mostly proteins and carbohydrates
Low-calorie diets (LCD) [57]	1000–1300 kcal per day administered in an effort to induce slow weight loss	Consisting of approximately 20% protein, < 30% fat, and 50–60% carbohydrates of energy consumed
Gluten-free diet [58]	Excludes products containing gluten. According to the European Commission guidelines, a gluten-free product consists of less than 20 mg/kg gluten. It is the only treatment for celiac disease	Excluded products are sausages, soups, soy sauce, ice cream, wheat, rye, barley, and oats Included products are legumes, fruit, vegetables, unprocessed meat, fish, eggs, and dairy products
Low-salt diet [59]	Maximum daily sodium intake: 3 g Na or 7.5 g of sodium chloride
Vegetarian diet [60]	Excludes meat consumption and animal slaughter by-products	Vegetable oils, nuts, soy, plant sterols, fruits, vegetables, whole grain, nuts, dairy products, honey, and eggs
Prudent diet (PD) [31]	Compared to the MD, it contains less fruits, vegetables, cereal, and fish and more red meat and juices	Root vegetables, dairy products, eggs, oil (both vegetable and olive), cereals, juices, low consumption of processed meat, fried foods, processed sweets, alcohol, and snacks
High-protein diet (HP) [61]	Almost double than recommended dietary allowance of protein	Increased protein content (1.6 g of protein/kg/day, 30% of total daily energy) (recommended protein intake 0.8 g of protein/kg/day approximately 10–15% of total daily energy)