Health experts recommend regular and sufficient consumption of fruits and vegetables for better health and to reduce risks for unwanted medical conditions such as cancer and heart diseases but some fruits and vegetables are better and healthier than the others.
Jennifer Di Noia, a researcher from the William Paterson University in New Jersey, has conducted a study to have a clear definition of the so called power house food and vegetables (PFV), which contain the highest amounts of crucial nutrients needed to avoid chronic diseases.
In her study "Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach" which was published in the Centers for Disease Control and Prevention (CDC) journal Preventing Chronic Disease, Di Noia looked at the amount of certain nutrients in different fruits and vegetables that fall to the loose definition of PFV.
Di Noia particularly looked for 15 nutrients that are considered of public health importance as recommended by the United Nations' Food and Agriculture Organization and the Institute of Medicine, which included fiber, protein, potassium, calcium, iron, riboflavin, thiamin, niacin, folate, zinc, and the vitamins A, B6, B12, C, D, E and K.
Of the 47 different foods that she examined, Di Noia identified 41 that meet the powerhouse criterion of providing at least 10 percent of the daily value per 100 kcal of the 17 key nutrients. Watercress, which received a nutrient density score of 100, topped the list of powerhouse vegetables and fruits.
"It is a nutrients-to-calories ratio that expresses the mean of percent daily values for the qualifying nutrients the food provides per 100 calories," Di Noia explained of the scoring system that she used. "So higher-ranking foods provide more nutrients-per-calories."
Watercress, which is also known as a good source of iodine and folic acid, is followed by chinese cabbage which got a score of 91.99, chard (89.27), beet greens (87.08), spinach (86.43), chicory (73.36), leaf lettuce (70.73), parsley (65.59), romaine lettuce (63.48), collard green (62.49), turnip green (62.12), mustard green (61.39), endive (60.44), chive(54.80), kale (49.07), dandelion green (46.34), red pepper (41.26), arugula (37.65), broccoli (34.89), pumpkin (33.82), brussels sprout (32.23), scallion (27.35), kohlrabi (25.92), cauliflower (25.13), cabbage (24.51),carrot (22.60), tomato (20.37), lemon (18.72), iceberg lettuce (18.28), strawberry (17.59), radish (16.91), all varieties of winter squash (13.89), orange (12.91), lime(12.23), pink and red grapefruit (11.64), rutabaga (11.58), turnip (11.43), blackberry (11.39), leek (10.69), sweet potato (10.51), and white grapefruit (10.47).
Di Noia included blueberry, raspberry, tangerine, cranberry, garlic and onion in the foods that she studied but these do not contain sufficient amounts of the qualifying nutrients. Although these foods were rich in phytochemicals, phytochemicals was not considered in the calculation of the nutrient density score.