Which vegies are the real nutrient powerhouses?

Move over kale. Watercress, followed by Chinese cabbage, silverbeet and spinach, is now top of the list as THE vegetable super food. So says a 2014 US study that ranked the top “powerhouse” fruits and vegetables according to their nutrient density score.

Next time you’re wolfing down a beef and watercress sandwich, ponder this - a new scientific report puts the peppery-tasting green at the top of a list of nutrient dense vegetables, herbs and fruits.

What is a powerhouse vegetable?

To compile the list, researchers from William Paterson University in New Jersey, USA looked at the nutrient density of more than 40 vegetables and fruits.

These foods were chosen because, on average, they provide 10 per cent or more of the daily recommended intake of 17 critical nutrients per 100 Calories.

These nutrients, which are considered of public health importance for reducing the risk of chronic diseases, are potassium, fibre, protein, calcium, iron, thiamin, riboflavin, niacin, folate, zinc plus the vitamins A, B6, B12, C, D, E and K.

Of the foods studied, 41 satisfied the powerhouse criterion providing preliminary evidence of the validity of the classification scheme which is offered as a tool for nutrition education and dietary guidance.

The top 41 winners

Watercress was the winner with a nutrient density score of 100, followed by close relatives including Chinese cabbage, collard and mustard greens.

Produce that belong to the cruciferous family (watercress, Chinese cabbage, collard green, kale, arugula – aka rocket) and the green leafy group (such as chard or silverbeet, beet greens, spinach, chicory, dark lettuces) were concentrated in the top half of the distribution of scores.

Produce belonging to the yellow/orange (carrot, tomato, winter squash, sweet potato), allium (scallion, leek), citrus (lemon, orange, lime, grapefruit), and berry (strawberry, blackberry) groups were concentrated in the bottom half.

The top fruits? Red capsicum or pepper, followed by pumpkin, tomato and lemon.

"The scores can serve as a platform for educating people on the concept of nutrient density," said study author Jennifer Di Noia. "The rankings provide clarity on the nutrient quality of the different foods and may aid in the selection of more nutrient-dense items within the powerhouse group."

However, some other nutrient-dense foods such as berries and garlic have not made the list because of the particular nutrient profiling that the study was based on, though in other nutrient density rankings they would rate highly, as Professor Di Noia acknowledged.

The 41 Powerhouse vegetables and fruit ranked by their Nutrient Density Score

^* Leaves from the tops of the round beetroot which look and cook up very similarly to Swiss chard or silverbeet.
^** All members of the Brassica or cabbage family which are similar in appearance to kale or cabbage.
^*** Dandelion is usually classified as an edible weed. Its long green leaves however are delicious and work well as a green leafy veg or in a salad.

Di Noia J. Defining Powerhouse Fruits and Vegetables: A Nutrient Density Approach. Preventing Chronic Disease 2014;11:130390.

The bottom line

You don’t have to eat just these 41 vegetables and fruits. All produce adds nutrition and variety to your meals. But these are the ones that stand head and shoulders above the rest. Any of them will add a nutrition bonus to your diet. You don’t HAVE to rely on kale.