Superfoods are foods — mostly plant-based but also some fish and dairy — thought to be nutritionally dense and thus good for one's health. The term has no set scientific meaning, however, and any list of "top" superfoods is purely subjective.
Superfoods are healthful, for the most part, aside from possible contamination, added sugars or over-consumption of them.
Lists of superfoods are extensive on the Internet. Some websites list as many as 50 or 100. At this point, the term "superfood" becomes largely meaningless or, at best, synonymous with just about any fruit or vegetable. Another problem with the term is that some so-called superfoods fall in and out of favor with dieticians, such as coffee or eggs.
A generic list of superfoods
At a very basic level, superfoods are said to be rich in particular nutrients. This could be an antioxidant, thought to ward off cancer; a healthy fat, thought to prevent heart disease; fiber, thought to prevent diabetes and digestive problems; or phytochemicals, the chemicals in plants responsible for deep colors and smells, which can have numerous healthful benefits.
Blueberries often top many lists of superfoods. This is because blueberries are rich in vitamins, phytochemicals and soluble fiber. While blueberries are indeed healthful, so are about any kind of (non-poisonous) berry. Blueberries aren't necessarily better than cranberries or raspberries, but they are usually more readily available and are quite palatable as is.
Kiwifruit also tops many a list. Its benefits are similar, for the most part, to berries, melons, citrus fruit, apples and pears. Kiwifruit is labeled a superfood perhaps because it contains a wider range of nutrients compared to some other fruits.
Beans and whole grains are standard additions to the superfood lists. Beans are a source of low-fat protein. Beans have insoluble fiber, which lowers cholesterol; soluble fiber, which provides a longer feeling of fullness; and loads of vitamins and trace minerals largely absent in the typical American diet, such as manganese. Whole grains have similar benefits, although they are inferior in regards to protein. Quinoa is not a grain, but it cooks up like one, and this too is a remarkable source of protein, vitamins, minerals, fiber and antioxidants.
Nuts and seeds contain high levels of minerals and healthy fats. Although these are common additions on superfood lists, the downside is that they are high in calories. Portion control is key. Shelled nuts and seeds, in this regard, are ideal because they take time to crack open and slow you down. A quick handful of shelled nuts or seeds could contain more than 100 calories. [Related: Reality Check: 5 Risks of Raw Vegan Diet]
Kale lives up to the hype of a superfood. But so do most dark, leafy greens: Swiss chard, collards, mustards (including radish greens), spinach (and others in the amaranth family), and cabbages. Add broccoli to that. It's in the cabbage-mustard family; the modern version is merely grown for its floret instead of leaves. These dark vegetables are loaded with vitamins A, C and K, as well as fiber, calcium and other minerals.
Sweet potato and squash also usually make the superfood list, for similar reasons. Both kinds of food are generally excellent sources of fiber, vitamin A, and much more. They are also naturally sweet and don't require the butter, cream, or salt typically added to potatoes.
Salmon, sardines, mackerel and certain other fatty fish are rich in omega-3 fatty acids, thought to lower the risk of heart disease and stroke. Most doctors say the benefits of eating fish far outweigh the risk of harming your health from the mercury these fish contain. If you worry, eat lower down on the food chain, such as sardines, smelt, and anchovy.
The "exotic fruit of the year will surely be on any superfood list, too. This might be acai berry, noni fruit, dragon fruit, rambutan or pomegranate. These might be healthful but there is no reason to believe they are any more super than blueberries. They might be rich in one particular nutrient; pomegranate has ellagitannins, which have anti-cancer properties. But so do red raspberries.
One could just as easily include green tea, coffee, dark chocolate, yogurt, and olives to the superfood list for a variety of reasons mentioned above.
Criticism of the nomenclature
As healthful as superfoods might be, the use of the term is largely a marketing tool. Scientists do not use the term. For example, a search for "superfood" on PubMed, the repository of most peer-reviewed biomedical journal articles, yields fewer than a dozen results. And several of these studies actually warn of dangers of superfoods, such as arsenic and pesticide residue in imported foods. [Infographic: Pesticides Lurk in Fruits & Veggies]
The first general criticism of the use of the term "superfood" is that, while the food itself might be healthful, the processing might not be. For example, green tea has several antioxidants. But green tea sold in the United States is generally cut with inferior teas and brewed with copious amounts of sugar. The Japanese and Chinese generally do not drink green tea with sugar. Many kinds of super-juices — acai berry, noni fruit, pomegranate — can be high in added sugar.
Similarly, many whole grains are processed in a way to be more palatable and less healthful. According to research by David Ludwig at Harvard University, instant whole-grain oats is as unhealthy as overly processed white bread in that it quickly spikes the sugar levels in the bloodstream once consumed and promotes insulin-resistance, obesity and diabetes.
A second criticism is that, because the term "superfood" is not scientific, it can mean very little and prompt some consumers to eat one kind of food over another. Is broccoli really that superior to asparagus?
Research has shown that the ideal diet is one that is largely plant-based with a wide, wide, wide variety of fruits, vegetables, whole grains and healthful animal products. Superfoods might be a good entry into healthy eating, and understanding their nutritional value is enlightening, but other whole foods can be just as healthy.