When we label these foods as 'super' and 'healthy,' people think they can eat them in unlimited quantities. But you do have to be cautious of the amount you eat, because you can gain weight from eating too much healthy food," Hyde said.
Similarly, many whole grains are processed in a way to be more palatable and less healthful. For example, instant whole-grain oats are as unhealthy as overly processed white bread in that they quickly spike sugar levels in the bloodstream once consumed, promoting insulin-resistance, obesity and diabetes, according to research by David Ludwig at Harvard University.
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.
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]
Salmon, sardines, mackerel and certain other fatty fish are rich in omega-3 fatty acids, which are thought to lower the risk of heart disease and stroke. The benefits of eating fish may far outweigh the risk of harming your health from the mercury these fish contain, according to Harvard's T.H. Chan School of Public Health. If you worry about the contaminants your fish dinner may contain, you can try eating lower down on the food chain. Certain fish, such as sharks, swordfish, king mackerel and tilefish, contain higher levels of mercury than smaller fish, like sardines, smelt, and anchovy. Pomegranate
Sweet potato and squash also usually make the superfood list, for similar reasons as those listed for leafy greens. 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.
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 list, as well. 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.
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 could contain more than 100 calories, according to Hyde. [Related: Reality Check: 5 Risks of Raw Vegan Diet] Kale