What’s a superfood? Broadly speaking, it’s a food with high nutrient density.

For example, 100 grams of chia seeds provide 34% of the protein you need in a day, 63% of the calcium, and 43% of the iron. Compare that with salmon, 100 grams of which gives you 42% of the protein you need in a day, but only 1% of the calcium and 2% of the iron.

Kale is a powerhouse of nutrition, providing significant amounts of protein, fiber, Vitamins A and C, plus calcium and iron. You’ll get more of all of those nutrients for just 49 calories if you eat 100 grams of kale, than if you eat the same amount of whole wheat bread — and that bread will come to more than 300 calories.

Since you can only eat so many calories in a day, you’d be better off having a big kale salad at lunch than having that slice of whole wheat bread… and just forget about those potato chips!

So superfoods are the foods that pack the most nutritional punch and give you the best chance of meeting your body’s nutritional requirements just by eating your daily meals.

The term is also used for foods that deliver a serving of nutritional elements that may not be easy to get in your daily diet without eating the specific foods. This is the case with tomatoes, for example. They give you 10% of your vitamin A and 38% of Vitamin C, but orange juice gives you 75% vitamin C and carrots offer 338% of Vitamin A. Tomatoes, however, are one of the few foods that provide lycopene.

One important thing to remember about superfoods is that the word has no official medical definition. There is no official list of superfoods, and anyone can use the term for any food they choose.

Another important thing is to make sure you’re comparing apples to apples., the source of the information in this article, always compares 100 grams of each food. But 100 grams isn’t always a serving.

For example, a normal serving of salmon runs 50 to 100 grams, so it makes sense to think it’s giving you about a third of your needed protein when you have salmon for lunch. You probably aim for about that much protein in each meal.

But a normal serving of chia seeds — that spoonful in your smoothie, for example — is about 15 grams. That is not giving you a third of your daily protein, no matter how super chia seeds might be.

When it comes to whole wheat, the normal serving size is about the same as for chia seeds. That tablespoon or so is about how much wheat flour there is in a piece of bread. The rest of the bread includes — well, it’s hard to say. Depending on the kind of bread, it might include eggs and milk, sugar, corn syrup and other sweeteners, corn starch, dough conditioners, oil, malt, and even cellulose fiber made from wood.

That large range of ingredients makes it hard to compare the nutritional value of processed foods. What’s more, adding a superfood to a dish doesn’t magically make it healthy. A cookie filled with sugar and shortening doesn’t become healthy just because you stirred in a few cacao nibs.

4 cups of summer squash, 2 beaten eggs, 2 T chia seeds, 1/4 c. grated Parmesan cheese, and 1/2 c cracker crumbs mixed together and baked at 350 degrees for about 30 minutes

So superfoods are hard to define and hard to compare. Should you forget about them completely?

No. Most lists of superfoods contain fresh fruits and vegetables, healthy seeds and nuts, and lean or healthy-fat sources of protein such as eggs and fish. These are good foods for most people to eat.

If you’re not sure that a particular food is a good choice for you, check with your health care provider.