Protein, fats, carbohydrates, fiber, vitamins, minerals, calories and food composition explained with practical context.
Frozen vegetables are not nutritionally second-rate. Blanching before freezing can reduce vitamin C and folate, but freezing then slows further loss. Fresh vegetables also lose sensitive vitamins during transport and refrigerator storage. Fiber, minerals and carotenoids are generally well retained in both forms.
The easiest way to raise fiber is to change several parts of the day rather than depend on one food. A cup of beans or lentils may provide roughly 12–16 g, a whole fruit 3–6 g, an ounce of nuts 2–4 g and whole grains several grams more. The U.S. Daily Value is 28 g; increase gradually if your current intake is much lower.
Foods highly concentrated in inulin and fructans include chicory root, Jerusalem artichoke and garlic. Composition studies place Jerusalem artichoke and chicory around 15–20 g inulin per 100 g fresh weight and garlic roughly 9–16 g, although values vary widely. Onions, leeks, artichokes and legumes are less concentrated but more practical everyday sources.
Spinach does contain meaningful iron, but the reputation needs context. Raw spinach has about 2.7 mg/100 g, while cooked spinach can look higher per 100 g because water and volume are lost. The iron is nonheme, so absorption is more variable and depends on the food matrix and the rest of the meal.
A U.S. large egg, about 50 g edible weight, contains roughly 6.3 g of protein. The white contributes about 3.6 g and the yolk about 2.7 g. Smaller eggs provide less and extra-large eggs more, so 'one egg' is not a perfectly fixed unit.
The most concentrated plant omega-3 foods provide mainly ALA. A 1 oz serving of flax provides about 6.4 g ALA, chia about 5 g, and walnuts about 2.57 g. The body converts only part of ALA into EPA and DHA; algae oil is a direct non-fish source of DHA and, depending on the product, EPA.
Avocado is not the only source of unsaturated fat. One tablespoon olive oil provides about 14 g fat, 1 oz almonds about 14 g, 1 oz walnuts about 18–19 g, and a 5 oz salmon serving roughly 17–20 g depending on species. Olive oil and avocado lean monounsaturated; walnuts and seeds are richer in polyunsaturated fat; fatty fish provides EPA and DHA.
You can get a substantial amount of protein without meat. Greek yogurt, cottage cheese, eggs, fish, tofu, tempeh, seitan, edamame and legumes can all contribute meaningfully; the useful comparison is how much protein a normal serving supplies, not which food looks most concentrated per 100 grams.
Oranges are excellent vitamin C sources, but they do not top the fruit list. Their reputation grew from convenience, availability, citrus marketing, and the fact that one ordinary orange supplies a meaningful amount. Kiwi, guava, and some berries can provide more vitamin C per 100 grams.
Bananas became strongly associated with potassium because they are convenient, inexpensive, portable, and common in sports nutrition—not because they contain more than every other food. A medium banana provides about 420 mg, a useful amount that many foods and servings can exceed.
Bananas are a useful potassium source, but they are not among the most concentrated foods. A banana provides about 358 mg per 100 g. Baked potatoes, cooked spinach, beans, avocado, and some fish can exceed that amount, and one medium baked potato can provide roughly 700–900+ mg depending on size and preparation.
Orange provides about 53 mg vitamin C per 100 g, but it does not lead the ranking. Raw red bell pepper is around 125–130 mg/100 g, kiwi about 90 mg, and raw broccoli close to 89 mg. Cooking can reduce vitamin C, so the state of the food matters as much as its position in a table.