Protein, fats, carbohydrates, fiber, vitamins, minerals, calories and food composition explained with practical context.
Plain Greek yogurt usually contains about twice as much protein as conventional plain yogurt, roughly 8–10 grams versus 3–5 grams per 100 grams. But “Greek” does not automatically mean more fat or less sugar: those depend on milkfat level, processing and whether sweeteners were added.
Canned sardines and tuna can both provide roughly 24–26 grams of protein per 100 grams, so protein is basically a tie. The difference appears in the rest of the package: sardines provide far more EPA and DHA, can add substantial calcium when the bones are eaten and average very low mercury. Tuna mercury varies by species.
Lean white fish often falls around 80–130 calories per 100 grams cooked, while many oily fish reach 180–250 because they contain more fat. That same fat explains their large advantage in EPA and DHA. Protein is much closer than the labels suggest: both groups commonly provide roughly 18–25 grams per 100 grams.
Red and white meat can provide almost the same amount of protein when lean cuts are compared. Red meat—beef, pork and lamb—usually provides more heme iron and vitamin B12, while white meat such as poultry can be leaner in cuts like breast. For fat and calories, the cut, skin and processing matter more than the color category.
Tuna and salmon are two very different ways to get protein. Per 100 grams cooked, yellowfin tuna has roughly 29 grams of protein and 130 calories, while Atlantic salmon is closer to 22 grams and 200–210 calories. Salmon's advantage shows up elsewhere: it provides far more EPA and DHA. Mercury in tuna also depends heavily on the species.
Cooked skinless chicken breast is leaner and more protein-dense, at roughly 31 g of protein and 165 calories per 100 g versus about 26 g and 209 calories in skinless thigh. Thigh contains more fat and is generally more forgiving and juicy; keeping the skin widens the gap.
Cooked skinless chicken and turkey breast both provide roughly 29–31 grams of protein per 100 grams. Turkey breast can be a little leaner and lower in calories, but the difference between breast, thigh and skin-on meat is larger than the difference between the two birds.
Lean beef and lean pork can provide very similar amounts of protein. Beef usually supplies more iron and vitamin B12, while pork is notably rich in thiamin. For fat and calories, the specific cut matters more than whether the meat came from cattle or pigs.
Among plant foods, soy and soy foods are the strongest practical options because they combine a complete essential-amino-acid profile with roughly 15–30 grams of protein per serving. Quinoa, amaranth and buckwheat also provide all essential amino acids, but a cooked serving contains much less total protein.
Cooked lentils, chickpeas and beans are more alike than their reputations suggest: all provide roughly 8–9 grams of protein per 100 grams. Chickpeas are more calorie-dense, lentils tend to edge higher in iron, and bean values vary by type.
Beef liver, clams and oysters are extraordinarily rich in vitamin B12. Salmon, tuna, meat, milk, yogurt and eggs provide less per serving but can contribute regularly. Plant foods do not provide reliable B12 unless they are fortified.
Oysters are in a different league for zinc: a 3-ounce serving can provide about 28–32 mg. Beef and other seafood provide less, while plant foods such as seeds and beans can contribute too, although phytate generally lowers zinc absorption from plant-based meals.