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You do not have to combine grains and beans in the same meal for plant protein to ‘work.’ What matters is enough total protein and a variety of sources across the day. Rice and beans are a useful combination, not a biochemical requirement at every plate.
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.
A complete protein provides all nine essential amino acids in proportions high enough relative to a reference pattern. A so-called incomplete protein usually contains those amino acids too; one is simply present in a lower proportion and becomes the limiting amino acid.
A normal serving of potatoes, beans, some cooked greens, fish, yogurt, or avocado can provide several hundred milligrams of potassium. Ranking foods by the amount people actually eat can look very different from a per-100-gram table.
Seeds are among the most concentrated magnesium sources, especially pumpkin and chia seeds, but an everyday diet can add substantial amounts through nuts, beans, whole grains and leafy greens. One ounce of pumpkin seeds provides about 156 mg.
Oranges are a good source of vitamin C, but they are not the champion. Red bell pepper, kiwi and several other fruits and vegetables can provide as much or more per serving, and prolonged storage or cooking can reduce some of the vitamin.
Chia, flax and walnuts are concentrated sources of the plant omega-3 ALA, while salmon, herring, sardines and mackerel provide mostly EPA and DHA. They belong to the same fatty-acid family but are not nutritionally interchangeable, so one combined ranking can mislead.
Oysters and liver stand out among animal foods, while beans, tofu, seeds and fortified foods can also provide substantial iron. The useful comparison is not just milligrams on a chart: serving size and the difference between heme and nonheme iron matter too.
Yogurt, milk, cheese, sardines with edible bones and tofu made with calcium salts can each provide roughly 250–400 mg of calcium in a normal serving. Seeds and some greens contribute too, but serving size and absorption make per-100-gram rankings misleading.
USDA guidance gives most properly refrigerated cooked meat and leftovers 3–4 days at 40°F / 4°C or below. That window assumes the food was refrigerated promptly; reheating later cannot make up for hours spent warm.