While I feel that these are all important nutrients and we need some of all of them, if I had to choose just one, it would have to be protein. And if I had to choose the very best protein source it would be beans because they are an important source of fiber and vitamins. The body needs protein to build and repair tissue. Protein is needed to make enzymes and hormones. Protein also builds bones and muscles.
The DRI (Dietary Reference Intake) is 0.8 grams of protein per kilogram of body weight, or 0.36 grams per pound. This means: 56 grams per day for the average man and 46 grams per day for the average woman. Active men and women would need more and heavy people would require more.
It is best to spread the protein thoughout the day rather than having it all at breackfast, maybe having 20 to 30 grams for each meal and maybe 10 grams for snacks.
I have listed these starting with the ones that have the highest protein value.
Soybeans - 28.5 g per 1 cup serving; Soybeans are one of the richest plant-based protein sources.
Boneless Pork Chops - 26 g per 3 oz. serving;
Yellowfin Tuna - 25 g per 3 oz. serving;
Chicken Breast (Boneless And Skinless) - 24 g per 3 oz. serving;
Turkey Breast - 24 g per 3 oz. serving;
Whey Protein - 24 g per scoop; Whey protein is one of the fastest digesting proteins.
Top Or Bottom Round Steak - 23 g per 3 oz. serving; .
Pinto Beans - 15.41 g per 1 cup serving; Women should consume between 21 and 25 grams of fiber each day, while men should consume 30 and 38 grams. Fiber promotes healthy digestion and reduces your chances of developing hemorrhoids and diverticular disease. The nutrient also lowers cholesterol levels and regulates blood sugar.
Cottage Cheese - 14 g per 1/2 cup serving; This cheese product is laced with casein protein, a slow digesting protein that supplies your growing muscles with a steady supply of vital amino acids. Its great for snack time, especially before bedtime. It is easy to make at home.
Gelatins, dry powder, unsweetened - 6 g per 1 Tablespoon; These amino acids are needed not only for proper skin, hair and nail growth, but for optimal immune function and weight regulation.
Glycine, which makes up about 1/3 of the amino acids in gelatin powder is anti-inflammatory and can help speed wound healing. Glycine in gelatin can also help improve sleep ease and quality.
Almonds - 5.9 g per 22 almonds;
Pistachios - 5.9 g per 49, dry roasted without salt;
Brown Rice - 5.03 g per 1 cup serving; Brown rice is an excellent source of manganese, and a good source of selenium, phosphorus, copper, magnesium, and niacin (vitamin B3).
Walnuts - 4.3 g per 14 halves;
Egg White - 3.6 g per the white of 1 large egg;
Mung Beans - 2.5 g per 1 cup serving of sprouted and cooked; Because mung bean sprouts are so small, they contain a concentrated amount of key vitamins and minerals such as iron, potassium, folate and vitamin C.
High Protein Canned Foods
Anchovies - 24 g per 3 oz. serving; To reduce their saltiness, soak anchovies in water for 30 minutes; then drain and pat dry.
Corned Beef - 24 g per 3 oz. serving;
** Try sauteing corned beef with chopped vegetables and serve over rice, or use it as a main protein in sandwiches.
Light Tuna - 22 g per 3 oz. serving; Canned light tuna actually provides a little more protein than more expensive canned white tuna. To save yourself some calories sourced from the oil use the water packed tuna instead.
Chicken - 21 g per 3 oz. serving; Pop the lid on white chicken meat to instantly add a high quality protein to your sandwiches and salads. Compare brands, looking for those that deliver lower amounts of sodium.
Sardines - 21 g per 3 oz. serving; Canned sardines also provide omega 3 fats and vitamin D.
Navy Beans - 20 g per 1 cup serving; Beans are a cheap source of protein and a cup supplies an impressive 13 g of dietary fiber.
Pinto Beans - 19.36 g per 1 cup serving; Pinto beans also contain vitamins and minerals.
Peanut Butter - 8 g per 2 tbsp serving;
Dried Beans and Grains
Dried Lentils - 13 g per 1/4 cup serving; Inexpensive dry lentils are a sure way to up your intake of protein, fiber, and a range of vital minerals. Unlike dried beans, lentils don't require a soaking. Simply simmer them in a pot of water until tender, about 20 minutes.
**For a nutritious lunch, toss cooked lentils with chopped turkey or chicken breast, diced vegetables, and a lemon vinaigrette.
Quinoa - 8 g per 1 cup serving; Quinoa contains essential amino acids, so it is a complete protein with muscle making potential.
**Toasting quinoa in a dry skillet or saucepan before simmering it in water can enhance its natural nutty flavor.
Wheat Germ - 6 g per 1 oz. serving; The wheat grain is made up of three components—endosperm, bran, and germ. The germ is the most nutrient dense part and includes notable amounts of plant based protein.
**You can use it to add a protein boost to your oatmeal, pancakes, and even shakes. To preserve freshness, it's best to store wheat germ in the refrigerator or freezer.
Air = a few minutes until death
Water = a few days until death happens
Food = a few weeks until death happens.
Carbs = a lifetime without once we past infancy
Fat = 6 months
Protein = 2 months
Vitamin = A few fat soluble vitamins we can do without for up to a year, water soluble ones I am not too sure about.
Chemical analysis showed the relatively higher level of crude protein (33.8%), crude fiber (9.1%), crude fat (3.6%), total ash (16.2%), carbohydrate (37.4%), and relatively lower energy value (307 kcal/100 g) as compared to wheat and barley flours.
This study further established that nettle plants as very good source of energy, proteins, high fiber, and a range of health benefitting bioactive compounds.
"Never doubt that a small group of thoughtful, committed citizens can change the world; indeed, it's the only thing that ever has."-Margaret Mead "The only thing worse than being blind, is having sight but no vision."-Helen Keller
There is one issue that I have and that is that if you were to be limited to a single nutrient, you would be on the road to extinction because that scenario is a mono culture and we are creatures that are designed to thrive on diversity.
No matter which "nutrient" you choose, you are leaving out so much of the necessary for life compounds that death would be imminent, the only question is how long before you succumb.
While protein does help build bone and muscle, it is incapable of doing so without calcium being present, along with boron, magnesium, manganese and lots of other minerals, those protein built bones will be very brittle and there will be no marrow for production of blood cells.
Now if you are in a survival situation, where you have only one item to choose to get you to a better location where you can pickup at least some of the missing ingredients for a good diet, then yes protein is a key element.
A body that feeds only on protein feeds upon it's self much quicker though. The body likes to metabolize proteins because they are easy food, once those are gone, you either get hungry or switch to fat stores in the body.