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How much protein should I take daily?

• Protein Calculator

Note: most protein calculators will suggest  your minimum percentages of protein you should take in each day. Comparing these  minimum numbers with the amount of complete protein we typically receive each day will heighten your awareness of our need to increase our intake of high quality complete proteins. Remember a complete protein needs to include all essential amino acids

• Harvard University on Protein

Other Links

• BMI Calculator
• What is the importance of Fiber in our diet
• What is the importance of Protein our diet
• Ideal Protein Media Coverage

Source: WHFoods

fiber, dietary

What can high-fiber foods do for you?

• Support bowel regularity
• Help maintain normal cholesterol levels
• Help maintain normal blood sugar levels
• Help keep unwanted pounds off

What events can indicate a need for more high fiber foods?

• Constipation
• Hemorrhoids if related to straining from constipation
• High blood sugar levels
• High cholesterol levels

Excellent food sources of fiber include: turnip greens, mustard greens, cauliflower, collard greens, broccoli, Swiss chard, and raspberries.

Even though the most commonly eaten grains are not included in our list of fiber food sources above, whole grains can be helpful in increasing your dietary fiber intake. However, when relying on whole grains for your dietary fiber intake, do not stop at the label information on the front of the package, even if the label says "contains whole grains." To assure yourself of optimal fiber intake from whole grains, be sure to take one of the following steps: (1) purchase your whole grains in bulk form (raw and unprocessed, and typically found in container bins in the bulk food section of the grocery store); (2) purchase products that stipulate "100% whole grain," or (3) flip the product over and take a close look at the Nutrient Facts panel for fiber content and make sure that you are getting between 4-14 grams of fiber per cooked cup.

 

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and processing Factors that affect function

Drug-nutrient interaction Nutrient interaction Health conditions Supplements Food Sources Public Recommendations References

Description

What is dietary fiber?

Dietary fiber is undoubtedly one of the most talked about nutrients for health promotion and disease prevention. In fact, dietary fiber is the focus of two FDA-approved health claims that appear on foods labels touting the benefits of high fiber foods for the prevention of heart disease and certain types of cancer.

Since the early 1950's, when the term "fiber" first began to be used in scientific journals, there has been considerable controversy among food scientists, nutritionists, and medical experts about the exact definition of dietary fiber.

In fact, even the United States Food and Drug Administration, the federal agency responsible for overseeing food labeling, has no formal, written definition of dietary fiber. For food labeling purposes and the determination of health claims, the FDA has adopted the analytical methods that the Association of Official Analytical Chemists uses for defining dietary fiber.

Although most experts agree that a key defining characteristic of dietary fiber is that it's derived from the edible parts of plants that are not broken down by human digestive enzymes, many people believe that this definition is too ambiguous and that a more clear, internationally-accepted definition is needed to ensure that the total fiber counts on food labels are consistent and accurate.

In recent years there has been a movement among various organizations to include the physiological benefits of dietary fiber in a new definition. For example, the American Association of Cereal Chemists proposed a new definition of dietary fiber that includes the statement "Dietary fibers promote beneficial physiological effects including laxation and/or blood cholesterol attenuation and/or blood glucose attenuation."

In addition, the Institute of Medicine at the National Academy of Sciences (the organization responsible for issuing Recommended Dietary Allowances) has proposed a new definition that differentiates between dietary fiber and added fiber. According to this definition, dietary fiber consists of nondigestible carbohydrates and lignin that are intrinsic and intact in plants.

Added fiber, which refers to fiber that is added to foods during food processing, consists of isolated nondigestible carbohydrates that have proven beneficial physiological effects in humans. For food labeling purposes, the Institute of Medicine defines Total Fiber as the sum of Dietary Fiber and Added Fiber.

Despite the controversy surrounding the exact definition of dietary fiber, experts agree on one important thing - dietary fiber is an important weapon in the fight against heart disease, colon cancer, diabetes, and obesity.

Categories of Dietary Fiber

• Cellulose, found in bran, legumes, peas, root vegetables, cabbage family, outer covering of seeds, and apples
• Hemicellulose, found in bran and whole grains
• Polyfructoses (Inulin and Oligofructans)
• Galactooligosaccharides
• Gums, found oatmeal, barley, and legumes.
• Mucilages
• Pectins, found in apples, strawberries, and citrus fruits
• Lignin, found in root vegetables, wheat, fruits with edible seeds (such as strawberries)
• Resistant Starches, found in ripe bananas, potatoes

How it Functions

What is the function of dietary fiber?

Until very recently, the functions of a specific type of fiber were determined by whether or not the fiber was classified as soluble or insoluble. Soluble fibers, such as the type found in oat bran, are known to reduce blood cholesterol levels and normalize blood sugar levels.

On the other hand, insoluble fiber, such as the type found in wheat bran, are known to promote bowel regularity. Many commonly used plant sources of fiber contain both soluble and insoluble fibers. Psyllium husks, for example, contain a mixture of 70% soluble and 30% insoluble fibers. Despite the widespread use of the terms "soluble" and "insoluble" to describe the health benefits of dietary fiber, many medical and nutrition experts contend that these terms do not adequately describe the physiological effects of all the different types of fiber. These experts are now proposing the use of the terms "viscous" and "fermentability" in place of soluble and insoluble to describe the functions and health benefits of dietary fiber.

Reducing Cholesterol Levels

Like soluble fibers, viscous fibers lower serum cholesterol by reducing the absorption of dietary cholesterol. In addition, viscous fibers complex with bile acids, which are compounds manufactured by the liver from cholesterol that are necessary for the proper digestion of fat. After complexing with bile acids, the compounds are removed from circulation and do not make it back to the liver. As a result, the liver must use additional cholesterol to manufacture new bile acids. Bile acids are necessary for normal digestion of fat. Soluble fiber may also reduce the amount of cholesterol manufactured by the liver.

Normalizing Blood Sugar Levels

Viscous fibers also help normalize blood glucose levels by slowing the rate at which food leaves the stomach and by delaying the absorption of glucose following a meal. Viscous fibers also increase insulin sensitivity. As a result, high intake of viscous fibers play a role in the prevention and treatment of type 2 diabetes. In addition, by slowing the rate at which food leaves the stomach, viscous fibers promote a sense of satiety, or fullness, after a meal, which helps to prevent overeating and weight gain.

Promoting Bowel Regularity

Certain types of fiber are referred to as fermentable fibers because they are fermented by the "friendly" bacteria that live in the large intestine. The fermentation of dietary fiber in the large intestine produces a short-chain fatty acid called butyric acid, which serves as the primary fuel for the cells of the large intestine and helps maintain the health and integrity of the colon.

Two other short-chain fatty acids produced during fermentation, propionic and acetic acid are used as fuel by the cells of the liver and muscles. In addition, propionic acid may be responsible, at least in part, for the cholesterol-lowering properties of fiber.

In animal studies, propionic acid has been shown to inhibit HMG-CoA reductase, an enzyme involved in the production of cholesterol by the liver. By lowering the activity of this enzyme, blood cholesterol levels may be lowered.

In addition, fermentable fibers help maintain healthy populations of friendly bacteria. In addition to producing necessary short-chain fatty acids, these bacteria play an important role in the immune system by preventing pathogenic (disease-causing) bacteria from surviving in the intestinal tract.

As is the case with insoluble fiber, fibers that are not fermentable in the large intestine help maintain bowel regularity by increasing the bulk of the feces and decreasing the transit time of fecal matter through the intestines. Bowel regularity is associated with a decreased risk for colon cancer and hemorrhoids (when the hemorrhoids are related to straining and constipation).

Deficiency Symptoms

What are deficiency symptoms for dietary fiber?

There is no identifiable, isolated deficiency disease caused by lack of fiber in the diet. However, research clearly indicates that low intake of dietary fiber (less than 20 grams per day) over the course of a lifetime is associated with development of numerous health problems including constipation, hemorrhoids, colon cancer, obesity and elevated cholesterol levels.

Toxicity Symptoms

What are toxicity symptoms for dietary fiber?

Intake of dietary fiber in excess of 50 grams per day may cause an intestinal obstruction in susceptible individuals. In most individuals, however, this amount of fiber will improve (rather than compromise) bowel health.

Excessive intake of fiber can also cause a fluid imbalance, leading to dehydration. Individuals who decide to suddenly double or triple their fiber intake are often advised to double or triple their water intake for this reason.

In addition, excessive intake of nonfermentable fiber, typically in supplemental form, may lead to mineral deficiencies by reducing the absorption or increasing the excretion of minerals, especially when mineral intake is too low or when mineral needs are increased such as during pregnancy, lactation, or adolescence.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect dietary fiber?

Many whole foods contain 5 or more grams of fiber, and in their whole, unprocessed form, would be highly supportive of health. When foods are processed, however, most or all of this fiber is often lost.

For example, most breads sold nationally in the United States use a 60% extraction process in which 60% of the original wheat grain is kept in the flour, but 40% is discarded. The discarded part of the wheat includes the bran and the germ; these two components of the grain contain virtually all of its fiber.

As a result, 60% extraction wheat flour contains almost no fiber, even though the whole, unprocessed wheat grain contains an ample amount. Fruit juices and vegetable juices are also good examples of products which started out high-fiber in their whole, unprocessed state but ended up with virtually no fiber as a result of processing.

Factors that Affect Function

What factors might contribute to a deficiency of dietary fiber?

Even though fiber is often defined as the "undigestable" part of food, a certain amount of healthy digestive function is important for realizing the health benefits of this nutrient.

Inadequate chewing can prevent the health benefits of fiber from being realized, since fibers that cannot be solubilized (like lignins, celluloses, and some hemicelluloses) require extra chewing in order to participate in biochemical processes.

Drug-Nutrient Interactions

What medications affect dietary fiber?

• Dietary fiber, especially the fiber found in fruit, beans, and oat bran, reduces the absorption of a class of cholesterol-lowering medications called HMG-CoA reductase inhibitors (for example, lovastatin) by binding to the drug in the gastrointestinal tract.
• Dietary fiber decreases the absorption of hydralazine, digoxin, and lithium.
• Diets high in dietary fiber may improve glucose control in people with type 2 diabetes, thereby reducing the dose of insulin or oral glucose lowering medications needed to control blood sugar.
• Certain medications, including pain medications (for example, codeine) and calcium channel blockers (for example, verapamil) can cause constipation.
• Increased intake of dietary fiber can reduce the constipation caused by these medications.

Nutrient Interactions

How do other nutrients interact with dietary fiber?

Foods high in nonfermentable fiber, or the fiber that passes all the way through the intestines unchanged, may reduce the absorption and/or increase the excretion of several minerals, including calcium and iron.

Health Conditions

What health conditions require special emphasis on dietary fiber?

A diet high in fiber may play a role in the prevention and/or treatment of the following health conditions:

• Breast cancer
• Cardiovascular disease
• Colon cancer
• Constipation
• Diabetes
• Diverticulitis
• Gallstones
• High cholesterol
• Irritable bowel syndrome
• Obesity
• Syndrome X

Form in Dietary Supplements

What forms of dietary fiber are found in dietary supplements?

As a dietary supplement and over-the-counter medication, fiber is available in powders that can be mixed with water or juice. These products often contain psyllium as the source of fiber, but may also contain pectin or guar gum. In addition, oat bran is available as a fiber-rich food ingredient that can be added to baked goods or hot cereal.

Food Sources

What foods provide dietary fiber?

Excellent food sources of dietary fiber include: turnip greens, mustard greens, cauliflower, collard greens, broccoli, Swiss chrd and raspberries.

Very good sources of dietary fiber include romaine lettuce, celery, spinach, fennel, green beans, eggplant, cranberries, strawberries and flax seeds.

Good sources of dietary fiber include cucumber, apricots, navy beans, grapefruit, rye, sweet potato, beets, buckwheat, shiitake mushrooms and oats.

 

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of dietary fiber. Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of dietary fiber contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

World's Healthiest Foods ranked as quality sources of: dietary fiber
Food	Serving Size	Cals	Amount (g)	DV (%)	Nutrient Density	World's Healthiest Foods Rating
Cinnamon, ground	2 tsp	11.8	2.48	9.9	15.1	very good
Turnip greens, cooked	1 cup	28.8	5.04	20.2	12.6	excellent
Basil, dried, ground	2 tsp	7.5	1.20	4.8	11.5	good
Coriander seeds	2 tsp	9.9	1.40	5.6	10.2	very good
Oregano, dried, ground	2 tsp	9.2	1.28	5.1	10.1	very good
Raspberries	1 cup	60.3	8.34	33.4	10.0	excellent
Thyme, dried, ground	2 tsp	7.9	1.08	4.3	9.8	good
Mustard greens, boiled	1 cup	21.0	2.80	11.2	9.6	excellent
Rosemary, dried	2 tsp	7.3	0.92	3.7	9.1	good
Romaine lettuce	2 cup	15.7	1.90	7.6	8.7	very good
Cauliflower, boiled	1 cup	28.5	3.35	13.4	8.5	excellent
Collard greens, boiled	1 cup	49.4	5.32	21.3	7.8	excellent
Broccoli, steamed	1 cup	43.7	4.68	18.7	7.7	excellent
Cloves, dried, ground	2 tsp	14.2	1.52	6.1	7.7	very good
Celery, raw	1 cup	19.2	2.04	8.2	7.7	very good
Swiss chard, boiled	1 cup	35.0	3.68	14.7	7.6	excellent
Cabbage, shredded, boiled	1 cup	33.0	3.45	13.8	7.5	very good
Spinach, boiled	1 cup	41.4	4.32	17.3	7.5	very good
Chili pepper, dried	2 tsp	25.5	2.64	10.6	7.5	very good
Black pepper	2 tsp	10.9	1.12	4.5	7.4	good
Fennel, raw, sliced	1 cup	27.0	2.70	10.8	7.2	very good
Green beans, boiled	1 cup	43.8	4.00	16.0	6.6	very good
Eggplant, cooked, cubes	1 cup	27.7	2.48	9.9	6.4	very good
Cayenne pepper, dried	2 tsp	11.2	0.96	3.8	6.2	good
Cranberries	0.50 cup	23.3	1.99	8.0	6.2	very good
Strawberries	1 cup	43.2	3.31	13.2	5.5	very good
Bell peppers, red, raw, slices	1 cup	24.8	1.84	7.4	5.3	very good
Winter squash, baked, cubes	1 cup	80.0	5.74	23.0	5.2	very good
Kale, boiled	1 cup	36.4	2.60	10.4	5.1	very good
Split peas, cooked	1 cup	231.3	16.27	65.1	5.1	very good
Summer squash, cooked, slices	1 cup	36.0	2.52	10.1	5.0	very good
Carrots, raw	1 cup	52.5	3.66	14.6	5.0	very good
Lentils, cooked	1 cup	229.7	15.64	62.6	4.9	very good
Brussel sprouts, boiled	1 cup	60.8	4.06	16.2	4.8	very good
Asparagus, boiled	1 cup	43.2	2.88	11.5	4.8	very good
Black beans, cooked	1 cup	227.0	14.96	59.8	4.7	very good
Green peas, boiled	1 cup	134.4	8.80	35.2	4.7	very good
Pinto beans, cooked	1 cup	234.3	14.71	58.8	4.5	very good
Cucumbers, slices, with peel	1 cup	13.5	0.83	3.3	4.4	good
Lima beans, cooked	1 cup	216.2	13.16	52.6	4.4	very good
Turmeric, powder	2 tsp	16.0	0.96	3.8	4.3	good
Flaxseeds	2 tbs	95.3	5.41	21.6	4.1	very good
Kiwifruit	1 each	46.4	2.58	10.3	4.0	very good
Wheat, bulgur, cooked	1 cup	151.1	8.19	32.8	3.9	very good
Tomato, ripe	1 cup	37.8	1.98	7.9	3.8	very good
Oranges	1 each	61.6	3.13	12.5	3.7	very good
Kidney beans, cooked	1 cup	224.8	11.33	45.3	3.6	very good
Barley, cooked	1 cup	270.0	13.60	54.4	3.6	very good
Apricots	1 each	16.8	0.84	3.4	3.6	good
Blueberries	1 cup	81.2	3.92	15.7	3.5	very good
Onions, raw	1 cup	60.8	2.88	11.5	3.4	very good
Garbanzo beans (chickpeas), cooked	1 cup	269.0	12.46	49.8	3.3	good
Papaya	1 each	118.6	5.47	21.9	3.3	good
Apples	1 each	81.4	3.73	14.9	3.3	good
Grapefruit	0.50 each	36.9	1.69	6.8	3.3	good
Beets, Boiled	1 cup	74.8	3.40	13.6	3.3	good
Navy beans, cooked	1 cup	258.4	11.65	46.6	3.2	good
Figs, fresh	8 oz-wt	167.8	7.48	29.9	3.2	good
Rye, whole grain, uncooked	0.33 cup	188.7	8.22	32.9	3.1	good
Pear	1 each	97.9	3.98	15.9	2.9	good
Soybeans, cooked	1 cup	297.6	10.32	41.3	2.5	good
Yam (Dioscorea species), cubed, cooked	1 cup	157.8	5.30	21.2	2.4	good
Sweet potato, baked, with skin	1 each	95.4	3.14	12.6	2.4	good
Avocado, slices	1 cup	235.1	7.30	29.2	2.2	good
Mustard seeds	2 tsp	35.0	1.08	4.3	2.2	good
Spelt grains, cooked	4 oz-wt	144.0	4.40	17.6	2.2	good
Prunes	0.25 cup	101.6	3.02	12.1	2.1	good
Buckwheat, cooked	1 cup	154.6	4.54	18.2	2.1	good
Shiitake mushrooms, raw	8 oz-wt	87.2	2.49	10.0	2.1	good
Olives	1 cup	154.6	4.30	17.2	2.0	good
Plum	1 each	36.3	0.99	4.0	2.0	good
Crimini mushrooms, raw	5 oz-wt	31.2	0.85	3.4	2.0	good
Oats, whole grain, cooked	1 cup	147.4	3.98	15.9	1.9	good
Miso	1 oz	70.8	1.86	7.4	1.9	good
Banana	1 each	108.6	2.83	11.3	1.9	good
Corn, yellow, cooked	1 cup	177.1	4.60	18.4	1.9	good
Pineapple	1 cup	76.0	1.86	7.4	1.8	good
Cantaloupe, cubes	1 cup	56.0	1.28	5.1	1.6	good
Potato, baked, with skin	1 cup	133.0	2.93	11.7	1.6	good
Sesame seeds	0.25 cup	206.3	4.24	17.0	1.5	good

World's Healthiest Foods Rating	Rule
excellent	DV>=75%	OR	Density>=7.6	AND	DV>=10%
very good	DV>=50%	OR	Density>=3.4	AND	DV>=5%
good	DV>=25%	OR	Density>=1.5	AND	DV>=2.5%

Public Health Recommendations

What are current public health recommendations for dietary fiber?

In its most recent 2005 public health recommendations for fiber (published as the Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients), National Academies Press, 2005), the National Academy of Sciences established an Adequate Intake (AI) level of 38 grams of total daily fiber for males 19-50 years of age and 25 grams for women in this same age range. It also noted that individuals in this age range in the United States only get about half this much fiber each day.

References

• American Association of Cereal Chemists. The definition of dietary fiber. Cereal Foods World 2001; 46(3), 112-127 2001.
• American Dietetic Association. Health implications of dietary fiber - - Position of the ADA. Journal of the American Dietetic Association 1997; 97:1157-1159 1997.
• Burton-Freeman B. Dietary fiber and energy regulation. J Nutr 2000 Feb;130(2S Suppl):272S-5S 2000. PMID:15360.
• Cohen LA. Dietary fiber and breast cancer. Anticancer Res 1999 Sep-1999 Oct 31;19(5A):3685-8 1999. PMID:15370.
• Davy BM and Melby CL. The effect of fiber-rich carbohydrates on features of Syndrome X. J Am Diet Assoc 2003 Jan;103(1):86-96 2003.
• De Moura FF, Lewis KD, and Falk MC. Applying the FDA Definition of Whole Grains to the Evidence for Cardiovascular Disease Health Claims. The Journal of Nutrition. Bethesda: Nov 2009. Vol. 139, Iss. 11; p. 2220S-2226S. 2009.
• Fernandez ML. Soluble fiber and nondigestible carbohydrate effects on plasma lipids and cardiovascular risk. Curr Opin Lipidol 2001 Feb;12(1):35-40 2001.
• Flamm G, Glinsmann W, Kritchevsky D, et al. Inulin and oligofructose as dietary fiber: a review of the evidence. Crit Rev Food Sci Nutr 2001 Jul;41(5):353-62 2001. PMID:15310.
• Garcia Peris P, Camblor Alvarez M. [Dietary fiber: concept, classification and current indications]. Nutr Hosp 1999 May;14 Suppl 2:22S-31S 1999. PMID:15380.
• Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995 1995.
• Institute of Medicine. Dietary Reference Intakes: Proposed Definition of Dietary Fiber. National Academy Press, Washington DC, 2001 2001.
• Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000 2000.
• Mahan K, Escott-Stump S. Krause's Food, Nutrition, and Diet Therapy. WB Saunders Company; Philadelphia, 1996 1996.
• McIntosh M, Miller C. A diet containing food rich in soluble and insoluble fiber improves glycemic control and reduces hyperlipidemia among patients with type 2 diabetes mellitus. Nutr Rev 2001 Feb;59(2):52-5 2001.
• Meseguer Soler I, Martinez Para MC, Farre Rovira R. [Dietary fiber (and II). Metabolism and physiologic implications]. Med Clin (Barc) 1998 Jan 17;110(1):32-7 1998. PMID:15390.
• Pereira MA, Ludwig DS. Dietary fiber and body-weight regulation. Observations and mechanisms. Pediatr Clin North Am 2001 Aug;48(4):969-80 2001. PMID:15320.
• Pereira MA, Pins JJ. Dietary fiber and cardiovascular disease: experimental and epidemiologic advances. Curr Atheroscler Rep 2000 Nov;2(6):494-502 2000. PMID:15350.
• Swanson KS, Fahey GC. New developments in the area of dietary fiber. Nutrition in Complementary Care Newsletter 2001; 4(1):5,12 2001.
• Zhao X, Yang Y, Song Z et al. Effect of superior fiber complex on insulin sensitivity index and blood lipids in non-insulin dependent diabetes mellitus rats. Zhonghua Yu Fang Yi Xue Za Zhi 2002 May;36(3):184-6 2002.

 

Source: WHFoods

Protein

What can high-protein foods do for you?

• Keep your immune system functioning properly
• Maintain healthy skin, hair and nails
• Help your body produce enzymes

What events can indicate a need for more high-protein foods?

• Muscle wasting
• Weight loss
• Fatigue and weakness
• Frequent infections
• Severe edema (fluid retention)
• Slow growth and development in children

Excellent sources of protein include tuna, shrimp and cod.

 

For serving size for specific foods, see Nutrient Rating Chart below at the bottom of this page.

Description Function Deficiency Symptoms Toxicity Symptoms Cooking, storage and processing Factors that affect function

Drug-nutrient interaction Nutrient interaction Health conditions Supplements Food Sources Public Recommendations References

Description

What is protein?

Protein was the first substance to be recognized as a vital part of living tissue. In fact, the word protein comes from the Greek word proteos, which means "primary" or "taking first place," indicating the importance of this nutrient in the function of the body. Accounting for 20 percent of our body weight, proteins perform a wide variety of functions throughout the body as vital components of body tissues, enzymes, and immune cells.

Proteins are complex molecules comprised of a combination of different amino acids, which are compounds that contain carbon, oxygen, hydrogen, nitrogen and sometimes sulfur. Amino acids link together in specific numbers and unique combinations to make each different protein.

Protein is an essential component of the diet, because it provides the amino acids that the body needs to synthesize its own proteins. In traditional nutrition textbooks, there have always been two types of amino acids: essential amino acids and non-essential amino acids. Essential amino acids have been defined as those amino acids that our body cannot synthesize on its own. Essential amino acids must therefore be obtained from our diet. As traditionally defined, the eight essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. There has been ongoing debate over the status of a ninth amino acid, histidine. Because the body appears routinely unable to make sufficient amounts of histidine during certain periods of development, this amino acid has sometimes been classified as essential and sometimes not.

Nonessential amino acids have traditionally been defined as those that the body can manufacture on its own. It is therefore not necessary to obtain these amino acids from the diet. As traditionally defined, the nonessential amino acids include glutamate, alanine, aspartate, and glutamine, as well as arginine, proline, serine, tyrosine, cysteine, taurine, and glycine.

This traditional separation of amino acids into the categories of "essential" and "non-essential" seems unrealistic. While it is true that the human body has the potential to manufacture all non-essential amino acids, this potential is not the same as actually making them. There are many circumstances in which the body cannot make nearly enough of the non-essential amino acids it needs. For example, when a person is exposed to large amounts of environmental toxins and pollutants, the amount of glycine (a non-essential amino acid) made by the body may be far from adequate. For this reason, it may be more constructive to think about all non-essential amino acids as "conditionally essential." This classification would point out that under certain physiological circumstances, the body would unable to manufacture enough of these amino acids and they would have to be obtained through diet (or supplementation). This concept of "conditionally essential amino acids" tells us that all of the amino acids can be equally important when it comes to our diet, and that it's worthwhile for us to pay attention to all amino acids when thinking about the nourishment we get from our food.

The body is only able to make the proteins it needs when there are sufficient quantities of all the necessary amino acids in the so-called "amino acid pool." If we are deficient in essential amino acids, the body will be unable to make proteins and will have to break down muscle proteins to obtain the amino acids it needs.

As a result, it is imperative that our daily intake of food contains each of the essential amino acids, which is easily accomplished by eating a variety of vegetables, beans, whole grains, nuts, seeds, and meat and animal products if desired.

How it Functions

What is the function of protein?

Protein, providing 4 calories per gram, is an important source of energy for the body, when carbohydrates and fats are not available. In addition to using protein to generate energy for cellular function whenever necessary, the body uses the amino acids contained in the protein we eat to manufacture its own proteins. The proteins synthesized by the body perform a variety of important physiological functions:

• Production and maintenance of structural proteins: The body manufactures several structural proteins, such as myosin, actin, collagen, elastin, and keratin, that maintain the strength and integrity of muscles, connective tissues (ligaments and tendons), hair, skin, and nails.
• Production of enzymes and hormones: All of the enzymes, which are compounds that catalyze chemical reactions in the body, are made from protein. In addition, the hormones involved in blood sugar regulation (insulin and glucagon) as well as the thyroid hormones are synthesized from proteins.
• Production of transport proteins and lipoproteins: Certain proteins are used by the body to carry various substances to body tissues. These transport proteins include hemoglobin (carries oxygen), transferrin (carries iron), ceruloplasmin (carries copper), retinol-binding protein (carries vitamin A), albumin and transthyretin (both carry other proteins). Lipoproteins participate in the transportation of fat and cholesterol.
• Production of antibodies: Antibodies, which are proteins, play an important role in the immune system by attaching to antigens (viruses, bacteria, or other foreign invaders), thereby inactivating the antigens and making them more visible to the immune cells (called macrophages) that destroy antigens.
• Maintenance of proper fluid balance: Proteins participate in the maintenance of osmotic pressure, which controls the amount of water that is found inside of cells.
• Maintenance of proper acid-base balance: Due to their ability to combine with both acidic and basic substances, proteins help to maintain the normal acid-base balance in the body.

Deficiency Symptoms

What are deficiency symptoms for protein?

Both adults and children can live healthfully on a low intake of protein, assuming they eat a sufficient amount of calories and all of the essential amino acids are present in the diet. As a result, the symptoms of protein deficiency are most often seen in impoverished people who have limited access to food.

Protein-energy malnutrition, caused by low intake of both protein and calories, is especially common in children in underdeveloped nations, because children require more protein per kilogram of body weight than adults to support the rapid growth and development that occurs during childhood.

According to the World Health Organization, approximately 300 million children throughout the world suffer from growth retardation due to protein-energy malnutrition. Additionally, children with protein-energy malnutrition have a 40% mortality rate, due to increased susceptibility to infections.

In developed countries, protein-energy malnutrition is most likely to affect people who have suffered severe physical trauma that increases protein needs (for example, extensive skin burns) or those who have a medical condition or psychological problem that impacts their desire or ability to eat. The elderly are also at risk for protein-energy malnutrition.

There are two types of protein-energy malnutrition: marasmus and kwashiorkor. Marasmus is a state of semi-starvation that can occur in people of all ages who have limited access to food, but is most common in non-breastfed children given diluted infant formula. The symptoms of marasmus include weight loss, muscle wasting, loss of visible fat stores, weakness and fatigue, and frequent infections due to diminished activity of the immune system.

Kwashiorkor, a Ghanian word for "the evil spirit that infects the child", was first described in 1933 and typically occurs in children younger than 4 years old fed diets high in carbohydrates with little or no protein. Symptoms of kwashiorkor include muscle wasting, edema (fluid retention), and an enlarged and fatty liver, with the preservation of visible fat stores.

Because meat and dairy foods are a primary source of protein in the American diet, many nutritionists caution that those following a vegetarian or vegan diet may be at risk for protein deficiency. However, vegetarians and vegans who eat a variety of vegetables, grains and legumes can easily meet or exceed current protein requirements.

Toxicity Symptoms

What are toxicity symptoms for protein?

Excessive intake of protein over many years may lead to kidney problems and/or accelerated bone loss eventually leading to osteoporosis. Due to the lack of a dose-response relationship at higher levels of protein intake, the National Academy of Sciences (NAS) decided not to set a Tolerable Upper Limit (UL) for protein in 2002. However, the NAS did note that the building blocks of protein, called amino acids, should not be consumed in amounts significantly above the amounts found in food.

Because the kidneys play a primary role in protein metabolism, individuals with end-stage kidney disease must carefully monitor their intake of protein.

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect protein?

When cooked or agitated (as occurs when egg whites are beaten), proteins undergo physical changes called denaturation and coagulation. Denaturation changes the shape of the protein, thereby decreasing the solubility of the protein molecule.

Coagulation causes protein molecules to clump together, as occurs when making scrambled eggs. Overcooking foods containing protein can destroy heat sensitive amino acids (for example, lysine) or make the protein resistant to digestive enzymes.

Factors that Affect Function

What factors might contribute to a deficiency of protein?

Protein digestion and metabolism involves the stomach, pancreas and liver. Hydrochloric acid, secreted by the stomach, is necessary for the initial digestion of protein. Pancreatic enzymes participate in the breakdown of protein. And the liver controls amino acid metabolism.

Consequently, any medical condition that comprises the function of the stomach, pancreas, or liver may negatively impact protein status. In addition, the ability of the body to manufacture non-essential amino acids may be hampered with inadequate intake of vitamin B6.

Individuals with bacterial or viral infections and those who have experienced severe physical trauma use up their protein stores rapidly, and may need to increase their intake of protein.

Drug-Nutrient Interactions

What medications affect protein?

Any medication that decreases the secretion, or neutralizes the action, of hydrochloric acid in the stomach may negatively impact protein digestion. Such medications include prescription and over-the-counter antacids (for example, Tums and Rolaids) and histamine blockers (for examples, Tagamet and Pepcid).

In addition, the steroidal anti-inflammatory medications (for example, prednisone) can cause muscle wasting. Consequently, physicians sometimes recommend that patients taking these medications increase their intake of protein.

Nutrient Interactions

How do other nutrients interact with protein?

Various proteins bind and carry certain vitamins and minerals including iron, copper, calcium, vitamin A, and vitamin D. As a result, inadequate protein intake may impair the function of these nutrients.

Health Conditions

What health conditions require special emphasis on protein?

Although adequate protein intake is necessary for health, protein is not often used therapeutically. However, high dietary intake of protein is beneficial for people who have experienced severe physical trauma and may be helpful for athletes. Additionally, several individual amino acids including glutamine, lysine, phenylalanine, tyrosine, arginine, and cysteine are commonly used therapeutically.

Form in Dietary Supplements

What forms of protein are found in dietary supplements?

A wide range of protein powders are available. Especially popular at present are those that contain soy protein, as soy has received much attention for its potential to prevent cardiovascular disease and cancer.

Food Sources

What foods provide protein?

Excellent sources of protein include tuna, shrimp, and cod.

Very good sources of protein include snapper, venison, halibut, salmon, scallops, turkey, chicken, lamb, beef, calf's liver, spinach, tofu, mustard greens, crimini mushrooms, soybeans, and mozarrella cheese.

Good sources of protein include eggs, milk, collard greens, cauliflower and many legumes including lentils, split peas, kidney beans, black beans, pinto beans and garbanzo beans.

When discussing food sources of protein, nutritionists often speak in terms of "complete" and "incomplete" proteins. Foods that provide complete protein are those that include all of the essential amino acid, while foods that provide some or none of the essential amino acids are said to be incomplete.

Eggs, dairy foods, meat, fish and poultry are typically considered to be complete proteins. Vegetarians, and especially vegans, often do not have a source of complete protein in their diets, but can easily obtain all of the essential amino acids by eating a variety of beans, grains, nuts, seeds, and vegetables.

 

Introduction to Nutrient Rating System Chart

In order to better help you identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of protein. Next to each food name, you'll find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of protein contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling." Read more background information and details of our rating system.

World's Healthiest Foods ranked as quality sources of: protein
Food	Serving Size	Cals	Amount (g)	DV (%)	Nutrient Density	World's Healthiest Foods Rating
Cod, baked/broiled	4 oz-wt	119.1	26.03	52.1	7.9	excellent
Tuna, yellowfin, baked/broiled	4 oz-wt	157.6	33.99	68.0	7.8	excellent
Shrimp, steamed/boiled	4 oz-wt	112.3	23.71	47.4	7.6	excellent
Snapper, baked/broiled	4 oz-wt	145.2	29.82	59.6	7.4	very good
Venison	4 oz-wt	179.2	34.25	68.5	6.9	very good
Halibut, baked/broiled	4 oz-wt	158.8	30.27	60.5	6.9	very good
Tamari (Soy Sauce)	1 tbs	10.8	1.89	3.8	6.3	good
Scallops, baked/broiled	4 oz-wt	151.7	23.11	46.2	5.5	very good
Turkey breast, roasted	4 oz-wt	214.3	32.56	65.1	5.5	very good
Chicken breast, roasted	4 oz-wt	223.4	33.79	67.6	5.4	very good
Mustard greens, boiled	1 cup	21.0	3.16	6.3	5.4	very good
Beef tenderloin, lean, broiled	4 oz-wt	240.4	32.04	64.1	4.8	very good
Lamb loin, roasted	4 oz-wt	229.1	30.15	60.3	4.7	very good
Calf's liver, braised	4 oz-wt	187.1	24.53	49.1	4.7	very good
Spinach, boiled	1 cup	41.4	5.35	10.7	4.7	very good
Romaine lettuce	2 cup	15.7	1.81	3.6	4.2	good
Crimini mushrooms, raw	5 oz-wt	31.2	3.54	7.1	4.1	very good
Salmon, chinook, baked/broiled	4 oz-wt	261.9	29.14	58.3	4.0	very good
Asparagus, boiled	1 cup	43.2	4.66	9.3	3.9	very good
Broccoli, steamed	1 cup	43.7	4.66	9.3	3.8	very good
Tofu, raw	4 oz-wt	86.2	9.16	18.3	3.8	very good
Soybeans, cooked	1 cup	297.6	28.62	57.2	3.5	very good
Mozzarella cheese, part-skim, shredded	1 oz-wt	72.1	6.88	13.8	3.4	very good
Swiss chard, boiled	1 cup	35.0	3.29	6.6	3.4	very good
Tempeh, cooked	4 oz-wt	223.4	20.63	41.3	3.3	good
Yogurt, low-fat	1 cup	155.1	12.86	25.7	3.0	good
Egg, whole, boiled	1 each	68.2	5.54	11.1	2.9	good
Collard greens, boiled	1 cup	49.4	4.01	8.0	2.9	good
Cauliflower, boiled	1 cup	28.5	2.28	4.6	2.9	good
Lentils, cooked	1 cup	229.7	17.86	35.7	2.8	good
Split peas, cooked	1 cup	231.3	16.35	32.7	2.5	good
Kidney beans, cooked	1 cup	224.8	15.35	30.7	2.5	good
Kale, boiled	1 cup	36.4	2.47	4.9	2.4	good
Lima beans, cooked	1 cup	216.2	14.66	29.3	2.4	good
Black beans, cooked	1 cup	227.0	15.24	30.5	2.4	good
Cow's milk, 2%	1 cup	121.2	8.13	16.3	2.4	good
Brussel sprouts, boiled	1 cup	60.8	3.98	8.0	2.4	good
Green peas, boiled	1 cup	134.4	8.58	17.2	2.3	good
Navy beans, cooked	1 cup	258.4	15.83	31.7	2.2	good
Pinto beans, cooked	1 cup	234.3	14.04	28.1	2.2	good
Miso	1 oz	70.8	4.06	8.1	2.1	good
Shiitake mushrooms, raw	8 oz-wt	87.2	4.98	10.0	2.1	good
Turnip greens, cooked	1 cup	28.8	1.64	3.3	2.0	good
Garbanzo beans (chickpeas), cooked	1 cup	269.0	14.53	29.1	1.9	good
Green beans, boiled	1 cup	43.8	2.36	4.7	1.9	good
Mustard seeds	2 tsp	35.0	1.88	3.8	1.9	good
Goat's milk	1 cup	167.9	8.69	17.4	1.9	good
Cabbage, shredded, boiled	1 cup	33.0	1.53	3.1	1.7	good
Summer squash, cooked, slices	1 cup	36.0	1.64	3.3	1.6	good
Peanuts, raw	0.25 cup	207.0	9.42	18.8	1.6	good
Pumpkin seeds, raw	0.25 cup	186.7	8.47	16.9	1.6	good
Rye, whole grain, uncooked	0.33 cup	188.7	8.31	16.6	1.6	good
Spelt grains, cooked	4 oz-wt	144.0	6.24	12.5	1.6	good
Garlic	1 oz-wt	42.2	1.80	3.6	1.5	good
Oats, whole grain, cooked	1 cup	147.4	6.08	12.2	1.5	good
Tomato, ripe	1 cup	37.8	1.53	3.1	1.5	good

World's Healthiest Foods Rating	Rule
excellent	DV>=75%	OR	Density>=7.6	AND	DV>=10%
very good	DV>=50%	OR	Density>=3.4	AND	DV>=5%
good	DV>=25%	OR	Density>=1.5	AND	DV>=2.5%

Public Health Recommendations

What are current public health recommendations for protein?

Recommendations for protein intake are based on the concept of "nitrogen balance." Protein contains nitrogen, and as proteins are broken down in the body, nitrogen is excreted. Consequently, nitrogen must be continually replaced through the diet (as protein) so that the body can continue to make proteins.

For most adults, an even nitrogen balance is ideal, meaning that the amount of nitrogen provided in the diet is equivalent to the amount of nitrogen excreted. In contrast, children require a positive nitrogen balance to support growth and development, meaning that more nitrogen is supplied by the diet (as protein) than is eliminated. Pregnant and lactating women also require a positive nitrogen balance.

In 2002, the National Academy of Sciences (NAS) set Recommended Dietary Allowances (RDAs) for protein for all age groups 7 months and older, and Adequate Intake (AI) levels for infants 0-6 months of age. The daily standards set by the NAS were as follows:

• Boys and girls aged 0-6 months: 9.1 grams
• Boys and girls aged 7 months to 1 year: 13.5 grams
• Boys and girls aged 1-3 years: 13 grams
• Boys and girls aged 4-8 years: 19 grams
• Boys and girls aged 9-13 years: 34 grams
• Males aged 14-18 years: 52 grams
• Males aged 19+: 56 grams
• Females aged 14+ years: 46 grams

Pregnant and lactating women require an additional 25 grams of protein per day for a total of 71 grams.

References

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• Denke MA. Metabolic effects of high-protein, low-carbohydrate diets. Am J Cardiol 2001 Jul 1;88(1):59-61 2001. PMID:15910.
• Fernstrom JD, Fernstrom MH. Monoamines and protein intake: are control mechanisms designed to monitor a threshold intake or a set point. Nutr Rev 2001 Aug;59(8 Pt 2):S60-5; discussion S66-8 2001. PMID:15900.
• Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995 1995.
• Lininger SW, et al. A-Z guide to drug-herb-vitamin interactions. Prima Health, Rocklin, CA, 2000 2000.
• Mahan K, Escott-Stump S. Krause's Food, Nutrition, and Diet Therapy. WB Saunders Company; Philadelphia, 1996 1996.
• McWilliams M. Foods. Prentice Hall Publishing Company: New Jersey, 1989 1989.
• Schaafsma G. The protein digestibility-corrected amino acid score. J Nutr 2000 Jul;130(7):1865S-7S 2000. PMID:15970.
• Stein K. High-protein, low-carbohydrate diets: do they work. J Am Diet Assoc 2000 Jul;100(7):760-1 2000. PMID:15960.
• Tipton KD, Wolfe RR. Exercise, protein metabolism, and muscle growth. Int J Sport Nutr Exerc Metab 2001 Mar;11(1):109-32 2001. PMID:15920.
• Wolfe RR. Protein supplements and exercise. Am J Clin Nutr 2000 Aug;72(2 Suppl):551S-7S 2000. PMID:15950.
• Wu GH, Zhang YW, Wu ZH et al. Modulation of postoperative immune and inflammatory response by immune-enhancing enteral diet in gastrointestinal cancer patients. World J Gastroenterol. 2001 Jun;7(3):357-62 2001.

Source:  Harvard University on Protein

The Nutrition Source

Protein