Protein may be the best-recognized of all nutrients in terms of its health importance.
|Food||Percentage of DRI per 100 grams|
Protein may be the best-recognized of all nutrients in terms of its health importance.
Public health recommendations in the U.S. have included an emphasis on dietary protein for over a century! The very name of this nutrient comes from the Latin word protos meaning "first," and that meaning is consistent with the approach of many researchers who have long considered protein to be a nutrient "of first importance." However, even though the importance of protein is so deeply-rooted in nutritional science, researchers may actually be in the early stages of understanding the full health benefits provided by this remarkable nutrient. The reason involves the surprising number of roles that protein plays in our body. Consider the following summary of basic functions played by protein in our everyday health.
|Body System||Function||Examples of Proteins Involved|
|Digestive||serves as digestive enzymes||amylases, chymotrypsin, disaccharides, lipases, peptidases, proteases, ribonucleases|
|Connective tissue (and extracellular fluid)||provide elasticity, provide fluid gel structures, allow for adhesiveness||amylases, chymotrypsin, disaccharides, lipases, peptidases, proteases, ribonucleases|
|Muscle||provide components that allow for contraction||actin, myosin, troponin, tropomysin, vinculin|
|Endocrine||serve as hormones||insulin, growth hormone, thyroid stimulating hormone (TSH), follicle stimulating hormone (FSH)|
|Nervous||provide amino acids for neurotransmitters||epinephrine, norepinephrine, serotonin, melatonin|
|Genetic||formation of DNA and RNA||histones, nucleic acid polymerizing enzymes|
|Cardiovascular||maintain correct blood pressure and transport a variety of substances||albumin, alpha-globulin, beta-globulin, fibronectin, Complement A|
|Cellular||provide structural integrity and protection||actin, tubulin, spectrin, intermediary filaments|
|Signaling||transfer chemical messages into and out of cells||GCPRs (G-protein coupled receptors)|
|Energy production||promote oxygen-based energy production inside of mitochondria||ATP synthetase, NADH reductase, succinate dehydrogenase|
|Detoxification||processing potential toxins to enable elimination from the body||cytochrome P450 enzymes, sulfotransferase enzymes, methyltransferase enzymes|
As you can see, there are few bodily processes that don't rely on protein in some shape or form!
Luckily, it is not difficult to find foods that contain protein. Half of our WHFoods serve as good, very good, or excellent sources of this nutrient. In addition, all but one of our WHFoods (the single exception is extra virgin olive oil) provide a measurable amount of protein. In addition to this wide-ranging availability of protein, you can pick a relatively small number of foods and reach the Daily Value (DV) for protein—50 grams—fairly easily. For example, four ounces of cod, four ounces of tofu, and 1.5 cups of green peas will give you the full 50 grams. However, we do not recommend that you select protein-rich foods solely based on total gram amounts. Total grams of protein are important. But they do not adequately address the issue of protein quality.
"Protein quality" is a common way of referring to the building blocks that are used to construct a protein. These building blocks are called amino acids. Amino acids are so important that we have given them their own nutrient on our website. But we want to mention enough about amino acids in this protein profile so that we can give you helpful guidelines for obtaining protein from your foods.
There are 20 different amino acids most commonly used to construct proteins. Different types of proteins require different combinations of amino acids because they have different roles to play in the body. Some proteins are quite small and only contain a few dozen total amino acids. Other proteins are extremely large and can contain tens of thousands of total amino acids. Most of the time, however, there are several hundred amino acids per protein, with several dozen of any particular amino acid. As you can see, it is common for proteins to provide significantly different amounts of both total and individual amino acids.
In addition to this significant amino acid diversity in forming proteins themselves so that they can serve the proper functions in our body, proteins also act as a "delivery systems" to provide our body with individual amino acids (or short chains of amino acids called peptides). Because proteins can be broken down in our digestive tract, they can serve as a way to provide our body with patterned amounts of individual amino acids. In other words, sometimes a protein is valuable in and of itself, and at other times it is valuable for the individual amino acids that it contains.
There are ongoing debates about the best way to measure the health benefits associated with the amino acid content of proteins. All of these debates fall under the heading of "protein quality," and you can learn more about this issue in our amino acids profile . However, regardless of the specific approach that is taken to protein quality, we believe that it is helpful to consume proteins that are rich in a variety of different amino acids. For example, we believe that sulfur-containing amino acids have a special value all their own, in the same way as branched-chain amino acids or aromatic amino acids. The best way to obtain a rich variety of amino acids from all of these smaller amino acid subgroups is to regularly enjoy a diversity of foods. More specifically, we would single out the following plant food groups as especially helpful to include over a 3-4 day period in your meal plan in order to obtain a healthy diversity of amino acids: Beans & Legumes, Nuts & Seeds, Vegetables, and Whole Grains. If you consume animal foods, you will find protein-rich choices in all types of animal foods ranging from Poultry & Meats to Seafood to Dairy & Eggs.
One final note in this Basic Description section for protein: while we have adopted the Daily Value (DV) recommendation for protein intake of 50 grams per day, we think about this level as a minimum rather than optimal amount. The reason for our approach involves a growing amount of new research that suggests potential benefits from higher levels of protein intake. While we provide more details about this research in our Role in Health Support section, it's important to know that a diet of 1,800 calories with 15% of those calories coming from protein would contain 67 grams of protein, and if 20% came from protein, that amount would jump up to 90 grams. Dietary studies involving 15-20% protein are becoming more and more common in nutrition research, and we believe the trend shows potential benefits to protein intake in this range.
Role in Health Support
It is impossible to find a general system in the body that does not rely on protein for healthy functioning. As outlined in our Basic Description section, all of our cells require proteins to exist. In addition, metabolic activities throughout our body require enzymes in order to function properly, and all of these enzymes are proteins. Hormones, nervous system messaging molecules (neurotransmitters), digestive enzymes, energy-producing enzymes—all depend on protein. However, it can be difficult to determine the exact levels or qualities of protein that are needed to support these many different body processes. For example, we know that all enzymes are proteins. But we don't know what level or quality of protein intake results in the best enzyme activity. The paragraphs below are designed to highlight some of the more recent findings on dietary protein and health benefits related to this key nutrient.
Maintaining the Integrity of Body Structures
Proper functioning of muscles and healthy formation of connective tissue (the structure that supports and connects our organs) both require sufficient protein intake. In recent studies on aging, adequate protein intake has been associated with decreased risk of hip fracture. This association is likely to be related to the role of protein in supporting healthy muscles and connective tissue. Interestingly, there is some evidence of better support when protein is consumed at the level of 1.2 grams per kilogram of body weight versus 0.8 grams. Since a 154-pound person would weigh 70 kilograms, this lower amount would translate in 56 grams of protein for a 154-pound person, while the higher amount would translate into 84 grams. Of course, the sturdiness of the body depends on far more than just adequate nourishment, since the strength, flexibility, and resilience of muscles and connective tissue require healthy amounts of physical activity and other lifestyle practices.
Improved Body Composition
Protein intake has been a much-debated subject in relationship to body weight and body composition. As a general rule, no specific amount or quality of protein intake can single-handedly improve a person's body composition or promote a healthier body weight. Body composition and body weight depend too heavily on many other factors, including calorie intake, fat intake, activity level, and hormonal balance - to name just a few. However, recent studies show potentially important roles for protein in helping to regulate appetite and alter various aspects of metabolism in a way that helps balance body composition. (In most studies, body composition was measured using body mass index, waist circumference, skinfold thickness, or similar measurements.) In addition, some studies show improved weight control when protein intake represents approximately 15-20% of total calorie intake rather than 10-15%. As mentioned earlier, an 1,800-calorie diet would provide 45 grams of protein at the 10% level, 67 grams of protein at the 15% level, and 90 grams of protein at the 20% level. In other words, a 15-20% protein diet would typically provide substantially more grams of total protein than the 50-gram Daily Value level.
It's worth noting that in most of the studies that we have reviewed, average protein intake associated with improved body composition has always started out above the DV level of 50 grams. Instead, protein intake has generally fallen into the 65-100 gram range. Interestingly, one group of researchers has suggested a general ballpark level of about 30 grams of protein per major meal as a helpful amount in regulating body weight and body composition. We want to emphasize the speculative nature of this recommendation, and also emphasize the great extent to which body weight and body composition fall under the control of other factors besides diet (for example, physical activity level). Still, we believe that there is a research trend here suggesting possible benefits for body composition with protein intake above the Daily Value.
Improved Blood Sugar Regulation
Adequate protein in meals and snacks has long been a mainstay in dietary advice for improved blood sugar regulation. The benefits of protein-rich foods for blood sugar control are largely due to two factors. First, protein is a nutrient that digests at a moderate pace. Protein is one of three basic "macronutrients." Macronutrients are nutrients that we need in relatively large (gram-sized) amounts. Among the three basic macronutrients, carbohydrates can often digest quite quickly. Fats, by contrast, often digest quite slowly. Protein is typically in the middle, and this intermediate position of protein digestion tends to help stabilize food digestion and blood sugar balance. Second, protein-rich foods tend to have very low glycemic index (GI) values. (While GI is related to speed of digestion, it is a measurement that is also related to other aspects of food digestion.) At WHFoods, the vast majority of our profiled foods (86 out of 100) have a GI value of either very low or low. Only 13 WHFoods have a medium GI score, and only 1 WHFood (potato) has a high GI score. Importantly, all of our Top 10 Protein-Rich foods score "very low" in GI, and all of our Top 25 Protein-Rich foods score either "very low" or "low". By contrast, none of our 14 foods with either "medium" or "high" GI scores rank as good, very good, or excellent protein sources. So as you can see, there is a very natural fit between protein-rich foods and foods that help stabilize blood sugar levels.
While there is no question that protein-rich foods can help to stabilize blood sugar levels, there remain plenty of questions about the total amount of protein intake that is best for blood sugar control. Studies on type 2 diabetes and insulin resistance show some mixed findings with respect to protein intake levels. On the one hand, some studies show improved insulin resistance and blood sugar regulation with protein intake in the 20-30% of total calories range. We've also seen a study showing a slight but perhaps still significant decrease in hemoglobin A1c levels (a lab test used to determine average blood sugar level over a 2-3 month period of time) in persons with type 2 diabetes when consuming protein in the range of 26-32% total calories for 6 months. At the same time, however, several large-scale studies have failed to show similar results. We suspect that this inconsistency in research findings is mostly related to the overall quality of the diets being consumed, and to other factors that extend beyond diet. For example, excessive intake of calories, or excessive intake of processed foods, or intake of high glycemic index foods could easily offset any potential benefits associated with higher levels of protein intake. And in studies where these factors were not fully controlled, we would not expect to see benefits from protein intake above the Daily Value. Similarly, factors unrelated to diet - like amount of exercise - also play a major role in blood sugar and insulin balance.
In summary, it is clear that protein-rich foods can help improve blood sugar and insulin levels. Having protein-rich foods on a meal-by-meal basis seems important in this regard. However, it is not clear whether total protein intake above the DV level is consistently helpful for improving blood sugar balance, even though some studies show benefits from higher levels of protein intake.
Other Potential Health Benefits
Two other areas of potential health benefit deserve special mention when considering protein intake. One area involves immune support, and the other area involves support of the cardiovascular system.
One of the most famous aspects of our immune system are its antibodies. Antibodies are molecules that help to identify and neutralize potential dangers to the body, for example, certain viruses and bacteria. What might be a lesser known fact about antibodies is that they actually proteins belonging to a special protein category called immunoglobulins. Our immune system relies on protein for production of other molecules as well, including complement proteins that are critical in supporting the function of our white blood cells. Without adequate supplies of protein, our immune system cannot mobilize adequate supplies of antibodies. In fact, one severe condition involving protein deficiency—called kwashiorkor—is well-known for triggering immune system-related problems.
The connection between immune function and protein status has been well-studied in athletes. Changes in blood flow during high-intensity exercise place strong demands on the immune system and redistribution of white blood cells. In the hours following intense exercise, the ability of the immune system to conduct good surveillance of the body is easily compromised, and for this reason, sufficient protein intake to restore healthy immune function can be important. Some studies show that a helpful level of protein intake for training athletes may require at least 20% of total calories. While this percentage may not sound particularly high, it is important to remember that a training athlete may consume 2,500 calories per day or more. At this calorie level, 20% protein would mean about 125 grams or higher.
In some studies on aging, risk of inflammatory disease has been shown to decrease with protein intake of 1.0 - 1.5 grams per kilogram of body weight. For a person weighing 154 pounds, this formula would mean 70 - 105 grams of daily protein. However, we also want to point out that in some other studies on aging, high protein intake has been shown to have the opposite impact: in these studies, low protein, high carbohydrate diets have slowed down the decline in immune system problems when compared with high protein, low carbohydrate diets. We suspect that the conflicting results in this area of protein, immune system and aging are largely due to the fact that total protein grams are not sufficient in and of themselves to provide us with immune system support. Instead, this total amount of protein must be evaluated within the bigger context of protein quality, overall dietary intake, and overall body health (including the health of the lungs, kidneys, and other body systems that can become compromised over the course of aging).
Potential cardiovascular benefits from protein intake greater than the Daily Value have a second research area with mixed findings. In one study, the fat content of liver cells (in the form of triglycerides) was found to be increased by a high carbohydrate (60% of total calories) and low protein (5% of total calories) diet, in comparison to a high protein (30% of calories) and low carbohydrate (35% of calories) diet. Similarly, risk of coronary heart disease associated with an 1,800-calorie diet emphasizing plant protein (93 grams) was found to be somewhat lower than the risk associated with a similar diet containing only 49 grams of plant-based protein. However, other studies have found no difference in risk associated with moderate versus high levels of protein intake, and even when differences have been found, they have not turned out to be statistically significant. Finally, we have reviewed a large-scale study on high blood pressure showing an association between high levels of protein intake (in the vicinity of 100 grams per day) and significantly decreased risk of high blood pressure over an 11-year period of time.
Since no whole food consists of pure protein, these cardiovascular-related studies surely encourage us to place protein intake into a bigger context. If proteins come from low quality foods, or are woven into a poorly balanced overall diet, it seems unlikely for greater amounts to lower our risk of cardiovascular problems (or any other problems). However, within the context of a well-balanced, high-quality, whole foods diet, protein intake above the Daily Value may offer important benefits.
Summary of Food Sources
It's probably not going to come as much of a surprise that fish, poultry and meats are our most abundant sources of protein. In fact, no other WHFoods make it into our Top 10 list when measured exclusively by the sheer amount of protein that they provide in grams. Meats and poultry also make up almost 40% of the protein intake of an average U.S. adult, with another 30% coming from fish, eggs, and dairy foods. Of course, these percentages simply reflect the food preferences of an average U.S. adult, and by no means imply that 70% of your protein intake should come from animal foods. Obtaining optimal protein intake does not require anyone to eat any animal foods.
Among plant foods, legumes tend to be strong sources of protein. We list a number of legumes that contain 30% or more of your daily protein need per one cup serving. Even when enjoyed in the form of a soup (like our Italian Navy Bean Soup with Rosemary), you can get close to 15 grams of protein from the legume-based nature of this recipe and many others. .
Nuts, seeds, and whole grains can all be significant contributors to protein intake. Expect that a serving of any of these three food groups should contain around 10-15% of your daily requirement. One ounce of pumpkin seeds can add 5 grams of protein to your daily meal plan. So can one cup of brown rice.
Vegetables can contain more protein than you might guess. Some categories of vegetable, brassicas and greens, for instance, can contain 5-10% of your protein needs per serving. You'll be getting over 5 grams of protein from a single cup of spinach or collards, and over 7 grams from a single cup of green peas.
Since it is fairly easy to build a diet that meets your protein needs using meats, poultry, and fish,, we'll not discuss this scenario in any detail. It is really as easy as eating one serving of meat, poultry or fish, and then getting enough calories from whole foods to fill out the rest of your day. Four ounces of chicken or turkey will put you at about 35 grams, while 4 ounces of most fish and meats will put you at about 25 grams. With any of these options, you will only be using up about 8-10% of your total daily calories (assuming an 1,800-calorie meal plan) and are almost guaranteed to get your remaining 15-25 grams from the other whole foods that you consume.
Let's instead attempt to build out a diet that meets protein needs using only vegetarian choices. At breakfast, let's start with 10-minute Energizing Oatmeal. This will start our day with 14 grams of protein, or about 30% of our daily requirement. For lunch, we'll choose the Fettuccini with Spinach Pesto, to get another 19 grams of protein. For dinner, let's do Black Bean Chili. Here, we'll get another 24 grams to round out our day.
We're already well over the protein Daily Value of 50 grams,, but since we're only at about 1300 calories, we'll want to add a couple of snacks or treats. About mid-afternoon, if our energy is down, we could include some 10-minute Peanut Bars, a snack that provides about 4 grams of protein. Perhaps we then could cap the day with the 10-Minute Fresh Berry Dessert with Yogurt and Chocolate for another 7 grams of bedtime protein. This sample day provides us with 68 grams of plant-based protein and doesn't go out of its way to focus on high-protein foods.
Nutrient Rating Chart
Introduction to Nutrient Rating System ChartIn 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|
|Chicken||4 oz||187.1||35.18||70||6.8||very good|
|Turkey||4 oz||166.7||34.17||68||7.4||very good|
|Soybeans||1 cup||297.6||28.62||57||3.5||very good|
|Salmon||4 oz||157.6||26.59||53||6.1||very good|
|Beef||4 oz||175.0||26.16||52||5.4||very good|
|Shrimp||4 oz||134.9||25.83||52||6.9||very good|
|Lamb||4 oz||310.4||25.57||51||3.0||very good|
|Scallops||4 oz||125.9||23.29||47||6.7||very good|
|Sardines||3.20 oz||188.7||22.33||45||4.3||very good|
|Tofu||4 oz||164.4||17.89||36||3.9||very good|
|Spinach||1 cup||41.4||5.35||11||4.7||very good|
|Asparagus||1 cup||39.6||4.32||9||3.9||very good|
|Beet Greens||1 cup||38.9||3.70||7||3.4||very good|
|Mustard Greens||1 cup||36.4||3.58||7||3.5||very good|
|Swiss Chard||1 cup||35.0||3.29||7||3.4||very good|
|Bok Choy||1 cup||20.4||2.65||5||4.7||very good|
|Dried Peas||1 cup||231.3||16.35||33||2.5||good|
|Pinto Beans||1 cup||244.5||15.41||31||2.3||good|
|Kidney Beans||1 cup||224.8||15.35||31||2.5||good|
|Black Beans||1 cup||227.0||15.24||30||2.4||good|
|Navy Beans||1 cup||254.8||14.98||30||2.1||good|
|Lima Beans||1 cup||216.2||14.66||29||2.4||good|
|Garbanzo Beans||1 cup||269.0||14.53||29||1.9||good|
|Pumpkin Seeds||0.25 cup||180.3||9.75||20||1.9||good|
|Green Peas||1 cup||115.7||7.38||15||2.3||good|
|Collard Greens||1 cup||62.7||5.15||10||3.0||good|
|Brussels Sprouts||1 cup||56.2||3.98||8||2.6||good|
|Cow's milk||4 oz||74.4||3.84||8||1.9||good|
|Green Beans||1 cup||43.8||2.36||5||1.9||good|
|Soy Sauce||1 TBS||10.8||1.89||4||6.3||good|
|Sea Vegetables||1 TBS||10.8||1.81||4||6.0||good|
|Mushrooms, Crimini||1 cup||15.8||1.80||4||4.1||good|
|Turnip Greens||1 cup||28.8||1.64||3||2.0||good|
|Summer Squash||1 cup||36.0||1.64||3||1.6||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%
Impact of Cooking, Storage and Processing
Our steaming, boiling, and healthy sauté cooking methods will not result in any significant protein loss from any of our WHFoods. Nor will storage of these foods using our recommended approach and suggested time frames. Protein tends to be a stable nutrient within the above context.
Proteins and their amino acids can interact with sugars under certain circumstances to form other compounds. Many of these chemical reactions - for example, the Maillard reaction - are actually very complicated in terms of their biochemistry and have yet to be fully researched. One possible result of protein-sugar interactions involves formation of molecules called advanced glycation end-products, or AGES. When excessive numbers of AGEs are formed in the body, we know that they can contribute to increased risk of chronic diseases including atherosclerosis, osteoarthritis, cataracts, neurodegenerative diseases, and cataracts. Relatively recent research indicates that AGEs can not only get preformed in food but can get absorbed up into our body in significant amounts and contribute to the "pool" of AGEs that have already been formed as a result of our own metabolism. The cooking methods that appear mostly likely to increase AGE formation in protein-rich foods including grilling, searing, and frying. Formation of AGEs from protein-sugar interactions is one of the reasons we avoid these cooking methods at WHFoods. A second area of concern in protein cooking involves possible formation of acrylamides. Potato chips, french fries, and grain-based coffee substitutes are processed foods in which acrylamide formation has been most extensively studied. You can find many more details in our Q & A, What is acrylamide and how is it involved with food and health?
Finally, we would like to note that caramelization of food (as exemplified by the heating and browing of onions) is not a protein-based chemical reaction but a reaction only involving food sugars and is not the same as the above-described AGE formation and acrylamide formation processes.
Risk of Dietary Deficiency
If you eat animal foods—meat, fish, dairy, eggs—on a daily basis, you are very likely to be meeting or exceeding the Daily Value of 50 grams for protein.
However, you don't need to eat animal foods much or even at all to meet the DV. . An average American lacto-ovo-vegetarian (a vegetarian who eats dairy and eggs) eats 89 grams of protein per day, almost twice the Daily Value (DV) of 50 grams. Even when we subtract the contributions of dairy and eggs, we still see about 60 grams of protein from purely plant sources.
It would actually be quite difficult to design a whole foods diet that provided less than 10% of its calories from protein. An 1,800-calorie whole foods diet consisting exclusively of fruit, for example, would typically still provide at least 40 grams of protein. An 1,800 calorie whole foods diet consisting exclusively of broccoli would provide 121 grams! Of course, we would never recommend either of these approaches to a meal plan, but they are helpful in demonstrating just how difficult it is to come up with a highly protein deficiency diet based on a whole foods approach to eating.
More up in the air is the question of health benefits from a meal plan that greatly exceeds the protein DV of 50 grams. As discussed earlier, we have seen the develop of a research trend that suggests possible advantages to a meal plan in which protein represents 15-25% of total calories (67-112 grams) instead of the 11% level represented by 50 grams. We definitely look forward to more research in this area.
Other Circumstances that Might Contribute to Deficiency
Disordered eating patterns can lead to protein-energy malnutrition, which can often become quite serious. As many as 24 million Americans suffer from one or more eating disorders. These disorders are often undiagnosed, and only one in ten people receives the medical treatment these conditions often require.
There are some severe disease states that cause an increase in protein breakdown. In these conditions, it may be difficult or even impossible to eat enough dietary protein to offset the loss.
While many sources recommend it, the National Academy of Sciences does not recommend a different protein requirement based on level of physical activity. The American College of Sports Medicine, however, does recommend at least paying attention to protein intake to make sure that needs are met during times of intensive training. You will find this issue discussed in more detail in our earlier section entitled "Other Potential Health Benefits" in our Role in Health Support section.
Relationship with Other Nutrients
As your protein intake goes up, so can your urinary loss of calcium. This phenomenon is related to the use of calcium as a buffer when proteins or their amino acids are primarily acidic. However, from a research standpoint, the jury is out on exactly how this natural physiologic process relates to any potential health risks. (For example, too much extraction of calcium from our bones could increase our risk of osteoporosis.) We expect future studies to help clarify the nature of these protein-and-calcium relationships. As mentioned earlier in our Impact of Cooking, Storage, and Processing section, proteins and amino acids can react with certain types of sugars to produce advanced glycosylation end-products (AGEs) and other compounds (including acrylamides). Please see that earlier section for more detail.
Risk of Dietary Toxicity
The National Academy of Sciences (NAS) established an Acceptable Macronutrient Distribution Ranges (AMDRs) for protein in 2005. Important, the NAS did not consider these ranges to be Dietary Reference Intake guidelines that established specific upper (or lower) limits for protein intake. Instead, these AMDRs were viewed as general guidelines that could be considered helpful in potentially lowering disease risk. These 2005 AMDRs for protein were established as follows:
- Adults: 10-35% of total calories
- Children 1-3 years: 5-20% of total calories
- Children and Teens 4-18 years: 10-30% of total calories
Let's take the adult guidelines of 10-35% and translate these percentages into more practical terms. And let's start out with the high end guideline for protein intake of 35% total calories. Here are the grams of protein that correspond to 35% of total calories at different calorie levels:
- 131 grams of protein in a 1,500-calorie diet
- 157 grams of protein in an 1,800-calorie diet
- 175 grams of protein in a 2,000-calorie diet
- 219 grams of protein in a 2,500-calorie diet
Now let's look at the low end of this protein guideline (10% of total calories). Here are the grams of protein that correspond to 10% of total calories at different calorie levels:
- 38 grams of protein in a 1,500-calorie diet
- 45 grams of protein in an 1,800-calorie diet
- 50 grams of protein in a 2,000-calorie diet
- 63 grams of protein in a 2,500-calorie diet
Since the Daily Value (DV) for protein is based on a 2,000-calorie meal plan, you can see how this lower limit of the AMDR for protein hits exactly at that 10% level. However, in this section on Risk of Dietary Toxicity, it is the high end of the AMDR that we are most concerned about, and you can see how this high end very roughly corresponds to protein intake in the 150-200 gram per day range.
It is very hard in practice to go beyond this level from whole foods! Whole foods set a natural limit on the total amount of protein that you can consume within any fixed amount of calories, because no whole food consists of pure protein. Instead, protein-containing whole foods also contain varying amounts of fat, and fat is a nutrient that contains more than double the calories of protein. So as a result, all whole foods end up increasing their calories at a quicker rate than their grams of protein. These ratios between protein, fat, and calories in whole foods enable you to stay within the AMDR guidelines in virtually any balanced meal plan.
- Anorexia and other eating disorders
- Malabsorption disorders
- Heavy exercise
- Weight loss
- Diabetes prevention
- Immunodeficiency problems
- Problems with insulin resistance
Public Health Recommendations
In 2005, the National Academy of Sciences established a set of Dietary Reference Intakes (DRIs) for protein that included age and gender specific Recommended Dietary Allowances (RDAs) for protein. Note that the recommendations for infants from 0-6 months of age were established as Adequate Intake (AI) levels. The complete set of DRIs is as follows: .
- 0-6 months: 9.1 grams
- 6-12 months: 11 grams
- 1-3 years: 13 grams
- 4-8 years: 19 grams
- 9-13 years: 34 grams
- 14-18 years, female: 46 grams
- 14-18 years, male: 52 grams
- 19+ years, female: 46 grams
- 19+ grams, male: 56 grams
- Pregnant women: 71 grams
- Lactating women: 71 grams
Note that for adults, these RDA assume an average body weight of 70 kg (or 154 lbs) for a male and 57.5 kg (or 126 lbs) for a female. For people significantly different from these target weights, you may choose to include 0.8 grams of dietary protein per kilogram (about 2.2 pounds) of body weight.
In 2005 the National Academy of Sciences (NAS) also issued a set of Acceptable Macronutrient Distribution Ranges (AMDRs) for protein as a percentage of total calories. They recommend keeping protein calories between 5 and 20% of calorie total in ages 1-3 years, 10 to 30% in children ages 4-18, and 10-35% in adults. The NAS did not consider these AMDRs to be part of the Dietary Reference Intakes (DRIs), but rather very general guidelines with the potential to lower risk of health problems. In our Risk of Dietary Deficiency section, you can find practical details about these AMDR guidelines.
The Daily Value (DV) recommendation for protein is 50 grams per day for adults. This is the standard you will see listed on food labels. It is also the standard that we have adopted at WHFoods as our recommended minimal amount of daily protein intake.
- American Dietetic Association, Dietitians of Canada, American College of Sports Medicine, et al. American College of Sports Medicine position stand. Nutrition and athletic performance. Med Sci Sports Exerc 2009;41:709-31.
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- Much grattidtude to George Mateljan,and the George Mateljan Foundation for www.whfoods.com