Instruct: Given a question, retrieve passages that can help answer the question.
Query: What is the recommended amount of dietary protein for adult humans?
The daily requirement for humans to remain in nitrogen balance is relatively small. The median human adult requirement for good quality protein is approximately 0.65 gram per kilogram body weight per day and the 97.5 percentile is 0.83 grams per kilogram body weight per day.[7] Children require more protein, depending on the growth phase. A 70kg adult human who was in the middle of the range would require approximately 45 grams of protein per day to be in nitrogen balance. This would represent less than 10% of kilocalories in a notional 2,200 kilocalorie ration. William Cumming Rose and his team studied the essential amino acids, helping to define minimum amounts needed for normal health. For adults, the recommended minimum amounts of each essential amino acid varies from 4 to 39 milligrams per kilogram of body weight per day. To be of good quality, protein only needs to come from a wide variety of foods; there is neither a need to mix animal and plant food together nor a need to complement specific plant foods, such as rice and beans.[8] The notion that such specific combinations of plant protein need to be made to give good quality protein stems from the book Diet for a Small Planet. Plant protein is often described as incomplete, suggesting that they lack one or more of the essential amino acids. Apart from rare examples, such as Taro,[8][9] each plant provides an amount of all the essential amino acids. However, the relative abundance of the essential amino acids is more variable in plants than that found in animals, which tend to be very similar in essential amino acid abundance, and this has led to the misconception that plant proteins are deficient in some way.
Nutritionally, Brazil nuts are an excellent source (> 19% of the Daily Value, DV) of dietary fiber (30% DV) and various vitamins and dietary minerals. A 100 gram amount (75% of one cup) of Brazil nuts contains rich content of thiamin (54% DV), vitamin E (38% DV), magnesium (106% DV), phosphorus (104% DV), manganese (57% DV) and zinc (43% DV) (right table). Brazil nuts are perhaps the richest dietary source of selenium, with a one-ounce (28 g) serving of 6 nuts supplying 774% DV. This is 10 times the adult U.S. Recommended Dietary Allowance, more even than the Tolerable Upper Intake Level, although the amount of selenium within batches of nuts varies greatly.
Several studies, however, have found no evidence of protein toxicity due to high protein intakes on kidney function in healthy people. Diets that regularly exceed the recommendations for protein intake have been found to lead to an increased glomerular filtration rate in the kidneys and also have an effect on the hormone systems in the body. It is well established that these physiological effects are harmful to individuals with renal disease, but research has not found these responses to be detrimental to those who are healthy and demonstrate adequate renal activity. In people with healthy kidney function, the kidneys work continuously to excrete the by-products of protein metabolism which prevents protein toxicity from occurring. In response to an increased consumption of dietary protein, the kidneys maintain homeostasis within the body by operating at an increased capacity, producing a higher amount of urea and subsequently excreting it from the body. Although some have proposed that this increase in waste production and excretion will cause increased strain on the kidneys, other research has not supported this. Currently, evidence suggests that changes in renal function that occur in response to an increased dietary protein intake are part of the normal adaptive system employed by the body to sustain homeostasis. In a healthy individual with well-functioning kidneys, there is no need for concern that an increased dietary protein intake will lead to protein toxicity and decreased renal function.
Caloric restriction (CR) or dietary restriction (DR) are helpful tools in understanding age and diet related health complications. In the 1972 Japan National Nutrition Survey it was determined that Okinawan adults consumed 83% of what Japanese adults did and that Okinawan children consumed 62% of what Japanese children consumed. It should be noted that today the difference in life expectancy between Okinawan and mainland Japanese is decreasing as the Okinawan are losing their dietary advantage. Recently, there is a decreasing trend in the life expectancy in Okinawa. This is evidenced by low birth weight, poor lactation, and the fact that the life expectancy for Okinawan men is lower than the national average. Scientist such as Dr. Éric Le Bourg believe that the Okinawa diet has more of a deleterious effect then beneficial one. Le Bourg and others alike think that the low protein intake can cause harmful effects on a human as they have done in animal studies. The individuals with a lower protein consumption were more vulnerable to pathogens. Another plausible reason for the decrease in life expectancy is westernization. After World War II, Okinawans started to consume more calories. This in part is due to Americanization of the diet, such as with fast food.
According to US & Canadian Dietary Reference Intake guidelines, women aged 19–70 need to consume 46 grams of protein per day while men aged 19–70 need to consume 56 grams of protein per day to minimize risk of deficiency. These Recommended Dietary Allowances (RDAs) were calculated based on 0.8 grams protein per kilogram body weight and average body weights of 57 kg (126 pounds) and 70 kg (154 pounds), respectively. However, this recommendation is based on structural requirements but disregards use of protein for energy metabolism. This requirement is for a normal sedentary person. In the United States, average protein consumption is higher than the RDA. According to results of the National Health and Nutrition Examination Survey (NHANES 2013-2014), average protein consumption for women ages 20 and older was 69.8 grams and for men 98.3 grams/day.
The protein requirement for each individual differs, as do opinions about whether and to what extent physically active people require more protein. The 2005 Recommended Dietary Allowances (RDA), aimed at the general healthy adult population, provide for an intake of 0.8 grams of protein per kilogram of body weight. A review panel stating that "no additional dietary protein is suggested for healthy adults undertaking resistance or endurance exercise."
Proteins are chains of amino acids. Nine of these proteinogenic amino acids are considered essential for humans because they cannot be produced from other compounds by the human body and so must be taken in as food. Recommended intakes, expressed as milligrams per kilogram of body weight per day, have been established. Other amino acids may be conditionally essential for certain ages or medical conditions. Amino acids, individually and in combinations, are sold as dietary supplements. The claim for supplementing with the branched chain amino acids leucine, valine and isoleucine is for stimulating muscle protein synthesis. A review of the literature concluded this claim was unwarranted. In elderly people, supplementation with just leucine resulted in a modest (0.99 kg) increase in lean body mass. The non-essential amino acid arginine, consumed in sufficient amounts, is thought to act as a donor for the synthesis of nitric oxide, a vasodilator. A review confirmed blood pressure lowering. Taurine, a popular dietary supplement ingredient with claims made for sports performance, is technically not an amino acid. It is synthesized in the body from the amino acid cysteine.
The "2015–2020 Dietary Guidelines for Americans" (DGA) recommends that men and teenage boys increase their consumption of fruits, vegetables and other under-consumed foods, and that a means of accomplishing this would be to reduce overall intake of protein foods. The 2015 - 2020 DGA report does not set a recommended limit for the intake of red and processed meat. While the report acknowledges research showing that lower intake of red and processed meat is correlated with reduced risk of cardiovascular diseases in adults, it also notes the value of nutrients provided from these meats. The recommendation is not to limit intake of meats or protein, but rather to monitor and keep within daily limits the sodium (< 2300 mg), saturated fats (less than 10% of total calories per day), and added sugars (less than 10% of total calories per day) that may be increased as a result of consumption of certain meats and proteins. While the 2015 DGA report does advise for a reduced level of consumption of red and processed meats, the 2015-2020 DGA key recommendations recommend that a variety of protein foods be consumed, including both vegetarian and non-vegetarian sources of protein.
Infants - either still 100% breastfeeding or partially/entirely on infant formula - and also young children - may be prone to a combined cow's milk and soy protein allergy referred to as "milk soy protein intolerance" (MSPI). A US state government website presents the concept, including a recommendation that nursing mothers discontinue eating any foods that contain dairy or soy ingredients. In opposition to this recommendation, a published scientific review stated that there was not yet sufficient evidence in the human trial literature to conclude that maternal dietary food avoidance during lactation would prevent or treat allergic symptoms in breastfed infants.
In setting human nutrient guidelines, government organizations do not necessarily agree on amounts needed to avoid deficiency or maximum amounts to avoid the risk of toxicity. For example, for vitamin C, recommended intakes range from 40 mg/day in India to 155 mg/day for the European Union. The table below shows U.S. Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for vitamins, PRIs for the European Union (same concept as RDAs), followed by what three government organizations deem to be the safe upper intake. RDAs are set higher than EARs to cover people with higher than average needs. Adequate Intakes (AIs) are set when there is not sufficient information to establish EARs and RDAs. Governments are slow to revise information of this nature. For the U.S. values, with the exception of calcium and vitamin D, all of the data date to 1997-2004.
School lunches must meet the applicable recommendations of the Dietary Guidelines for Americans, which state that no more than 30 percent of an individual's calories should come from fat, and no more than 10 percent from saturated fat. School lunches must also provide one-third of the recommended daily allowances of calories, protein, vitamin A, vitamin C, iron, and calcium. However, decisions about what specific foods to serve and how to prepare them are made by local school officials. The 2007 School Nutrition Dietary Assessment Study III, based on research by the USDA during the 2004–05 school year, found that students in more than 90 percent of schools surveyed had the opportunity to select lunches that met dietary standards for fat and saturated fat.
Consumed worldwide by billions of people, wheat is a significant food for human nutrition, particularly in the least developed countries where wheat products are primary foods. When eaten as the whole grain, wheat is a healthy food source of multiple nutrients and dietary fiber recommended for children and adults, in several daily servings containing a variety of foods that meet whole grain-rich criteria. Dietary fiber may also help people feel full and therefore help with a healthy weight. Further, wheat is a major source for natural and biofortified nutrient supplementation, including dietary fiber, protein and dietary minerals.
The World Health Organization (WHO) has issued recommendations regarding nutrient requirements in HIV/AIDS. A generally healthy diet is promoted. Dietary intake of micronutrients at RDA levels by HIV-infected adults is recommended by the WHO; higher intake of vitamin A, zinc, and iron can produce adverse effects in HIV positive adults, and is not recommended unless there is documented deficiency. Dietary supplementation for people who are infected with HIV and who have inadequate nutrition or dietary deficiencies may strengthen their immune systems or help them recover from infections, however evidence indicating an overall benefit in morbidity or reduction in mortality is not consistent.
The U.S. Institute of Medicine has not confirmed that boron is an essential nutrient for humans, so neither a Recommended Dietary Allowance (RDA) nor an Adequate Intake have been established. Adult dietary intake is estimated at 0.9 to 1.4 mg/day, with about 90% absorbed. What is absorbed is mostly excreted in urine. The Tolerable Upper Intake Level for adults is 20 mg/day.
Concerns over the safety of consumption of genetically-modified plant materials that contain Cry proteins have been addressed in extensive dietary risk assessment studies. While the target pests are exposed to the toxins primarily through leaf and stalk material, Cry proteins are also expressed in other parts of the plant, including trace amounts in maize kernels which are ultimately consumed by both humans and animals.
The efforts of the US Federal Government to establish a scientific basis for human nutrition began with Wilbur Olin Atwater, who published the first dietary recommendations for Americans in 1894, notably stating that, "We live not upon what we eat, but upon what we digest."
In a 100-g reference amount, cumin seeds provide high amounts of the Daily Value for fat (especially monounsaturated fat), protein, and dietary fiber (table). B vitamins, vitamin E, and several dietary minerals, especially iron, magnesium, and manganese, are present in substantial Daily Value amounts (table). Cumin seeds contain petroselinic acid.
Dietary nickel may affect human health through infections by nickel-dependent bacteria, but it is also possible that nickel is an essential nutrient for bacteria residing in the large intestine, in effect functioning as a prebiotic. The U.S. Institute of Medicine has not confirmed that nickel is an essential nutrient for humans, so neither a Recommended Dietary Allowance (RDA) nor an Adequate Intake have been established. The Tolerable Upper Intake Level of dietary nickel is 1000 µg/day as soluble nickel salts. Dietary intake is estimated at 70 to 100 µg/day, with less than 10% absorbed. What is absorbed is excreted in urine. Relatively large amounts of nickel – comparable to the estimated average ingestion above – leach into food cooked in stainless steel. For example, the amount of nickel leached after 10 cooking cycles into one serving of tomato sauce averages 88 µg.
The American Dietetic Association recommends that the average adult consume 25 to 38 grams of dietary fibre per day. However, research has shown that the average American only consumes 14 to 15 grams per day. To reach the recommended amount of fibre, consumption of dietary fibre from foods (e.g. plants, vegetables, legumes, and grains) instead of supplements is preferred because they contain additional beneficial nutrients and non-nutritive components (e.g. antioxidants and phytoestrogens). Nevertheless, a fibre supplement may be needed to prevent constipation when food intake is low, which is the case among inactive elderly. A cereal bran such as psyllium seed husk, or a synthetic fiber such as methylcellulose is often used in this case.
In order to improve the effectiveness of PD drugs such as L-DOPA, a diet low in excessive protein is recommended since L-DOPA competes with these dietary proteins for access to the blood and brain. It is therefore recommended that the drug be taken so that it is not affected by digestion. It is recommended to take L-DOPA ideally 30 minutes before eating or at least 1 hour afterwards. A protein redistribution diet is sometimes recommended in which most protein should be eaten in the afternoon. However, with the development of dyskinesias the protein redistribution diet need not apply because slowing the absorption of L-DOPA may be beneficial. Plenty of water with the intake of L-DOPA ensures that the drug will be absorbed more quickly. L-DOPA can cause nausea in some subjects when taken on an empty stomach. Methods to reduce nausea include taking carbidopa (Sinemet), sugary drinks to calm the stomach, and avoidance of orange and grapefruit juices due to high acidity. Some PD medications are known to cause the subject to become thirsty, and methods to reduce thirst include drinking plenty of water as well as limiting caffeine uptake because it may interfere with medication or increase thirst.
Infants – either still 100% breastfeeding or on infant formula – and also young children may be prone to a combined cow's milk and soy protein allergy, referred to as "milk soy protein intolerance" (MSPI). A U.S. state government website presents the concept, including a recommendation that nursing mothers discontinue eating any foods that contain dairy or soy ingredients. In opposition to this recommendation, a published scientific review stated that there was not yet sufficient evidence in the human trial literature to conclude that maternal dietary food avoidance during lactation would prevent or treat allergic symptoms in breastfed infants.
Modest amounts of gases such as carbon dioxide, methane, and hydrogen are also produced in intestinal fermentation. One review estimated that the acceptable daily intake of resistant starch may be as high as 45 grams in adults, an amount exceeding the total recommended intake for dietary fiber of 25–38 grams per day. When isolated resistant starch is used to substitute for flour in foods, the glycemic response of that food is reduced.
The United States Department of Agriculture and United States Department of Health and Human Services attempt to provide evidence based recommendations for the types and amounts of certain foods people should eat to maintain a healthy diet in a document called The Dietary Guidelines for Americans. These recommendations are updated every 5 years and the most recent version (2015-2020 Dietary Guidelines for Americans) recommends the following:
Most simians consume the vitamin in amounts 10 to 20 times higher than that recommended by governments for humans. This discrepancy constitutes much of the basis of the controversy on current recommended dietary allowances. It is countered by arguments that humans are very good at conserving dietary vitamin C, and are able to maintain blood levels of vitamin C comparable with simians on a far smaller dietary intake, perhaps by recycling oxidized vitamin C.
In 2009, results of a clinical trial of golden rice with adult volunteers from the US were published in the "American Journal of Clinical Nutrition". The trial concluded that "beta carotene derived from golden rice is effectively converted to vitamin A in humans". A summary for the American Society for Nutrition suggested that "Golden Rice could probably supply 50% of the Recommended Dietary Allowance (RDA) of vitamin A from a very modest amount — perhaps a cup — of rice, if consumed daily. This amount is well within the consumption habits of most young children and their mothers".