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Wilbur Olin Atwater (May 3, 1844 – September 22, 1907) was an American chemist known for his studies of human nutrition and metabolism , and is considered the father of modern nutrition research and education. He is credited with developing the Atwater system , which laid the groundwork for nutrition science in the United States and inspired modern Olympic nutrition.

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59-499: The Atwater system , named after Wilbur Olin Atwater , or derivatives of this system are used for the calculation of the available energy of foods . The system was developed largely from the experimental studies of Atwater and his colleagues in the later part of the 19th century and the early years of the 20th at Wesleyan University in Middletown, Connecticut . Its use has frequently been

118-520: A $ 5,600 contribution from the Connecticut legislature for a two-year trial period, the first agricultural experiment station was created in the United States. Atwater served as administrator of the trial run from 1875 until 1877 with initial research focused on fertilizers. Before the two year trial was over, the Connecticut legislature agreed to regular funding of the station but had decided to move

177-563: A Nutrition Laboratory in Boston with funding from the Carnegie Corporation . Initially, the funding was meant construct a new laboratory for Atwater and fund his continued work; however, with the realization that he would not be returning, the funds were transferred to the Boston laboratory project. Benedict continued Atwater's work and used the respiration calorimeter to further measure metabolism and other bodily processes. Benedict studied

236-564: A calculated heat of combustion of 9.37 kcal/g (39.2 kJ/g) compared with that of cow milk fat of 9.19 kcal/g (38.5 kJ/g). Monosaccharides have heats of combustion of around 3.75 kcal/g (15.7 kJ/g), disaccharides 3.95 kcal/g (16.5 kJ/g) and polysaccharides 4.15 to 4.20 kcal/g (17.4 to 17.6 kJ/g). The heat of hydrolysis is very small and these values are essentially equivalent when calculated on a monosaccharide basis. Thus 100 g sucrose gives on hydrolysis 105.6 g monosaccharide and 100 g starch gives on hydrolysis 110 g glucose. The human digestive tract

295-494: A food, as measured by bomb calorimetry is equal to the sum of the heats of combustion of the components – protein (GE p ), fat (GE f ) and carbohydrate (GE cho ) (by difference) in the proximate system. G E = G E p + G E f + G E c h o . {\displaystyle {GE}={{GE}_{\mathrm {p} }+{GE}_{\mathrm {f} }+{GE}_{\mathrm {cho} }}.} Atwater considered

354-461: A good scientist, he reported the data and was very upset that alcohol companies used his research" to advertise their products. In 1904, Atwater suffered a stroke and remained unable to work until his death in 1907. He is interred at Indian Hill Cemetery in Middletown, Connecticut . During his decline, the program at Wesleyan continue through his associates. His collaborator and successor, Frances Benedict continued his work and helped establish

413-573: A heat of combustion of 3.95 kcal/g (16.53 kJ/g) and starch 4.15 kcal/g (17.36 kJ/g). Secondly it does not provide for the fact that sugars and starch are virtually completely digested and absorbed, and thus provide metabolisable energy equivalent to their heat of combustion. The unavailable carbohydrates (dietary fibre) are degraded to a variable extent in the large bowel. The products of this microbial digestion are fatty acids, CO 2 (carbon dioxide), methane and hydrogen. The fatty acids (acetate, butyrate and propionate) are absorbed in

472-480: A low variance and have the appearance of constants. This is spurious since faecal excretion is variable even on a constant diet, and there is no evidence to suggest that faecal excretion is in fact related to intake in the way implied by these coefficients. The calculation of energy values must be regarded as an alternative to direct measurement, and therefore is likely to be associated with some inaccuracy when compared with direct assessment. These inaccuracies arise for

531-403: A man inside a cabinet, or a respiration chamber, as it is called. It is in fact a box of copper incased [ sic ] in walls of zinc and wood. In this chamber he lives—eats, drinks, works, rests, and sleeps. There is a constant supply of fresh air for ventilation. The temperature is kept at the point most agreeable to the occupant. Within the chamber are a small folding cot-bed, a chair, and a table. In

590-412: A mixture in the intestine, and from a practical view point, such studies with humans are difficult to control with the required accuracy. The carbohydrate by difference approach presents several problems. First, it does not distinguish between sugars, starch and the unavailable carbohydrates (roughage, or " dietary fibre "). This affects first the gross energy that is assigned to carbohydrate—sucrose has

649-407: A number of reasons The theoretical and physiological objections to the assumptions inherent in the Atwater system are likely to result in errors much smaller than these practical matters. Conversion factors were derived from experimental studies with young infants, but these produced values for metabolisable energy intake that were insignificantly different from those obtained by direct application of

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708-566: A platform for swapping farm tips. The publication was a means for the Hatch Act stations to report their research to the USDA, while also holding scientists accountable to particular standards of research and reporting. At the same time, Farmers' Bulletins were created to provide farmers with an easy to read and understand presentation of the findings of agricultural research stations and other scientific institutions. Through Atwater's role as director he

767-434: A protein from amino-acid data, as some of the heats of combustion are not known accurately. Preliminary calculations on cow's milk suggest a value of around 5.5 kcal/g (23.0 kJ/g). Analogously the experimental evidence is limited, but since the fatty acids differ in their heats of combustion one should expect fats to vary in heats of combustion. These differences are, however, relatively small – for example, breast milk fat has

826-565: A system for calculating faecal energy losses. Digestible energy = G E p ( D p ) + G E f ( D f ) + G E c h o ( D c h o ) , {\displaystyle {\text{Digestible energy}}={{GE}_{\mathrm {p} }(D_{\mathrm {p} })}+{{GE}_{\mathrm {f} }(D_{\mathrm {f} })}+{{GE}_{\mathrm {cho} }(D_{\mathrm {cho} })},} where D p , D f , and D cho are respectively

885-473: Is a very efficient organ, and the faecal excretion of nitrogenous material and fats is a small proportion (usually less than 10%) of the intake. Atwater recognised that the faecal excretion was a complex mixture of unabsorbed intestinal secretions, bacterial material and metabolites, sloughed mucosal cells, mucus, and only to a small extent, unabsorbed dietary components. This might be one reason why he chose to use availability rather than digestibility . His view

944-452: Is different from those eaten in the US in the early 20th century. Atwater measured a large number of digestibility coefficients for simple mixtures, and in substitution experiments derived values for individual foods. These he combined in a weighted fashion to derive values for mixed diets. When these were tested experimentally with mixed diets they did not give a good prediction, and Atwater adjusted

1003-414: Is different. This system relies on having measured heats of combustion of a wide range of isolated proteins, fats and carbohydrates. It also depends on data from digestibility studies, where individual foods have been substituted for basal diets in order to measure the apparent digestibility coefficients for those foods. This approach is based on the assumption that there are no interactions between foods in

1062-414: Is due to an effect on small intestinal absorption is not clear. The increased faecal nitrogen losses on high fibre diets are probably due to an increased bacterial nitrogen content of the faeces. Both these effects however lead to reductions in apparent digestibility, and therefore the Atwater system warrants small changes in the proper energy conversion factors for those diets. The experimental evidence for

1121-781: The American Civil War , instead pursuing his undergraduate education, first at the University of Vermont and then moving to Wesleyan University in Connecticut, where he would complete his general education in 1865. For the next three years, Atwater was a teacher at various schools and in 1868, he enrolled in Yale University 's Sheffield Scientific School , where he studied agricultural chemistry under William Henry Brewer and Samuel William Johnson . During his time at Yale, Atwater worked part time as Johnson's assistant analyzing fertilizers for specific mineral content; he also performed

1180-494: The 1882-1883 school year, Atwater took a leave of absence from Wesleyan to study the digestibility of lean fish with von Voit in Germany. Together, they found fish comparable to lean beef; during this time he became aware of how German scientists were studying nutrition and hoped to bring similar research to the United States upon his return. In 1885, Atwater's first series of studies on peas grown in nutrient solution were published in

1239-498: The Act was passed, Atwater was named director of the second agricultural experiment station in Connecticut that was established at Storrs Agricultural College , and he served there until 1892. The following year, the Office of Experiment Stations was created as a means to monitor and appraise the experiments and activities of the stations; Atwater was chosen as the first director. He accepted

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1298-636: The American Chemical Journal. That same year, the Massachusetts Bureau of Statistics of Labor requested a study of data that had been collected by the bureau concerning family food purchases. In the study, Atwater calculated the daily per capita supplies of carbohydrates, fat, and protein provided within the data, and taking into account the included cost data, made recommendations on how more economical diets, while still having adequate nutritional value, could be chosen. The report he prepared

1357-578: The European model of scientific laboratories in domestic experiment stations. By 1885, Atwater and Johnson had begun advising Congress and President Grover Cleveland on the creation of experiment stations at the land-grant colleges created through the Morrill Act in 1862. In 1887, the Hatch Act was passed, which gave federal funds ($ 15,000 each) to the land-grant colleges to create experiment stations. As

1416-491: The Office of Experiment Stations from 1898 to 1903; she went on to have a career as a home economics specialist and served as the first full time editor of the Journal of Home Economics . His granddaughter, Catherine Merriam Atwater , the daughter of his son, Charles, was an author whom married economist John Kenneth Galbraith . Atwater's legacy is acknowledged through the yearly W.O. Atwater Memorial Lecture , sponsored through

1475-527: The Storrs station was created, Atwater and his colleagues had begun conducting and publishing studies on the chemical compositions of food. In 1891, he resigned as director of the Office of Experiment Stations in order to return to the Storrs and focus exclusively on nutrition research. After his resignation, Atwater was appointed special agent in charge of nutrition programs. Through this position he organized extensive food analyses, dietary studies, experiments on

1534-478: The United States Department of Agriculture, Agricultural Research Service . Each year, a scientist is recognized for their unique contribution toward improving diet and nutrition globally. Atwater and his family's papers are held across multiple institutions, and the collections are, for the most part related to the holding institution. The Wilbur O. Atwater Laboratory at the University of Connecticut

1593-576: The United States similar to the agricultural experiment stations they saw in Europe. Atwater even described the German agricultural experiment stations in an 1875 report to the Department of Agriculture. To persuade the Connecticut legislature to appropriate money for a station, Orange Judd donated funds and Wesleyan offered laboratory facilities and Atwater's services on a part-time basis. Through their work and

1652-537: The United States to teach chemistry at East Tennessee University and the next year moved to Maine State College. While there, Atwater met Marcia Woodard (1851-1932) of Bangor, Maine, the daughter of Abram Woodard. They married in 1874 and in 1876, their daughter Helen was born and son Charles was born in 1885. Wilbur Atwater returned to Wesleyan as a professor of chemistry in 1873 and remained there until his death in 1907. Both he, and his mentor from Yale, Samuel Johnson, were proponents of bringing organizations to

1711-429: The agricultural experiment stations of Europe. During his time there, Atwater studied under German physiologist and dietitian, Carl von Voit and worked alongside Voit's student, Max Rubner . Atwater spent time traveling throughout Scotland , Rome , and Naples ; on his trip he wrote articles about his observations for local newspapers based in the places he had lived in the United States. In 1871, Atwater returned to

1770-499: The air . As his experiments and accomplishments became known, Atwater's assistance was requested for a variety of projects. From 1879 to 1882, he conducted extensive human food studies on behalf of the United States Fish Commission and Smithsonian Institution. In 1879, the U.S. Fish Commission offered Atwater funds to study the composition and nutritional value of North American species of fish and invertebrates. For

1829-942: The cause of dispute, but few alternatives have been proposed. As with the calculation of protein from total nitrogen, the Atwater system is a convention and its limitations can be seen in its derivation. Available energy (as used by Atwater) is equivalent to the modern usage of the term metabolisable energy (ME). Metabolisable Energy = ( Gross Energy in Food ) − ( Energy lost in Faeces, Urine, Secretions and Gases ) . {\displaystyle {\text{Metabolisable Energy}}=\left({\text{Gross Energy in Food}}\right)-\left({\text{Energy lost in Faeces, Urine, Secretions and Gases}}\right).} In most studies on humans, losses in secretions and gases are ignored. The gross energy (GE) of

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1888-489: The coefficients for mixed diets. The energy/nitrogen ratio in urine shows considerable variation and the energy/organic matter is less variable, but the energy/nitrogen value provided Atwater with a workable approach although this has caused some confusion and only applies for subjects in nitrogen balance. Based on the work of Atwater, it became common practice to calculate energy content of foods using 4 kcal/g for carbohydrates and proteins and 9 kcal/g for lipids . The system

1947-488: The country together, to unify their work, and to put them into communication with the great world of science." He immediately established a journal, the Experiment Station Record , meant to be a means of keeping the stations abreast of the scientific research being conducted by their colleagues and scientists abroad. Atwater made clear that the publication was meant to be a collection of scientific papers and not

2006-483: The daytime the bed is folded and laid aside, so as to leave room for the man to sit at the table or to walk to and fro. His promenade, however, is limited, the chamber being 7 feet long, 4 feet wide, and 6 feet high. Food and drink are passed into the chamber through an aperture which serves also for the removal of the solid and liquid excretory products, and the passing in and out of toilet materials, books, and other things required for comfort and convenience." His research

2065-433: The dietary standards, based on observations from his work with Voit, who had used a Rubner respiration calorimeter to conduct similar experiments on small animals. Together with Charles Ford Langworthy , they compiled a digest of close to 3,600 metabolic experiments as a primer to the research they would conduct. Atwater went on to work with Physicist Edward Bennett Rosa and Nutritionist Francis Gano Benedict to design

2124-977: The digestibility coefficients of protein, fat and carbohydrate calculated as intake − faecal excretion intake {\displaystyle {\frac {{\text{intake}}-{\text{faecal excretion}}}{\text{intake}}}} for the constituent in question. Urinary losses were calculated from the energy to nitrogen ratio in urine. Experimentally this was 7.9 kcal/g (33 kJ/g) urinary nitrogen and thus his equation for metabolisable energy became M E = ( G E p − 7.9 6.25 ) D p + G E f D f + G E c h o D c h o . {\displaystyle {ME}=\left({GE}_{\mathrm {p} }-{\frac {7.9}{6.25}}\right)D_{\mathrm {p} }+{GE}_{\mathrm {f} }D_{\mathrm {f} }+{GE}_{\mathrm {cho} }D_{\mathrm {cho} }.} Atwater collected values from

2183-621: The digestibility of food, investigations of energy requirements using human subjects, and studies of the cost and economics of food use and production. In 1894, Atwater received his first congressional appropriation, allocated to his laboratory for human nutrition research. Atwater's studies during this time were used to create dietary standards. He based the standards off of average intakes, but did not regard them as quantitatively accurate; they logically varied based on age, sex, and activity level but he stressed that they were not metabolic studies. He went on to conduct metabolic studies related to

2242-523: The energy value of feces in the same way. G E F = G E p F + G E f F + G E c h o F . {\displaystyle {GE}^{\mathrm {F} }={{GE}_{\mathrm {p} }^{\mathrm {F} }+{GE}_{\mathrm {f} }^{\mathrm {F} }+{GE}_{\mathrm {cho} }^{\mathrm {F} }}.} By measuring coefficients of availability or in modern terminology apparent digestibility , Atwater derived

2301-464: The experiments he demonstrated that whatever amount of energy consumed by humans that could not be used was stored in the body. Through the calorimetry studies, greater awareness was brought to the food calorie as a unit of measure both for consumption and metabolism. Atwater reported on the weight of the calorie as a means to measure the efficiency of a diet and that different types of food produced different amounts of energy. Through his research, he

2360-495: The field of nutrition but also in the work of the agricultural experiment stations. Both he and Johnson are considered responsible for focusing the role of the experiment stations on scientific study in service of the public and the tables and formulas Atwater created through his research are still in use today. "His careful studies of nutrition and those that followed helped spur federal policies that have done much to alleviate childhood hunger. We see reflections of his influence on

2419-518: The first chemical analysis of food or feed in the United States. Atwater received his doctorate in 1869 in agricultural chemistry, his thesis was entitled The Proximate Composition of Several Types of American Maize, in it he used variations of the proximate analysis system to analyze four varieties of corn. Afterwards, he continued his education for the next two years in Leipzig and Berlin , studying physiological chemistry and acquainting himself with

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2478-440: The first direct calorimeter large enough to accommodate human subjects for a period of days. The calorimeter, or human respiration apparatus, was built to precisely measure the energy provided by food. Atwater wanted to use it to study and compare the nutrient contents of different foods and how the human body consumes those nutrients under various conditions of rest and work. The calorimeter measured human metabolism by analyzing

2537-544: The heat produced by a person performing certain physical activities; in 1896 they began the first of what would accumulate into close to 500 experiments. Through their experiments, they were able to create a system - which became known as the Atwater system , to measure the energy in units, known as food calories . With the machine, the dynamics of metabolism could be quantified and the relationship between food intake and energy output could be measured. "The experiments are made with

2596-413: The initial phase of the first experiment station, Atwater expanded his fertilizer program and began to study and experiment with the growth and composition of field crops. The field crop research continued even after the appropriation ceased on a nearby farm; Atwater became particularly interested in plant metabolism and was one of the first researchers to provide proof that legumes assimilate nitrogen from

2655-444: The labels of products in our grocery stores, and we’re beginning to see nutritional information on the menus of restaurants. Today’s familiar food pyramid, a quick and easy visual guide to the recommended daily intake of food, is a tribute to Atwater and his successors." Atwater's daughter, Helen W. Atwater , served as one of his laboratory assistants, namely assisting with manuscript preparation. She served as an editorial assistant in

2714-405: The large intestine and provide some metabolisable energy. The extent of degradation depends on the source of the dietary fibre (its composition and state of division), and the individual consuming the dietary fibre. There is insufficient data to give firm guidance on the energy available from this source. Finally dietary fibre affects faecal losses of nitrogen and fat. Whether the increased fat loss

2773-412: The literature and also measured the heat of combustion of proteins, fats and carbohydrates. These vary slightly depending on sources and Atwater derived weighted values for the gross heat of combustion of the protein, fat and carbohydrate in the typical mixed diet of his time. It has been argued that these weighted values are invalid for individual foods and for diets whose composition in terms of foodstuffs

2832-426: The magnitude of this variation is very limited, but as the heats of combustion of the individual amino-acids are different it is reasonable to expect variations between different proteins. An observed range of from 5.48 for conglutin (from blue lupin) to 5.92 for Hordein (barley) was reported, which compares with Atwaters' range of 5.27 for gelatin to 5.95 for wheat gluten. It is difficult to calculate expected values for

2891-733: The modified Atwater factors. Wilbur Olin Atwater Atwater was director of the first United States Agricultural Experiment Station at Wesleyan University in Middletown, Connecticut and he was the U.S. Department of Agriculture 's first chief of nutrition investigations. Atwater was born in Johnsburg, New York , the son of William Warren Atwater, a Methodist Episcopal minister, temperance advocate, and librarian of Yale Law School and Eliza (Barnes) Atwater. He grew up in, and spent much of his life in New England . He opted not to fight in

2950-403: The nutritional value of alcohol, Atwater proved alcohol could be oxidized in the body and used to some extent as fuel. Information gained from Atwater’s experiments was used by the liquor trade in the promotion of alcohol. "[Atwater] was very prominent in the temperance movement, and every year he would lecture the students about temperance and tried to promote [abstention from alcohol]," ... "Being

3009-707: The permanent Connecticut Experiment Station to the Sheffield Scientific School at Yale with Samuel Johnson as first director. During this time, Atwater wrote numerous articles for scientific periodicals detailing his research and findings in physiological and agricultural chemistry and on research being conducted abroad (specifically in Germany). Many of his articles appeared in a column called "Science Applied to Farming", mostly discussing agricultural fertilizers in Orange Judd's American Agriculturalist . During

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3068-535: The position on the condition of being able to maintain both his professorship, and his position of director of the Storrs Agricultural Experiment Station . Atwater spent about 8 months of the year in Washington and had deputies act for him in his other positions during his absence. Atwater saw his mission as director of the Office of Experiment Stations to be "to bring the stations throughout

3127-624: The varying metabolism rates of infants born in two hospitals in Massachusetts, athletes, students, vegetarians, Mayans living in the Yucatán, and normal adults. He even developed a calorimeter large enough to hold twelve girl scouts for an extended period of time. His biggest improvement was the invention of portable field respiration calorimeters. In 1919, Francis Benedict published a metabolic standards report with extensive tables based on age, sex, height, and weight. Atwater's legacy endures not only in

3186-559: Was able to demonstrate that calories from different sources might affect the body differently and in turn, published tables that compared calories in various foods. Atwater also studied the effect of alcohol on the body. His findings showed humans generated heat from alcohol just as they generated heat from a carbohydrate. At a time when the Scientific Temperance Federation and the Woman's Christian Temperance Union doubted

3245-476: Was able to guide agricultural experiment station research towards scientific and experiment based methods. Throughout his career, Atwater had been interested in human nutrition studies; having conducted the studies on behalf of the U.S. Fish Commission and the Smithsonian Institution, he had continued human nutrition research and the Storrs experiment station became known for nutritional studies. Once

3304-533: Was included in the Bureau's 1886 Annual Report. Throughout this time, Atwater continued to campaign and support the expansion of state agricultural experiment stations. Due to their European research and experience with the government-funded European experiment stations, Atwater and Johnson had become consultants to the USDA and vocal promoters of federally regulated and funded agricultural research. Atwater had even begun writing in USDA publications in support of adopting

3363-428: Was informed by the first law of thermodynamics , taking into account that energy can be transformed but it cannot be created or destroyed, despite the belief at the time that the law only applied to animals because humans were unique. Earlier experiments concerning calorie intake and expenditure had proven that the first law applied to animals and Atwater's findings demonstrated the law applied to humans as well. Through

3422-451: Was later improved by Annabel Merrill and Bernice Watt of the USDA , who derived a system whereby specific calorie conversion factors for different foods were proposed. This takes cognizance of the fact that first the gross energy values of the protein, fats and carbohydrates from different food sources are different, and second, that the apparent digestibility of the components of different foods

3481-457: Was that these faecal constituents were truly unavailable and that his apparent disregard of the nature of faecal excretion was justifiable in a practical context. The ratio intake − faecal excretion intake , {\displaystyle {\frac {{\text{intake}}-{\text{faecal excretion}}}{\text{intake}}},} wherever faecal excretion is small, will approximate to unity and thus these coefficients have

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