National Institute of Biomedical Innovation

A new study of thousands of people reveals a wide range in the amount of water people consume around the globe and over their lifespans, definitively spilling the oft-repeated idea that eight, 8-ounce glasses meet the human body's daily needs. Differences in environment, body composition and activity level contribute to daily water turnover of as little as 1 liter and as much as 10 liters. A new study of thousands of people reveals a wide range in the amount of water people consume around the globe and over their lifespans, definitively spilling the oft-repeated idea that eight, 8-ounce glasses meet the human body's daily needs. "The science has never supported the old eight glasses thing as an appropriate guideline, if only because it confused total water turnover with water from beverages and a lot of your water comes from the food you eat," says Dale Schoeller, a University of Wisconsin-Madison emeritus professor of nutritional sciences who has been studying water and metabolism for decades. "But this work is the best we've done so far to measure how much water people actually consume on a daily basis -- the turnover of water into and out of the body -- and the major factors that drive water turnover." That's not to say the new results settle on a new guideline. The study, published today in the journal Science, measured the water turnover of more than 5,600 people from 26 countries, ages ranging from 8 days to 96 years old, and found daily averages on a range between 1 liter per day and 6 liters per day. "There are outliers, too, that are turning over as much as 10 liters a day," says Schoeller, a co-author of the study. "The variation means pointing to one average doesn't tell you much. The database we've put together shows us the big things that correlate with differences in water turnover." Previous studies of water turnover relied largely on volunteers to recall and self-report their water and food consumption, or were focused observations -- of, say, a small group of young, male soldiers working outdoors in desert conditions -- of questionable use as representative of most people. The new research objectively measured the time it took water to move through the bodies of study participants by following the turnover of "labeled water." Study subjects drank a measured amount of water containing trackable hydrogen and oxygen isotopes. Isotopes are atoms of a single element that have slightly different atomic weights, making them distinguishable from other atoms of the same element in a sample. "If you measure the rate a person is eliminating those stable isotopes through their urine over the course of a week, the hydrogen isotope can tell you how much water they're replacing and the elimination of the oxygen isotope can tell us how many calories they are burning," says Schoeller, whose UW-Madison lab in the 1980s was the first to apply the labeled-water method to study people. More than 90 researchers were involved in the study, which was led by a group that includes Yosuke Yamada, a former UW-Madison postdoctoral researcher in Schoeller's lab and now section head of the National Institute of Biomedical Innovation, Health and Nutrition in Japan, and John Speakman, zoology professor at the University of Aberdeen in Scotland. They collected and analyzed data from participants, comparing environmental factors -- such as temperature, humidity and altitude of the participants' hometowns -- to measured water turnover, energy expenditure, body mass, sex, age and athlete status. The researchers also incorporated the United Nations' Human Development Index, a composite measure of a country that combines life expectancy, schooling and economic factors. Water turnover volume peaked for men in the study during their 20s, while women held a plateau from 20 through 55 years of age. Newborns, however, turned over the largest proportion daily, replacing about 28 percent of the water in their bodies every day. Physical activity level and athletic status explained the largest proportion of the differences in water turnover, followed by sex, the Human Development Index, and age. All things equal, men and women differ by about half a liter of water turnover. As a baseline of sorts, the study's findings expect a male non-athlete (but of otherwise average physical activity) who is 20 years old, weighs 70kg (154 pounds), lives at sea level in a well-developed country in a mean air temperature of 10 degrees C (50 Fahrenheit) and a relative humidity of 50%, would take in and lose about 3.2 liters of water every day. A woman of the same age and activity level, weighing 60 kg (132 pounds) and living in the same spot, would go through 2.7 liters (91 ounces). Doubling the energy a person uses will push their expected daily water turnover up by about liter, the researchers found. Fifty kilograms more body weight adds 0.7 liters a day. A 50% increase in humidity pushes water use up by 0.3 liters. Athletes use about a liter more than non-athletes. The researchers found "hunter-gatherers, mixed farmers, and subsistence agriculturalists" all had higher water turnover than people who live in industrialized economies. In all, the lower your home country's Human Development Index, the more water you go through in a day. "That's representing the combination of several factors," Schoeller says. "Those people in low HDI countries are more likely to live in areas with higher average temperatures, more likely to be performing physical labor, and less likely to be inside in a climate-controlled building during the day. That, plus being less likely to have access to a sip of clean water whenever they need it, makes their water turnover higher." The measurements will improve our ability to predict more specific and accurate future water needs, especially in dire circumstances, according to Schoeller. "Look at what's going on in Florida right now, or in Mississippi -- where entire regions have been exposed by a calamity to water shortages," he says. "The better we understand how much they need, the better prepared we are to respond in an emergency." And the better we can prepare for long-term needs and even notice short-term health concerns, the researchers believe. "Determining how much water humans consume is of increasing importance because of population growth and growing climate change," says Yamada. "Because water turnover is related to other important indicators of health, like physical activity and body fat percent, it has potential as a biomarker for metabolic health." The study and access to the data was funded by agencies around the world, including the International Atomic Energy Agency, the National Science Foundation and National Institutes of Health in the United States, and the Chinese Academy of Sciences.

Researchers have developed an innovative way to 'see' the fine structure and chemical composition of human cells with unmatched clarity and precision. Their technique takes a creative approach to signal detection. Researchers at the Beckman Institute for Advanced Science and Technology developed a new method to 'see' the fine structure and chemical composition of a human cell with unmatched clarity and precision. It's why Jaws swam out of sight for more than an hour and hints at the glamour of giftwrap. In movie theaters, living rooms, and even labs, the thrill of the unseen can be counted on to keep us guessing. But when it comes to the hidden chemical world of cells, scientists need no longer wonder. Inspired by this same thrill, researchers at the Beckman Institute for Advanced Science and Technology developed an innovative way to 'see' the fine structure and chemical composition of a human cell with unmatched clarity and precision. Their technique, which appeared in PNAS earlier this week, takes a creative -- and counterintuitive -- approach to signal detection. "Biology is one of the most exciting sciences of our time because there has always been a divide between what we can see and what we cannot see," said Rohit Bhargava, a professor of bioengineering at the University of Illinois Urbana-Champaign who led the study. As the smallest functional units in our bodies, cells have long commanded the attention of researchers interested in determining what they're made of and where each element resides. Together, the "what" and the "where" form an all-purpose cellular blueprint that can be used to study biology, chemistry, materials, and more. Before this study, obtaining a high-resolution copy of that blueprint ranked among the impossible. "Now, we can see inside cells in a much finer resolution and with significant chemical detail more easily than ever," Bhargava said. "This work opens a range of possibilities, including a new way to examine the combined chemical and physical aspects that govern human development and disease." The researchers' work builds on prior strides in the field of chemical imaging. Whereas optical microscopy uses visible light to illuminate surface-level features like color and structure, chemical imaging uses invisible infrared light to reveal a sample's inner workings. When a cell is exposed to IR light, its temperature rises, and it expands. We know from night vision goggles that no two objects absorb IR wavelengths in exactly the same way; comparing a poodle to a park bench is evidence enough that warmer objects emit stronger IR signatures than cooler ones. The same is true inside a cell, where each type of molecule absorbs IR light at a subtly different wavelength and emits a unique chemical signature. Examining the absorption patterns -- a method called spectroscopy -- allows researchers to pinpoint the whereabouts of each. Unlike night vision goggles, the researchers do not analyze the absorption patterns as a color spectrum. Instead, they interpret the IR waves with a signal detector: a minute beam fastened to the microscope on one end, with a fine tip that scrapes the cell's surface like the nanoscale needle of a record player. Innovations in spectroscopy over the last decade have focused on steadily increasing the strength of the initial IR wavelengths. "It's an intuitive approach because we are conditioned to think of larger signals as being better. We think, 'The stronger the IR signal, the higher a cell's temperature becomes, the more it expands, and the easier it will be to see,'" Bhargava said. A sizeable setback is hidden within this approach. As the cell expands, the motion of the signal detector becomes more exaggerated and generates "noise": so-called static that impedes accurate chemical measurements. "It's like turning up the dial on a staticky radio station -- the music gets louder, but so does the static," said Seth Kenkel, a postdoctoral researcher in Professor Bhargava's lab and the study's lead author. In other words, no matter how powerful the IR signal became, the quality of the chemical imaging could not advance. "We needed a solution to stop the noise from increasing alongside the signal," Kenkel said. The researchers' remedy to noisy cellular imaging works by divorcing the IR signal from the detector's movement, allowing for amplification without the added noise. Instead of focusing their energies on the strongest possible IR signal, the researchers began by experimenting with the smallest signal they could manage, ensuring that they could effectively implement their solution before upping the strength. Though "counterintuitive," according to Kenkel, starting small allowed the researchers to honor a decade of spectroscopy research and lay critical groundwork for the future of the field. Bhargava likens the approach to a road trip gone awry. "Imagine that spectroscopy researchers were in a car, headed to the Grand Canyon. Of course, everyone would think that the faster the car moves, the faster they'll reach the destination. But the problem is that the car is headed east from Urbana," he said. Increasing the hypothetical car's speed is analogous to strengthening the IR signal. "We pulled over, looked at a map, and pointed the car in the correct direction. Now, the increased speed -- the increased signal -- can effectively move the field forward." The researchers' "map" enables high-resolution chemical and structural imaging of cells at the nanoscale -- a scale 100,000 times smaller than a strand of hair. Notably, this technique is free of fluorescent labeling, or dyeing molecules to increase their visibility under a microscope. While the facilities in Beckman's Microscopy Suite were critical to the study's experimental stage, the idea itself arose not from sophisticated technology, but from a culture that supported curiosity, unconventional problem-solving, and diverse perspectives. "This is why the Beckman Institute is an amazing place," Bhargava said. "This project needed ideas from spectroscopy, from mechanical engineering, from signal processing, and of course biology. You can't combine these fields seamlessly anywhere other than Beckman. This study is a classic example of Beckman's blend of interdisciplinary science at the cutting edge of advanced science and technology." Research reported in this press release was supported in part by the National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under award numbers T32EB019944 and R01EB009745, as well as the National Science Foundation under award number 2153032. This content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Researchers have developed modified alginate hydrogels that can endure the growth of bacteria, allowing them to synthesize important enzymes. Encapsulating cells -- both prokaryotic and eukaryotic -- allows researchers to carry out experiments in hydrated environments over prolonged periods of time. However, cell growth under these conditions can exert a lot of pressure on the encapsulating shells, resulting in cell leakage. In a new study, researchers at the University of Illinois Urbana-Champaign have developed modified alginate hydrogels that can endure the growth of bacteria, allowing them to synthesize important enzymes. Hydrogels are polymers that are reinforced by different chemical bonds, and are capable of absorbing water and swelling without breaking down. As a result, biotechnology researchers have often turned to these structures to provide stability and structural support for their cell cultures. "Hydrogel capsules have been utilized for over 50 years. There are many different types that can be made by combining different kinds of cells in different hydrogel environments," said Yoon Jeong, a graduate student in the Irudayaraj (CGD/EIRH) lab. "The problem with combining microorganisms with hydrogel capsules is that they leak out." To address this problem, Jeong decided to focus on alginate, a naturally occurring, edible compound found in brown algae. Although it has been previously looked at, using it to encapsulate bacteria has been challenging. "My strategy was to make a hydrogel membrane on the surface of the hydrogel structure," Jeong said. Although the change may seem small, it works well. Jeong tested his system with genetically-modified Lactococcus lactis and saw that without the layer, the bacteria leaked out and were unable to form biofilms -- a collection of microorganisms that stick to each other. On the other hand, L. lactis colonies inside the modified hydrogels were able to grow for over 10 days; the hydrogels provided a stable platform that did not rupture. Jeong also looked genetically-modified Escherichia coli, which can synthesize a host of different molecules, only when they are able to achieve a high cell density. He looked at E. coli cells that can produce green fluorescent protein, which emits a green signal when the cells are subjected to ultraviolet light. "Although growing GFP-producing E. coli is simple, they quickly die," Jeong said. "I showed that inside the hydrogel they form colonies, which continuously increase in size, produce GFP, and do not leak out." He achieved the same results when he used E. coli cells that are bioluminescent. These bacteria encode the lux genes that result in blue cells that glow in the dark. The researchers saw that once the bacteria reached a certain cell density, the luminescence continued to increase for the next 3 days. The main purpose of making these hydrogels is to develop bioreactors that can support the growth of bacteria while they make important compounds. To test whether the modified hydrogels were capable of sustaining such processes, Jeong also tested the ability of L. lactis to make nisin, a peptide that is used as a food preservative. In agreement with their previous results, the bacteria were able to grow well in the modified hydrogels and were able to produce the compound. "Although at a glance it can seem simple to make these hydrogel structures, it is actually difficult. You have to control their size, thickness, and prevent agglomeration since these capsules stick together," Jeong said. "Researchers who have a different scientific background have found this process difficult. We plan to publish a detailed protocol soon so that people can use this cheap and easy technique." The researchers are also interested in continuing their tests in human and cancer cells, with the hope that the hydrogels will be able to provide a reliable platform for a wide range of applications. The work was partially funded by the National Institute of Biomedical Imaging and Bioengineering of the NIH.