Friday, September 16, 2022

New study links ultra-processed foods and colorectal cancer in men

For many Americans, the convenience of pre-cooked and instant meals may make it easy to overlook the less-than-ideal nutritional information, but a team led by researchers at Tufts University and Harvard University hope that will change after recently discovering a link between the high consumption of ultra-processed foods and an increased risk of colorectal cancer.

In a study published Aug. 31 in The BMJ, researchers found that men who consumed high rates of ultra-processed foods were at 29% higher risk for developing colorectal cancer -- the third most diagnosed cancer in the United States -- than men who consumed much smaller amounts. They did not find the same association in women.

"We started out thinking that colorectal cancer could be the cancer most impacted by diet compared to other cancer types," said Lu Wang, the study's lead author and a postdoctoral fellow at the Friedman School of Nutrition Science and Policy at Tufts. "Processed meats, most of which fall into the category of ultra-processed foods, are a strong risk factor for colorectal cancer. Ultra-processed foods are also high in added sugars and low in fiber, which contribute to weight gain and obesity, and obesity is an established risk factor for colorectal cancer."

The study analyzed responses from over 200,000 participants -- 159,907 women and 46,341 men -- across three large prospective studies which assessed dietary intake and were conducted over more than 25 years. Each participant was provided with a food frequency questionnaire every four years and asked about the frequency of consumption of roughly 130 foods.

For the study in BMJ, participants' intake of ultra-processed foods was then classified into quintiles, ranging in value from the lowest consumption to the highest. Those in the highest quintile were identified as being the most at risk for developing colorectal cancer. Although there was a clear link identified for men, particularly in cases of colorectal cancer in the distal colon, the study did not find an overall increased risk for women who consumed higher amounts of ultra-processed foods.

The Impacts of Ultra-Processed Foods

The analyses revealed differences in the ways that men and women consume ultra-processed foods and the prospective associated cancer risk. Out of the 206,000 participants followed for more than 25 years, the research team documented 1,294 cases of colorectal cancer among men, and 1,922 cases among women.

The team found the strongest association between colorectal cancer and ultra-processed foods among men come from the meat, poultry, or fish-based, ready-to-eat products. "These products include some processed meats like sausages, bacon, ham, and fish cakes. This is consistent with our hypothesis," Wang said.

The team also found higher consumption of sugar-sweetened beverages, like soda, fruit-based beverages, and sugary milk-based beverages, is associated with an increased risk of colorectal cancer in men.

However, not all ultra-processed foods are equally harmful with regard to colorectal cancer risk. "We found an inverse association between ultra-processed dairy foods like yogurt and colorectal cancer risk among women," said co-senior author Fang Fang Zhang, a cancer epidemiologist and interim chair of the Division of Nutrition Epidemiology and Data Science at the Friedman School.

Overall, there was not a link between ultra-processed food consumption and colorectal cancer risk among women. It's possible that the composition of the ultra-processed foods consumed by women could be different than that from men.

"Foods like yogurt can potentially counteract the harmful impacts of other types of ultra-processed foods in women," Zhang said.

Mingyang Song, co-senior author on the study and assistant professor of clinical epidemiology and nutrition at the Harvard T.H. Chan School of Public Health, added that, "Further research will need to determine whether there is a true sex difference in the associations, or if null findings in women in this study were merely due to chance or some other uncontrolled confounding factors in women that mitigated the association."

Although ultra-processed foods are often associated with poor diet quality, there could be factors beyond the poor diet quality of ultra-processed foods that impact the risk of developing colorectal cancer.

The potential role of food additives in altering gut microbiota, promoting inflammation, and contaminants formed during food processing or migrated from food packaging may all promote cancer development, Zhang noted.

Analyzing the Data

With more than a 90% follow-up rate from each of the three studies, the research team had ample data to process and review.

"Cancer takes years or even decades to develop, and from our epidemiological studies, we have shown the potential latency effect -- it takes years to see an effect for certain exposure on cancer risk," said Song. "Because of this lengthy process, it's important to have long-term exposure to data to better evaluate cancer risk."

The studies included:

  • The Nurses' Health Study (1986-2014): 121,700 registered female nurses between the ages of 30 and 55
  • The Nurses' Health Study II (1991-2015): 116,429 female nurses between the ages of 25 and 42
  • The Health Professional Follow-up Study (1986-2014): 51,529 male health professionals between the ages of 40 and 75.

After an exclusionary process for past diagnoses or incomplete surveys, the researchers were left with prospective data from 159,907 women from both NHS studies and 46,341 men.

The team adjusted for potential confounding factors such as race, family history of cancer, history of endoscopy, physical activity hours per week, smoking status, total alcohol intake and total caloric intake, regular aspirin use, and menopausal status.

Zhang is aware that since the participants in these studies all worked in the healthcare field, the findings for this population may not be the same as they would be for the general population, since the participants may be more inclined to eat healthier and lean away from ultra-processed foods. The data may also be skewed because processing has changed over the past two decades.

"But we are comparing within that population those who consume higher amounts versus lower amounts," Zhang reassured. "So those comparisons are valid."

Changing Dietary Patterns

Wang and Zhang previously published a study that identified a trend in increased ultra-processed food consumption in U.S. children and adolescents. Both studies underscore the idea that many different groups of people may be dependent on ultra-processed foods in their daily diets.

"Much of the dependence on these foods can come down to factors like food access and convenience," said Zhang, who is also a member of the Tufts Institute for Global Obesity Research. "Chemically processing foods can aid in extending shelf life, but many processed foods are less healthy than unprocessed alternatives. We need to make consumers aware of the risks associated with consuming unhealthy foods in quantity and make the healthier options easier to choose instead."

Wang knows that change won't happen overnight, and hopes that this study, among others, will contribute to changes in dietary regulations and recommendations.

"Long-term change will require a multi-step approach," Wang added. "Researchers continue to examine how nutrition-related policies, dietary recommendations, and recipe and formula changes, coupled with other healthy lifestyle habits, can improve overall health and reduce cancer burden. It will be important for us to continue to study the link between cancer and diet, as well as the potential interventions to improve outcomes.

Research reported in this article was supported by awards from the National Institutes of Health's National Institute on Minority Health and Health Disparities (R01MD011501), National Cancer Institute (UM1CA186107; P01CA087969; U01CA176726; U01CA167552; and R00CA215314), and a Mentored Research Scholar Grant in Applied and Clinical Research from the American Cancer Society. The content is solely the authors' responsibility and does not necessarily represent the official views of the National Institutes of Health.

Journal Reference:

  1. Lu Wang, Mengxi Du, Kai Wang, Neha Khandpur, Sinara Laurini Rossato, Jean-Philippe Drouin-Chartier, Euridice Martínez Steele, Edward Giovannucci, Mingyang Song, Fang Fang Zhang. Association of ultra-processed food consumption with colorectal cancer risk among men and women: results from three prospective US cohort studies. BMJ, 2022; e068921 DOI: 10.1136/bmj-2021-068921 

Courtesy:

Tufts University, Health Sciences Campus. "New study links ultra-processed foods and colorectal cancer in men: Researchers found that men who consumed high rates of ultra-processed foods were at higher risk for developing colorectal cancer than those who did not." ScienceDaily. ScienceDaily, 31 August 2022. <www.sciencedaily.com/releases/2022/08/220831210024.htm>.

 

Wednesday, September 14, 2022

Artificial photosynthesis can produce food without sunshine

Scientists have found a way to bypass the need for biological photosynthesis altogether and create food independent of sunlight by using artificial photosynthesis. The technology uses a two-step electrocatalytic process to convert carbon dioxide, electricity, and water into acetate. Food-producing organisms then consume acetate in the dark to grow. The hybrid organic-inorganic system could increase the conversion efficiency of sunlight into food, up to 18 times more efficient for some foods.

Photosynthesis has evolved in plants for millions of years to turn water, carbon dioxide, and the energy from sunlight into plant biomass and the foods we eat. This process, however, is very inefficient, with only about 1% of the energy found in sunlight ending up in the plant. Scientists at UC Riverside and the University of Delaware have found a way to bypass the need for biological photosynthesis altogether and create food independent of sunlight by using artificial photosynthesis.

The research, published in Nature Food, uses a two-step electrocatalytic process to convert carbon dioxide, electricity, and water into acetate, the form of the main component of vinegar. Food-producing organisms then consume acetate in the dark to grow. Combined with solar panels to generate the electricity to power the electrocatalysis, this hybrid organic-inorganic system could increase the conversion efficiency of sunlight into food, up to 18 times more efficient for some foods.

"With our approach we sought to identify a new way of producing food that could break through the limits normally imposed by biological photosynthesis," said corresponding author Robert Jinkerson, a UC Riverside assistant professor of chemical and environmental engineering.

In order to integrate all the components of the system together, the output of the electrolyzer was optimized to support the growth of food-producing organisms. Electrolyzers are devices that use electricity to convert raw materials like carbon dioxide into useful molecules and products. The amount of acetate produced was increased while the amount of salt used was decreased, resulting in the highest levels of acetate ever produced in an electrolyzer to date.

"Using a state-of-the-art two-step tandem CO2 electrolysis setup developed in our laboratory, we were able to achieve a high selectivity towards acetate that cannot be accessed through conventional CO2 electrolysis routes," said corresponding author Feng Jiao at University of Delaware.

Experiments showed that a wide range of food-producing organisms can be grown in the dark directly on the acetate-rich electrolyzer output, including green algae, yeast, and fungal mycelium that produce mushrooms. Producing algae with this technology is approximately fourfold more energy efficient than growing it photosynthetically. Yeast production is about 18-fold more energy efficient than how it is typically cultivated using sugar extracted from corn.

"We were able to grow food-producing organisms without any contributions from biological photosynthesis. Typically, these organisms are cultivated on sugars derived from plants or inputs derived from petroleum -- which is a product of biological photosynthesis that took place millions of years ago. This technology is a more efficient method of turning solar energy into food, as compared to food production that relies on biological photosynthesis," said Elizabeth Hann, a doctoral candidate in the Jinkerson Lab and co-lead author of the study.

The potential for employing this technology to grow crop plants was also investigated. Cowpea, tomato, tobacco, rice, canola, and green pea were all able to utilize carbon from acetate when cultivated in the dark.

"We found that a wide range of crops could take the acetate we provided and build it into the major molecular building blocks an organism needs to grow and thrive. With some breeding and engineering that we are currently working on we might be able to grow crops with acetate as an extra energy source to boost crop yields," said Marcus Harland-Dunaway, a doctoral candidate in the Jinkerson Lab and co-lead author of the study.

By liberating agriculture from complete dependence on the sun, artificial photosynthesis opens the door to countless possibilities for growing food under the increasingly difficult conditions imposed by anthropogenic climate change. Drought, floods, and reduced land availability would be less of a threat to global food security if crops for humans and animals grew in less resource-intensive, controlled environments. Crops could also be grown in cities and other areas currently unsuitable for agriculture, and even provide food for future space explorers.

"Using artificial photosynthesis approaches to produce food could be a paradigm shift for how we feed people. By increasing the efficiency of food production, less land is needed, lessening the impact agriculture has on the environment. And for agriculture in non-traditional environments, like outer space, the increased energy efficiency could help feed more crew members with less inputs," said Jinkerson.

This approach to food production was submitted to NASA's Deep Space Food Challenge where it was a Phase I winner. The Deep Space Food Challenge is an international competition where prizes are awarded to teams to create novel and game-changing food technologies that require minimal inputs and maximize safe, nutritious, and palatable food outputs for long-duration space missions.

"Imagine someday giant vessels growing tomato plants in the dark and on Mars -- how much easier would that be for future Martians?" said co-author Martha Orozco-Cárdenas, director of the UC Riverside Plant Transformation Research Center.

Andres Narvaez, Dang Le, and Sean Overa also contributed to the research.

The research was supported by the Translational Research Institute for Space Health (TRISH) through NASA (NNX16AO69A), Foundation for Food and Agriculture Research (FFAR), the Link Foundation, the U.S. National Science Foundation, and the U.S. Department of Energy. The content of this publication is solely the responsibility of the authors and does not necessarily represent the official views of the Foundation for Food and Agriculture Research.

Journal Reference:

  1. Elizabeth C. Hann, Sean Overa, Marcus Harland-Dunaway, Andrés F. Narvaez, Dang N. Le, Martha L. Orozco-Cárdenas, Feng Jiao, Robert E. Jinkerson. A hybrid inorganic–biological artificial photosynthesis system for energy-efficient food production. Nature Food, 2022; 3 (6): 461 DOI: 10.1038/s43016-022-00530-x 

Courtesy:

University of California - Riverside. "Artificial photosynthesis can produce food without sunshine." ScienceDaily. ScienceDaily, 23 June 2022. <www.sciencedaily.com/releases/2022/06/220623122624.htm>.