Scientific Update
By Reed Mangels, PhD, RD
Red Meat and Colorectal Cancer
Colorectal cancer is the third most common type of cancer in the United States. More than 50,000 people in the United States die of it each year. Black Americans, compared to other racial/ethnic groups, have the highest rates of colorectal cancer and are more likely to die from it at a younger age. The reasons for these disparities are not known. Diet is one factor that affects the risk of developing colorectal cancer. Unprocessed red meat (e.g. beef, lamb, and pork) and processed red meat (e.g. bacon, sausage, and ham) are associated with an increased risk of colorectal cancer, but most of the evidence for this comes from research on older people with European ancestry.
The Black Women's Health Study started in 1995 and is ongoing. More than 50,000 women are participating in this study, which seeks to assess risk factors for various diseases in U.S. Blacak women. Women answered questions about their food habits and their health at several time points over a more than 20-year period. Unprocessed red meat was significantly associated with colorectal cancer, with a 33% higher risk for every 3-ounce portion of unprocessed red meat eaten per day. Among those women who ate 0-2 servings of red meat per week, eating less than five servings of fruits and vegetables per day was associated with a markedly higher risk of colorectal cancer than in those eating more fruits and vegetables. Women who ate four or more servings of red meat per day and ate lots of fruits and vegetables had a higher risk of colorectal cancer than women who ate similar amounts of fruits and vegetables but fewer servings of red meat. This suggests that higher consumption of fruits and vegetables is helpful but does not offset the negative effects of high red meat consumption. Women eating the lowest amount of fruits and vegetables and the highest amounts of red meat had the highest risk of developing colorectal cancer. These results suggest reducing red meat consumption is one way to reduce the risk of developing colorectal cancer.
Yiannakou I, Barber LE, Li S, et al. A prospective analysis of red and processed meat intake in relation to colorectal cancer in the Black Women's Health Study. J Nutr. 2022;152(5):1254-1262.
How Many Vegetarians Are There?
Surveys are commonly used to estimate the number of vegetarians in a country. When The Vegetarian Resource Group commissions a survey, people are asked which foods they never eat. Those responding "meat, fish, seafood, poultry" are classified as vegetarian; those responding "meat, fish, seafood, poultry, dairy, eggs" are classified as vegans.
Another survey method is to ask people if they would describe themselves as vegetarian or vegan. This is likely to result in larger numbers than a survey that classified people based on food avoidances. A recent publication describes a survey that asked people if they described themselves as vegetarian or vegan. This study is unique in that it was done in five countries—Australia, Canada, Mexico, the UK, and the U.S.—using consistent methods so that results can be compared across countries.
The surveys were conducted online in 2018 and 2019. The highest percentage of people who described themselves as vegetarians (not including vegans) was found in the UK where 5% said they were vegetarian.
Canada had the lowest percentage of vegetarians (3.7%) with Australia, Mexico, and the U.S. inter-mediate. The largest percentage of people describing themselves as vegans was found in Mexico, where 5% said they were vegan. Canada had the lowest percentage of vegans (2.5%) with Australia, the UK, and the U.S. intermediate.
More than four in 10 people overall were trying to reduce meat or dairy products. Respondents from Mexico were more likely to report trying to consume less meat in general, red meat in particular, and dairy than were respondents from other countries. Women in Australia, Canada, and the UK were more likely to be reducing dairy consumption than men were. In all countries, women were more likely than men to be reducing red meat consumption. Older people were more likely to be reducing meat consumption while younger people were more likely to be vegan, vegetarian, or pescatarian.
Vanderlee L, Gómez-Donoso C, Acton RB, et al. Meat-reduced dietary practices and efforts in five countries: Analysis of cross-sectional surveys in 2018 and 2019. J Nutr. 2022;152:57S-566S.
Children's Views of Animals
Many people lavish care on some animals but don't question the horrible conditions under which other animals live and die. The concept of speciesism is used to explain this seemingly contradictory behavior.
Speciesism is the practice of treating members of one species as morally more important than members of other species. For example, people might not consider harming a dog but would allow harm to be done to a pig. To begin to understand the development of speciesism, a recent study examined whether there are differences in the ways that children and adults think about the treatment of animals.
Researchers studied 479 people from three age groups:
- 9- to 12-year-old children,
- 18- to 21-year-old young adults
- 29- to 59-year-old adults.
Participants answered survey questions including:
- "Would you categorize a pig/cow/chicken/cat/dog/hamster as food, pet, or object?"
- "How well should humans treat rats/dogs/pigs/chimpanzees/other humans?"
- "How OK is it to eat animals?"
- "How OK is it to eat things that come from animals like eggs, milk, or cheese?"
Children were less likely than other age groups to categorize "farm animals" as "food" and more likely to categorize them as "pets." Children indicated that pigs should be treated better than did young adults or adults; there were no differences by age group in how well "pets" or other humans should be treated. Children rated eating animals and animal products as significantly less morally OK than did older age groups. These results suggest that conversations about our relationships with animals should begin early, since children are more likely than adults to think critically about the ways that some animals are treated.
McGuire L, Palmer SB, Faber NS. The development of speciesism: Age-related differences in the moral view of animals. Soc Psychol Personal Sci. 2022; 1-10.
The Cost of Food Waste
by Cierra Peterlin, University of Maryland
Dietetic Intern
Food waste affects environmental and human health. In research based on survey data from over 39,000 individuals from 2001-2016, an average daily cost of food and food wasted among U.S. adults was determined. The researcher looked at information about the food people consumed and the price of food to determine how much was spent on food and what percentage of that food was inedible or became food waste. The term "inedible" was used to describe the portions of food that are not typically eaten, such as banana peels and avocado pits, and "wasted food" was used to refer to the portions of edible food that are not consumed in a meal.
The average daily food cost for an individual was $13.27, with 27% of this or $3.62 being wasted, 14% or $1.88 inedible, and 59% or $7.77 consumed. Meat and seafood were the foods that accounted for the most money spent on food that was then wasted, with fruits and vegetables second. The remaining money spent on wasted food was accounted for by grains, sweets, dairy, nonalcoholic beverages, nuts and seeds, eggs, frozen foods, fats and oils, and other, in that order. Alcoholic beverages were not accounted for.
The researcher estimated that, on average, food that is ultimately wasted costs a consumer $1,300 per year. This is more than what the average single family spent annually on gasoline, household heating and electricity, or household maintenance and repairs in 2017, when the study was completed. The researcher suggested some ways that consumers can reduce food waste and food costs, including purchasing less meat and seafood, sharing meals or ordering/making smaller portions, saving and eating leftover meals, and storing produce properly.
Conrad, Z. Daily cost of consumer food wasted, inedible, and consumed in the United States, 2001-2016. Nutr J. 2020;19:35.
