Walnuts may be good for the gut and help promote heart health

Walnuts may not just be a tasty snack, they may also promote good-for-your-gut bacteria. New research suggests that these "good" bacteria could be contributing to the heart-health benefits of walnuts.

In a randomized, controlled trial, researchers found that eating walnuts daily as part of a healthy diet was associated with increases in certain bacteria that can help promote health. Additionally, those changes in gut bacteria were associated with improvements in some risk factors for heart disease.

Kristina Petersen, assistant research professor at Penn State, said the study -- recently published in the Journal of Nutrition -- suggests walnuts may be a heart- and gut-healthy snack.

"Replacing your usual snack -- especially if it's an unhealthy snack -- with walnuts is a small change you can make to improve your diet," Petersen said. "Substantial evidence shows that small improvements in diet greatly benefit health. Eating two to three ounces of walnuts a day as part of a healthy diet could be a good way to improve gut health and reduce the risk of heart disease."

Previous research has shown that walnuts, when combined with a diet low in saturated fats, may have heart-healthy benefits. For example, previous work demonstrated that eating whole walnuts daily lowers cholesterol levels and blood pressure.

According to the researchers, other research has found that changes to the bacteria in the gastrointestinal tract -- also known as the gut microbiome -- may help explain the cardiovascular benefits of walnuts.

"There's a lot of work being done on gut health and how it affects overall health," said Penny Kris-Etherton, distinguished professor of nutrition at Penn State. "So, in addition to looking at factors like lipids and lipoproteins, we wanted to look at gut health. We also wanted to see if changes in gut health with walnut consumption were related to improvements in risk factors for heart disease."

For the study, the researchers recruited 42 participants with overweight or obesity who were between the ages of 30 and 65. Before the study began, participants were placed on an average American diet for two weeks.

After this "run-in" diet, the participants were randomly assigned to one of three study diets, all of which included less saturated fat than the run-in diet. The diets included one that incorporated whole walnuts, one that included the same amount of alpha-linolenic acid (ALA) and polyunsaturated fatty acids without walnuts, and one that partially substituted oleic acid (another fatty acid) for the same amount of ALA found in walnuts, without any walnuts.

In all three diets, walnuts or vegetable oils replaced saturated fat, and all participants followed each diet for six weeks with a break between diet periods.

To analyze the bacteria in the gastrointestinal tract, the researchers collected fecal samples 72 hours before the participants finished the run-in diet and each of the three study diet periods.

"The walnut diet enriched a number of gut bacteria that have been associated with health benefits in the past," Petersen said. "One of those is Roseburia, which has been associated with protection of the gut lining. We also saw enrichment in Eubacteria eligens and Butyricicoccus."

The researchers also found that after the walnut diet, there were significant associations between changes in gut bacteria and risk factors for heart disease. Eubacterium eligens was inversely associated with changes in several different measures of blood pressure, suggesting that greater numbers of Eubacterium eligens was associated with greater reductions in those risk factors.

Additionally, greater numbers of Lachnospiraceae were associated with greater reductions in blood pressure, total cholesterol, and non-HDL cholesterol. There were no significant correlations between enriched bacteria and heart-disease risk factors after the other two diets.

Regina Lamendella, associate professor of biology at Juniata College, said the findings are an example of how people can feed the gut microbiome in a positive way.

"Foods like whole walnuts provide a diverse array of substrates -- like fatty acids, fiber and bioactive compounds -- for our gut microbiomes to feed on," Lamendella said. "In turn, this can help generate beneficial metabolites and other products for our bodies."

Kris-Etherton added that future research can continue to investigate how walnuts affect the microbiome and other elements of health.

"The findings add to what we know about the health benefits of walnuts, this time moving toward their effects on gut health," Kris-Etherton said. "The study gives us clues that nuts may change gut health, and now we're interested in expanding that and looking into how it may affect blood sugar levels."

Kids twice as likely to eat healthy after watching cooking shows with healthy food

Television programs featuring healthy foods can be a key ingredient in leading children to make healthier food choices now and into adulthood.

A new study in the Journal of Nutrition Education and Behavior, published by Elsevier, found kids who watched a child-oriented cooking show featuring healthy food were 2.7 times more likely to make a healthy food choice than those who watched a different episode of the same show featuring unhealthy food.

Researchers asked 125 10- to 12-year-olds, with parental consent, at five schools in the Netherlands to watch 10 minutes of a Dutch public television cooking program designed for children, and then offered them a snack as a reward for participating. Children who watched the healthy program were far more likely to choose one of the healthy snack options -- an apple or a few pieces of cucumber -- than one of the unhealthy options -- a handful of chips or a handful of salted mini-pretzels.

"The findings from this study indicate cooking programs can be a promising tool for promoting positive changes in children's food-related preferences, attitudes, and behaviors," said lead author Frans Folkvord, PhD, of Tilburg University,Tilburg, Netherlands.

This study was conducted at the children's schools, which could represent a promising alternative for children learning healthy eating behaviors. Prior research has found youth are more likely to eat nutrient-rich foods including fruits and vegetables if they were involved in preparing the dish, but modern reliance on ready-prepared foods and a lack of modeling by parents in preparing fresh foods have led to a drop-in cooking skills among kids.

"Providing nutritional education in school environments instead may have an important positive influence on the knowledge, attitudes, skills, and behaviors of children," Dr. Folkvord said.

This study indicates the visual prominence of healthier options in both food choice and portion size on TV cooking programs leads young viewers to crave those healthier choices then act on those cravings.

The effect that exposure to healthier options has on children is strongly influenced by personality traits. For example, children who don't like new foods are less likely to show a stronger desire for healthier choices after watching a TV program featuring healthier foods than a child who does enjoy trying new foods. As they grow older, though, they start to feel more responsible for their eating habits and can fall back on information they learned as children. Researchers believe this may indicate watching programs with healthier options can still have a positive impact on children's behavior, even if it is delayed by age.

"Schools represent the most effective and efficient way to reach a large section of an important target population, which includes children as well as school staff and the wider community," Dr. Folkvord commented. "Positive peer and teacher modeling can encourage students to try new foods for which they exhibited distaste previously."

Poor dietary habits during childhood and adolescence have multiple negative effects on several health and wellness indicators, including achievement and maintenance of healthy weights, growth and development patterns, and dental health.

"The likelihood of consuming fruits and vegetables among youth and adults is strongly related to knowing how to prepare most fruits and vegetables. Increased cooking skills among children can positively influence their consumption of fruit and vegetables in a manner that will persist into adulthood," Dr. Folkvord added.

Date: January 3, 2020

Source: Elsevier

Holiday celebrations often revolve around eating, but for those with food restrictions, that can produce an incongruous feeling when dining with friends and loved ones: loneliness.

People with restricted diets -- due to allergies, health issues or religious or cultural norms -- are more likely to feel lonely when they can't share in what others are eating, new Cornell University research shows.

"Despite being physically present with others, having a food restriction leaves people feeling left out because they are not able to take part in bonding over the meal," said Kaitlin Woolley, assistant professor of marketing in the Samuel Curtis Johnson Graduate School of Management and lead author of the research.

Across seven studies and controlled experiments, researchers found that food restrictions predicted loneliness among both children and adults.

The research also offers the first evidence, Woolley said, that having a food restriction causes increased loneliness. For example, in one experiment, assigning unrestricted individuals to experience a food restriction increased reported feelings of loneliness. That suggests such feelings are not driven by non-food issues or limited to picky eaters, Woolley said.

"We can strip that away and show that assigning someone to a restriction or not can have implications for their feeling of inclusion in the group meal," she said.

Further evidence came from a survey of observers of the Jewish holiday of Passover. When reminded during the holiday of the leavened foods they couldn't enjoy with others, participants' loneliness increased. Yet, within their own similarly restricted group, they felt a stronger bond.

Bonding over meals is an inherently social experience, Woolley notes. In previous research, she found that strangers felt more connected and trusting of each other when they shared the same food, and eating food from the same plate increased cooperation between strangers.

But when restricted from sharing in the meal, people suffer "food worries," Woolley said. They fret about what they can eat and how others might judge them for not fitting in.

Those worries generated a degree of loneliness comparable to that reported by unmarried or low-income adults, and stronger than that experienced by schoolchildren who were not native English speakers, according to the research. Compared with non-restricted individuals, having a restriction increased reported loneliness by 19%. People felt lonelier regardless of how severe their restriction was, or whether their restriction was imposed or voluntary.

The study concluded that food restrictions and loneliness are on the rise and "may be related epidemics," warranting further research.

To date, Woolley said, children have been the primary focus of research on the effects of food restrictions. A nationally representative survey she analyzed from the Centers for Disease Control did not track the issue among adults.

But increasingly, she said, food restrictions are being carried into adulthood, or adults are choosing restricted diets such as gluten-free, vegetarian and vegan for health or ethical reasons. Up to 30% of all participants in her research deal with restrictions, Woolley said.

"This is a problem that I don't think people are quite aware of," she said, "and that has implications for people's ability to connect with others over eating."