Don't make major decisions on an empty stomach, research suggests

We all know that food shopping when hungry is a bad idea but new research from the University of Dundee suggests that people might want to avoid making any important decisions about the future on an empty stomach.
The study, carried out by Dr Benjamin Vincent from the University's Psychology department, found that hunger significantly altered people's decision-making, making them impatient and more likely to settle for a small reward that arrives sooner than a larger one promised at a later date.
Participants in an experiment designed by Dr Vincent were asked questions relating to food, money and other rewards when satiated and again when they had skipped a meal.
While it was perhaps unsurprising that hungry people were more likely to settle for smaller food incentives that arrived sooner, the researchers found that being hungry actually changes preferences for rewards entirely unrelated to food.
This indicates that a reluctance to defer gratification may carry over into other kinds of decisions, such as financial and interpersonal ones. Dr Vincent believes it is important that people know that hunger might affect their preferences in ways they don't necessarily predict.
There is also a danger that people experiencing hunger due to poverty may make decisions that entrench their situation.
"We found there was a large effect, people's preferences shifted dramatically from the long to short term when hungry," he said. "This is an aspect of human behaviour which could potentially be exploited by marketers so people need to know their preferences may change when hungry.
"People generally know that when they are hungry they shouldn't really go food shopping because they are more likely to make choices that are either unhealthy or indulgent. Our research suggests this could have an impact on other kinds of decisions as well. Say you were going to speak with a pensions or mortgage advisor - doing so while hungry might make you care a bit more about immediate gratification at the expense of a potentially more rosy future.
"This work fits into a larger effort in psychology and behavioural economics to map the factors that influence our decision making. This potentially empowers people as they may forsee and mitigate the effects of hunger, for example, that might bias their decision making away from their long term goals."
Dr Vincent and his co-author and former student Jordan Skrynka tested 50 participants twice - once when they had eaten normally and once having not eaten anything that day.
For three different types of rewards, when hungry, people expressed a stronger preference for smaller hypothetical rewards to be given immediately rather than larger ones that would arrive later.
The researchers noted that if you offer people a reward now or double that reward in the future, they were normally willing to wait for 35 days to double the reward, but when hungry this plummeted to only 3 days.
The work builds on a well-known psychological study where children were offered one marshmallow immediately or two if they were willing to wait 15 minutes.
Those children who accepted the initial offering were classed as more impulsive than those who could delay gratification and wait for the larger reward. In the context of the Dundee study, this indicates that hunger makes people more impulsive even when the decisions they are asked to make will do nothing to relieve their hunger.
"We wanted to know whether being in a state of hunger had a specific effect on how you make decisions only relating to food or if it had broader effects, and this research suggests decision-making gets more present-focused when people are hungry," said Dr Vincent.
"You would predict that hunger would impact people's preferences relating to food, but it is not yet clear why people get more present-focused for completely unrelated rewards.
"We hear of children going to school without having had breakfast, many people are on calorie restriction diets, and lots of people fast for religious reasons. Hunger is so common that it is important to understand the non-obvious ways in which our preferences and decisions may be affected by it."

Eating cheese may offset blood vessel damage from salt

Cheese lovers, rejoice. Antioxidants naturally found in cheese may help protect blood vessels from damage from high levels of salt in the diet, according to a new Penn State study.
In a randomized, crossover design study, the researchers found that when adults consumed a high sodium diet, they also experienced blood vessel dysfunction. But, when the same adults consumed four servings of cheese a day alongside the same high sodium diet, they did not experience this effect.
Billie Alba, who led the study while finishing her PhD at Penn State, said the findings may help people balance food that tastes good with minimizing the risks that come with eating too much salt.
"While there's a big push to reduce dietary sodium, for a lot of people it's difficult," Alba said. "Possibly being able to incorporate more dairy products, like cheese, could be an alternative strategy to reduce cardiovascular risk and improve vessel health without necessarily reducing total sodium."
While sodium is a mineral that is vital to the human body in small doses, the researchers said too much dietary sodium is associated with cardiovascular risk factors like high blood pressure. The American Heart Association recommends no more than 2,300 milligrams (mg) of sodium a day, with the ideal amount being closer to 1,500 mg for most adults.
According to Lacy Alexander, professor of kinesiology at Penn State and another researcher on the study, previous research has shown a connection between dairy products -- even cheeses high in sodium -- and improved heart health measures.
"Studies have shown that people who consume the recommended number of dairy servings each day typically have lower blood pressure and better cardiovascular health in general," Alexander said. "We wanted to look at those connections more closely as well as explore some of the precise mechanisms by which cheese, a dairy product, may affect heart health."
The researchers recruited 11 adults without salt-sensitive blood pressure for the study. They each followed four separate diets for eight days at a time: a low-sodium, no-dairy diet; a low-sodium, high-cheese diet; a high-sodium, no-dairy diet; and a high-sodium, high-cheese diet.
The low sodium diets had participants consume 1,500 mg of salt a day, while the high sodium diets included 5,500 mg of salt per day. The cheese diets included 170 grams, or about four servings, of several different types of cheese a day.
At the end of each week-long diet, the participants returned to the lab for testing. The researchers inserted tiny fibers under the participants' skin and applied a small amount of the drug acetylcholine, a compound that signals blood vessels to relax. By examining how each participants' blood vessels reacted to the drug, the researchers were able to measure blood vessel function.
The participants also underwent blood pressure monitoring and provided a urine sample to ensure they had been consuming the correct amount of salt throughout the week.
The researchers found that after a week on the high sodium, no cheese diet, the participants' blood vessels did not respond as well to the acetylcholine -- which is specific to specialized cells in the blood vessel -- and had a more difficult time relaxing. But this was not seen after the high sodium, high cheese diet.
"While the participants were on the high-sodium diet without any cheese, we saw their blood vessel function dip to what you would typically see in someone with pretty advanced cardiovascular risk factors," Alexander said. "But when they consumed the same amount of salt, and ate cheese as a source of that salt, those effects were completely avoided."
Alba said that while the researchers cannot be sure that the effects are caused by any one specific nutrient in cheese, the data suggests that antioxidants in cheese may be a contributing factor.
"Consuming high amounts of sodium causes an increase in molecules that are harmful to blood vessel health and overall heart health," Alba said. "There is scientific evidence that dairy-based nutrients, specifically peptides generated during the digestion of dairy proteins, have beneficial antioxidant properties, meaning that they have the ability to scavenge these oxidant molecules and thereby protect against their damaging physiological effects."
Alba said that in the future, it will be important to study these effects in larger studies, as well as further research possible mechanisms by which dairy foods may preserve vascular health.

Meatballs might wreck the anti-cancer perks of tomato sauce

Eating your tomato sauce with meatballs piled on top could have a surprising downside, new research suggests.
Some of the anti-cancer benefits of tomatoes, specifically those from a compound called lycopene, could disappear when they're eaten with iron-rich foods, according to a new study from The Ohio State University.
Researchers analyzed the blood and digestive fluid of a small group of medical students after they consumed either a tomato extract-based shake with iron or one without iron. Lycopene levels in digestive fluid and in the blood were significantly lower when the study subjects drank the liquid meal mixed with an iron supplement, meaning there was less for the body to use in potentially beneficial ways.
"When people had iron with their meal, we saw almost a twofold drop in lycopene uptake over time," said the study's lead author, Rachel Kopec, an assistant professor of human nutrition at Ohio State.
"This could have potential implications every time a person is consuming something rich in lycopene and iron - say a Bolognese sauce, or an iron-fortified cereal with a side of tomato juice. You're probably only getting half as much lycopene from this as you would without the iron."
Iron is essential in the diet, performing such critical functions as allowing our bodies to produce energy and get rid of waste. But it's also a nutrient that is known to monkey with other cellular-level processes.
"We know that if you mix iron with certain compounds it will destroy them, but we didn't know if it would impair potentially beneficial carotenoids, like lycopene, found in fruits and vegetables," Kopec said.
Carotenoids are plant pigments with antioxidant properties responsible for many bright red, yellow and orange pigments found in the produce aisle. These include lycopene, which is found in abundance in tomatoes and also colors watermelon and pink grapefruit. Scientists have identified several potential anti-cancer benefits of lycopene, including in prostate, lung and skin cancers.
The small study, which included seven French medical students who had repeated blood draws and digestive samples taken from tubes placed in their stomachs and small intestines, took this research out of the test tube and into the human body, allowing for a better examination of human metabolism in action, Kopec said.
It's unclear precisely what is happening that is changing the uptake of lycopene, but it could be that the meal with iron oxidizes the lycopene, creating different products of metabolism than those followed in the study.
"It's also possible that iron interrupts the nice emulsified mix of tomato and fats that is critical for cells to absorb the lycopene. It could turn it into a substance like separated salad dressing - oil on top and vinegar on the bottom - that won't ever mix properly," Kopec said.
Researchers continue to work to better understand lycopene's role in fighting cancer, and the importance of its interplay with other compounds and nutrients.
"Nutrition can play an important role in disease prevention, but it's important for us to gather the details about precisely how what we eat is contributing to our health so that we can give people reliable, science-based recommendations," Kopec said.

Skin cancer risk: The dangers of ultraviolet radiation

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The dangers of ultraviolet radiation exposure, which most often comes from the sun, are well-known. Speaking at The Physiological Society's Extreme Environmental Physiology conference next week, W. Larry Kenney, Penn State University, will discuss how broad its effects can be, from premature aging to cancer, and how this can be influenced by different skin tones and the use of sunscreen.

Athletes ranging from hikers, to tennis and runners exceed the recommended ultraviolet exposure limit by up to eight-fold during the summer and autumn months. While regular physical activity is associated with a reduced risk of most cancers, skin cancer is an exception. For malignant skin cancer, those in the 90th percentile for physical activity have an increased risk of cancer than those in the 10th percentile. Sun protection in these groups is especially important as multiple studies demonstrate an elevated risk of skin cancer for those who regularly participate in outdoor sports or exercise.
The ultraviolet radiation spectrum is categorized by wavelength as UV-A (320-400 nm), UV-B (290-320 nm), and UV-C (200-290 nm) and the biological effects vary per type. UV-A constitutes around 95% of ultraviolet radiation that reaches the earth's surface, with the remainder being UV-B. In the skin, UV-A is able to reach the skin's blood circulation but most of UV-B is absorbed in the outer layers of the skin (called the epidermis and upper dermis) due to its shorter wavelengths.
Skin pigmentation is another factor that affects our response to sun exposure. UV radiation affects the body's ability to create two important substances, vitamin D and folate, which contribute to both a health pregnancy and early childhood development. It helps vitamin D be synthesised, whereas it causes folate to break down.
There is a theory that suggests that early human populations, living in equatorial Africa, evolved skin pigmentation to protect themselves from folate degradation. This theory also says that depigmentation then occurred as humans moved away from the equator to allow for higher levels of vitamin D synthesis.
Commenting on his talk, Professor Kenney said:
"Sun protection in athletes is especially important as multiple studies demonstrate an elevated risk of skin cancer for those who regularly participate in outdoor sports or exercise. Surprisingly, fewer than 25% of surveyed athletes reported regular use of sunscreen, so there is clearly more awareness-raising that needs to be done."

Once or twice weekly daytime nap linked to lower heart attack/stroke risk

But no such association found for greater frequency or duration of naps

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A daytime nap taken once or twice a week may lower the risk of having a heart attack/stroke, finds research published online in the journal Heart. But no such association emerged for either greater frequency or duration of naps.

The impact of napping on heart health has been hotly contested. Many of the published studies on the topic have failed to consider napping frequency, or focused purely on cardiovascular disease deaths, or compared regular nappers with those not opting for a mini siesta, say the researchers.
In a bid to try and address these issues, they looked at the association between napping frequency and average nap duration and the risk of fatal and non-fatal cardiovascular disease 'events,' such as heart attack, stroke, or heart failure, among 3462 randomly selected residents of Lausanne, Switzerland.
Each participant was aged between 35 and 75, when recruited between 2003 and 2006 to the CoLaus study. This has been looking at the factors behind the development of cardiovascular disease.
Participants' first check-up took place between 2009 and 2012, when information on their sleep and nap patterns in the previous week was collected, and their health was then subsequently monitored for an average of 5 years.
Over half (58%, 2014) of the participants said they didn't nap during the previous week; around one in five (19%, 667) said they took one to two naps; around one in 10 (12%, 411) said they took three to five; while a similar proportion (11%, 370) said they took six to seven.
Frequent nappers (3-7 naps a week) tended to be older, male, smokers, weigh more, and to sleep for longer at night than those who said they didn't nap during the day.
And they reported more daytime sleepiness and more severe obstructive sleep apnea -- a condition in which the walls of the throat relax and narrow during sleep, interrupting normal breathing.
During the monitoring period, there were 155 fatal and non-fatal cardiovascular disease 'events'.
Occasional napping, once to twice weekly, was associated with an almost halving in attack/stroke/heart failure risk (48%) compared with those who didn't nap at all.
This association held true after taking account of potentially influential factors, such as age, and nighttime sleep duration, as well as other cardiovascular disease risks, such as high blood pressure/cholesterol.
And it didn't change after factoring in excessive daytime sleepiness, depression, and regularly sleeping for at least 6 hours a night. Only older age (65+) and severe sleep apnea affected it.
But the 67% heightened cardiovascular risk initially observed for frequent nappers virtually disappeared after taking account of potentially influential factors. And no associations with cardiovascular disease 'events' were found for nap length (from 5 minutes to 1 hour plus).
This is an observational study, and as such, can't establish cause, added to which the information on nap and sleep patterns relied on personal recall. But nap frequency may help to explain the differing conclusions reached by researchers about the impact of napping on heart health, suggest the study authors.
In a linked editorial, Drs Yue Leng and Kristine Yaffe, of the University of California at San Francisco, USA, point out that research in this area is hampered by the absence of a gold standard for defining and measuring naps, making it "premature to conclude on the appropriateness of napping for maintaining optimal heart health."
But they add: "While the exact physiological pathways linking daytime napping to [cardiovascular disease] risk is not clear, [this research] contributes to the ongoing debate on the health implications of napping, and suggests that it might not only be the duration, but also the frequency that matters."
And they conclude: "The study of napping is a challenging but also a promising field with potentially significant public health implications. While there remain more questions than answers, it is time to start unveiling the power of naps for a supercharged heart."

Fatty foods necessary for vitamin E absorption, but not right away

A fresh look at how to best determine dietary guidelines for vitamin E has produced a surprising new finding: Though the vitamin is fat soluble, you don't have to consume fat along with it for the body to absorb it.
"I think that's remarkable," said the study's corresponding author, Maret Traber of Oregon State University, a leading authority on vitamin E who's been researching the micronutrient for three decades. "We used to think you had to eat vitamin E and fat simultaneously. What our study shows is that you can wait 12 hours without eating anything, then eat a fat-containing meal and vitamin E gets absorbed."
The study was published today in The American Journal of Clinical Nutrition.
Vitamin E, known scientifically as alpha-tocopherol, has many biologic roles, one of which is to serve as an antioxidant, said Traber, a professor in the OSU College of Public Health and Human Sciences, and Ava Helen Pauling Professor at Oregon State's Linus Pauling Institute.
Federal dietary guidelines call for 15 milligrams of vitamin E daily (by comparison, 65-90 milligrams of vitamin C are recommended). The new research could play a role in future vitamin E guidelines.
Vitamin E in human diets is most often provided by oils, such as olive oil. Many of the highest levels are in foods not routinely considered dietary staples, such as almonds, sunflower seeds and avocados.
"There's increasingly clear evidence that vitamin E is associated with brain protection, and now we're starting to better understand some of the underlying mechanisms," Traber said.
In this latest study, Traber and collaborators used a novel technique involving deuterium-labeled vitamin E, administered both orally and intravenously, to study fractional vitamin E absorption in a group of non-obese, non-diabetic women ages 18-40 with normal blood pressure.
Fractional absorption means just what you would think - the fraction of the dose absorbed by the body rather than metabolized and excreted. Fractional absorption dictates how much of something, in this case vitamin E, a person needs to take to maintain the correct level in his or her body.
Deuterium, the vitamin E marker in this study, is an isotope of hydrogen with double the atomic mass of the regular version; deuterium has both a proton and a neutron, compared to just a proton for normal hydrogen, and is a common tracer in investigations of biochemical reactions.
Study subjects at the National Institutes of Health Clinical Center were given both oral and IV vitamin E and drank a liquid meal containing either 40% fat or no fat. Researchers then used a combination of tightly controlled dietary intakes to determine the roles fat and fasting played in vitamin E absorption.
"What this study says is, vitamin E gets taken up into the intestinal cell and sits there and waits for the next meal to come along," Traber said. "It's in a fat droplet, sitting there, waiting to be picked up, like a cargo container, and loaded onto a chylomicron truck."
Chylomicrons are lipoprotein particles that transport dietary lipids - fats - around the body through the blood plasma.
The IV portion of the study, used in conjunction with the oral dosing to calculate fractional absorption, also yielded remarkable findings, Traber said.
"We injected the vitamin E in a lipid emulsion and expected it would take some time to disappear from the plasma and them come slowly back into circulation, but it was gone within 10 minutes," Traber said. "High-density lipoproteins quickly acquired the vitamin E, and the chylomicrons quickly disappeared from circulation into the liver.
"The IV vitamin E we put into the body over three days, almost none of it came out again, like 2% of the dose," she added. "No one had ever seen that before - normally you absorb about half of what you consume. That vitamin E that's staying in the body, we don't know where it goes, and finding that out is important for studying how much vitamin E you need to eat every day."
Vitamin E is a group of eight compounds - four tocopherols and four tocotrienols, distinguished by their chemical structure. Alpha-tocopherol is what vitamin E commonly refers to and is found in supplements and the European diet; gamma-tocopherol is the type of vitamin E most commonly found in the American diet.
"Plants make eight different forms of vitamin E and you absorb them all, but the liver only puts alpha-tocopherol back into the bloodstream," Traber said. "All of the other forms are metabolized and excreted. That tells us the body is working very hard to get all the nutrients it can and will sort out what the toxins are later. That's really exciting, because it explains why the liver needs an alpha-tocopherol transfer protein but the intestine does not."

Use of antibiotics in preemies has lasting, potentially harmful effects

Nearly all premature babies receive antibiotics in their first weeks of life to ward off or treat potentially deadly bacterial infections. Such drugs are lifesavers, but they also cause long-lasting collateral damage to the developing microbial communities in the babies' intestinal tracts, according to research from Washington University School of Medicine in St. Louis.
A year and a half after babies leave the neonatal intensive care unit (NICU), the consequences of early antibiotic exposure remain, the study showed. Compared to healthy full-term babies in the study who had not received antibiotics, preemies' microbiomes contained more bacteria associated with disease, fewer species linked to good health, and more bacteria with the ability to withstand antibiotics.
The findings, published Sept. 9 in Nature Microbiology, suggest that antibiotic use in preemies should be carefully tailored to minimize disruptions to the gut microbiome - and that doing so might reduce the risk of health problems later in life.
"The type of microbes most likely to survive antibiotic treatment are not the ones we typically associate with a healthy gut," said senior author Gautam Dantas, PhD, a professor of pathology and immunology, of molecular microbiology, and of biomedical engineering. "The makeup of your gut microbiome is pretty much set by age 3, and then it stays pretty stable. So if unhealthy microbes get a foothold early in life, they could stick around for a very long time. One or two rounds of antibiotics in the first couple weeks of life might still matter when you're 40."
Healthy gut microbiomes have been linked to reduced risk of a variety of immune and metabolic disorders, including inflammatory bowel disease, allergies, obesity and diabetes. Researchers already knew that antibiotics disrupt the intestinal microbial community in children and adults in ways that can be harmful. What they didn't know was how long the disruptions last.
To find out whether preemies' microbiomes recover over time, Dantas and colleagues - including first author Andrew Gasparrini, PhD, who was a graduate student at the time the study was conducted, and co-authors Phillip I. Tarr, MD, the Melvin E. Carnahan Professor of Pediatrics, and Barbara Warner, MD, director of the Division of Newborn Medicine - analyzed 437 fecal samples collected from 58 infants, ages birth to 21 months. Forty-one of the infants were born around 2 ½ months premature, and the remainder were born at full term.
All of the preemies had been treated with antibiotics in the NICU. Nine had received just one course, and the other 32 each had been given an average of eight courses and spent about half their time in the NICU on antibiotics. None of the full-term babies had received antibiotics.
The researchers discovered that preemies who had been heavily treated with antibiotics carried significantly more drug-resistant bacteria in their gut microbiomes at 21 months of age than preemies who had received just one course of antibiotics, or full-term infants who had not received antibiotics. The presence of drug-resistant bacteria did not necessarily cause any immediate problems for the babies because most gut bacteria are harmless - as long as they stay in the gut. But gut microbes sometimes escape the intestine and travel to the bloodstream, urinary tract or other parts of the body. When they do, drug resistance can make the resulting infections very difficult to treat.
Moreover, by culturing bacteria from fecal samples taken eight to 10 months apart, the researchers discovered that the drug-resistant strains present in older babies were the same ones that had established themselves early on.
"They weren't just similar bugs, they were the same bugs, as best we could tell," Dantas said. "We had cleared an opening for these early invaders with antibiotics, and once they got in, they were not going to let anybody push them out. And while we didn't show that these specific bugs had caused disease in our kids, these are exactly the kind of bacteria that cause urinary tract and bloodstream infections and other problems. So you have a situation where potentially pathogenic microbes are getting established early in life and sticking around."
Further studies showed that all of the babies developed diverse microbiomes by 21 months of age - a good sign since lack of microbial diversity is associated with immune and metabolic disorders in children and adults. But heavily treated preemies developed diverse microbiomes more slowly than lightly treated preemies and full-term infants. Further, the makeup of the gut microbial communities differed, with heavily treated premature infants having fewer healthy groups of bacteria such as Bifidobacteriaceae and more unhealthy kinds such as Proteobacteria.
The findings already have led Warner, who takes care of premature infants in the NICU at St. Louis Children's Hospital, and her fellow neonatalogists to scale down their use of antibiotics.
"We're no longer saying, 'Let's just start them on antibiotics because it's better to be safe than sorry,'" Warner said. "Now we know there's a risk of selecting for organisms that can persist and create health risks later in childhood and in life. So we're being much more judicious about initiating antibiotic use, and when we do start babies on antibiotics, we take them off as soon as the bacteria are cleared. We still have to use antibiotics - there's no question that they save lives - but we've been able to reduce antibiotic use significantly with no increase in adverse outcomes for the children."