Late night snack with cottage cheese has no major adverse metabolic effects

Associate Professor of Nutrition, Food and Exercise Sciences Michael Ormsbee and former Florida state university graduate student Samantha Leyh found that consuming 30 grams of protein about 30 minutes before bed appears to have a positive effect on muscle quality, metabolism, and overall health. They compared protein from whole food (cottage cheese) versus liquid protein shake and placebo. In their results they showed no difference between whole food and liquid protein shake in terms of appetite and metabolic changes. Research suggests that no adverse impact of pre-sleep protein on metabolic activity. Research findings are published in the British Journal of Nutrition.

Study participants active young women in their early 20s ate samples of cottage cheese 30 to 60 minutes before bedtime. Researchers specifically wanted to see if this food may have an impact on the metabolic rate and muscle recovery.

“Until now, we presumed that whole foods would act similarly to the data on supplemental protein, but we had no real evidence,” Ormsbee said. “This is important because it adds to the body of literature that indicates that whole foods work just as well as protein supplementation, and it gives people options for presleep nutrition that go beyond powders and shaker bottles.”

Leyh, who is now a research dietitian with the Air Force, said the results serve as a foundation for future research on precise metabolic responses to whole food consumption.

Ormsbee said that his research team will start examining more presleep food options and longer-term studies to learn more about the optimal food choices that can aid individuals in recovery from exercise, repair and regeneration of muscle and overall health.

Citation:Leyh, Samantha M., Brandon D. Willingham, Daniel A. Baur, Lynn B. Panton, and Michael J. Ormsbee. “Pre-sleep Protein in Casein Supplement or Whole-food Form Has No Impact on Resting Energy Expenditure or Hunger in Women.” British Journal of Nutrition120, no. 9 (2018): 988-94. doi:10.1017/s0007114518002416.

Diets rich in fruits and vegetables associated with lower depression risk

People who eat vegetables, fruit and whole grains may have lower rates of depression over time, according to a preliminary study that will be presented at the American Academy of Neurology’s 70th Annual Meeting.

Research found that people whose diets adhered more closely to the Dietary Approaches to Stop Hypertension (DASH) diet were less likely to develop depression than people who did not. DASH diet consists of fruit, vegetables, whole grains and fat-free or low fat dairy products. This diet limits intake of foods that contain sugar and saturated fats. Previous research have shown health benefits such as lowering high blood pressure and bad cholesterol (LDL), along with lowering body weight.

“Depression is common in older adults and more frequent in people with memory problems, vascular risk factors such as high blood pressure or high cholesterol, or people who have had a stroke,” said study author Laurel Cherian, MD, of Rush University Medical Center in Chicago and a member of the American Academy of Neurology. “Making a lifestyle change such as changing your diet is often preferred over taking medications, so we wanted to see if diet could be an effective way to reduce the risk of depression.”

For the study, 964 participants with an average age of 81 were evaluated yearly for an average of six-and-a-half years. They were monitored for symptoms of depression and also filled out questionnaires about how often they ate various foods, and the researchers looked at how closely the participants’ diets followed diets such as the Dietary Approaches to Stop Hypertension (DASH) diet, Mediterranean diet and the traditional Western diet.

Participants were divided into three groups based on how closely they adhered to the diets. People in the two groups that followed the Dietary Approaches to Stop Hypertension (DASH) diet most closely were less likely to develop depression than people in the group that did not follow the diet closely.  On the other hand, the more closely people followed a Western diet, a diet that is high in saturated fats and red meats and low in fruits and vegetables the more likely they were to develop depression.

Cherian noted that the study does not prove that the Dietary Approaches to Stop Hypertension (DASH) diet leads to a reduced risk of depression; it only shows an association.

“Future studies are now needed to confirm these results and to determine the best nutritional components of the Dietary Approaches to Stop Hypertension (DASH) diet to prevent depression later in life and to best help people keep their brains healthy,” said Cherian.

Adapted from press release by the American Academy of Neurology.

Calorie restricted diet promotes intestinal regeneration after injury

Dramatic calorie restriction have long been known to boost healthy lifespan and reduce the risk of heart attack, diabetes and other age-related conditions. In animal studies it is shown to extend life span in most animal species examined. Further research has shown that animals fed restricted-calorie diets are also better able to regenerate numerous tissues after injury.

When mice were allowed to eat without limit and were then exposed to radiation, their intestinal cells’ (in red) regeneration was limited (left). Mice fed a calorie-restricted diet showed a greatly enhanced regenerative capacity in their intestinal tissue (right). Credit: University of Pennsylvania.

A new study led by University of Pennsylvania researchers pinpoints the cell responsible for these improved regenerative abilities in the intestines. According to the scientists’ work, when a calorie-restricted mouse is subjected to radiation, a particular type of stem cell in the intestines, known as reserve stem cells, can survive and quickly rebuild intestinal tissues. The findings align with observations by oncologists that short-term fasting prior to chemotherapy can mitigate the severity of gastrointestinal destruction.

Christopher Lengner, an associate professor in Penn’s School of Veterinary Medicine collaborated on the work with lead author Maryam Yousefi, a graduate student in the Cell and Molecular Biology program at Penn Medicine and a Howard Hughes Medical Institute International Student Fellow, and other colleagues from Penn and China Agricultural University. Their work appears in the journal Stem Cell Reports.

One theory has been that calorie restriction slows age-related degeneration and enables more efficient tissue function by influencing the integrity and activity of adult stem cells, the precursor cells that dwell within specific tissues and give rise to the diversity of cell types that compose that tissue.

In prior work, Lengner’s lab has studied how certain stem cells in the intestines resist DNA damage. Perhaps, the researchers reasoned, calorie restriction is somehow targeting these stem cells to enhance their ability to resist damage.

Recent studies focused on the effects of calorie restriction on the active intestinal stem cells. While these active stem cells bear the burden of daily tissue turnover and act as the workhorses of intestinal function, they are also known to be highly susceptible to DNA damage, such as that induced by radiation exposure, and thus are unlikely to be the cells mediating the enhanced regeneration seen under calorie restriction, the Penn team reasoned.

Instead of looking at these active stem cells, Lengner’s group examined a second population of intestinal stem cells known as reserve stem cells. Lengner’s group and others had previously shown that these reserve stem cells normally reside in a dormant state and are protected from chemotherapy and radiation. Upon a strong injury that kills the active cells, these reserve stem cells “wake up” to regenerate the tissue.

To investigate this hypothesis, the scientists focused on how a subpopulation of mouse intestinal stem cells responded under calorie restriction and then when the animals were exposed to radiation. When mice were fed a diet reduced in calories by 40 percent from normal, the researchers observed that reserve intestinal stem cells expanded five-fold. Paradoxically, these cells also seemed to divide less frequently, a mystery the researchers hope to follow up on in later work.

When the research team selectively deleted the reserve stem cells in calorie-restricted mice, their intestinal tissue’s regeneration capabilities were cut in half, implicating these cells as having an important role in carrying out the benefits of calorie restriction.

“These reserve stem cells are rare cells,” Lengner said. “In a normal animal they may make up less than half a percentage of the intestinal epithelium and in calorie restricted animals maybe slightly more. Normally, in the absence of injury, the tissue can tolerate the loss, due to the presence of the active stem cells, but, when you injure the animal, the regeneration is compromised and the enhanced regeneration after calorie restriction was compromised in the absence of the reserve stem cell pool.”

To tease out the mechanism by which these cells were acting, the researchers compared the genes that were turned on in normal versus calorie-restricted animals. “It was very obvious,” Lengner said. “These reserve stem cells that we had shown were important for the beneficial effects of calorie restriction, were repressing many pathways that are all known to be regulated by the protein complex mTOR, which is most well known as being a nutrient-sensing complex.”

The finding made intuitive sense; researchers studying other tissue types had shown that activating mTOR can drive dormant cells out of quiescence, a necessary step for regeneration. Here, researchers found that reserve stem cells had low mTOR activity, and this was even lower upon calorie restriction. Lower mTOR activity correlated with resistance to injury. Yet in order to regenerate after the injury was over, these cells would need mTOR again.

“Curiously, we see that, when they’re injured, the calorie-restricted mice were actually better able to activate mTOR than their counterparts,” Lengner said. “So somehow, even though mTOR is being suppressed initially, it’s also better poised to become activated after injury. That’s something we don’t fully understand.”

The researchers, led by Yousefi, conducted experiments using leucine, an amino acid that activates mTOR, and rapamycin, a drug -which inhibits mTOR, to confirm that mTOR acted within these reserve stem cells to regulate their activity. Reserve stem cells exposed to leucine proliferated, while those exposed to rapamycin were blocked.

Pretreating the animals with leucine make the reserve stem cells more sensitive to radiation and less able to regenerate tissue following radiation injury, while rapamycin protected the reserve stem cells as they were more likely to remain dormant.

Lengner cautions, however, that rapamycin cannot be used as a stand-in for calorie restriction, as it would linger and continue to block mTOR activation even following injury, hindering the ability of the reserve stem cells to spring into action and regenerate intestinal tissue.

In future work, the researchers hope to drill down deeper, looking beyond nutrient signaling to see what type of signaling molecules can modulate the activation of reserve stem cells.

doi: 10.1016/j.stemcr.2018.01.026

Research funding: Howard Hughes Medical Institute, National Natural Science Foundation of China, National Institute of Diabetes and Digestive and Kidney Diseases, National Cancer Institute, and Center for Molecular Studies in Digestive and Liver Diseases.

Adapted from press release by the University of Pennsylvania.

Role of soy protein in inflammatory bowel disease

A diet supplemented with soy protein may be an effective adjunct therapy for inflammatory bowel diseases, Penn State researchers reported after completing a study that included mice and cultured human colon cells. The findings are significant because inflammatory bowel diseases affect nearly 4 million people worldwide and have an economic impact of more than $19 billion annually in the United States alone.

Joshua Lambert, associate professor of food science in the College of Agricultural Sciences said his team found that soy-protein concentrate can exert antioxidant and cytoprotective effects in cultured human bowel cells and can moderate the severity of inflammation in mice that have an induced condition similar to ulcerative colitis.

Zachary Bitzer and Amy Wopperer, former graduate students in the Department of Food Science and the lead researchers, substituted soy-protein concentrate into the diet of the mice and removed corresponding amounts of the other protein sources, equaling about 12 percent. They kept human equivalents in mind as they determined the amount. The dietary soy-protein concentrate at the 12-percent dose level ameliorated body-weight loss and swelling of the spleen in the mice with induced inflammatory bowel disease.

Results of study in mice and cultured colon cells are published in The Journal of Nutritional Biochemistry. Next step is finding if these results are reproducible in Humans. Lambert believes human studies could be arranged in the near future. Lambert’s laboratory soon will start a related investigation of whether the inflammation-moderating effects triggered in the mouse colons are due solely to the soy protein or also may be caused by soy fiber. Soy-protein concentrate is 70 percent protein by weight, but it also has quite a bit of soybean fiber in it, he explained.

Research Funding: Pennsylvania Soybean Board, American Institute for Cancer Research, US Department of Agriculture’s Hatch Program.
Adapted from press release by the Penn State University.

Dietary changes can impact cardiovascular risk by a quarter

Exchanging few commercially regular-consumed food items with improved fat quality reduces total and LDL cholesterol. A new double-blind randomized controlled trial published in British Journal of Nutrition suggests almost 30% reduction in cardiovascular disease risk

Exchanging few regular-consumed food items with improved fat quality in the daily diet for eight weeks reduces the serum total cholesterol and LDL-cholesterol by 9 % and 11 %, respectively. This change corresponds to a 27 % reduction in cardiovascular disease risk. In the human trial saturated fat was replaced by polyunsaturated fat in key food items such as spread on bread, fat for cooking, cheese, bread and cereals.

Cardiovascular disease (CVD) remains the major contributor to the global burden of disease worldwide. Even though there has been substantial reduction in CVD mortality over the last 30 years, new reports show an increase in acute myocardial infarction among the younger population in Norway, and similar observations have been reported also from other countries.

Elevated plasma low-density lipoprotein cholesterol (LDL-C) is an established risk factor of CVD, and dietary fatty acids play a significant role in modulating plasma LDL-C and thereby influencing the risk of CVD. In particular there is strong evidence that replacing saturated fatty acids (SFA) with polyunsaturated fatty acids (PUFA) will reduce the risk of CVD. However, controversy still exist about beneficial versus potential harmful effects of n-6 PUFA since n-6 PUFA has been suggested to promote inflammation.

Adherence to a healthy Nordic diet based on the Nordic nutrition recommendations has previously been shown to have beneficial effect on blood lipids among subjects at risk of CVD. However the extent of food changes needed to achieve these effects is less explored. In order to increase compliance to dietary fat intake recommendations in the general population it is important that one can achieve this with relatively small dietary changes, leading to improved lipid profile.

The aim of the study was to investigate the effects of exchanging few commercially regularly-consumed key food items (e.g. spread on bread, fat for cooking, cheese, bread and cereals) with improved fat quality on total cholesterol, LDL-C and inflammatory markers in a double-blind randomized, controlled trial.

In total 115 moderately hypercholesterolemic non-statin treated adults (25-70 y) were randomly assigned to an experimental diet group (Ex-diet group) or control diet group (C-diet group) for eight weeks with commercially available food items with different fatty acid composition (replacing saturated fatty acids with mostly n-6 polyunsaturated fatty acids).

In the Ex-diet group, serum total cholesterol (P<0.001) and LDL-C (P<0.001) were reduced after eight weeks, compared to the C-diet group. The difference in change between the two groups at the end of the study was -9 % and -11 % in total cholesterol and LDL-C, respectively. No difference in change in plasma levels of inflammatory markers was observed between the groups.

In conclusion, exchanging few regularly-consumed food items with improved fat quality reduces total cholesterol, with no negative effect on levels of inflammatory markers. This shows that an exchange of few commercially available food items was easy and manageable and leads to clinically relevant cholesterol reduction potentially affecting future CVD risk.

Publication: Exchanging a few commercial, regularly consumed food items with improved fat quality reduces total cholesterol and LDL-cholesterol: a double-blind, randomised controlled trial.
Journal: British Journal of Nutrition –  News

Adapted from press release by University of Oslo