News Round-up
Growth Failure in Preterm Infants tied to Altered Gut Bacteria
Distinct microbiome features might point to new ways to predict, prevent and treat growth failure in premature infants.
Extremely premature infants who fail to grow as expected have delayed development of their microbiome, or communities of bacteria and other micro-organisms living in the gut, according to a new study published in Scientific Reports. Analysis of these infants’ metabolism revealed that their bodies are responding as if they were fasting, despite caloric intake similar to extremely premature infants with appropriate growth. The study findings also suggest that the unique makeup of the microbiome in infants with growth failure might contribute to their inability to properly metabolise nutrients.
“Our identification of the distinct features within the microbiome and metabolism associated with growth failure might point to new ways to predict, prevent and treat this pervasive problem among preterm infants,” says one of the senior authors Patrick Seed, MD, PhD, Associate Chief Research Officer of Basic Sciences at Stanley Manne Children’s Research Institute at Ann & Robert H. Lurie Children’s Hospital of Chicago, and Research Professor of Paediatrics, Microbiology and Immunology at Northwestern University Feinberg School of Medicine. “Currently we lack the means to identify infants at highest risk of growth failure. The microbiome might give us the insights we need to guide individualised interventions and measure response to therapy.”
The human microbiome is estimated to consist of over a trillion bacteria in a single person, with 10 times the number of microbial cells to every human cell. Research has established that specific microbiome characteristics play causal roles in obesity, allergy, asthma, diabetes, autoimmune disease, depression and a variety of cancers. Studies have shown stark differences in the microbiome composition of preterm infants compared to full term infants. Recent studies also found that childhood malnutrition is associated with persistent immaturity of the gut microbiome.
“In our study, we investigated the relationships between intestinal microbiome, metabolism and growth in preterm infants,” says Dr Seed, who also is Division Head of Infectious Diseases at Lurie Children’s. “The significant associations we found will need to be reproduced by more studies in the future. We are looking to determine if the specific signatures of microbiome and metabolism maturation we discovered apply broadly to infants with and without growth failure.”
Growth failure in preterm infants is a risk factor for cognitive and motor impairment and may predispose these children to obesity, type 2 diabetes and heart disease later in life.
The study included 58 infants who were born at or before 27 weeks of pregnancy, weighing less than two pounds on average. Growth failure in these infants was defined as weight less that the third percentile on sex-specific growth charts at 40 weeks of postmenstrual age (birth gestational age plus chronological age). In the study, 36 infants had growth failure, while the rest had appropriate growth. These groups had consistent differences in the microbiome and metabolism regardless of complications of prematurity, such as sepsis (blood infection), necrotising enterocolitis (intestinal inflammation), or intestinal perforation.
Infants with growth failure had disrupted maturation of the intestinal microbiome, characterised by low bacterial diversity, dominance of certain disease-causing bacteria (Staphylococcus and Enterobacteriaceae) and low proportions of harmless bacteria (such as Veillonella). They also displayed delayed metabolic development with features that suggest deficiencies in metabolism of glucose and other non-lipid fuels, leading to greater reliance on fatty acids. The infants with growth failure were in a persistent physiologic state that resembled fasting.
“Our analyses of the relationship between the microbiome of infants with growth failure and the byproducts of their metabolism suggest that the unique composition of bacterial communities living in their gut might play a role in this metabolic state with similarities to fasting,” says Dr Seed. “This might explain why simply increasing caloric supply for infants with growth failure often does not work. In order to develop effective treatments, we need to better understand how their inability to utilise nutrients for energy is influenced by delayed maturation of the microbiome and metabolism.”
This study was funded in part by the Eunice Kennedy Shriver National Institute of Child Health and Human Development.
Bone Health not Improved by Increasing Protein Intake in Healthy Adults
Increasing protein intake beyond official recommendations has little to no benefit for bone health in healthy adults, new research in the journal Osteoporosis International reports.
In the most comprehensive study of its kind, researchers from the Department of Nutritional Sciences at the University of Surrey investigated if protein intake can impact bone health of adults and children.
Examining 127 previous studies published over a 40-year period, which scrutinised the link between protein and bone density, bone mineral content and relative risk of osteoporotic fractures, researchers discovered increasing protein intake had minimal benefit for bone health in healthy adults.
Researchers found that only 4% of bone density and bone mineral content in adults is dependent on protein intake with the remaining 96% due to other factors. These were not examined in the research but could include other nutritional factors including, age, body weight and genetics. For children a strong relationship between protein intake and bone health was identified, accounting for up to 14% of bone mineral content. However, in adults, protein supplementation via protein shakes or tablets was also not found to reduce the risk of fractures nor improve bone health. No detrimental effect of having an increased protein intake was identified.
Confusion currently exists about the role of protein in the skeletal system and if it has a positive or negative impact. Protein is a chain of amino acid molecules and is a necessary part of our diet to help cell growth and repair. Proponents of a positive link highlight dietary protein’s known ability to increase secretion of an insulin-like growth hormone which stimulates development. They point to its role in increasing calcium absorption from the gut which is likely to be beneficial for bone mineralisation. Opponents argue that a high intake of protein, which is rich in sulphur amino acids, may be bad for bone health as it increases body acidity resulting in a rise in osteoclast activity which absorbs bone tissue during growth and healing.
Lead author Dr Andrea Darling, Research Fellow at the University of Surrey, said: “Protein is an essential part of our diet and is required for a number of bodily functions including cell growth and repair. What we have found is that in healthy adults, who are meeting the nutritional requirement for protein, increased levels of protein have no extra benefit for bone health, but equally is not detrimental. This may differ in the older population who tend to have lower protein intakes and whose bones have become weaker with age. Moreover, more research is needed to examine the impact extra protein can have on this particular group.”
The Taboo Subject of Constipation: Undermining patient’s quality of life and putting a preventable strain on NHS
Independent multidisciplinary organisation The Bowel Interest Group has released its ‘Cost of Constipation’ report revealing the impact that the taboo subject of constipation has on the UK. This latest report not only explores the significant cost of constipation to the NHS but highlights the damaging impact on patient lives.
The report shows that poor bowel health and chronic constipation, which are debilitating for hundreds and thousands of people in the UK, cost the NHS a preventable £71 million in unplanned hospital admissions for constipation in 2017/18. This cost is likely to be much higher when GP visits, home visits and over the counter laxatives are taken into account. Specifically, the report shows that:
- In 2017/18, 71,430 people with constipation were admitted to hospital in England. This is equivalent to 196 per day.
- Close to three quarters of these were unplanned emergency admissions, equivalent to 144 per day.
- £91 million was spent on prescription laxatives in 2017/18.
- The cost of treating constipation in 2017/18 is equivalent to funding 7043 newly-qualified nurses for a year.
- On average, 6.3 people visit a GP about constipation each week.
The Cost of Constipation report also lays bare the embarrassment and distress caused by the condition, revealing that one in five people are embarrassed to talk about constipation with their GP, and some people find themselves unable to leave the house for social activities. In addition to the physical problems constipation can cause such as haemorrhoids, chronic pain and urinary tract infections, the report highlights the high incidence of anxiety disorders and depression in people with constipation.
Dr Benjamin Disney, Consultant Gastroenterologist, University Hospitals Coventry and Warwickshire NHS Trust, comments: “Many people see constipation as a simple, straightforward, easily treated condition that does not greatly affect people. However, from the Cost of Constipation report and my clinical experience, this is often not the case, with the condition being under-reported and often poorly managed, leading to a significant cost to the NHS and having a negative impact on patients’ overall health and quality of life. The Bowel Interest Group aims to tackle and raise awareness of the important issue of constipation.”
Patients, clinicians and other interested parties may download the full report free of charge by visiting: https://bowelinterestgroup.co.uk/cost-of-constipation-report-2019-public.
Meal Timing Strategies Appear to Lower Appetite and Improve Fat Burning
Researchers have discovered that meal timing strategies, such as intermittent fasting or eating earlier in the daytime, appear to help people lose weight by lowering appetite rather than burning more calories, according to a report published online today in the journal Obesity, the flagship journal of The Obesity Society. The study is the first to show how meal timing affects 24-hour energy metabolism when food intake and meal frequency are matched.
“Coordinating meals with circadian rhythms, or your body’s internal clock, may be a powerful strategy for reducing appetite and improving metabolic health,” said Eric Ravussin, PhD, one of the study’s authors and Associate Executive Director for Clinical Science at Louisiana State University’s Pennington Biomedical Research Center in Baton Rouge, USA.
“We suspect that a majority of people may find meal timing strategies helpful for losing weight or to maintain their weight since these strategies naturally appear to curb appetite, which may help people eat less,” said Courtney M. Peterson, PhD, lead author of the study and an assistant professor in the Department of Nutrition Sciences at the University of Alabama at Birmingham.
Peterson and her colleagues also report that meal timing strategies may help people burn more fat on average during a 24-hour period. Early Time-Restricted Feeding (eTRF) – a form of daily intermittent fasting where dinner is eaten in the afternoon – helped to improve people’s ability to switch between burning carbohydrates for energy to burning fat for energy, an aspect of metabolism known as metabolic flexibility. The study’s authors said, however, that the results on fat-burning are preliminary. “Whether these strategies help people lose body fat need to be tested and confirmed in a much longer study,” said Peterson.
For the study, researchers enrolled 11 adult men and women who had excess weight. Participants were recruited between November 2014 and August 2016. Adults, in general good health, aged 20-to-45-years old were eligible to participate if they had a body mass index between 25 and 35 kg/m2 (inclusive), body weight between 68 and 100 kg, a regular bedtime between 9:30 pm and 12 am, and for women, a regular menstrual cycle.
Participants tried two different meal timing strategies in random order: a control schedule where participants ate three meals during a 12-hour period with breakfast at 8:00 am and dinner at 8:00 pm and an eTRF schedule where participants ate three meals over a six-hour period, with breakfast at 8:00 am and dinner at 2:00 pm. The same amounts and types of foods were consumed on both schedules. Fasting periods for the control schedule included 12 hours per day, while the eTRF schedule involved fasting for 18 hours per day.
Study participants followed the different schedules for four days in a row. On the fourth day, researchers measured the metabolism of participants by placing them in a respiratory chamber – a room-like device – where researchers measured how many calories, carbohydrates, fat and protein were burned. Researchers also measured the appetite levels of participants every three hours while they were awake, as well as hunger hormones in the morning and evening.
Although eTRF did not significantly affect how many calories participants burned, the researchers found that eTRF did lower levels of the hunger hormone ghrelin and improved some aspects of appetite. It also increased fat-burning over the 24-hour day.
“By testing eTRF, we were able to kill two birds with one stone,” said Peterson, adding that the researchers were able to gain some insight into daily intermittent fasting (time restricted-feeding), as well as meal timing strategies that involve eating earlier in the daytime to be in sync with circadian rhythms. The researchers believe that these two broader classes of meal timing strategies may have similar benefits to eTRF.
Peterson and colleagues said prior research was conflicted on whether meal timing strategies help with weight loss by helping people burn more calories or by lowering appetite. Studies in rodents suggest such strategies burn more calories, but data from human studies were conflicting – some studies suggested meal timing strategies increase calories burned, but other reports showed no difference. The study’s authors said, however, that previous studies did not directly measure how many calories people burned or were imperfect in other ways.
Ravussin E, et al. (2019). Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity: https://doi.org/10.1002/oby.22518
