Scientists may have discovered a way of identifying dieters who are prone to piling the pounds back on after weight loss. A study at Maastricht University’s Department of Human Biology found a link between a gene involved in regulating blood pressure and post-diet weight gain in women. Women who regained weight after slimming had a high change in the concentration of a particular protein in their blood during dieting, research showed. Researchers now hope to develop a test to indicate how prone people are to yo-yo dieting.
Edwin Mariman, professor of functional genetics at Maastricht, said: “It was a surprising discovery, because until now there has been no clear link between this protein and obesity. “We do not yet have an explanation for the results, but it does appear that it should be possible within a few years to use this finding to develop a test to show who is at high risk of putting weight back on after a diet.”
Hospitals already conduct tests for the protein, known as the angiotensin I converting enzyme (ACE). But the test is currently carried out to check its activity in regulating blood pressure, rather than its concentration. Up 80% of dieters suffer from the yo-yo effect, returning to their original weight within a year.
The study looked at around 100 women aged 20 to 45, half of whom had maintained their post-diet weight and half of whom had put weight back on. The findings of the research have been published by Dr Ping Wang, a scientist in Professor Mariman’s research group, in the online scientific journal PloS ONE.
One of Australia’s leading juvenile justice services providing secure and safe care of up to 500 young offenders.
Review adequacy of summer and winter menus to address concerns raised to the State by the public.
Ensure compliance with Nutrient Reference Values for Australia and New Zealand
Ensure compliance with Dietary Guidelines for Children and Adolescents in Australia
Ensure compliance with Standards for Juvenile Custodial Facilities
Review of custodial health findings in various State jurisdictions around Australia and overseas.
Computer based macro and micro nutrient analysis of menus and individual recipes including protein, fat, carbohydrate and protein percentages
Computer based energy analysis of menus and individual recipes
Analysis of menus against nutrient reference values and appropriate recommendations.
Analysis of menus against dietary guidelines and appropriate recommendations
Analysis of food variety and appropriate recommendations
Analysis of special dietary needs and appropriate recommendations
Analysis of food choice and satisfaction and appropriate recommendations
Chronic kidney disease (CKD) patients who consume a diet high in vegetables rather than meat may prevent the accumulation of toxic phosphorus levels, according to a study published online Dec. 23 in the Clinical Journal of the American Society of Nephrology.Sharon M. Moe, M.D., of the Indiana University School of Medicine in Indianapolis, and colleagues conducted a crossover trial in nine patients with a mean estimated glomerular filtration rate of 32 ml/min to compare vegetarian and meat diets containing equivalent nutrients prepared by clinical research staff.
The investigators found that one week of a vegetarian diet led to lower serum phosphorus levels, decreased phosphorus excretion in the urine, and reduced fibroblast growth factor-23 levels compared with a meat diet, despite equivalent protein and phosphorus concentrations in the two diets.
“In summary, this study demonstrates that the source of protein has a significant effect on phosphorus homeostasis in patients with CKD. Therefore, dietary counseling of patients with CKD must include information on not only the amount of phosphate but also the source of protein from which the phosphate derives,” the authors write.
The most common type of breast cancer in older women — estrogen and progesterone receptor (ER/PR) positive breast cancer — has been linked to a protein that fends off aging-related cellular damage. A new study led by Vanderbilt-Ingram Cancer Center researcher David Gius, M.D., Ph.D., now shows how a deficiency in this aging-associated protein may set the stage for these tumors to develop.
The findings, published in Molecular Cell, provide information that could assist in the screening, prevention and treatment of these common age-related cancers. While the young are certainly not spared cancer’s wrath, cancer is primarily a disease of aging, with the majority of cases occurring in people over 50. However, the biological processes that underlie this association are not clear.
“The connection between aging and cancer is one of the most established phenomena in cancer research,” said Gius, associate professor of Cancer Biology, Pediatrics and Radiation Oncology. “The problem to address this clinically significant question is that this field lacks in vivo models to study this.”
In the late-1990s, proteins called “sirtuins” were linked to extended lifespan observed in several species maintained on a calorically restricted diet. These nutrient-sensing sirtuin proteins seemed to defend against aging-related cellular damage. Sirtuins are present in all living organisms, with humans having seven different sirtuin proteins. “When (the sirtuins) were discovered, it seemed obvious to conclude that there might be a mechanistic connection between the genes that determine length of survival and cancer,” Gius said. Previously, while at the National Cancer Institute, Gius and colleagues created mice lacking some of these sirtuins.
They reported last January in Cancer Cell that when they knocked out Sirt3 — a sirtuin localized in the mitochondria, the cellular “power plants” — the mice developed ER/PR positive breast tumors, the most common type of breast cancer in postmenopausal women. These tumors also exhibited increased levels of damaging free radicals and “reactive oxygen species” (ROS) — including superoxide, the primary metabolite of oxygen in the mitochondria — which provided an important clue as to how Sirt3 deficiency might permit these tumors to develop. “The mechanism, at least in part, for why these mice develop receptor positive breast cancer is altered mitochondrial ROS, including superoxide,” Gius said. But how deficiency in a longevity gene led to increased ROS was not clear. Since superoxide is generally removed from the cell with the help of a detoxifying enzyme called manganese superoxide dismutase (MnSOD), Gius hypothesized that the Sirt3 deficiency may abnormally regulate MnSOD.
In the current study, the researchers show that Sirt3 knockout mice have decreased MnSOD activity despite having normal levels of the protein. Gius and colleagues determined that the MnSOD in Sirt3 knockout mice was abnormally modified (with a chemical “acetyl” group) at a specific amino acid (lysine 122). This aberrant modification of MnSOD reduced the enzyme’s ability to detoxify superoxide and appeared to explain the increase in ROS in Sirt3 knockout mouse tumors. “These results suggest that aberrant regulation of MnSOD plays a role in receptor positive breast cancer,” said Gius.
Gius and colleagues also developed an antibody that can assess the acetylation status of MnSOD, which he says can potentially be used “to screen breast tissue samples to determine what women are at risk for (receptor positive) cancer or for recurrence because of this dysregulation of MnSOD.” Additionally, agents that target the acetylation of this amino acid on MnSOD may be useful as chemopreventive therapies in women at risk of these cancers and of recurrence, he noted. The research was supported by grants from the National Cancer Institute and the Department of Defense.
New findings from the Monell Center reveal that weight gain of formula-fed infants is influenced by the type of formula the infant is consuming. The findings have implications related to the infant’s risk for the development of obesity, diabetes and other diseases later in life. “Events early in life have long-term consequences on health and one of the most significant influences is early growth rate,” said study lead author Julie Mennella, Ph.D., a developmental psychobiologist at Monell. “We already know that formula-fed babies gain more weight than breast-fed babies. But we didn’t know whether this was true for all types of formula.”
While most infant formulas are cow’s milk-based, other choices include soy-based and protein hydrolysate-based formulas. Protein hydrolysate formulas contain pre-digested proteins and typically are fed to infants who cannot tolerate the intact proteins in other formulas. In adults, pre-digested proteins are believed to act in the intestine to initiate the end of a meal, thus leading to smaller meals and intake of fewer calories. Based on this, the authors hypothesized that infants who were feeding protein hydrolysate formulas would eat less and have an altered growth pattern relative to infants feeding cow’s milk-based formula.
In the study, published online in the journal Pediatrics, infants whose parents had already decided to bottle-feed were randomly assigned at two weeks of age to feed either a cow’s milk-based formula (35 infants) or a protein hydrolysate formula (24 infants) for seven months. Both formulas contained the same amount of calories, but the hydrolysate formula had more protein, including greater amounts of small peptides and free amino acids. Infants were weighed once each month in the laboratory, where they also were videotaped consuming a meal of the assigned formula. The meal continued until the infant signaled that s/he was full.
Over the seven months of the study, the protein hydrolysate infants gained weight at a slower rate than infants fed cow milk formula. Linear growth, or length, did not differ between the two groups, demonstrating that the differences in growth were specifically attributable to weight. “All formulas are not alike,” said Mennella. “These two formulas have the same amount of calories, but differ considerably in terms of how they influence infant growth.”
When the data were compared to national norms for breast-fed infants, the rate of weight gain of protein hydrolysate infants was comparable to the breast milk standards; in contrast, infants fed cow’s milk formula gained weight at a greater rate than the same breast milk standards. Analysis of the laboratory meal revealed the infants fed the protein hydrolysate formula consumed less formula during the meal. “One of the reasons the protein hydrolysate infants had similar growth patterns to breast-fed infants, who are the gold standard, is that they consumed less formula during a feed as compared to infants fed cow’s milk formula” said Mennella. “The next question to ask is: Why do infants on cow’s milk formula overfeed?”
The findings highlight the need to understand the long-term influences of infant formula composition on feeding behavior, growth, and metabolic health. Future studies will utilize measures of energy metabolism and expenditure to examine how the individual formulas influence growth, and how each differs from breastfeeding. Also contributing to the study, which was funded by the National Institute of Child Health and Human Development, were Monell scientists Gary Beauchamp and Alison Ventura.
To test their hypothesis that environmental influences experienced by the father can be passed down to the next generation in the form of changed epigenetic information, Rando and colleagues fed different diets to two groups of male mice. The first group received a standard diet, while the second received a low-protein diet. To control for maternal influences, all females were fed the same, standard diet. Rando and colleagues observed that offspring of the mice fed the low-protein diet exhibited a marked increase in the genes responsible for lipid and cholesterol synthesis in comparison to offspring of the control group fed the standard diet.
These observations are consistent with epidemiological data from two well-known human studies suggesting that parental diet has an effect on the health of offspring. One of these studies, called the Överkalix Cohort Study, conducted among residents of an isolated community in the far northeast of Sweden, found that poor diet during the paternal grandfather’s adolescence increased the risk of diabetes, obesity and cardiovascular disease in second-generation offspring. However, because these studies are retrospective and involve dynamic populations, they are unable to completely account for all social and economic variables. “Our study begins to rule out the possibility that social and economic factors, or differences in the DNA sequence, may be contributing to what we’re seeing,” said Rando. “It strongly implicates epigenetic inheritance as a contributing factor to changes in gene function.”
The results also have implications for our understanding of evolutionary processes, says Hans A. Hofmann, PhD, associate professor of integrative biology at the University of Texas at Austin and a co-author of the study. “It has increasingly become clear in recent years that mothers can endow their offspring with information about the environment, for instance via early experience and maternal factors, and thus make them possibly better adapted to environmental change. Our results show that offspring can inherit such acquired characters even from a parent they have never directly interacted with, which provides a novel mechanism through which natural selection could act in the course of evolution.” Such a process was first proposed by the early evolutionist Jean-Baptiste Lamarck, but then dismissed by 20th century biologists when genetic evidence seemed to provide a sufficient explanation.
Taken together, these studies suggest that a better understanding of the environment experienced by our parents, such as diet, may be a useful clinical tool for assessing disease risk for illnesses, such as diabetes or heart disease. “We often look at a patient’s behavior and their genes to assess risk,” said Rando. “If the patient smokes, they are going to be at an increased risk for cancer. If the family has a long history of heart disease, they might carry a gene that makes them more susceptible to heart disease. But we’re more than just our genes and our behavior. Knowing what environmental factors your parents experienced is also important.”
The next step for Rando and colleagues is to explore how and why this genetic reprogramming is being transmitted from generation to generation. “We don’t know why these genes are being reprogrammed or how, precisely, that information is being passed down to the next generation,” said Rando. “It’s consistent with the idea that when parents go hungry, it’s best for offspring to hoard calories, however, it’s not clear if these changes are advantageous in the context of a low-protein diet.”
FRANCE'S most popular weight-loss regimes, including the number one Dukan diet, are ineffective and potentially dangerous to people's health, doctors have warned. The Agence Nationale de Sécurité Sanitaire has issued a warning over 14 of the most fashionable diet regimes in France. Researchers at the Institut Pasteur in Lille assessed each regime, including Atkins and Montignac, for its nutritional value and potential side-effects. Head of nutritional research Jean-Michel Lecerf, who led the study, said the diets disrupted the body's natural metabolism and led to serious nutritional imbalances.
In nearly all the diets, the protein content was typically much higher than the recommended daily intake, especially the Dukan diet, which is France's top-seller. Some of the diets contained 10 times less fibre than the recommended level and up to twice as much salt. They also lacked vital vitamins and minerals. The study also pointed to an increased risk of fractures and other bone problems, muscle wastage and cardiovascular problems in some of the regimes.
Dr Lecerf said that in 95 per cent of cases, people who follow a dietary regime regain weight as soon as they finish. In some instances, the weight they regain is greater than the amount lost. He said: “Each regime is less effective than the one before, and the weight gain afterwards is greater each time.” According to the study, about 70 per cent of people in France have followed some sort of weight-loss programme, many without consulting a doctor beforehand.
The Régime Dukan is the most popular diet in France at the moment. Like Atkins, it is high in protein in the initial “attack” phase, but low in fat. Next comes the “cruise” phase, with protein-only days and protein-and-veg days. Potatoes are banned, as are high-calorie vegetables such as peas, carrots and sweetcorn.
More than two million copies of the Dukan book Je ne sais pas maigrir have been sold in France.
Throughout the project, the families received expert guidance from dietitians and were asked to provide blood and urine samples.
Diogenes: The five diet types
The design comprised the following five diet types:
- A low-protein diet (13% of energy consumed) with a high glycemic index (GI)*
- A low-protein, low-GI diet
- A high-protein (25% of energy consumed), low-GI diet
- A high-protein, high-GI diet
- A control group which followed the current dietary recommendations without special instructions regarding glycemic index levels
A high-protein, low-GI diet works best
A total of 938 overweight adults with a mean body mass index (BMI) of 34 kg/sq m were initially placed on an 800-kcal-per-day diet for eight weeks before the actual diet intervention was initiated. A total of 773 adult participants completed this initial weight-loss phase and were then randomly assigned to one of five different diet types, where 548 participants completed the six-month diet intervention (completion rate of 71%).
Fewer participants in the high-protein, low-GI groups dropped out of the project than in the low-protein, high-GI group (26.4% and 25.6%, respectively, vs. 37.4%; P = 0.02 and P = 0.01 for the two comparisons, respectively). The initial weight loss on the 800-kcal diet was an average of 11.0 kg.
The average weight regain among all participants was 0.5 kg, but among the participants who completed the study, those in the low-protein/high-GI group showed the poorest results with a significant weight gain of 1.67 kg. The weight regain was 0.93 kg less for participants on a high-protein diet than for those on a low-protein diet and 0.95 kg less in the groups on a low-GI diet compared to those on a high-GI diet.
The children's study
The results of the children's study have been published in a separate article in Pediatrics. In the families, there were 827 children who only participated in the diet intervention. Thus, they were never required to go on a diet or count calories – they simply followed the same diet as their parents. Approx. 45% of the children in these families were overweight. The results of the children's study were remarkable: In the group of children who maintained a high-protein, low-GI diet the prevalence of overweight dropped spontaneously from approx. 46% to 39% – a decrease of approx. 15%.
Proteins and low-GI foods ad libitum – the way ahead
The Diogenes study shows that the current dietary recommendations are not optimal for preventing weight gain among overweight people. A diet consisting of a slightly higher protein content and low-GI foods ad libitum appears to be easier to observe and has been documented to ensure that overweight people who have lost weight maintain their weight loss. Furthermore, the diet results in a spontaneous drop in the prevalence of overweight among their children.
Citation: Thomas Meinert Larsen, Ph.D., Stine-Mathilde Dalskov, M.Sc., Marleen van Baak, Ph.D., Susan A. Jebb, Ph.D., Angeliki Papadaki, Ph.D., Andreas F.H. Pfeiffer, M.D., J. Alfredo Martinez, Ph.D., Teodora Handjieva-Darlenska, M.D., Ph.D., Marie Kunešová, M.D., Ph.D., Mats Pihlsgård, Ph.D., Steen Stender, M.D., Ph.D., Claus Holst, Ph.D., Wim H.M. Saris, M.D., Ph.D., and Arne Astrup, M.D., Dr.Med.Sc. for the Diet, Obesity, and Genes (Diogenes) Project, 'Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance', N Engl J Med 2010; 363:2102-2113 November 25, 2010
Supplementing diet with whey-based protein may help reduce high blood pressure, a U.S. researcher says.
Nutritional biochemist Susan Fluegel of Washington State University in Spokane says daily doses of commonly available whey brought a more than 6-point reduction in the average blood pressure of men and women with elevated systolic and diastolic blood pressures. Whey is a by-product of cheese-making. “One of the things I like about this is it is low-cost,” Fluegel says in a statement. “Not only that, whey protein has not been shown to be harmful in any way.”
The study, published in International Dairy Journal, finds not everyone drinking the whey-supplemented drink has changes in blood pressure.
The supplement did not lower the blood pressure of subjects who did not have elevated pressure to begin with. That's good, says Fluegel, since low blood pressure can also be a problem. However, blood-pressure reductions — as seen in those with elevated pressure in this study — can bring a 35 percent to 40 percent reduction in fatal strokes, says Fluegel.
Fluegel and colleagues looked at 71 student subjects ages 18-26, but Fluegel says older people with blood pressure issues would likely get similar results. The supplement was delivered in fruit-flavored drinks developed at the university's creamery.
Working in the laboratory, the scientists isolated fragments of DNA in cells to study the effects of exposure to calcitriol, the “active” form of vitamin D. Their findings are published in the journal Genome Research.
Vitamin D influences DNA through a “go-between” protein called the vitamin D receptor (VDR). The protein is activated by the vitamin and attaches itself to DNA at the binding sites the researchers identified. VDR binding was enriched in disease-associated regions of the genetic code and also areas linked to traits such as tanning, height and hair colour.
Study leader Dr Sreeram Ramagopalan, from the Wellcome Trust Centre for Human Genetics, at Oxford University, said: “There is now evidence supporting a role for vitamin D in susceptibility to a host of diseases. Vitamin D supplements during pregnancy and the early years could have a beneficial effect on a child's health in later life. “Some countries, such as France, have instituted this as a routine public health measure.”
Vitamin D is chiefly made in the body as a result of the skin's exposure to sunlight. A small number of foods also contain the vitamin, including oily fish and eggs, but 90% comes from being in the sun. In many northern countries, a lack of sun can lead to vitamin D deficiency. Over-zealous use of sunscreen can also prevent vitamin D production. It is estimated that more than half the UK population do not get enough vitamin D, and worldwide a billion people may be deficient in the vitamin. Lack of vitamin D affects bone growth and development, leading to rickets in children and bone fractures in adults.
The study supports the theory that lighter, more sun-sensitive skins evolved as people migrated north out of Africa to maximise vitamin D production in the body. A significant number of the VDR binding sites were in DNA regions where genetic changes are commonly found in people of European and Asian descent.
“Vitamin D status is potentially one of the most powerful selective pressures on the genome in relatively recent times,” said co-author Professor George Ebers, also from the Wellcome Trust Centre for Human Genetics. “Our study appears to support this interpretation and it may be we have not had enough time to make all the adaptations we have needed to cope with our northern circumstances.”