Friday, June 9, 2017
High fat, high sugar diet during pregnancy 'programs' for health complications
Eating a high fat and high sugar diet when pregnant leads to metabolic impairments in both the mother and her unborn child, which may "program" them for potential health complications later in life, researchers have shown.
In a study carried out in pregnant mice, a team of academics found that an obesity-causing high fat and high sugar diet disrupted processes within the pregnant mother's body, leading to poor metabolic control. These changes were found just prior to birth and may make her more susceptible to conditions such as type 2 diabetes and heart disease, as well as to further fat accumulation, in later motherhood.
The exact impact on her child during pregnancy was harder to ascertain, but the researchers found that metabolic dysfunction in the mother compromised the flow of nutrients to the foetus, altering its growth and metabolism at critical stages during its development. This strongly suggests that an obesogenic diet (a diet which promotes obesity) also has consequences for foetal development. It may also explain why babies from mothers who are obese or eat obesogenic diets during pregnancy have a tendency to develop conditions such as obesity, hypertension and type 2 diabetes as adults.
In particular, the researchers found that a higher than recommended intake of fat and sugar exacerbates and distorts metabolic changes which occur naturally as a result of the pregnancy, so that the mother can appropriately allocate nutrients to the foetus.
The study was carried out by a team of researchers at the University of Cambridge. The lead author is Dr Amanda Sferruzzi-Perri, from St John's College, Cambridge, and the Centre for Trophoblast Research in the Department of Physiology, Development and Neuroscience. She said that the findings were especially relevant for women in western countries.
"In places like the UK, the US and Australia, many women of child-bearing age are also eating higher amounts of fat and sugar than the National Dietary Recommendations," she said. "We know that obesity during pregnancy is a risk factor for health complications for mother and baby both during and after pregnancy. This study offers insight into the mechanisms operating during pregnancy that may cause this."
The study involved feeding a diet that contained high amounts of fat and sugar to pregnant mice. The researchers then assessed the impact of this on both the metabolism of the mother and her levels of body fat, compared to mice which were fed a more balanced diet.
They related these changes in whole-body metabolism to the expression of proteins in the mother's tissues, which are responsible for processing and storing nutrients, as well as to the supply of nutrients, growth and metabolism of her developing foetuses. All of the experiments were carried out in line with the UK Home Office Animals (Scientific Procedures) Act 1986.
Overall, the researchers found that excessive consumption of sugar and fat compromised the mother's glucose tolerance and her sensitivity to insulin - the hormone that controls blood sugar levels.
Specifically, they found that the mother's ability to respond to insulin was reduced in tissues like her muscle and fat, which take up glucose from the circulation. By contrast, the sensitivity of the maternal liver to insulin was increased, which reduces glucose production during pregnancy. As a result, the mother was unable adequately to control glucose levels or produce enough glucose to support the pregnancy.
The high fat, high sugar diet also changed the expression of proteins in the mother's body that control fat storage, leading to an increase in body fat. Collectively, the researchers suggest that these effects promote a "pre-diabetic state" in the mother, resembling many aspects of gestational diabetes; a pregnancy complication which affects up to 5% of women in the UK.
One of the main reasons for this may be that an obesogenic diet exaggerates natural metabolic changes associated with pregnancy. "During a normal pregnancy, the mother's body will change the way it handles nutrients so that some can be freed up for the foetus," Sferruzzi-Perri explained. "The mother's metabolism is shifted to an insulin resistant, glucose intolerant state, such that her own glucose use is limited in favour of foetal supply. We think that in cases where the mother has a high fat, high sugar diet, these metabolic changes are exacerbated or perturbed."
These effects, the researchers suggest, may alter the mother's disposition to develop health complications after she has given birth as well - a phenomenon that they refer to as a "metabolic memory", putting her at greater risk of type 2 diabetes, obesity and cardiovascular problems in later life.
The study also found that the defects in the mother's metabolism impaired nutrient flow to the foetus, as they resulted in the preferential storage of nutrients within the mother's tissues, in favour of allocating these to the developing foetus.
Because the placenta also plays an important role in nutrient allocation (as previous studies have shown), the babies of mice fed the obesogenic diet were still born at a normal size. However, because the foetus receives different amounts of nutrients and shows defects in its ability to use these during development, the researchers believe that the child will still be more susceptible to metabolic dysfunction later in life.
"We still don't know what the exact consequences for the foetus are, but the findings match existing research which already suggests that the individual will suffer from these metabolic problems during adulthood," Sferruzzi-Perri said. "This is because changes to the nutrient and oxygen supply, at a stage when individual organs are developing, can cause a permanent change in the structure and function of certain tissues."
Omega-3 in mothers' diets may lower children's risk of type 1 diabetes
New research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]) suggests that omega 3 polyunsaturated fatty acids (PUFAs), derived primarily from fish in maternal diet during pregnancy or lactation, may help protect infants at high risk of type 1 diabetes (T1D) from developing the disease.
If confirmed, this could mean that increasing the intake of fish-derived fatty acids and the duration of breastfeeding may have beneficial effects by reducing the autoimmune responses that lead to T1D.
More than 20 million people worldwide are affected by T1D -- an autoimmune disease in which the immune system turns on the body and destroys insulin-producing beta cells in the pancreas. The subclinical disease process can be detected in asymptomatic individuals by identifying autoantibodies that develop in infancy or early childhood. Fatty acids have been shown to alter the immune system and inflammatory reactions and may play a role in the development of type 1 diabetes-related autoimmunity. However, evidence to date has been inconclusive.
In this new study, Dr Sari Niinistö at the National Institute of Health and Welfare, Helsinki, Finland and colleagues investigated whether serum fatty acid levels during infancy are related to the development of autoimmunity among children at increased genetic risk of developing T1D from the Finnish 'Type 1 Diabetes Prediction and Prevention Study'. In particular, they looked at whether especially high levels of omega 3 PUFAs reduce the risk of autoimmune responses that are associated with clinical disease.
Between 1997 and 2004, 7782 genetically predisposed newborns were monitored for islet cell autoantibodies, with blood samples drawn at regular intervals between 3 and 24 months of age, and then annually thereafter up to age 15, to determine islet autoimmunity. Questionnaires and food diaries were used to record breastfeeding and formula use--the main dietary sources of fatty acids in early infancy. 240 infants who developed islet autoimmunity (and 480 matched control infants) had their serum total fatty acid composition analysed from samples collected at the age of 3 and 6 months. The research team also assessed these positive cases for earlier signs of insulin and glutamic acid decarboxylase (GAD) autoantibodies -- both closely related to the development of type 1 diabetes.
Results showed that high serum levels of fish-derived fatty acids (docosahexaenoic acid; DHA and docosapentaenoic acid; DPA) were associated with lower risk of early (insulin) autoimmunity. However, high serum levels of alpha-linolenic acid (ALA) and high ratios of arachidonic acid (AA):DHA and omega 6:omega 3 PUFA were linked to higher risk.
The researchers also found that fatty acid status in infants strongly reflected the type of milk feeding. Breastfed infants had higher serum levels of fatty acids (e.g., pentadecanoic, palmitic, DPA, and DHA) associated with lower risk of type 1 diabetes-related autoimmunity compared to non-breastfed infants. Quantity of breast milk consumed further reduced the risk, whereas the amount of cow's milk-based formula was associated with higher risk of developing earlier (insulin) autoimmunity.
Despite the relatively small number of cases of insulin and GAD autoimmunity, the study revealed a number of clear links between fatty acid levels in infancy and type 1 diabetes-related autoimmunity. These were not affected when the researchers took into account other potential variables such as familial diabetes, maternal education, and amount of cow's milk in diet.
The results point to new directions for tackling type 1 diabetes. But the authors caution that an association does not imply causality, and they say that more studies are needed to confirm whether fatty acids can protect children from autoimmune responses that can trigger type 1 diabetes. However, they add, "[Our] findings support the view that breastfeeding, or some components of breast milk, including fatty acids, are protective, particularly with early autoimmunity...[and] that long-chain omega-3 status during the early months, at a time when the immune system is maturing and being programmed, is critical."
Drinking diet beverages during pregnancy linked to child obesity
Children born to women who had gestational diabetes and drank at least one artificially sweetened beverage per day during pregnancy were more likely to be overweight or obese at age 7, compared to children born to women who had gestational diabetes and drank water instead of artificially sweetened beverages, according to a study led by researchers at the National Institutes of Health. Childhood obesity is known to increase the risk for certain health problems later in life, such as diabetes, heart disease, stroke and some cancers. The study appears online in the International Journal of Epidemiology.
According to the study authors, as the volume of amniotic fluid increases, pregnant women tend to increase their consumption of fluids. To avoid extra calories, many pregnant women replace sugar-sweetened soft drinks and juices with beverages containing artificial sweeteners. Citing prior research implicating artificially sweetened beverages in weight gain, the study authors sought to determine if diet beverage consumption during pregnancy could influence the weight of children.
“Our findings suggest that artificially sweetened beverages during pregnancy are not likely to be any better at reducing the risk for later childhood obesity than sugar-sweetened beverages,” said the study’s senior author, Cuilin Zhang, Ph.D., in the Epidemiology Branch at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “Not surprisingly, we also observed that children born to women who drank water instead of sweetened beverages were less likely to be obese by age 7.”
The researchers analyzed data collected from 1996 to 2002 by the Danish National Birth Cohort, a long-term study of pregnancies among more than 91,000 women in Denmark. At the 25th week of pregnancy, the women completed a detailed questionnaire on the foods they ate. The study also collected data on the children’s weight at birth and at 7 years old.
In the current study, the NICHD team limited their analysis to data from more than 900 pregnancies that were complicated by gestational diabetes, a type of diabetes that occurs only during pregnancy.
Approximately 9 percent of these women reported consuming at least one artificially sweetened beverage each day. Their children were 60 percent more likely to have a high birth weight, compared to children born to women who never drank sweetened beverages. At age 7, children born to mothers who drank an artificially sweetened beverage daily were nearly twice as likely to be overweight or obese.
Consuming a daily artificially sweetened beverage appeared to offer no advantages over consuming a daily sugar-sweetened beverage. At age 7, children born to both groups were equally likely to be overweight or obese. However, women who substituted water for sweetened beverages reduced their children’s obesity risk at age 7 by 17 percent.
It is not well understood why drinking artificially sweetened beverages compared to drinking water may increase obesity risk. The authors cited an animal study that associated weight gain with changes in the types of bacteria and other microbes in the digestive tract. Another animal study suggested that artificial sweeteners may increase the ability of the intestines to absorb the blood sugar glucose. Other researchers found evidence in rodents that, by stimulating taste receptors, artificial sweeteners desensitized the animals’ digestive tracts, so that they felt less full after they ate and were more likely to overeat.
The authors caution that more research is necessary to confirm and expand on their current findings. Although they could account for many other factors that might influence children’s weight gain, such as breastfeeding, diet and physical activity levels, their study couldn’t definitively prove that maternal artificially sweetened beverage consumption caused the children to gain weight. The authors mention specifically the need for studies that use more contemporary data, given recent upward trends in the consumption of artificially sweetened beverages. They also call for additional investigation on the effects of drinking artificially sweetened beverages among high-risk racial/ethnic groups.
Is eating for 2 a good idea? Maintaining a healthy weight during pregnancy helps mother and baby
Pregnant women can improve their health and even reduce the risk of complications during childbirth by maintaining a healthy weight through diet and exercise. Research has shown that gaining too much weight during pregnancy increases the risk of gestational diabetes, high blood pressure, large babies, and delivery by caesarean section; and newborns with large birth weights are at risk of childhood obesity.
An updated systematic review published in The Cochrane Library reveals that diet or exercise interventions, or a combination of both, can prevent excessive weight gain in pregnancy. The original version of the review published in 2012 found only inconclusive evidence, that dietary and exercise programs had beneficial effects for pregnant women and their babies. In the updated version of the review, the research team incorporated evidence from 37 new studies published between October 2011 and November 2014. The review findings are now based on evidence from 11,444 women.
Researchers found that around 36% of women who were allocated to interventions to help them manage their weight, had excessive weight gain over the course of their pregnancy compared with around 45% in the control groups. Interventions involving low sugar diets, exercise only, or diet and exercise combined, all led to similar reductions in the number of women gaining excessive weight. Exercise interventions were mainly of moderate intensity and included various individual or group activities such as walking, aerobics, Pilates and dance.
Women receiving the interventions were less likely to be found to have high blood pressure. In addition, evidence suggested that the interventions may lead to a small reduction in caesarean deliveries from 29% to 27%, and reductions in the chances of having a baby with a large birthweight (more than 4 kilograms. Reviewers were unable to determine whether supervised interventions were better than counselling interventions and data from several ongoing trials will hopefully answer this question in the future.
"The review's findings will be important for informing antenatal care guidelines," said lead author Benja Muktabhant, an Associate Professor in the Department of Nutrition at Khon Kaen University, in Thailand. "However, we need more studies on the effectiveness of these interventions in low-income countries and in women with non-Western lifestyles." A new World Health Organization (WHO) guideline on antenatal care is in development and is expected to include recommendations based on this evidence.
"Pregnancy is a time when women have a lot of contact with healthcare providers, therefore there is no better time to engage and support women to make healthy lifestyle choices," said co-author Tess Lawrie. "We hope that these findings will encourage women not to overeat and to exercise regularly with the knowledge that their efforts will be rewarded with lower pregnancy weight gain and better health outcomes for themselves and their baby."
The researchers advise that pregnant women should refer to the Royal College of Obstetricians and Gynaecologists guidelines on exercise in pregnancy, and that before embarking on a new exercise program that they discuss it with their midwife or doctor.
For pregnant women with flu, the earlier the better for antiviral treatment
Fast Facts
- Among pregnant women hospitalized with severe flu who were treated early with an antiviral medication, the median length of their hospital stay was about five days shorter compared to similar patients treated later.
- Pregnant women who were hospitalized with severe cases of flu illness were half as likely to have been vaccinated as women with non-severe illness.
- Annual vaccination against flu is recommended for everyone 6 months of age and older, including pregnant women, who are at high risk of serious flu illness and complications.
"Treating pregnant women who have influenza with antiviral drugs can have substantial benefit in terms of reducing length of stay in the hospital," said Sandra S. Chaves, MD, MSc, of the Centers for Disease Control and Prevention (CDC) and senior author of the study. CDC recommends treatment of suspected cases of flu among pregnant women with antiviral drugs as soon as possible, without waiting for test results to confirm influenza. "The earlier you treat, the better chances you have to modify the course of the illness."
Past studies have suggested that flu antiviral therapy is safe and beneficial for pregnant women. The current study, based on data from a nationwide flu surveillance network including 14 states, focused on pregnant women hospitalized with laboratory-confirmed flu over four recent flu seasons, from 2010 to 2014. During the study period, 865 pregnant women were hospitalized with flu. Sixty-three of these patients, or about 7 percent, had severe illness.
After adjusting for underlying medical conditions, vaccination status, and pregnancy trimester, the researchers found that early treatment with the antiviral drug oseltamivir was associated with a shorter hospital stay. Among pregnant women with severe flu illness who were treated early -- within two days of the start of symptoms -- the median length of stay was about five days shorter compared to hospitalized pregnant women with severe flu illness who were treated later (2.2 days vs. 7.8 days). Pregnant women hospitalized with less severe illness who were treated early also had a shorter hospital stay than those treated later, but the difference was not as great.
In the study, pregnant women hospitalized with severe flu illness were half as likely to have been vaccinated as women hospitalized with milder illness (14 percent vs. 26 percent). CDC recommends annual flu vaccination for everyone 6 months of age and older, including pregnant women during any trimester of their pregnancy. Earlier studies have suggested that immunization during pregnancy may protect not only the mother from flu, but also her newborn baby during the first 6 months of life.
"All pregnant women should receive annual influenza vaccination to prevent influenza and associated complications for themselves and their infants," the study authors wrote.
A related editorial commentary by Alan T. N. Tita, MD, PhD, and William W. Andrews, PhD, MD, of the University of Alabama at Birmingham, accompanies the new study in The Journal of Infectious Diseases.
"Overall, considering the accumulating evidence of fetal benefit and safety, influenza vaccination of pregnant and postpartum women should be a public health priority in accordance with national recommendations," the commentary authors wrote. "Prompt initiation of antiviral therapy if infection occurs, preferably within two days of suspected or confirmed influenza infection, is encouraged."
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Pregnant mother's weight, glucose and blood pressure affect baby's size
Being overweight or obese in pregnancy causes babies to be born larger, according to new research. The study, led by the universities of Exeter and Bristol, also found that having higher blood glucose (sugar) during pregnancy causes babies to be born larger. Conversely, having higher blood pressure in pregnancy causes babies to be smaller.
It has long been known that women who are overweight or who have diabetes in pregnancy tend to have bigger babies. However, up to now it has been unclear whether the size of the baby has been caused by these characteristics in the mother, or what factors might be important in linking a mother's size to that of her babies.
Now, in an international research collaboration led by the universities of Exeter and Bristol, researchers have shown that excess weight and higher glucose levels in mothers cause their babies to be born heavier, while higher blood pressure causes lower birth weights. The team concluded that mothers with higher blood sugar tend to have bigger babies, even within a healthy range. Unlike some previous studies, the research, published in the medical journal JAMA, also found that mothers' blood lipids (levels of fat) that are also related to being overweight did not seem important in determining the baby's size.
Dr Rachel Freathy, of the University of Exeter Medical School, who co-led the study, said: "Being born very large or very small can carry health risks for a newborn baby, particularly when that's at the extreme end of the spectrum. Higher and lower birth weights are also associated with diseases such as Type 2 diabetes later on in life. Understanding which characteristics of a mother influence the birth weight of her offspring, may eventually help us to tailor management of a healthy pregnancy and reduce the number of babies born too large or too small."
The researchers used data from more than 30,000 healthy women and their babies across 18 studies. They examined genetic variants associated with mothers' body mass index, blood glucose and lipid levels and blood pressure, along with measurements of those characteristics in pregnancy. They also studied the weight of all the babies at birth. All the women had European ancestry and were living in Europe, America or Australia. Babies born between 1929 and 2013 were included in the study.
Dr Jess Tyrrell, of the University of Exeter Medical School, co-lead on the paper, said: "A lot of research into pregnancy and birth weight has been based on observation, but this can make it very difficult to determine what is cause and what is effect, creating a confusing picture for mothers, clinicians and healthcare workers. Our genetic method is more robust, giving clear evidence that mothers' weight, glucose and blood pressure affect the size of the baby."
Interestingly, even though being overweight or obese is usually associated with having a higher blood pressure, the researchers found that higher blood pressure causes babies to be born smaller, suggesting that there are complicated factors affecting growth in the womb.
Professor Debbie Lawlor, of the University of Bristol, who co-led the study, said: "This is really important research than could only be done with collaboration from a large number of scientists and the involvement of participants from several countries, and we are grateful to everyone involved. We will continue to work together to answer the next important question, which is whether the effects of mothers' weight, glucose and blood pressure on their babies weight at birth has a lasting effect as their children grow and become adults themselves - do children born to women with high glucose levels in pregnancy continue to be heavier throughout their lives?"
Pregnant women's high-fat, high-sugar diets may affect future generations
New research suggests that mothers who eat high-fat, high-sugar diets can predispose multiple generations to metabolic problems, even if their offspring consume healthy diets.
While other studies have linked a woman's health in pregnancy to her child's weight later in life, a mouse study at Washington University School of Medicine in St. Louis is the first to indicate that even before becoming pregnant, a woman's obesity can cause genetic abnormalities that subsequently are passed through the female bloodline to at least three generations, increasing the risk of obesity-related conditions such as type 2 diabetes and heart disease.
"Our findings indicate that a mother's obesity can impair the health of later generations," said Kelle H. Moley, MD, the School of Medicine's James P. Crane Professor of Obstetrics and Gynecology and senior author of the study. "This is particularly important because more than two-thirds of reproductive-age women in the United States are overweight or obese."
The study is published online in the journal Cell Reports.
The research shows that a mother's obesity - and its associated metabolic problems - can be inherited through mitochondrial DNA present in the unfertilized oocyte, or egg. Mitochondria often are referred to as the powerhouses of cells because they supply energy for metabolism and other biochemical processes. These cellular structures have their own sets of genes, inherited only from mothers, not fathers.
"Our data are the first to show that pregnant mouse mothers with metabolic syndrome can transmit dysfunctional mitochondria through the female bloodline to three generations," Moley said. "Importantly, our study indicates oocytes - or mothers' eggs - may carry information that programs mitochondrial dysfunction throughout the entire organism."
From six weeks prior to conception until weaning, the researchers fed mice a high-fat, high-sugar diet comprised of about 60 percent fat and 20 percent sugar. "This mimics more of the Western diet," Moley said. "Basically, it's like eating fast food every day."
Offspring then were fed a controlled diet of standard rodent chow, which is high in protein and low in fat and sugar. Despite the healthy diet, the pups, grand pups and great-grand pups developed insulin resistance and other metabolic problems. Researchers found abnormal mitochondria in muscle and skeletal tissue of the mice.
"It's important to note that in humans, in which the diets of children closely mirror those of their parents, the effects of maternal metabolic syndrome may be greater than in our mouse model," Moley said.
More research is needed to determine if a consistent diet low in fat and sugar, as well as regular exercise, may reverse genetic metabolic abnormalities.
"In any case, eating nutritiously is critical," Moley said. "Over the decades, our diets have worsened, in large part due to processed foods and fast foods. We're seeing the effects in the current obesity crisis. Research, including this study, points to poor maternal nutrition and a predisposition to obesity."
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