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Showing posts with label DNA. Show all posts
Showing posts with label DNA. Show all posts

Tuesday, April 19, 2011

Bad Diet for Expectant Mother Can Mean a Fat Baby and Later a Diabetic Adult

AN expectant mother’s diet can create an obesity time bomb for her unborn child by altering the baby's DNA in the womb, increasing its risk of obesity, heart disease and diabetes in later life, a groundbreaking study has revealed.

The process ‒ called epigenetic change ‒ can lead to her child tending to lay down more fat. Importantly, the study shows that this effect acts independently of how fat or thin the mother is and of child's weight at birth. The study found there was an element in a woman's diet, particularly during the first third of a pregnancy that was of crucial importance.

The epigenetic changes ‒ which alter the function of our DNA without changing the actual DNA sequence inherited from the mother and father ‒ can also influence how a person responds to lifestyle factors such as diet or exercise for many years to come. The changes were noticed in the RXRA gene that makes a receptor for vitamin A, which is involved in the way cells process fat.

The study ‒ to be published on April 26 in the journal Diabetes ‒ shows that the epigenetic effect work independently of how fat or thin the mother is - meaning thin mothers who eat badly are just as likely to cause obesity in their children as fat ones.

The scientists drew their conclusions after measuring epigenetic changes in nearly 300 children at birth (samples first taken after birth using umbilical cord tissue DNA), and relating these to obesity rates at six or nine years of age.

What was surprising was the size of the effect: children vary in how fat they are, but measurement of the epigenetic change at birth allowed the researchers to predict 25 per cent of this variation, basically by mapping data to the topology they had and achieving results which would be the placebo effect in a medical study.

Keith Godfrey, Professor of Epidemiology and Human Development at the University of Southampton, who led the international study, said: "It is both a fascinating and potentially important piece of research. All women who become pregnant get advice about diet, but it is not always high up the agenda of health professionals. The research suggests women should follow the advice as it may have a long term influence on the baby's health after it is born."

Speaking in Auckland, Peter Gluckman, from Auckland University's Liggins Institute, who led the New Zealand team, said the rate of epigenetic change was possibly linked to a low carbohydrate diet in the first three months of pregnancy, but it was too early to draw a definitive conclusion and further studies were needed. He said one theory was that an embryo fed a diet containing few carbohydrates ‒ which provide the body with energy ‒ assumed it would be born into a carbohydrate-poor environment and altered its metabolism to store more fat, which could be used as fuel when food was scarce.

"This study provides the most compelling evidence yet that just focusing on interventions in adult life will not reverse the epidemic of chronic diseases, not only in developed societies but in low socio-economic populations too," he said.


Gluckman added that it is not just women who should be mindful, as it is likely obese fathers change the DNA in the sperm, ultimately influencing how the baby develops its control of blood sugar and fat deposition after that baby grows up.

"There is good evidence in animals, and there is some supportive evidence in humans that fathers who are obese have impact on the gene switches of their babies as well. We should not imagine that father has no role in determining the outcome of the baby's health."

It has long been known a mother's diet can affect her unborn child, but the research reveals how much of an influence it can have on a child's health. While it is not clear exactly which foods have the greatest influence on the DNA of unborn babies, a link was found with mothers on low carb diets.

Humans originally ate food as it came in nature ‒ legumes, pulses, things like lentils and chick peas, and fruits. Root vegetables and potatoes are a lovely source of carbohydrate as well. It is therefore important mothers are educated about the effects of diets.

Low-carb diets are in fashion and women have used them to control their weight, but where that information has gone awry is people have become confused and cut-out really important sources of carbs like legumes and fruit.

The study will continue for a at least two more years as scientists look into which foods are the most harmful for unborn babies, but in the meantime their advice for expectant mothers is to eat a balanced diet.


Thursday, January 27, 2011

Fat Fathers Pass on Diabetes


It stands to reason that chubby mothers give birth to chubby babies. After all, they share food for the nine months before delivery.

But what about chubby fathers passing on the health consequences of their bad eating habits? Evidence that they do comes from an Australian study with rats showing that chubby fathers could be passing on diabetes to their offspring.

Male rats fed a high-fat diet and mated with healthy female rats went on to produce offspring that had trouble with blood-sugar levels even though the offspring were eating low-fat foods.

"I think what's really exciting about this work is what's novel about it," Margaret Morris said of the study she supervised at the University of New South Wales.

"This is the first report of non-genetic, intergenerational transmission of metabolic consequences of a high-fat diet from father to offspring."

Conventional thinking


Morris looked at fathers because their role has largely been ignored. After all, conventional thinking is that their role stops after they pass on the DNA in their sperm cells. Morris wanted to test this, believing that both mother and father play a role.

"There's no question that the role of the uterus during the development of the baby is important, but I think it's important to realise that the father can be having a non-genetic effect as well," she said.

The findings of the study, published in the US journal Nature, relate to rats but are very likely to hold true for humans as well.

"If it's true in the human, it really underlines the necessity for both parents to be approaching pregnancy in the best possible physical shape," Morris said.

The critical aspect of the study - the non-genetic transmission - is something that is not a big surprise to Diabetes Australia chief executive Greg Johnson. That genes play a part in the passing on of diabetes is a certainty but the role of environmental factors are not well understood.

"There are things that people can do to help reduce their risk of developing type-2 diabetes," Johnson said. "Most of those modifiable things that they can do relate to eating a good healthy balanced diet and maintaining good physical activity and exercise and a healthy body weight."

But, of course, we knew that; what we did not know - and still do not know for sure - is that a healthy diet and keeping in shape has consequences for a man's offspring as well as for himself.

Monday, January 17, 2011

Diabetes Damages Sperm

Researchers at Queens University, Belfast, have found that sperm from diabetic men shows moreDNA damage than the sperm from men without diabetes.

It was the first time medical researchers had compared the sperm of healthy men with those who had diabetes and their findings suggest that men with diabetes may experience problems with their fertility.

Of 27 diabetic men who had their sperm samples examined, semen volume was significantly less than in samples from healthy men. Although the sperm looked normal, when it was measured for DNA damage it was found to have greater levels of fragmentation and more deletions in DNA - in the mitochondria, or energy generating structures in the cells.

Diabetes May Cause Infertility
Queen’s research fellow, Dr Ishola Agbaje, said: “As far as we know, this is the first report of the quality of DNA in the nucleus and mitochondria of sperm in diabetes. Our study identifies important evidence of increased DNA fragmentation of nuclear DNA and mitochondrial DNA deletions in sperm from diabetic men. These findings cause concern, as they may have implications for fertility.”

The incidence of type one and type two diabetes is increasing rapidly worldwide. Type two diabetes (late onset) is usually related to poor diet and obesity. Type one diabetes is usually diagnosed in childhood or in the teen years and the number of European children with type one diabetes is increasing by 3% every year. The reason is unclear, but scientists think that a combination of factors may be at play, such as genes and environmental factors like exposure to viruses.

Because there is such a large and growing community of people affected by diabetes, this could potentially cause a substantial number of male factor infertility cases.

Sperm Disorders
Dr. Agbaje added, "One in six couples require specialist investigation to conceive. The last 50 years have seen a decline in semen quality. Sperm disorders may cause or contribute to infertility in 40-50% of infertile couples. The increasing incidence of systemic diseases like diabetes may further exacerbate this decline in male fertility."

Professor Sheena Lewis, of Queen’s Reproductive Medicine Research Group, said: "Our study shows increased levels of DNA damage in sperm from diabetic men. From a clinical perspective this is important, given the growing body of evidence that sperm DNA damage can impair male fertility and even the health of future generations."

Fragmented sperm can cause failure to implant, failure of the embryo to develop, early miscarriage or even failure to get pregnant in the first place.

Further studies with men who have diabetes are being planned to determine whether DNA damage caused by diabetes has the same detrimental affect on fertility that DNA damage caused by smoking does.

Source: Insulin Dependent Diabetes Mellitus: Implications for Male Reproductive Function. Human Reproduction, 3rd May 2007.