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Showing posts from January, 2012

Parental conflict, genes and obesity

We inherit two copies of each gene in our DNA, one from Mum and one from Dad. There are no exceptions. However, there are about 100 genes, known as imprinted genes, in which one of the parental copies is completely silenced. Effectively, we have only one functioning copy of these genes, either a paternal copy or a maternal copy. Somehow or other, cells know that they carry either the maternal or paternal copy and they behave differently depending on the parental version they carry. In a normal person, there are about equal amounts of the maternal-only and the paternal-only copies. Mice can be bred to have the usual two sets of DNA but instead of having 50:50 maternally or paternally imprinted genes, we can make all the imprinted genes paternal or maternal. All of these mice contain each and every gene a normal mouse needs, except that for the 100 imprinted genes, they are either all maternal or all paternal. These embryos do not survive which tells us that we need some maternally impri…

Drones, queens and genes

We inherit our genetic code from our parents and from cradle to grave that genetic sequence is immutable. We all know that forensic medicine can take any part of the human body, however small, and sequence the DNA, thus obtaining our absolutely unique genetic code. If every part of the human body contains the full sequence of DNA inherited from our parents, then why is your ear not your nose? What makes the different parts of our body different from one another is that the inherited sequence of DNA is “tweaked” so that genes that are not needed are turned down or off and those that are needed are turned up. Effectively, nature gave us a genetic dimmer switch which cannot change the sequence of genes but which can change the extent to which individual genes are expressed. By far the most striking example is the queen bee. All bee larvae contain the exact same genetic code obtained from the queen and thus they are clones. When a queen passes her sell by date so to speak, the worker bees…

Markets and malnutrition

In 1985, the rock star Bob Geldof organised Live Aid to raise money to combat famine in northern Ethiopia. Some 8 million persons suffered sever famine of whom 1 million died. What wasn’t known at the time was that in southern Ethiopia, there was ample food. So great was the glut that prices fell by 80% and subsequently, almost 300,000 tonnes of maize was left to rot in the fields.The co-existence of food shortages and food gluts comes down to a failure of markets and during this period and for decades afterwards, the Washington suits of the World Bank and IMF were adamant that governments stay away from price support and agricultural subsidies. Leave it all to the markets was the theory. That happily has now been abandoned and there is a clear recognition that markets only work when the proper infrastructure exists.
African agriculture has a long way to go to make real progress. Only 7% of arabale land in Africa is irrigated compared to 45% in Asia. Road density is 6 times greater in…

Banning food colours. Bad science ~ Bad legislation

Philippus Aureolus Theophrastus Bombastus von Hohenheim was born in 1493 and, perhaps not surprisingly, changed his name to Paracelsus. Celsus was a Roman physician who gave the element zinc its name and this pompous Swiss German medic decided to re-name himself‘Equal to Celsus’. He is famous for his dictat: ”Sola dosis facet venum”, which translates from the Latin into “The dose alone makes the poison”. In other words, everything is toxic at the right dose and under the right circumstances. Pure Alpine air is highly toxic if a certain dose is injected intravenously. The exact dose remains unknown since no such experiment has ever been done but you get my drift, I hope.
In 2007, a group of researchers from Southampton University published a paper in the prestigious medical journal, The Lancet, showing that a cocktail of food additives (6 colours and 1 preservative) caused hyperactivity and reduced cognitive function in children.The study was well conducted. It used a placebo (identical…

Weight loss new year resolutions

Across the globe, millions of people will commit themselves to a New Year resolution to lose weight. Almost all will fail. The 5-year cure rate for obesity is less than the 5-year cure rate for the worst cancer, a view articulated by the American Medical Association’s Council on Scientific Affairs almost 25 years ago. If dieting were a drug, it would have failed the regulatory process given that it is generally not a long-term success. Yes, there are successes but they require life long adherence to a restricted food intake.Basically speaking, when we gain weight and retain that gain for some time, it is recognised biologically as a new norm. When we lose weight, that same norm is constantly there and constantly wishing to re-establish itself. Losing weight is easy. It’s retaining that weight loss which is huge challenge. Rule number one in weight management: Whatever your weight is now, don’t gain any more. That is a battle you can win. There is a second battle you can win and that is…