Wednesday, October 16, 2013
Rasher of bacon a day can harm a man's fertility: Half portion of processed meat 'significantly harms sperm quality'
Just the usual correlational rubbish. Men who eat fish rather than bacon are probably more middle class
Men who eat just one rasher of bacon a day could be reducing their chances of becoming fathers. Half a portion of processed meat such as a rasher or a small sausage can significantly harm sperm quality, scientists believe.
Those who want to boost the odds of having a child should eat fish instead – with species such as cod or halibut appearing to have a particularly dramatic effect on fertility.
The findings add to the growing evidence that a couple’s chances of having children is strongly governed by their lifestyle – with smoking, alcohol and stress having a detrimental effect and exercise and diet enhancing it.
Experts are still unclear why certain foods can harm or promote fertility, but red meat is thought to contain high levels of pesticides and other substances that can interfere with hormones. White fish is rich in zinc, which is believed to boost fertility.
In a study to be presented this week at a meeting of the American Society for Reproductive Medicine in Boston, Harvard University researchers compared the eating habits of 156 men undergoing IVF treatment with their partners.
They were each questioned how often they ate a range of foods including processed meat, white meat, red meat, white fish and tuna or salmon. Men who consumed just half a portion of processed meat a day had just 5.5 per cent ‘normal’ shaped sperm cells, compared to 7.2 per cent of those who ate less.
Men who had dishes containing white fish at least every other day – or half a portion daily – had far better sperm quality than those who ate it rarely.
Lead researcher Dr Myriam Afeiche said: ‘We found the effect of processed meat intake lowered quality and fish raised quality.’
But Dr Allan Pacey, chairman of the British Fertility Society, was cautious about the findings.
‘The relationship between diet and men’s fertility is an interesting one and there is certainly now convincing evidence that men who eat more fresh fruit and vegetables have better sperm than men who don’t,’ he said.
‘However, less is known about the fertility of men with poor diets and whether specific foods can be linked to poor sperm quality.
‘In this instance, the authors link men’s intake of processed meat with the size and shape of their sperm. This may be a real effect, but the study is small and we know that accurately measuring sperm size and shape in the laboratory is fraught with error.
‘However, it is already known that high intake of processed meat is linked to other health issues and so advising men to limit their intake of processed food may improve their health generally as well as possibly be good for their fertility.’
Last year, Cambridge University researchers calculated that the number of cases of bowel cancer, heart disease and diabetes would drop by 10 per cent if men halved their intake of processed meat.
Could that low-fat diet make you EVEN FATTER? As experts question conventional wisdom on diets, the extraordinary results of one man's experiment
Everyone who has ever tried to lose weight knows the formula: eat less and move more. According to this, what you eat doesn't matter so much, as long as you keep an eye on the total number of calories - though it's best to avoid fat because not only has it got more calories, but one type of fat, the saturated kind, raises your risk of heart disease, too.
This has been the thinking behind the low-fat, high-carbohydrate diet that has been the cornerstone of dieting and healthy eating for more than 40 years.
But today, this mantra is increasingly being questioned by clinicians and nutritional scientists - not least because it seems to have failed to halt the obesity epidemic.
The sceptics believe that the idea of all calories being equal is flawed. Indeed, Professor David Lawrence, an expert in nutrition and obesity data analysis, said recently in the journal BMC Medicine that the idea is based 'on an outdated understanding of the science'.
The sceptics argue that calories from different sources have different effects on the body, with calories from carbohydrates more likely to encourage weight gain.
Not only is the calorie theory under attack, but evidence is also emerging to show that lowering fat might not cut heart-disease risk, after all.
A major study published in the authoritative New England Journal of Medicine compared the clinical benefits of a conventional low-fat diet with two types of Mediterranean diet, which are naturally considerably higher in fat.
The study had to be stopped early because the heart attack and stroke rate in the Mediterranean options was so much lower it was deemed irresponsible to keep patients on the conventional diet.
WILL CREAM AND BACON HELP YOU LOSE WEIGHT?
Faced with mounting evidence, Swedish dietary experts recently made a dramatic U-turn, recommending a low-carb, rather than low-fat, diet for weight loss.
The bombshell came from the Council on Health Technology Assessment, which advises the Swedish government. Based on a review of 16,000 studies, it said the best sorts of food for losing weight were the likes of olive oil, double cream and bacon.
So the rules are being rewritten: to lose weight, cut down on carbs and eat more fat.
So what, precisely, is behind this new thinking? It comes down to the effect different foods have on your hormones.
The most important of these hormones, and the one that's crucial for weight loss, is insulin.
Insulin is the hormone that controls fat storage. A high-carb diet increases the amount of glucose in the bloodstream, which in turn means you produce more insulin. The more insulin the body produces, the more fat gets stored. A low-carb diet means less insulin, making it easier to lose weight because less fat is then stored.
MORE CALORIES, BUT SLIMMER WAIST
Dramatic new evidence for this has come from a unique experiment conducted by a personal trainer from East London. As Sam Feltham explains: 'My business is helping people to lose weight, and if all calories aren't equal, that could make a real difference.'
A few months ago, Sam upped his intake to a massive 5,000 calories every day. For three weeks he got these calories from a low-fat, high-carb diet; for another three, he ate more fat and cut right back on carbs.
He did exactly the same, moderate exercise regimen each time.
Now, according to the conventional wisdom, the weight gain would be the same on both regimens. After all, a calorie is just a calorie.
In fact, on the low-fat diet Sam stacked on 16 lb - more than a stone - and gained 3.7 in(9.5 cm) around his middle.
But when he ate more fat and cut his carbs, he added just 2½ lb and lost 1 in (2.5 cm) from his waistline.
'I've long been sceptical of the claim that all calories are created equal,' says Sam, who's just over 6 ft tall and normally weighs 14 st (89 kg).
For the low-carb, high-fat part of the experiment, Sam got his 5,000 calories from foods such as eggs, mackerel (which is very fatty), steak, green veg and coconut oil, interspersed with three snacks of nuts - walnuts, pecans or almonds (which are naturally high in fat).
While 72 per cent of his total calorie intake came from fats, 22 per cent came from protein and just 5.9 per cent from carbs. Each meal was exactly the same every day.
With the high-carb diet, most of his calories (63 per cent) came from carbohydrates, 13 per cent from protein, and 22 per cent from fat.
He ate garlic bread, low-fat lasagne, crumpets, low-fat yoghurts and rice pudding, chocolate muffins and wholemeal bread.
Admittedly the types of fat on his high-fat diet weren't your usual fatty foods, such as cream and butter. And his high-carb diet wasn't exactly 'healthy'.
The effects of the high-fat diet: Sam pictured on Day 1 and Day 21 of his new diet. He gained 2.5 lb and lost an inch off his waist
But the point was not comparing the health benefits of the two, says Sam. 'It was an experiment to test the idea that different foods affect your body's biochemistry differently. 'If it is true that cutting calories is the key to weight loss, then excess calories should put on the same amount of weight whether they come from a “healthy” diet full of fat or a poor diet full of carbs.'
He says he was 'really surprised' at how little weight he put on with the low-carb/high-fat diet, while on the high-carb/low-fat diet his body fat increased from 12.7 per cent of his body weight to 16.9 per cent.
CARBS MAY RAISE CHOLESTEROL
While Sam's experiment was by no means a scientific one, as well as the weight gain, what was even more striking was what an unhealthy effect the high carbohydrate regimen had on standard markers for heart health.
For when Sam had his blood tested after his three weeks on high carbs, 'the diet effectively gave him metabolic syndrome', says Dr Aseem Malhotra, a cardiologist at the Royal Free Hospital in London (who speaks with the added authority of having recently co-authored a report on tackling obesity for the Academy of Medical Royal Colleges).
Metabolic syndrome is a precursor to heart disease and diabetes.
'Particularly worrying was that his triglycerides (fats in his blood) had gone up four times, while his so-called 'good' (HDL) cholesterol had dropped,' says Dr Malhotra.
'That is not a good combination. Add to that the increase in his waist measurement, and he was looking a lot less healthy than he had been.
'What's more, a level of inflammation in his liver had doubled, which is also linked with diabetes and heart disease. 'If someone came into my clinic in that state, I'd make it clear they needed to make some serious changes to their diet and start eating a diet low in carbs. I was really surprised that the damaging changes had happened so quickly.'
Posted by jonjayray at 12:16 AM