Wednesday, February 27, 2013
NYT has orgasm over latest Mediterranean diet study -- but orgasm fades half way through the article (justifiably)
The NYT article is here and the NEJM article is here. The title in the NEJM is "Primary Prevention of Cardiovascular Disease with a Mediterranean Diet" by Estruch et al. I would normally reproduce one of the articles concerned but I don't think either is worth reading, unless for amusement
I feel sorry for Estruch et al. They really put a big effort into their study but their findings must be disappointing to them. But they made the best of a bad job and managed to get a report into NEJM. That NEJM published it reflects badly on NEJM, though.
To cut immediately to the most spectacular failure. As the NYT admits, the existing evidence for benefit from a Mediterranean diet is mainly that a Mediterranean diet reduces heart disease. That is the big marching song of the diet. So guess what? Estruch et al. found that (I quote): "In fully adjusted analyses, we found significant results for the combined cardiovascular end point and for stroke, but not for myocardial infarction alone." BONG! End of story. The diet does NOT reduce heart attacks. The study found exactly the opposite to what Estruch et al. and the NYT wanted.
I don't know if I should go on about other hilarity in the study. Sampling is the great weakness of most medical research and so it was here too. The group studied here were elderly Spaniards with health problems. I could find no mention of sampling in the article so we do not know if the results are even generalizable to all elderly Spaniards with health problems, let alone generalizable to anyone else.
And quite bizarre was the control group used: A similar group on a low-fat diet! The authors report that compliance was poor in the low fat diet but some effect of that regimen can surely not be ruled out.
And the logic of calling the low-fatters the normals is bizarre. It grieves me that I have to mention it but in Spain, a Mediterranean diet is normal. Though the prevalence of a more "American" diet among the young (not in the current "sample") must be acknowledged. So the (marginally) higher death-rate among the low-fatters, shows that low-fatters die younger than normals. Fat is good for you! GAACK! Another nasty one for the food freaks.
I could go on (weak correlations etc.) but enough is enough. This is already one of the most amusingly misreported pieces of research I have seen. I dare NEJM to offer me the chance of putting up a full and sober critique of their ridiculous publication. I have had many critiques published in academic journals in my time so would be eminently qualified.
Dubious soya products
Soya was marketed as a wonder food, the Orient’s remedy for the West’s health problems.
However, the health virtues attributed to soya were soon challenged by researchers.
In 2006, for example, an American Heart Association review of a decade-long study of soya’s supposed benefits cast doubt on the ‘heart healthy’ claims and concluded that soya did not reduce hot flushes in women or help prevent cancer.
A study at Massachusetts General Hospital’s infertility clinic in 2008, where men were asked to consume various soya products, including tofu, veggie burgers, soya milk and protein shakes, found ‘higher intake of soya foods is associated with lower sperm concentration’.
The jury is out on the long-term health impact of eating soya, but there are reasons to be wary.
Soya beans contain naturally occurring toxins. These include phytic acid, which reduces our ability to absorb essential minerals, such as iron and zinc, and might therefore cause mineral deficiencies, and trypsin inhibitors, which impair the body’s capacity to digest protein.
These toxins are also found in other foods, such as chickpeas and wheat, but at lower levels.
Processing soya is designed to substantially reduce or remove these toxins, but traces may remain.
Soya also contains isoflavones — potent plant compounds that mimic the female hormone, oestrogen.
In 2011, the European Food Safety Authority’s scientific panel dismissed claims made by the soya industry that isoflavones helped hair growth, eased menopause symptoms, supported heart health and protected cells against oxidative damage.
It concluded a cause-and-effect relationship between consumption of soya products and health benefits ‘had not been established’.
Meanwhile, there have been suggestions that, far from being protective, eating too much soya protein can be harmful because of its hormonal effect.
In 2003, the UK government’s Committee on Toxicity identified three groups where evidence suggested there might be a potential risk from consuming large amounts of soya: babies fed on soya-based formula, people with an under-active thyroid and women diagnosed with breast cancer.
But the industrial nature of soya protein manufacture also raises concerns.
While some soya foods, such as tofu, miso, soya milk and yoghurt, are lightly processed, pure soya proteins — the sort you might find in a veggie sausage or vegan cheese — are commonly extracted by washing soya flour in acid in aluminium tanks.
This raises the possibility that aluminium, which is bad for the brain and nervous system, can leach into the product.
Another potential concern is the chemical solvent hexane — a component in glue and cement — is used to extract the oil from soya beans. It is known to poison the human nervous system.
Through repeated exposure, people can develop neurological problems similar to those experienced by solvent abusers.
The soya industry claims only trace residues of hexane find their way into the finished product.
Processing also frees up glutamic acid from the soya, a substance that can trigger allergic reactions.
Soya is one of the eight most common food allergens, according to the U.S. Food and Drug Administration.
A further issue with many soya products is not the soya itself, but what is added to it.
As soya protein is pale, odourless and almost taste-free, many manufacturers rely on sweeteners, artificial flavourings, salt and colourings to make their products more appealing.
Soya protein is almost taste-free, so many veggie products need a host of sweeteners, artificial flavourings, salt and colourings to make them appealing.
For instance, this is the ingredients list for Tesco’s meat-free burgers: water, textured soya protein (12 per cent), egg white, onion, vegetable oil, textured wheat protein (3.5 per cent), flavouring, onion puree, soya protein concentrate (2 per cent), dried egg white, stabiliser (methyl cellulose), pea protein, potato starch, yeast extract, garlic powder, onion powder, barley malt extract.
So the irony is that in trying to avoid meat, vegetarians may be buying products with as many additives and industrialised ingredients as are found in cheap, processed meats
But can soya really be so bad when Asian populations have been eating it for centuries, with no apparent problem?
It’s true that popular ingredients such as soy sauce and miso feature prominently in oriental cuisine.
But the soya in these products, when traditionally prepared, has been fermented, using time- honoured methods.
These involve soaking the beans, adding natural bacteria to encourage fermentation and a lengthy ageing process.
All this helps neutralise toxins in the beans.
So traditionally made, fermented soya foods are a different animal from modern soya proteins, which are produced using a fast-track chemical method.
Asian cultures also include soya in their diets in a different way from those in the West. Asian people don’t drink pints of soya milk each day as we do (think of all those soya lattes you hear people ordering in coffee shops).
Nor do they rely on soya as their main protein source.
In China, a vegetable dish containing a small amount of tofu would be just one element in a meal that featured meat or fish, and lots of veg.
We are far from fully understanding the impact of modern soya protein consumption.
As this ingredient has been in our diet for only three decades, there is no track record of safe use.
But while we await the answer, it may be wise to be cautious.
Posted by jonjayray at 12:13 AM