As studies of eating behavior, why you do not need to rush to change their habits after each news on the popular science website and what are reliable methods to become more healthy.
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The past summer has dealt two blows at once one of the most beloved (after the overthrow of vitamin C) panaceas – omega-3 fatty acids. First major UK study of the use of appropriate supplements – fish oil capsules 1 g per day – not shown to reduce the frequency of cardiovascular diseases and mortality in the group of 15 480 people with diabetes.
For patients over the age of forty years were followed on average 7.4 years. In order to eliminate a placebo effect, as required by the standard to conduct such studies, part of the group received dummy – olive oil, – without knowing it. So everything is fair and controlled.
And then struck a second, much stronger impact. Cochrane international organization dealing with the study of efficiency of medical technologies, has published a major analysis of 79 studies investigating the effect of fish oil on the risk of cardiovascular disease, and again found no positive effects. 79 works on 112 059 subjects – sounds like a checkmate. But how is it that scientists – a sort of collective scientific mind – so praised omega-3 fatty acids, and now you changed your mind?
“They eat a lot of fish, perhaps the reason health in this”
The founder of a group of compounds referred to, is alpha-linolenic acid (ALA). The most important representatives of this group of long-chain omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Linseed oil, wheat germ, walnuts (and other foods containing ALA) will not be a substitute fish that is rich in ready-made EPA and DHA. Initially, they are synthesized by microalgae that feeds on zooplankton. It, in turn, eats the fish, where omega-3 and accumulated.
The human body these compounds does not produce. The interest of scientists to them, as well as to the entire spectrum of human nutrition, due to one purpose – to make people more healthy and long-lived.
How to understand what is useful and what is not? It all starts with the so-called common knowledge of life. Something like: “In Japan, people live longer, there is less heart disease, how can we become like them? What we now differ? Ah! They eat a lot of fish, perhaps the reason in this.”
This consumer hypothesis needs scientific confirmation. First and simplest, but also most inaccurate method of surveillance. In 1970 Danish scientists Hans OLF Bang and Jon, Danberg took blood tests among residents of remote Greenlandic villages, the diet of the inhabitants of which were based on whale meat and fish. Analysis of 130 blood samples showed that their blood less cholesterol, which was associated with the occurrence of cardiovascular diseases.
At that time it was attracted to a scientific discovery, scientists suggested that the beneficial impact of omega-3 fatty acids. In 1989 he published a work is not observational, but experimental in nature. 2000 men from Wales who had already had heart problems, started to stick to a diet with a high content of oily fish. It turned out that in the following two years the mortality rate in this group fell by almost a third. About thus was born the legend of the fish oil.
Why is fish people prefer fish oil capsules and other supplements? I would venture to suggest that here the case involved social, not medical reasons. The turbulent twentieth century brought us to a technocratic view of the world and the same rhetoric – the taming of the fire, the subordination of nature, the conquest of space. Mankind rushed to build a new world to replace the old, and in the Soviet project it was expressed especially clearly – he built exactly what a new type of man.
It seemed that all you can take and fix, so biohacking and other lessons “how to sleep two hours a day and sleep” – heirs of the same cultural gene correction of nature.
Interested in it and actively stirs it and the market – in 2015 dietary supplements with fish oil were sold for $31 million 20-25 million tonnes of fish annually goes into the production of these supplements, but would be better if people ate them in the form of fish.
Photo: Jo Christian Oterhals / Flickr
We are not laboratory mice to exclude any effects is impossible
Since the experiment to build the new man failed, and the people we are the most common, as tens of thousands of years ago, on our health throughout life influences so many factors. That is why it is so difficult to study the impact of only one of them: we are not laboratory mice, and to exclude all outside influence impossible. In addition to food, human health is affected by physical activity, environmental factors, stress, and sleep quality.
For example, for 2,000 men from Wales joining the experiment could become a trigger for awareness of their health problems. So if, as a result some of them quit Smoking, this effect is blocked the possible benefits of the fish. But control is very difficult.
The food itself is, in turn, is a very complex system. It contains hundreds and thousands of different chemicals. And our digestive system in the process of evolution has adapted to the necessary substances from this complex combination of substances digested in the presence of each other is not the way I would do it alone.
This is the catch with all vitamins and supplements: if our body is able to absorb from food, in combination with other compounds of a certain vitamin or mineral, it doesn’t mean that it can replace a tablet.
Its metabolism may be quite different. In addition, the role of many substances is complex, and it is difficult to pinpoint one specific influence.
It turns out that we know more about the trace minerals that we consume in very small quantities – and about the dangers, not the benefits. Iodine deficiency is harming its main consumer – the thyroid gland. The lack of calcium – bones and teeth, and its excess – joints. The decrease in the level of potassium in the blood disturbs the heart beat and so on. But the macronutrients fats, proteins and carbohydrates in our body too many “cases,” so to single out the effect will not work.
Therefore, to identify healthy and unhealthy food habits scientists have to use statistics. They can use data to study large amounts of information about the health and habits of any population and try to infer the causes of a particular state. For example, the “50-60-year-old man who claims that addiction to alcohol, complain of the heart.”
But that’s not evidence-based medicine, we cannot talk about causality. Bit more accurate the data will be released, if you find a control group – non-drinking men of the same age and from the same population. More precisely – cohort studies, in which for a large group of people – tens of thousands – directionally observe over a long period of time – decades. In the regular questionnaires they fix their habits associated with them data of medical examinations.
But here still not talking about the experiment: it is conducted in randomized, controlled studies, when homogeneous groups of people are gaining experimental and control group. The experimental group receives the test substance, a test dummy (placebo). To this type of research is concerned with the work that was described in the beginning.
To obtain more accurate data of identical experiments of this kind are placed simultaneously in several scientific centers – this allows to mitigate the environmental factor and human factor. Finally, the highest degree of evidence have meta-analyzes – work, which carefully collect, study and analyze data of all tests of a specific substance, published in the scientific literature. A Cochrane analysis, which we also discussed above, refers to this type of research and has such authority and weight.
Lying scientists, quoted by the media
Likely not lying to anybody. “Lying” here implies deliberate falsification of data or conflict of interest – a deliberate desire to come to a particular conclusion. The proportion of such unscrupulous contractors seem small, and the forgery is usually possible to uncover.
Although this scenario is not innocuous: the legend about the development of autism due to vaccinations against measles, rubella and mumps live, but the author caught on fraud and conflicts of interest, and now he is forbidden to engage in medical practice.
Conflicting information about nutrition can get perfectly good scientists due to the fact that they used enough the exact method failed to take into account environmental factors or wishful thinking is a random deviation for the systematic observation. So there are conflicting statements about the benefits or of the Carcinogenicity of coffee.
Photo: Unsplash
This does not mean that such work should not do, but to accept them as a guide to action is not worth it. Moreover, many works published in scientific journals, are generally not designed for transfer to the press. They are not secrets, but they are not and news: a scientist made an observation and publish it to share it with your colleagues, discuss it, invite them to the discussion.
It is this – rather than later the news media – is the original purpose of the Institute scientific publications. But the articles on nutrition too attractive to not too conscientious journalists to pass up. It has gone so far that experienced journalists have already warned about this problem colleagues. “Don’t take on faith: why journalists should avoid lighting the greater part of research on nutrition” is the title of the latest article by the medical journalist Kelly Crowe, addressed to colleagues. A guide to action can be considered only a small number of rarely published major and time-tested statements made serious large specialized medical centers.
Not the diet and correction of lifestyle forever
Proven advice and simple yet complex.
Should be eaten in moderation and try to provide a varied diet – eating fruits and vegetables, fish and meat, do not abuse the latter. Not to overeat and to move more.
One of the few attempts to present the principles of evidence-based science of nutrition in the Russian language – book doctor Elena Motova “My best friend’s stomach. Food for smart people”.
The simplicity of the stated principles are deterred by a variety of individual diets gurus and coaches on nutrition – there is no place for “copyright approach.” But even more discouraged by the complexity of their implementation: it is not about the two-week course, and on the correction of lifestyle is slow, but forever.
The same recommendation provides one of the authors of the Cochrane analysis, Lee Hooper.”All I can say is: human nutrition is a very complex system, and the effect of its individual components is too small on the background factors in the development of chronic diseases. We would be happy to confirm the positive expectations from omega-3 fatty acids – it would be a simple way to combat cardiovascular disease! But they do not work. To protect your heart, you need to contact the lifestyle changes that give real results: quality food, moderate alcohol consumption, quitting Smoking and physical activity. I advise patients to spend the money that you can save money on supplements, that’s it.”