How nutrition misinformation may end up as fact
Nutrition research is continually emerging with very exciting new results.
However, it is important to treat new information with some care. You need to know where the research was done? Has it been repeated by other research workers? Was it carried out on people like yourself?
Be cautious in evaluating new nutrition information
It is important to recognise that many new nutritional studies are not performed in large groups of the general population. This would be far too expensive. Instead many studies are done on population sub-groups especially on people at high risk of common disease conditions such as heart disease.
Results in these people, while often useful and interesting, may be different from the results you would get on others in the population.
Other studies may not be done in humans at all but may be carried out in different kinds of animals such as mice or pigs. These animals have different digestive systems from humans and so results may again be somewhat different from those that would occur in a healthy human.
Many studies both in humans and animals are done using specific foods or extractions of nutrients. Yet humans eat mixed diets and not single foods. So how an extract behaves when it is eaten alone may differ from the effects when it is eaten as part of a mixed diet. In particular, the dose or amount that is eaten in one day may be very different from the dose or amount used in an experimental study.
We need to be very cautious applying and generalising results of new nutritional studies to larger population groups and especially to the general population.
Nutrition in the media
The media is usually very interested in reporting new and interesting nutrition and food news and often reports the findings of new studies.
Let’s examine a recent reporting about coconut oil. An article in an Australian newspaper reported that scientific researchers had found that coconut oil:
is easy to digest
helps prevent insulin resistance.
The newspaper article explained how coconut oil can be added to your diet by “adding one teaspoon of coconut oil to your usual intake each day, slowly increasing to four teaspoons to help with weight loss”.
What is the problem with this information?
Firstly, readers are not given much background information about this study. From the details provided it was not possible to trace the original paper where this study was described.
What other information is missing that would allow you to determine whether this is reliable advice?
A comparison with nutrition findings in a scientific article
The newspaper article also referred to a second study stating that coconut oil:
protects against insulin resistance
reduces the risk of Type 2 diabetes
contains MCFA (medium chain fatty acids) that can reduce the amount of fat we store and improve insulin sensitivity.
Why shouldn’t you follow newspaper reports?
While again the results are very interesting, there are many reasons why it might not be helpful for you to apply to your diet:
The study was carried out on highly inbred strains of mice and rats (C57BL6/J and Wistar strains, respectively) that may differ somewhat in their digestion and metabolism from humans. Also only male rats were used in the study so more evidence is needed on what happens in females.
The diets fed to these mice and rats were enriched with long and medium chain fats extracted from coconut oil (for the test group) or from lard (for the control group). These extracts were added to pellets of basic rat and mouse feed. So you can see that the experiment did not examine the effects of whole coconut oil and it did not examine the effect of coconut oil as a component of a human-type diet.
In addition the mice and rats were fed very high levels of the coconut oil or lard extracts. These extracts provided 45% to 60% of total energy which is at a much higher level than would be present in most normal human (or rodent!) diets.
The mice and rats were fed their experimental diets containing coconut oil for only 4 to 5 weeks. This does not tell us whether it would be beneficial or dangerous to continue this diet over an entire lifetime.
At the end of the experimental diets, the authors investigated the effects on specific serum and tissue markers in the rats and mice. They found that the experimental diet improved some markers relating to insulin use and that it also reduced body fat in the test animals.
However, the authors also give a warning that was not noted in the newspaper reports “Unfortunately the downside to eating medium chain fatty acids is that they can lead to fat build up in the liver, an important fact to be taken into consideration by anyone considering using them as a weight loss therapy.”
So you can see that a scientific study that was well carried out and reported in a well regarded scientific journal has not been very well explained in a subsequent newspaper article.
Find out more
If you’d like to find out more about research and current thinking in this area, consider reading Q&A: Taking Nutrition Headlines with a Grain of Salt and then exploring Enhancement of Muscle Mitochondrial Oxidative Capacity and Alterations in Insulin Action Are Lipid Species Dependent and Behind the Headlines - a guide to science that makes the news.
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