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Interviews with Vegetarian/Vegan Activists
February 2007

Interview on Research Related to Vegetarianism

Paul and Galina ApplebyPaul Appleby is a founder member of the IVU Science group and Secretary of Oxford Vegetarians:  Professionally, he serves as a Principal Statistician at the Cancer Epidemiology Unit of the University of Oxford . [right: Paul and Galina Appleby - about 10 years ago!]

IVU News: The news media is full of reports of research related to health. What are some common errors that the media make in interpreting this research?

Paul Appleby: The media sometimes fail to see the bigger picture, forgetting that a single study is rarely definitive.  They may also extrapolate results from a particular study and apply them to the population as a whole, rather than to the population from which the study subjects were drawn.  As good example of this was the misinterpretation of a study of undernourished Kenyan children in which the children whose diet was supplemented with meat performed better on one measure of mental development than the children whose diet was supplemented with either milk or vegetable oil.  In some sections of the media this study was presented as proof that “it's unethical for parents to bring up their children as strict vegans”, although the research was of no relevance to well fed children reared on a varied vegan diet.

IVU News: What are some common errors that the public make in attempting to apply this research to their own health?

Paul Appleby: Like the media they may fail to see the bigger picture, preferring to ‘cherry pick’ the findings that support their particular beliefs whilst ignoring those that do not.  They may also forget that we are all unique individuals, and that results that apply to a particular group of people may not apply to them.  It is often said, especially by representatives of the food industry, that there is no such thing as an unhealthy food, only unhealthy diets.  This may be true, but it ignores the fact that unhealthy diets contain too many foods of low nutritional quality.  For example, dark chocolate has some desirable nutritional properties that may confer some beneficial effects, but that does not make it a ‘health food’ and like everything else it should be eaten in moderation.

IVU News: Researchers themselves often disagree on how to conduct research and on how to interpret the results. How can this be? Aren’t they all trained in the same scientific tradition?

Paul Appleby: Yes, but remember that researchers are human too.  They all have prejudices that can cloud their judgment, and they naturally tend to value their own research above that of others.  This does not mean that what researchers say is wrong, rather that theirs is one voice among many, and that until a consensus is reached it is best not to place too great a reliance on the results from a particular study.

IVU News: Are there certain words to watch out for? For example, if someone writes, “This study ‘proves’ that ____”, should we be wary? Conversely, what words should be used instead?

Paul Appleby: Epidemiology [the study of the patterns and causes of disease in human populations] is not an exact science because it is based on probabilities.  Thus, epidemiological studies can, at best, provide “strong evidence” or “good evidence” for a particular hypothesis.

IVU News: In looking at the research on health, sometimes one might feel overwhelmed with how complicated it is to get all the nutrition the experts say we need. For example, recently I was reading something from Vegan Outreach about iodine. It said that even if you eat the right foods, it depends if the plants were grown in soil that was rich in iodine. The matter is further complicated because you could end up getting too much iodine.

Paul Appleby: It all too easy to give up in despair at what appear to be conflicting findings and to think that what you eat makes little or no difference to your health.  However, there is a broad consensus as to what constitutes a healthy diet*, and following such a diet should ensure that most nutrients are obtained in adequate but not excessive quantities.  The good news for vegetarians is that a healthy diet is one based of plant foods, although vegans in particular may need to supplement their diet with some vitamins and minerals that are difficult to obtain from plant foods. (* According to the WCRF/AICR (World Cancer Research Fund/American Institute for Cancer Research)  report “Food, Nutrition and the Prevention of Cancer: a global perspective”, individuals should “choose predominantly plant-based diets rich in a variety of vegetables and fruits, pulses (legumes) and minimally processed starchy staple foods”.)

IVU News: Einstein is quoted as having said that "Not everything that counts can be counted, and not everything that can be counted counts." Is it possible that there are some important health factors that are not easily measured which could be significant?

Paul Appleby: Absolutely.  An individual’s state of mind is undoubtedly an important factor in determining their state of health but it is very difficult to measure.  Epidemiologists must assume that non-measurable factors even themselves out in their studies – a reasonable assumption if their study is large enough and randomized where appropriate to avoid selection bias.

IVU News: In addition to research on health, other types of research are relevant to vegetarians, such as research on the intelligence, emotions and personalities of our fellow animals. What is your advice on understanding such research?

Paul Appleby: My advice would be to apply the same criteria as when judging the validity of health-related research.  For example, you should ask yourself whether the research is generally applicable and, if not, what are the constraints, whether the researchers had a potential conflict of interest that might have influenced their interpretation of the results, and whether their findings corroborate or contradict previous studies.  A dose of healthy skepticism never did anyone any harm!

Note: Qualified people are welcome to join the IVU Science group which Paul helped to found. Professional scientists, nutritionists, doctors, etc., plus editors of publications of IVU member societies are the intended participants. For more info, please visit