You go out for breakfast with friends and order the poached eggs and a skinny latte, thinking you are starting your day off with a balanced meal. But then, as you’re reading the morning paper, you come across the headlines: ‘Egg consumption linked to breast cancer’ and ‘Skinny milk is making you fat’. Confusing, right?
It seems that every second day a new article in the mainstream media outlines the danger or miracle of another food. In the past, red wine, coffee, red meat, eggs and milk have all been in the spotlight, and it’s hard to predict what will be next. Consumers are constantly bombarded with contradictory information about healthy eating. It’s exhausting, misleading and can result in many people distrusting or ignoring nutrition advice altogether.
So, why does it feel like nutrition advice is constantly changing and seemingly healthy foods can get a bad wrap?
Nutrition research is pretty new and we are still making discoveries
Compared to other scientific fields, such as biology or physics, nutrition science is a relatively young discipline. Major discoveries about vitamins and minerals weren’t made until the late 19th and early 20th Centuries, and researchers have only been studying, for example, trans fats and artificial sweeteners, for the last few decades. Therefore, nutrition science is rapidly evolving and we are still learning, evaluating and reevaluating how certain foods affect our short and long-term health.
Media headlines can sensationalise or incorrectly interpret studies
It’s great that people want to know about healthy eating and nutrition science, but unfortunately, in a competitive media environment, the nutrition-related stories likely to be most read are those that are different, exciting or controversial. This often leads to articles publicising the results of the latest nutrition studies with click-bait headlines and angles that can at best lead to confusion among consumers and at worst misreport a study’s outcomes. In many cases, media stories rarely investigate or explain any limitations of the research or the complexity of the findings of studies they report on, or discuss or compare previous research findings on the same or similar topic. To get the most readers, stories can hype up small or preliminary studies and state findings as fact, ignoring potentially years of solid scientific but contradictory evidence. This is exemplified in the many articles, for instance, ‘debunking’ the supposed ‘myths’ around alcohol consumption (particularly red wine) and explaining how new studies show that it can be beneficial for health.
It’s really hard to design good nutrition studies, and some are better than others
Nutrition studies are actually very hard to conduct. It’s extremely difficult and often impossible to change only one element of a person’s diet in order to study it in the short term, let alone the long term. Many other factors besides a particular food of interest can influence health outcomes such as other foods and nutrients, genetics, weight, metabolism, disease and environmental factors. So it is important to keep in mind whether a study shows a causal or correlational relationship.
Correlation means there is an association (weak or strong) between a factor and an outcome. For example, a study of school children may correlate students with more fruit in their lunch box taking less sick days. However, if the study doesn’t control for other factors that may influence the number of sick days a child takes, it can’t be concluded that more fruit causes children to take less sick days.
Causation can only be concluded through a randomised controlled trial where all factors in an environment are controlled so that a cause-and-effect relationship can be studied between two variables, such as a nutrient and a health outcome. For example, fruit in lunch boxes and sick days. The randomised element of a controlled trial is also important. By randomly allocating participants to the group exposed to a variable (e.g. fruit in lunch boxes) or not exposed (e.g. no fruit in lunch boxes), the impact of participant and researcher bias can be reduced, improving the quality of the results.
Further, many food and nutrition studies are based on self-reported food intakes. This can be problematic, as it relies on participants’ memory and willingness to accurately record their eating habits and can lead to under or over-reporting of food intake.
The quality of nutrition studies is an important concept to understand. Many media publications may report on research that can only conclude a correlational relationship between two variables but use a headline such as ‘No fruit in school lunch boxes is causing kids to be sick’.
What nutrition advice should you follow then?
Consumers confused about what to believe and follow among all the reported nutrition advice should look to advice that is echoed by government and other reputable organisations such as the World Health Organisation, Australia’s National Health and Medical Research Council, Nutrition Australia, Diabetes Australia, the Heart Foundation and the Cancer Council. The advice these organisations promote is generally based on reputable, scientific studies and guidelines, including the Australian Dietary Guidelines. And when reading the latest article on the benefits/risks of a certain food, it’s important to become a critical thinker – look into the research method and likely implications and conclusions that can be drawn from the original study the author bases their claims on, as well as the qualifications and credibility of the author and publication.
Although the field of nutrition is constantly developing and we are still making discoveries, the Australian Dietary Guidelines are still the most recognised source for what we should be eating for good health. In short, consumers can do well to make a large proportion of their diet plant-based foods, such as vegetables, fruits, legumes, nuts and seeds, combined with whole grains, and protein from animal products such as lean red and white meat, seafood and low-fat dairy foods. It’s also important to limit consumption of salt, alcohol, and high-fat and sugar snacks. But enjoy these from time to time if you wish (because they are delicious!). Overall, consumers can benefit from following the Dietary Guidelines and ignoring the ever-changing and click-bait headlines telling them otherwise.