Nutrition Hotline
By Reed Mangels, PhD, RD
QUESTION: I keep seeing articles referring to “evidence-based.” What does that mean?
CS, via email
ANSWER: One definition of evidence-based reads, “denoting an approach to medicine, education, and other disciplines that emphasizes the practical application of the findings of the best available current research.” 1 An example of evidence-based practice is when health care providers base their recommendations for treatment of a condition on high-quality research rather than on strictly anecdotal information or their own unsupported opinions. For example, a new medication is developed and tested to make sure that it is safe and that it effectively treats a disease?€?let's say the flu. A health care provider should not recommend use of this medication for an unrelated condition, such as kidney stones, based on a feeling that the medication might work.
Similarly, in nutrition, recommendations should be made based on the best available current research and not on opinion. For example, if I really, really like apples and feel more awake when I eat one, I can't say to someone who consults me for nutrition advice, “Eat an apple whenever you feel tired.” There is a sizable body of evidence that eating more fruits and vegetables will reduce a person's risk of several diseases, but I'm not aware of good evidence that eating an apple will make everyone feel less tired.
There are several kinds of studies that are commonly used in nutrition research. Some of the most common are prospective studies, retrospective studies, and randomized clinical trials. For example, to answer the question “What can I eat to keep from getting diabetes?” researchers could do a prospective study in which they collect information on the diets of groups of people for many years and see which people get diabetes, and which don't, and look for dietary differences between those with and without diabetes. Other scientists might conduct a retrospective study and interview people with and without diabetes about what they ate as children. Other researchers might randomly give some people with pre-diabetes vitamin X and other people, also with pre-diabetes, a placebo and see if vitamin X is associated with less risk of pre-diabetes progressing to diabetes. This type of study is called a randomized clinical trial. Results of all these types of studies are together used to develop evidence-based recommendations.
As you can imagine, different types of studies have different limitations, ranging from people's faulty memories to the role of non-diet-related factors to the feasibility of doing a long- term clinical trial. Evidence-based nutrition practice involves looking at the totality of the evidence and seeing what most studies say. There are ways to evaluate the quality of studies that are used when developing nutrition recommendations so that they are based on the best quality evidence available. All of this — gathering evidence, assessing the quality of evidence, continually updating information — is part of evidence-based practice.
REFERENCE: 1 Oxford Dictionary. lexico.com
