What are dietary patterns?

PROFESSOR ALEXANDRA JOHNSTONE: Dietary pattern analysis is a relatively new direction in nutritional epidemiology. Recently, dietary pattern analysis has emerged as an alternative and complementary approach to examining the relationship between diet and the risk of chronic diseases. Instead of looking at individual nutrients or foods, pattern analysis examines the effect of overall diet. Conceptually, dietary patterns represent a broader picture of food and nutrient consumption and may, thus, be more predictive of disease risk than individual foods or nutrients. Several studies have suggested that dietary patterns derived from cluster or factor analysis can predict disease risk or mortality.

In addition, there’s growing interest in using dietary quality indices to evaluate whether the adherence of a certain dietary pattern, for example, Mediterranean diet pattern, or indeed current dietary guidelines can lower the risk of developing disease. So the characterization of different dietary patterns has emerged largely as a reaction to concerns about the oversimplification of diet-disease relationships by concentrating only on single nutrients or foods. This is, perhaps too, because people do not consume nutrients or single foods– in reality they consume many combinations of foods in a variety of different quantities and proportions.

Some examples of well-studied dietary patterns where they have been associated with lower risk of cardiovascular disease– in the United States of America, we’ve got the DASH dietary approach, which is a dietary approach to stop hypertension or high blood pressure, which you can have a look at the link there. Or indeed, the Mediterranean diet– we’ve got the Mediterranean diet pyramid in terms of examples of different dietary patterns in order to reduce health risk. So we consider food choice as a part of a dietary behaviour. For example, physical activity is a form of behaviour and we consider our dietary choices and our eating habits are also a form of behaviour. A pattern of dietary behaviours is sometimes called a dietary pattern.

But the use of these terms has not been standardised in the field of nutrition. Beyond analysis of the total diet, researchers are interested in understanding how meals are consumed and how this can influence diet and health. This can involve, for example, analysis of diet data by time of consumption to assess impact on chrono-nutrition. Chrono, meaning time and nutrition, meaning food eaten, which infers that there is an impact on the circadian rhythm or of the circadian rhythm. To give an example, studies have shown a positive association between breakfast consumption and overall diet quality, cognitive ability, and an inverse association with BMI, meaning that people who skip breakfast perhaps might have a higher BMI than those who regularly consume breakfast.

Some other examples of dietary behaviours can include snacking in front of a TV, having meals with family members, eating outside, the speed of eating, drinking at a pub, binge drinking, and different cooking practises. This is an introductory lecture and this will be considered more in week two in terms of why do we eat, in terms of psychology of food choice, and the impact of energy and reward on food choice and eating behaviour. So in this second half of the lecture, I want to consider now what tool you should use to assess diet, nutrition, or indeed dietary patterns. There are some useful questions that you should ask yourself when you’re trying to answer this question.

Are you measuring food intake in an individual or a group? Are you making one single measurement or are you wanting to monitor change over time, over days, weeks, months? What is the measurement period, hours, days, months? There’s an excellent website, which I’ve given you the address there, hosted by the Medical Research Council and they call it their DAPA Toolkit, dietary assessment tools. On this website, there’s dietary information which is very detailed on the different assessment tools. What we’re going to cover is the food frequency questionnaire, the weighed dietary record, and the 24 hour recall. And I would encourage you to have a look at the website for more specific information on each of these tools.