Textbook of Lifestyle Medicine - Labros S. Sidossis

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in a specific geographic area (e.g., Mediterranean diet, Asian diet); (ii) those that have been shown to be healthy through epidemiological studies (e.g., the Prudent Dietary Pattern); (iii) those developed to serve certain health goals (e.g., the Dietary Approaches to Stop Hypertension [DASH] and the Therapeutic Lifestyle Changes [TLC] diet); and (iv) those created to be consistent with certain moral principles (e.g., vegetarian diet).

       Key Point

      Humans consume complex combinations of foods in the context of their meals, rather than individual foods or food groups.

      A dietary pattern is categorized as “healthy” by either (i) an a priori‐defined healthy diet quality score/index based on the existing dietary guidelines; or (ii) a posteriori‐derived healthy dietary pattern based on variations in food intake, developed using principal component analysis (PCA).

      An example of a well‐known dietary quality score/index is the Healthy Eating Index (HEI), originally published in 1995 to evaluate the extent to which Americans are following the dietary recommendations. Since then, the HEI index has been revised several times. The index has a number of questions, each of which receives a specific score as a reflection of an important aspect of diet quality. Higher scores indicate higher consumption and better adherence to a healthy dietary pattern. The DASH score and several Mediterranean diet scores (MedDietScore) are also well‐established examples of such indexes, and they will be further discussed in later chapters of this book.

      The second approach to define a healthy dietary pattern is to use PCA. PCA is a statistical method that is used to identify potential patterns from weighted food frequency questionnaires (FFQs) or 24‐hour dietary recalls within a specific population. In other words, the method clusters variables that “behave in a similar way,” forming new components instead of analyzing these variables independently. For example, someone eats a lot of vegetables but at the same time eats a lot of fruits and whole grains. Every new component can thereafter be associated with several characteristics of a study's sample.

      Despite evidence of the efficacy of both approaches, major drawbacks exist. Scores are based on the current understanding of the relationship between diet and disease without taking into consideration possible unknown factors. Therefore, false‐positive associations might be generated. A classic example is the one of serum cholesterol and eggs. While there is not a true relationship between the consumption of eggs with CHD and stroke, positive associations persist as eggs are high in cholesterol and saturated fat. Furthermore, an a posteriori‐defined dietary pattern is derived from the population under consideration, but it is often not reproducible across populations.

      Scientific findings provide moderate‐to‐strong evidence that healthy dietary patterns are closely related to decreased prevalence of chronic diseases, such as CVDs, T2DM, and several types of cancer. Major dietary patterns that have been shown to have protective effects against diet‐related diseases are the healthy Nordic dietary pattern, the healthy Asian dietary pattern, the healthy vegetarian pattern, and the healthy Mediterranean‐style dietary pattern. These dietary patterns share some typical features – increased consumption of fruits and vegetables, whole‐grain cereals, legumes, and nuts, a modest alcohol intake, and moderate to low consumption of red and processed meats, refined grains, and sweets.

       Key Point

      People who adopt a healthy dietary pattern are also more likely to adopt other healthy lifestyle behaviors.

      This is why in 2015 the US Dietary Guidelines Advisory Committee proposed the following:

       A healthy dietary pattern is higher in vegetables, fruits, whole grains, low‐ or non‐fat dairy, seafood, legumes, and nuts; moderate in alcohol (among adults); lower in red and processed meats; and low in sugar‐sweetened foods and drinks and refined grains.

      Even though most dietary patterns share common features, they differ significantly in the types of basic ingredients they use and the cooking methods. Hence, there is no one healthy dietary pattern for all, but people can adopt the one they prefer that satisfies not only their taste but also their sociocultural identity in an attempt to achieve long‐term adherence to it and, eventually, better health.

      Take‐Home Messages

       It appears that examining the relationship between a single dietary factor and disease is not enough, since chronic diseases have multiple causes.

       The interplay between human metabolism and all of the compounds found in foods of plant or animal origin create an intricate nexus of interactions, rendering the isolation of a single effect difficult and possibly misleading.

       Food compounds interact into the food matrix in which they are found, developing additive or even antagonistic effects. This combined effect is defined as food synergy and food antagonism.

       Nutrition epidemiology examines the correlations between dietary patterns and human health and disease occurrence.

       Two approaches exist for defining a prudent/healthy pattern: (i) an a priori‐defined healthy diet quality score (or index) or (ii) an a posteriori‐derived healthy dietary pattern based on variations in food intake, developed using PCA.

       There is no one healthy dietary pattern for all, but people can adopt the one they prefer that satisfies not only their taste but also their sociocultural identity in an attempt to achieve long‐term adherence to it and, eventually, better health.

      Self‐Assessment Questions

      1 Modern nutritional epidemiology examines:the prevalence of nutritional deficiencies, e.g., ascorbic acid deficiency and scurvythe health effects of acute viral and bacterial infectionsthe impact of nutrition on chronic diseases, such as heart disease, cancer, and diabetesnone of the above

      2 Which of the following sentences is correct?Scurvy is caused by ascorbic acid deficiency.Oranges, but not lemons, are high sources of ascorbic acid.Scurvy is caused by lack of niacin (vitamin B3).Scurvy is caused by lack of thiamin (vitamin B1).

      3 Describe the types of beri‐beri disease.

      4 Which of the following sentences is correct?Diseases caused by specific nutrient deficiencies usually manifest soon after initiating the nutrient‐deficient diet.The degenerative chronic diseases are caused by specific nutrient deficiencies.The effects of a single nutrient deficiency are more important compared to the interaction of food components into the food matrix.“Food synergy” is a concept that can rarely explain how food and food groups affect health and disease.

      5 Define the terms food synergy and food antagonism.

      6 Why were eggs thought to be a risk factor for the development of CVD in the past?

      7 The health effects of foods depend on:the time of their consumption during the daythe biological properties that their nutrients maintain after digestiontheir energy contentthe combined effects of their nutrients, synergistic or antoagonistcall of the above

      8 What are the available methods to categorize a dietary pattern as healthy?

      9 Provide an example of a well‐known dietary quality score/index.

      10 What is principal component analysis (PCA)?

      11 Which of the following dietary

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