CHAPTER 1
The Link between Sub-optimal Diet and Physical Inactivity with Non-communicable Diseases

• Introduction
• Sub-optimal Diet in Terms of Nutrients
  • Low Dietary Fiber Intake
  • High Dietary Sodium Intake
  • High Saturated Fatty Acid Intake
  • High Trans Fatty Acids Intake
• Sub-optimal Diet in Terms of Foods and Food Groups
  • Low Consumption of Fruits and Vegetables
  • Low Consumption of Whole-grain Products
  • High Intake of Added/Free Sugar and Sweetened Beverages
  • Foods and Food Groups Rich in Saturated Fatty Acids
  • High Processed-meat Consumption
• Sub-optimal Diet in Terms of Dietary Patterns
  • The Western Dietary Pattern
• Physical Inactivity
• Key Points
• Self-assessment Questions
• References
• Further Reading
  • Bibliography
  • Links

INTRODUCTION

Non-communicable diseases (NCDs), also known as chronic diseases, are medical conditions linked with genetic, physiological, behavioral, and environmental factors among others. NCDs are the leading cause of death worldwide, equivalent to 71% of all deaths globally (WHO, 2021). The NCDs with the highest numbers of deaths globally are cardiovascular diseases (CVDs) followed by cancers, respiratory diseases, and diabetes mellitus (DM). Other health problems included under the umbrella of NCDs are obesity, hypertension, gastrointestinal diseases, liver, and renal disorders. Although nothing can be done about non-modifiable risk factors such as age, gender, genetic factors, race, and ethnicity, most of these disorders could be prevented if behavioral and metabolic changes are achieved (Budreviciute et al., 2020). Key metabolic changes that increase the risk of NCDs include hypertension, overweight/obesity, hyperglycemia, and hyperlipidemia (WHO, 2021). The main modifiable behavioral risk factors involve unhealthy diets (i.e., specific nutrients, foods, and food groups as well as dietary patterns) physical inactivity, tobacco use, and alcohol abuse. In 2017, a sub-optimal diet was responsible for more deaths than any other risks globally, including tobacco smoking: 11 million deaths and 255 million disability-adjusted life-years (DALYs; 22% of all deaths and 15% of all DALYs in adults aged 25 years or older) (Figure 1.1) (Murray et al., 2020).

With regards to nutrients, high sodium intake (defined by WHO [World Health Organization] as >2 g/day, equivalent to 5 g salt/day) ranks first for mortality worldwide (Murray et al., 2020). High sodium intake contributes to high blood pressure and increases the overall risk for stroke and heart disease. Moreover, the low intake of whole grains and fruit along with high sodium intake constitute more than half of all diet-related deaths and two-thirds of diet-related DALYs (Forouhi & Unwin, 2019). Sub-optimal intake of fruits and vegetables increases the risk for ischemic heart disease, stroke, and gastrointestinal cancers. Also, a high consumption of processed meat is associated with increased all-cause mortality as well as several types of cancer, DM and CVD mortality.

FIGURE 1.1 (a) Number of deaths and DALYs and (b) age-standardized mortality rate and DALY rate (per 100?000 population) attributable to individual dietary risks at the global and SDI level in 2017. DALY = disability-adjusted life-year. SDI = Socio-demographic Index.

Source: Adapted from (Afshin et al., 2019).

Along with sub-optimal diet, according to a 2010 WHO report (WHO, 2010), insufficient physical activity was the fourth leading risk factor for mortality, leading to 3.2 million deaths and 32.1 million DALYs (about 2.1% of global DALYs) annually. In 2016, 27.5% of adults globally were insufficiently physically active.

In the following paragraphs, we will focus on the link between a sub-optimal diet and physical inactivity with NCDs.

SUB-OPTIMAL DIET IN TERMS OF NUTRIENTS

LOW DIETARY FIBER INTAKE

Based on a 2017 Global Burden of Disease (GBD) report, in the European Union (EU), the deaths and DALYs attributable to a diet low in fiber (defined as an average daily consumption of <23.5 g/day) account for approximately 97?000 deaths and more than 1?440?000 DALYs, mainly ischemic heart disease as well as colon and rectal cancer (European Commission. Health Promotion and Disease Prevention Knowledge Gateway; Stanaway et al., 2018).

Fiber, according to the US Food and Drug Administration (FDA), is the edible part(s) of plants that are resistant to digestion and absorption in the human small intestine. Good fiber sources are whole grains, vegetables, pulses, and some fruits. Based on their physicochemical characteristics, namely their solubility in water (i.e., they dissolve in water), their viscosity (i.e., the degree of resistance to flow), and their fermentation in the colon, they are categorized as soluble (fermentable)-like pectin, gum, mucilage, ß-glucan and polydextrose-and insoluble (non-fermentable)-like cellulose, resistance starches, chitosan, hemicellulose, and lignin-fibers (Figure 1.2) (Gill, Rossi, Bajka, & Whelan, 2021). Fiber, like carbohydrates, fats, and proteins, is a source of metabolic energy for the human body and provides, on average, 2 kcal/g (European Commission. Health Promotion and Disease Prevention Knowledge Gateway).

FIGURE 1.2 Spectrum of the physicochemical characteristics of dietary fiber. The physicochemical characteristics of fiber (solubility, viscosity, and fermentability) form a continuum and work in concert to determine its functional properties in the gastrointestinal tract. The combination of these three physicochemical characteristics determines the functional effects of fiber in the gut.

Source: (Gill et al., 2020).

Dietary fiber is considered a protective nutrient against the risk of NCDs, namely type 2 diabetes (T2D), CVDs, and colorectal cancer as well as a reduced risk of gaining weight. This is because high fiber intake improves gut microbiome diversity while increasing the production of short-chain fatty acids (SCFAs) and reduces the risk of obesity and other diseases such as DM and inflammation.

In an umbrella review of systematic reviews with 18 meta-analyses (that included 298 prospective observational studies), the highest versus the lowest quantile of dietary fiber intake was associated with a lower risk of CVD (i.e., coronary artery disease and CVD-related death). Evidence also associate the highest category of dietary fiber intake compared to the lowest with a lower risk of several cancers (e.g., pancreatic, gastric, esophageal adenocarcinoma, colon, endometrial, breast, and renal), stroke, and T2D (Veronese et al., 2018).

According to the Dietary Reference Intakes (DRIs) recommended by the United States Department of Agriculture (USDA), the adequate daily intake of fiber from all sources including fruits, vegetables, grains, legumes, and pulses is 14 g per 1,000 kcal, which is approximately 25 g/day for women and 38 g/day for men (European Commission. Health Promotion and Disease Prevention Knowledge Gateway).

HIGH DIETARY SODIUM INTAKE

Although the global age-standardized rates of deaths and DALYs attributable to high sodium intake decreased for both sexes between 1990 and 2019, the total absolute number of deaths and DALYs have increased due to population growth and aging (Chen, Du, Wu, Cao, & Sun, 2021). As most of the diseases associated with high sodium intake are age-related, the burden is expected to increase. Indeed, there is a long-standing association between high dietary sodium intake and hypertension as well as CVD (Rhee, 2015). This is related to water retention, systemic peripheral resistance increase, changes in the endothelial function, changes within the structure and function of large elastic arteries, altered activity of the sympathetic system, and altered autonomic neuronal modulation of the cardiovascular system (Grillo, Salvi, Coruzzi, Salvi, & Parati, 2019). High sodium intake is also associated with an increased risk of kidney disease and stomach cancer (Chen et al., 2021).

Numerous meta-analyses have indicated the positive association, either linear or U-shaped, between CVD risk and high sodium intake. In a 2020 meta-analysis of 36 cohort studies that included 616?905 participants, researchers identified a linear relationship between dietary sodium intake and CVD risk, with an increase in risk up to 6% for every 1 g increase in sodium intake per day (Y.-J. Wang, Yeh, Shih, Tu, & Chien, 2020). The U-shaped association was supported in another meta-analysis of cohort studies in which participants with both low (<115 mmol) and high (>215 mmol) sodium intakes had higher mortality compared to participants with a recommended dietary sodium intake (115-215 mmol) (Graudal, Jürgens, Baslund, & Alderman,...