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. 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, β‐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). 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, 2014). Salt (a combination of sodium and chloride) is the major source of sodium in the diet. Classic sources of salt are processed foods, ready‐to‐eat meals, salt added during food preparation and cooking as well as table salt (Y.‐J. Wang et al., 2020) (Figure 1.3). The WHO recommends an overall sodium intake of less than 2 000 mg/day of sodium (<5 g of salt/day) (WHO, 2012), whereas the 2020–2025 US Dietary Guidelines for adults recommend limiting sodium intake to 2 300 mg/day (US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025). However, the average sodium intake across the US exceeds these recommendations at 3 393 mg/day (range 2000–5000mg/day) for those ages 1 and older (US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025). FIGURE 1.3 Source and average intake of sodium for US populations ages 1 and older. Source: (US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2020‐2025). A reduction in dietary sodium can reduce blood pressure in both hypertensive and normotensive individuals, regardless of sex and ethnic group, as well as the incidence of hypertension; it was also linked to a reduction in morbidity and mortality from CVDs (Grillo et al., 2019). More details will be discussed in Chapter 16. Over the last decade, numerous studies have investigated the role of saturated fats on several cardiovascular outcomes, but they fail to demonstrate rigorous evidence that supports continued recommendations to either limit saturated fatty acid (SFA) consumption or replace them with poly‐unsaturated fatty acids (PUFAs) like omega‐3 (Astrup et al., 2021). However, the 2020–2025 Dietary Guidelines for Americans continued the recommendation to limit SFAs to 10% or less of total energy intake, based on insufficient and inconsistent evidence (Dietary Guidelines Advisory Committee, 2020). Indeed, results from clinical trials data are inconclusive. Although researchers concluded that reducing dietary saturated fat for at least 2 years could reduce the risk of combined cardiovascular events by 21%, a systematic review of 15 randomized controlled trials (RCTs) with about 59 000 participants, found little or no effect of reducing saturated fat on all‐cause mortality or cardiovascular mortality, including non‐fatal myocardial infarction, stroke, and coronary heart disease (CHD) events. Little or no effect was also found for cancer diagnoses, DM diagnosis, HDL cholesterol, serum triglycerides, or blood pressure. There were small reductions in weight, serum total cholesterol, LDL cholesterol, and BMI (Hooper et al., 2020). Similarly, the epidemiological data from several meta‐analyses of prospective observational studies have shown no significant associations between SFA consumption and CHD or CVD (Heileson, 2020). Trans fatty acids (TFAs) are unsaturated fatty acids with one or more unconjugated double bonds in the trans configuration. They are present in foods from ruminant animals (i.e., cattle, sheep, goats, and camels), although most are generated during the manufacturing processing of partially hydrogenated vegetable and marine oils, such as margarines, confectionery fats, and fat spreads. The amount of TFAs in partially hydrogenated vegetable oils can be as high as 60%. Foods that commonly contain margarine, such as deep‐fried foods, baked goods, and snacks are therefore high in TFAs. Compared to animal fats, hydrogenated vegetable oils are more stable and less likely to become rancid during repeated deep‐frying processes. Thus, they are widely used commercially (Oteng & Kersten, 2019). Collectively, evidence strongly suggests that industrial TFA consumption is associated with increased risk of CHD‐related mortality and CVD. Therefore, several countries have passed laws that either restrict or completely ban food companies from incorporating TFAs into their food products. However, there is an ongoing debate as to whether industrially or naturally produced ruminant TFAs exert the same effects on cardiovascular health (Pipoyan et al., 2021). Α meta‐analysis of RCTs that explored naturally occurring or industrially produced TFAs and plasma LDL‐to‐HDL ratios revealed that, independent of their source, all TFAs could lead to an increase in the LDL‐to‐HDL ratio. However, a systematic review and meta‐analysis of prospective studies found that industrially produced, but not naturally occurring TFAs, are associated with an increased risk of CHD. Interestingly, new evidence supports that specific animal‐derived TFAs do not have detrimental health effects but may be beneficial for human health (Pipoyan et al., 2021). In a 2016 systematic review and meta‐analysis authorized by the WHO, replacing total or industrial TFAs with either cis‐MUFA or cis‐PUFA improved lipid and lipoprotein profiles, which further lead to a reduction of CVD risk. According to a 2020 review, mechanistically, in vivo and in vitro studies show that industrial TFAs might promote inflammation, endoplasmic reticulum (ER) stress, and fat storage in the liver instead of adipose tissue, compared with cis‐unsaturated fatty acids and SFAs (Oteng & Kersten, 2020). Therefore, in 2018, the WHO published an action package to reduce the TFA use in the global food supply called the ‘REPLACE action package’ (Figure 1.4). Based on a six‐step strategy, each country should implement actions to eliminate industrially produced TFAs. The low consumption of fruit and vegetables is associated with an increased risk of CVD, T2D, and cancer. The WHO recommends eating five portions of fruit and vegetables per day (equivalent to 400 g). According to a meta‐analysis of 27 prospective cohort studies as well as the results from the Nurses’ Health Study (1984–2014, 66 719 women) and the Health Professionals Follow‐up Study (1986–2014, 42 016 men), fruit and vegetable intake was inversely associated with with total mortality and cause‐specific mortality attributable to cancer, CVD, and respiratory disease. Interestingly, consuming about 5 servings/day of fruit and vegetables, or two fruit servings and three vegetable servings, was associated with the lowest mortality, without additional risk reduction at higher intakes (D. D. Wang et al., 2021). FIGURE 1.4 The ‘REPLACE’ action package developed by the WHO to reduce trans fatty acids from the global food supply. Source: [https://www.who.int/teams/nutrition‐and‐food‐safety/replace‐trans‐fat (accessed 3 May 2022)]. In 2017, the Healthy Grain Forum (Ross et al., 2017) in accordance with the International Carbohydrate Quality Consortium (ICQC) Scientific Consensus on Whole Grains, published a definition for whole‐grain foods. According to this definition, a food might be labeled as whole grain “if it contains at least 30% whole‐grain ingredients in the overall product and more whole grain than refined grain ingredients, both on a dry‐weight basis” (Ross et al., 2017). A low consumption of whole‐grain food products usually leads to a low fiber intake (especially insoluble fractions) as well as B vitamins, minerals, and phytochemicals with antioxidant properties, all of which are linked to many health benefits. Epidemiological data support that the high intake of whole grains is correlated with decreased mortality from CVD as well as the prevention and management of T2D (Tieri et al., 2020). Moreover, whole grains are considered an important factor for maintaining a healthy body weight and reducing the risk of obesity (Tieri et al., 2020). Despite the health benefits from high consumption, the intake of whole grains globally is lower than general recommendations, which increases the risk for mortality associated with chronic disease (Tieri et al., 2020). With regards to morbidity, low whole‐grain intake is associated with the highest number of DALYs (Murray et al., 2020). There are several recommendations for the daily consumption of whole grains; in the USA, it is recommended to consume at least 85 g/day (Arnold, Harding, & Conley, 2021), while in European countries, such as Denmark, it is 75 g or 10 megajoules (MJ, 2 388 kcal) per day (Frølich, Åman, & Tetens, 2013). The WHO defines added/free sugar as “monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook, or consumer, and sugars naturally present in honey, syrups, fruit juices, and fruit juice concentrates” (WHO, 2015). In many high‐income countries, sugar‐sweetened beverages and added/free sugars are consumed above the recommended daily limits (Table 1.1), while it is on the rise in low‐ and middle‐income countries. This is a major problem for public health, as there is a strong association between a high sugar diet and obesity, which was stated in 2015 reports from both the WHO (WHO, 2015) and the UK’s Scientific Advisory Committee on Nutrition (SACN) (Carbohydrates and Health Report, 2015). Added/free sugars, particularly those coming from sugar‐sweetened beverages (SSBs), increase overall energy intake while lowering the intake of nutritional foods, leading to an unhealthy diet, weight gain, and increased risk of NCDs (WHO, 2015). A major concern is also the positive association between free sugar intake and dental caries. Similarly, results from prospective cohort studies have linked SSBs to an increased risk of T2D (Moore & Fielding, 2016). Both obesity and T2D are important risk factors for cardio‐metabolic diseases, which supports the evidence that a very high sugar diet could also be associated with CVD mortality (Moore & Fielding, 2016). Table 1.1 Recently published recommendations on the consumption of dietary sugars. Source: (Moore and Fielding, 2016). The harmful association between SSBs and several health outcomes may reflect a general unhealthy lifestyle whereby individuals with greater SSB intake are more likely to have a poorer diet quality, higher caloric intake, and a sedentary lifestyle (Semnani‐Azad et al., 2020). The pathophysiology behind the high amounts of sugar consumption via SSBs and ultra‐processed foods is that the latter may lead to the production of high reactive oxygen‐carbons (ROCs), which further increases the possibility of atherosclerosis, hypertension, peripheral vascular disease, coronary artery disease, cardiomyopathy, heart failure, and cardiac arrhythmia (Haque et al., 2020). Based on the aforementioned evidence, most scientific organizations, in order to limit the rising trends of obesity and related metabolic diseases, suggest reducing total dietary intake of added/free sugars to 5% to 10% of total energy intake (Table 1.1). Nevertheless, the effect of specific dietary sugars, e.g., glucose, fructose and others, on metabolism and human health is less clear (Moore & Fielding, 2016
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
Organization (year)
Recommendations
2020–2025 Dietary Guidelines for Americans (US Department of Agriculture and US Department of Health and Human Services. Dietary Guidelines for Americans, 2020)
Consume less than 10% of calories per day from added sugars.
World Health Organization (2015) (WHO, 2015)
The intake of free sugars should be reduced to less than 10% of total energy intake in both adults and children.
UK Scientific Advisory Committee on Nutrition (SACN) (2015) (Carbohydrates and Health Report, 2015)
The average population intake of free sugars should not exceed 5% of the total dietary energy for age groups from 2 years onward.
2015–2020 Dietary Guidelines for Americans (2015) (US Department of Health and Human Services and US Department of Agriculture, 2015)
Consume less than 10% of calories per day from added sugars.
Australian National Health and Medical Research Council (2013) (Australian Guidelines, 2013)
Limit intake of foods and drinks containing added sugars such as confectionery; sugar‐sweetened soft drinks and cordials; fruit drinks; vitamin waters; energy and sport drinks.
European Food Safety Authority (2010) (EFSA Panel on Dietetic Products & Allergies, 2010)
The available evidence is insufficient to set an upper limit for the intake of (added) sugars based on their effects on body weight or a risk reduction of dental caries.
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