The term epigenetic mechanisms refers to the parameters involved in the modifications of gene regulation, including DNA methylation, histone modifications, and RNA‐based mechanisms. Nutrigenomics is the epigenomics sector focusing on the effects of food and food constituents on gene expression. For example, adoption of a Mediterranean diet pattern rich in olive oil for 3 years can reduce the detrimental effects of the risk variant of the IL‐6 gene, associated with weight gain, among middle‐aged and older persons with high CVD risk. Compared to the noncarriers and those heterozygous for the risk allele of the IL‐6 gene, the homozygous ones had higher adiposity indexes pre‐intervention, but after three years on the Mediterranean diet rich in olive oil, they appeared to have the most weight loss.
FIGURE 3.7 Epigenetic mechanisms.
Source: National Institutes of Health (2018).
Key Point
Nutrigenomics is the epigenomics sector focusing on the effects of food and food constituents on gene expression.
Moreover, variations in the gene‐expressing adipokine (hormone) adiponectin have been implicated in weight gain in a cohort of middle‐aged and elderly individuals at increased risk for CVD. Nevertheless, following a Mediterranean diet for three years proved to be advantageous in reversing weight gain among the carriers of the adiponectin gene SNPs, compared to noncarriers. Similarly, when the carriers of the fat‐mass obesity (FTO) polymorphism, which is responsible for increased body weight, followed a Mediterranean diet pattern for three years, they appeared to have the lowest increase in weight after intervention, compared to the noncarriers.
The phytochemicals present in fruits and vegetables, herbs, and spices have been shown to be protective not only against oxidative stress but also chronic low‐grade inflammatory responses, which constitute established risk factors of age‐related brain impairments. Moreover, phytochemicals hold the potential to attenuate the oxidative damage of macromolecules, such as DNA. They can also protect against the deranged expression of genes, which can progressively lead to debilitating effects on brain function and the advent of brain disorders associated with aging.
The Effect of Maternal Health and Lifestyle Habits During Gestation
It is now widely accepted that maternal health and lifestyle habits, as well as infants' early nutrition and exposure to environmental factors, are involved in the development of metabolic diseases later in life. For instance, the presence of gestational diabetes mellitus (GDM) is related to reductions in methylation of the mesoderm‐specific transcript (MEST) gene, a feature detected also among morbidly obese adults. When the fetus is exposed to GDM, the abnormal programming of the MEST gene increases the susceptibility of developing obesity later in life.
Another prenatal condition with future ramifications on the epigenome is that of famine exposure. Being exposed to famine prenatally can lead to alterations in the DNA methylation. Findings from a cohort study revealed that more young adults exposed to famine in gestation were underweight compared to young adults that were either exposed to famine postnatally or were never exposed. In contrast, more young adults exposed to famine postnatally were overweight compared to those gestationally exposed or unexposed. Underweight adults exposed to famine in gestation were hyperglycemic following a glucose tolerance test, and those exposed postnatally had elevated fasting glucose, compared to those unexposed.
Take‐Home Messages
An unhealthy diet has been associated with the development of a number of diseases, including CVD, cancer, diabetes, hypertension, liver and gallbladder diseases, and obesity.
Excess caloric intake can adversely affect insulin sensitivity as well as plasma glucose, insulin, and triglyceride levels, which are all linked to obesity. Overeating has also been associated with increased aging rate and the development of age‐related diseases.
The effects of SFAs on CVD depend on what replaces them in the diet. Replacing saturated fat with PUFAs lowers the risk of coronary heart disease; on the other hand, replacing saturated fat with refined carbohydrates has no benefit on the prevention of coronary heart disease and may even increase the corresponding risk.
Dairy products (e.g., yogurt and cheese) may have a neutral or even beneficial effect on CVD risk; in fact, it seems that CVD risk decreases from moderate dairy consumption.
TFA intake has been positively and robustly associated with increased risk of CHD and related mortality.
Dietary fiber has been associated with reduced all‐cause and cardiovascular‐related mortality, incidence of CHD, stroke incidence and mortality, T2DM, and colorectal cancer. The adequate daily intake of fiber is 14 g/1000 kcal, or 25 g/day for women and 38 g/day for men.
Overconsumption of calories and unhealthy dietary patterns, such as the Western dietary pattern, might be the main contributing factors for chronic diseases.
Western‐type diets are positively associated with chronic diseases by increasing ROS production, insulin secretion, and insulin resistance; promoting low‐grade inflammation and abnormal activation of the sympathetic nervous system and the renin‐angiotensin system; and leading to gut microbiota alterations.
Very‐high and very‐low carbohydrate diets have been associated with increased all‐cause mortality, with the lowest risk observed at 50–55% carbohydrate intake.
Physical inactivity can explain 6–10% of the main NCDs and 9% of premature mortality, while physical activity may increase quality of life and possibly life expectancy.
Obesity grades 2 and 3 (BMI > 35 kg/m2) may be a risk factor of NCD development, even in the absence of other major risk factors.
Tobacco use increases the incidence of a variety of chronic diseases, such as stroke, CHD, diabetes, respiratory problems, impaired immune function, and several types of cancer.
Excessive alcohol intake has been linked to the development of more than 200 major diseases.
Stress can trigger the inflammatory response in the circulatory system, mainly in the coronary arteries, which is thought to be one of the mechanisms mediating the development of CVD.
The term epigenetic mechanisms refers to the parameters involved in the modifications of gene regulation, including DNA methylation, histone modifications, and RNA‐based mechanisms.
Maternal health and lifestyle habits, as well as infants' early nutrition and exposure to environmental factors, are involved in the development of metabolic diseases later in life.
Self‐Assessment Questions
1 Which of the following sentences is correct?Excess caloric intake has favorable effects on insulin sensitivity.Overeating has been associated with increased aging rate.One week of hypercaloric feeding does not affect fasting plasma insulin.a and b
2 Fill in the blanks:The substitution of ________ for SFAs might reduce CHD risk.Replacing SFA _________ reduces CVD risk.Results from prospective studies show ________ in CVD risk from full‐fat dairy consumption.The highest degree of _________ is generated during the manufacturing process of hydrogenated vegetable and marine oils, such as margarines, confectionary fats, and fat spreads.Diets restricted in red meat may have ________ effect on cardiometabolic outcomes and cancer incidence and mortality._________ smoking can lead to important benefits in terms of longevity and mortality risk.Very‐high and very‐low carbohydrate diets have been associated with increased all‐cause