The Power of Nutrition (Part 1): How Food Determines Our Health
Health professionals around the world are facing a profound crisis: despite advancements in pharmacology and tremendous personal and financial efforts in health care systems, chronic, so called non-communicable diseases (NCDs) cannot be treated adequately (1). More than 50% of all Disability-Adjusted Life Years (DALYs), expressing the number of years lost due to ill-health, disability and early death (2) and almost 70% of the 55 million deaths per year globally (3) can be attributed to NCDs.
Cardiovascular diseases, diabetes, obesity and cancer are undiminished and on the rise: in the last three decades, deaths from cardiovascular diseases alone have risen over 40% (4), while deaths related to diabetes have increased by a staggering 93% (5).
In addition to the deteriorating effect that NCDs have on people’s lives, they are also a major economic concern. By the year 2040, it is estimated that global spending on health will increase from US $9 trillion to $24 trillion per year (6), with up to half of this spending due to NCDs (7).
A Longer Life in Good Health
While NCDs are on the rise worldwide, there are populations that are an exception to these frightening dynamics.
Populations in the so-called blue zones live healthier and longer than average, showing an exceptionally high number of healthy and active people above the age of 90.
The five blue zones are located in Sardinia (Italy), Okinawa (Japan), Loma Linda (California, USA), Nicoya Peninsula (Costa Rica), and Icaria (Greece). Despite their various geographical distribution, the blue zones’ populations share similar lifestyle habits (8). One of the most influential habits they share is what they eat.
The traditional diets are essentially whole food, plant-based, centered around lots of fruits, vegetables, legumes, whole grains, and potatoes or other starchy vegetables. Many spices and herbs are used as well, for example turmeric, ginger, and mugwort in Okinawa. Meat is consumed very sparingly, e.g. as a celebratory food or a small side dish once or twice a week. This pattern creates a diet generally low in caloric density, fat, and sodium with relatively few proteins and rich in micronutrients, phytochemicals, and complex carbohydrates.
But can nutrition really be the main reason for the exceptional health and longevity in the blue zones?
Your Food Builds and Fuels You
Every bodily function depends on the adequate intake of the right substrate, i.e. nutrients, and the metabolism, i.e. the correct processing of the substrate. Proteins, for example, serve as structural elements and constituents of enzymes, the engine of our metabolism. Carbohydrates are primarily used for processes that require energy, and fatty acids fulfill both functions and are, for example, also needed for cell communication. But it’s not only energy that comes from our food; it also supplies us with essential substances like vitamins and minerals that function as cofactors for our metabolism to work properly.
Taking all of this into consideration, one can easily imagine how the amount and the composition of our food that we consume can influence our development and our bodily functions in a powerful way. The excess or the lack of one or more specific kinds of substrates an individual needs might lead to symptoms of deficiency, to an accelerated decline (i.e. aging) or to one of the many non-communicable diseases.
Your Food Influences Your Genes
But food and its components are far more than a mere substrate for our hardware and energy supply. Studies show that diet also has an impact on our genes, even beyond generations.
This is called epigenetics – heritable changes in gene expression due to environment and lifestyle, which are not accompanied by alterations in DNA sequence itself. Various studies in humans, animals, and cell cultures have demonstrated that food nutrients regulate gene expression. The influence is quite enormous and even starts in the fetus. The nutrition of the mother determines not only the development of the fetus, but also its health outcomes in later life, such as obesity, insulin resistance, type 2 diabetes, and even food preferences (9). Methylation of the insulin-like growth factor 2 (IGF2) gene is a modulator of a newborn’s fetal growth and development, and it could be seen that poor diet during pregnancy leads to less methylation of the IGF2 gene (10). In contrast, a calorie dense maternal diet leads to obesity and epigenetically alters fetal chromatin structure in primates via covalent modifications of histones, which allow for heritable gene regulation without altering the nucleotide sequence (11). Similarly, maternal obesity during pregnancy increases the risk of obesity in the offspring of mice via altered methylation and gene expression of dopamine and opioid-related genes, and thus increases preferences for foods high in fat and sugar (12). Not only does macronutrient intake during pregnancy influence metabolic changes in the human’s adult life, but micronutrients do as well. A deficiency in vitamin B12 and folate concentrations during pregnancy were found to lead to insulin resistance in the offspring (13). Another clinical study could show that the underlying mechanism of periconceptional folic acid use is associated with epigenetic changes in the IGF2 gene in the child that may affect intrauterine programming of growth and development, influencing health and disease throughout life (14).
Your Food Choices Matter
While we do not have an influence on our mother’s diet, the good news is that we seem to be able to induce epigenetic changes ourselves. Various studies in humans, animals, and cell cultures have demonstrated that macronutrients, e.g. fatty acids, micronutrients such as vitamins, and secondary plant compounds (such as flavonoids, carotenoids, coumarins, and phytosterols) naturally occurring in foods, are directly involved in metabolic reactions and even regulate gene expression. Some of the biochemicals in foods, such as genistein found in soy or sulforaphane, an isothiocyanate produced by cruciferous vegetables such as broccoli, are ligands for transcription factors and thus directly alter gene expression and influence pathways within the cell cycle. They were found to regulate the expression and activity of important enzymes activating and silencing specific genes which are, for example, involved in aging and cancer formation (15, 16, 17).
It’s Not Only About Your Genes
Nutrition not only influences OUR genes, but it also has an impact on the occurrence and genes of the trillions of microbes inhabiting our body, especially our gut. These microbes influence our metabolism, our immune system, and our brain function, and also have an impact on our genes. Interestingly, the gut microbiota in patients with certain diseases, such as Alzheimer’s, depression, diabetes, rheumatoid arthritis and inflammatory bowel diseases, has been found to differ from healthy controls (18). It was found that we can influence the composition of our gut microbes through diet. A diet low in plant derived fiber and high in animal products leads to a reduction in microbes that produce short chain fatty acids (SFCA), and these changes have been suspected as one of the triggers for inflammatory diseases (19). In contrast, eating more fiber-rich plant foods increases those bacteria responsible for forming short-chain fatty acids from those fibers. SCFA in turn affect lipid, glucose, and cholesterol metabolism and serve as an energy substrate for the brain and the gut mucosa cells. This way they keep the gut wall healthy and build the link in the brain/gut axis as they can pass the blood-brain barrier. Also, it was shown that the SCFA butyrate can protect the brain and enhance plasticity in neurological disease models (20).
So feeding ourselves and our gut microbes the right foods has a great potential to beneficially influence our health.
Looking at these powerful effects of food on our metabolism, our genes and our microbiome,– can we translate them to a certain diet? Let us have a look at the epidemiological and clinical data existing so far.
A diet that has been the focus of research regarding overall health over the last decades is the Mediterranean diet, which is high in fruits, vegetables, whole grains, legumes and nuts, includes some olive oil, fish and very little meat. The data from prospective studies showed that adherence to the Mediterranean diet was associated with 23% reduced risk of developing type 2 diabetes (21), more than 50% lower cardiovascular risk (22), and almost 50% reduction in the risk of all-cause mortality (23) and a potential protective role with regard to the prevention of depressive disorders (24). Interestingly, within the Mediterranean population, a high fruit and vegetable intake was inversely associated with BP levels despite a high intake in fat (25).
Another dietary pattern that promotes the consumption of fruits, vegetables, legumes, whole grains and nuts, containing some low-fat dairy products, poultry and fish, while attempting to reduce the intakes of red meat, sweets, sugar-containing beverages, total fat, saturated fat and cholesterol, is the DASH diet. In a prospective study, evidence for the cardioprotective effects of the DASH diet was found: accordance to a DASH resulted in a 20% lower risk of stroke, a 13% lower risk of total incident CVD, and CVD-related mortality also showed strong inverse associations with DASH accordance in a UK context (26).
So obviously plant foods seem to play a big role when it comes to health and prevention. This was underpinned by further observations from large cohorts, such as within the Nurse Health Study and the EPIC Oxford Study or Adventist Health Study, which gave insights into different diet forms that people were following, as well as certain foods and their correlation with specific diseases.
It was found that lacto-ovo vegetarians and vegans had lower total and LDL cholesterol levels (27), lower blood pressure (28, 50), and a reduced mortality rate for cardiovascular disease when compared to people who ate meat (29, 30).
Vegans and vegetarians also had a significantly reduced risk (12-15%) of all-cause mortality (31), approximately 16%-19% lower cancer risk (32, 33), and a 60% reduction in the risk of type 2 diabetes mellitus (34, 35) than non-vegetarians.
When the researchers looked into specific foods, it could be seen that meat and cheese consumption were positively associated, and fiber intake was inversely proportional to the total cholesterol concentration in both men and women (36). Specifically, nuts and whole grains seem to reduce the risk of cardiovascular diseases, while refined carbohydrates and trans-fat increased the risk. Also, a higher intake in vegetables, especially green leafy vegetables, reduced the risk of coronary artery disease and cognitive impairment (37, 38).
Of the many study designs, the gold standard level of proofing treatments and therapies are Randomized Controlled Trials (RCTs). So let us have a look and see if diet can pass this test too.
In fact, recent clinical studies confirm the power of nutrition in the context of disease: In a RCT, adherence to a Mediterranean diet was associated with the methylation of the genes related to inflammation, which seems to be related to the diet’s favourable effects on cardiovascular risk, blood pressure, inflammation, and other complications related to excessive adiposity (39). Several clinical studies on the DASH diet showed that adherence also improved cardiovascular risk factors and appeared to have greater beneficial effects in subjects with an increased cardiometabolic risk (40).
But is it the reduction of meat or the increase in plant fiber that is responsible for the beneficial effects?
It might be both: In randomized controlled trials, substituting animal protein with plant protein decreased LDL cholesterol and apolipoprotein B (41). And the same was seen for fiber. While it plays an important role for our gut bacteria, it also influences blood lipids, and the polysaccharide β-glucan, found in barley and oats had a significant effect on LDL and total Cholesterol (42, 43).
Looking at other non-communicable diseases like obesity, diabetes, and rheumatoid arthritis, specifically plant-based diets showed a great therapeutic potential. A low-fat vegan diet improved β-cell function and insulin resistance within 16 weeks (44). Also, body weight could be significantly reduced in obese subjects through a plant-based diet intervention (45), even when there was no caloric restriction (46). Patients with rheumatoid arthritis, who fasted initially for 7-10 days and were then put first on a vegan and then a vegetarian diet, improved their symptoms significantly in comparison to a control group (47).
Considering that only a few lifestyle risk factors account for up to 80% (48) of premature death, each of us has the power to take care of our health. More specifically: Nutrition has the potential to prevent and reverse many of the most pressing health issues of our time as the major risk factor for life quality and life years lost is poor diet (49).
Food’s different mechanisms of impact on our metabolism, our genes, and our microbiome, as well as epidemiological and clinical evidence, are pointing heavily in the same direction. The more whole plant foods a diet includes, the better people’s health, and the lower the chances for chronic disease.
By using this power of nutrition as health professionals in prevention and therapy, we increase the likelihood of truly restoring health and stopping our crisis of chronic diseases.
Together we can empower our patients, save and improve their lives and those of their families. We can reduce health care costs significantly to redirect financial resources towards medical fields, where those resources are needed badly. Last but not least, we can reduce the tremendous pressure that we know health professionals have and create a more satisfying environment for both patients and ourselves.
This is the introductory article of our series “The Power of Nutrition”. Please find all related articles here:
Part #1: The Power of Nutrition
Part #2: The Global Burden of Non-Communicable Diseases
Part #3: The Blue Zones
Part #4: Epigenetics
Part #5: The Human Microbiome
Part #6: How Does Nutrition Work?
Part #7: The Clarity of Evidence
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