Who I am
I am a medical doctor with a clinical doctorate in nutrition and a doctorate in science obtained for my research into the diagnosis and treatment of nutritional disorders. I also have 35 years of practical experience treating malnutrition and changing UN policy on nutrition as well as that of many governments. My life’s work has been dedicated to helping people improve their nutritional status, albeit generally treating and preventing severe starvation. During that time, I have experienced first-hand the power of nutrition to either heal or conversely, to cause disease and have been involved in bringing hundreds of thousands of people back to good health from the brink of death – all through good nutrition. With such an experience of what nutrition can do, I find it painful that so many people needlessly suffer from ill health and die prematurely because of what and how they eat, when small easy to implement changes can easily avoid so much of this suffering.
In these posts I will draw on my experiences at the forefront of nutritional research to try to shed light on some key aspects on modern nutritional thinking and to explain the particular research and science underlying the products that we are developing at Aronia Ireland.
At the start, I am going to introduce the concept of metabolic health with its many different aspects as this is central to an understanding of how nutrition affects health. I’ll then describe some basics of the key dietary elements such as carbohydrates, fats and fibre before going on to describe the importance of the microbiota. I’ll follow that with a brief discussion of what happens after eating and during fasts plus the physiology of weight loss. Lastly, I’ll give an overview of the importance of phytonutrients and polyphenols in particular, describing some of the ways they impact the processes described.
Although I draw heavily on published peer revied papers and will in the future provide the references I have used at the start, the discussion will of necessity, hugely simplify the complex process involved in nutrition and metabolism. So please take these posts as a primer rather than any sort of definitive account of what is an extremely complicated subject. I don’t plan to list which foods are rich in the different nutrients – this information is available elsewhere and easy to find. Rather I aim to increase understanding of why certain foods are healthy and others not. By explaining some of the basics, together with the reasons behind recent changes in nutritional thinking, I hope that I can help people understand better the basis of modern nutritional advice. In so doing, maybe I can restore some confidence in the ability of nutritional science to offer dietary advice that can improve health and vitality over the longer term
My core aim is to highlight simple changes in nutrition and lifestyle that are easily “doable” without demanding changes or major hardship – but that can cause dramatic improvements in health and vitality. After years of being sold a difficult ineffective calorie restriction/dieting model of healthy nutrition, you might be surprised just how easy and effective small changes based on modern nutritional thinking can be!
In due course, I will post further articles and updates that expand on the individual elements of these initial posts – and provide the academic references that I have drawn on for those who want to look in more depth. If you ever have any questions, arising from what I have written here, please do not hesitate to get in touch.
The importance of nutrition in human health
The critical importance of nutrition in human health has been known for millennia with Hippocrates, the father of medicine, stating in 400BC: “Let thy food be thy medicine and thy medicine be thy food.” Sadly, despite this encouraging start, with the early dramatic successes of pharmaceutically-based, curative health care, the focus on nutrition in the prevention of disease waned and the 20th century saw an increasingly dominant curative focused bio-medical model. This led to the role of nutrition and serious scientific research into nutrition becoming marginalised. Although this is still very much the case, modern nutritional research has driven a rapidly increasing understanding of the mechanisms by which nutrition impacts on physiology and has resulted in major breakthroughs in our understanding of what constitutes a healthy diet.
There is however, a long way to go as human metabolism (the sum of the chemical reactions taking place in the body), is immensely complicated with thousands of enzymes and co-enzymes catalysing thousands upon thousands of different chemical reactions. Each reaction requires the right nutrients in the right quantities and in the right form – and to date our understanding of all these is very far from complete. Over the last 20 years the picture has become even more complicated with the discovery of the microbiota, the trillions of bacteria in the human digestive system that play a critical role in all aspects of nutrition and human health.
The nature of progress in science and nutrition
As in any walk of life, increasing understanding comes with realisations that accepted truths are incorrect or inadequate. In the same way that in physics Newtonian mechanics has given way to quantum theory and the theory of relativity, in nutrition new discoveries about how metabolism works, the effect of different nutrients on metabolism and the microbiota are leading to radical changes in the way that a “healthy diet” is understood.
Major changes in nutritional thinking that alter the dietary advice that we give, affect people far more immediately than do changes in nuclear physics; one moment you are advised to eat one thing, the next something else. The downside of this progress and changing advice is that it leads to an erosion of confidence. I often hear people asking why they should trust nutritionists when their latest advice appears to directly contradict previous guidance. For example, until recently, the advice to improve cardio-vascular health and lose weight was to reduce or even avoid fat and decrease calories. Data now indicates that this approach has not been effective and only 1 in 5 people lose weight over the long term on a calorie restricted diet. Furthermore, the rates of obesity, cardiovascular disease and diabetes, three serious consequences of poor diet and lifestyle, are massively increasing.
The massive problem on nutritional disorders
In the US the prevalence of obesity has increased from 30.5% of adults in 2000 to 42.4% 2018. One in three American adults also now suffer from obesity combined with diabetes, high blood pressure and disordered blood fat profiles – so called metabolic syndrome (see later). This is a disaster both for the individuals whose quality of life and longevity of active life are curtailed – and at the national level where caring for such huge numbers of people with chronic debilitating illness is increasingly unaffordable. Even back in 2008 the US was spending an additional $147 billion per year on obesity and as numbers escalate and the price of new therapeutic regimes increase, these costs are rising dramatically. This failure to address such a serious problem combined with clinical research into the role of nutrition in its pathogenesis, is now forcing profound changes in the understanding of what constitutes a good diet.
The credibility of Nutritional advice
As a result of recent research and improved understanding, the advice as to what constitutes a healthy diet is changing. Modern thinking emphasises much lower intakes of refined sugars or carbohydrates with a high glycaemic index and load (see later); places less emphasis on the amount of fat in the diet; further increases the focus on the importance of adequate amounts of vegetables and fruit, especially berries and lastly, advocates short fasts, 12 or more hour periods without eating, several times a week. Sadly, the loss of confidence in nutritionists and nutritional advice, means that these new recommendations are often falling on deaf ears.
The need for change
Ultimately the necessity to address the vast, global problems of obesity, diabetes and metabolic syndrome plus the trillions of dollars/euros it is costing the world; combined with the huge amounts of avoidable suffering it is causing, means that there will have to be a change of emphasis towards prevention. This must come predominantly, from improved diet and lifestyle changes. However, as I have already stated, efforts so far have been ineffective, and a change of approach plus innovation are required. We have established Aronia Ireland to develop and offer innovative and appealing products based on latest research and evidence, thereby contributing to the changes that are needed.
METABOLIC HEALTH AND WHY IT MATTERS
Metabolism is the foundation of health and so is a good place to start these discussions. Your metabolism is the trillions of chemical reactions that take place in all the cells of your body and that serve three critical purposes to keep you alive and healthy.
- Firstly, there are the reactions that break down your food and drink to provide energy to run all the processes that are going on in the cells in your body.
- Secondly, there are the reactions that serve to convert the food and drink you consume into the building blocks that your body needs to maintain itself, grow and fight diseases.
- Thirdly, there are the reactions and processes that serve to eliminate the non-useful or toxic by-products of all the above chemical reactions.
To be healthy, all these processes must work efficiently and in harmony and this requires a supply of a wide range of nutrients in the right amounts and right chemical forms. Noticeable signs and symptoms such as excess body fat, particularly central fat around the abdomen, fatigue and a lack of vitality, indicate a struggling metabolism, that if not addressed, often gravitates towards more serious problems in the form of metabolic syndrome. This can include high blood pressure, high blood sugar and/or raised blood levels of triglycerides and bad cholesterol and is associated with multiple chronic conditions such as diabetes, cardiac disease, strokes, eye disease, cancer and dementia, to mention but a few.
Traditionally nutrients are divided into macro-nutrients such as protein, carbohydrates and fats that are required in large quantities and micro-nutrients such as vitamins, minerals and choline that are required in smaller quantities. However, a large and ever-increasing body of research is now indicating that this is an oversimplification and polyphenols, so called phytonutrients that are obtained from plants, don’t fall neatly into these categories but do have a vital role to pay in promoting metabolic health. Critically, these compounds cannot be synthesised in the body but must be consumed in the diet.
Sugars and monosaccharides
Carbohydrates come in many different forms. The simplest are the monosaccharides often called simple sugars and there are three that commonly occur in the diet; glucose, fructose, and galactose. These are the 6 carbon molecules that form the basic building blocks of all other carbohydrates. They are also, particularly glucose, the main fuel burned by the body to provide energy for metabolism.
Monosaccharides are linked together to form ever more complex carbohydrates. The of these polymers are the disaccharides that consist of two monosaccharide molecules bound together. Sucrose (or common table sugar) that consists of one glucose molecule linked to one fructose molecule, is the best-known disaccharide but lactose found in milk and consisting of one glucose molecule linked to one galactose molecule, is also very commonly consumed in dairy products. Next in complexity are the oligosaccharides that are chains of 2 to 10 monosaccharides that are found in a wide variety of food, particularly fruit, grains, vegetables, and pulses (beans/lentils) as well as in human breast milk. Many of these oligosaccharides cannot be broken down into their constituent monosaccharides by the digestive enzymes in our gut. They therefore cannot be absorbed into blood stream in the small intestine and travel on to the large intestine where they provide an important food source for the microbiome and constitute an important element of soluble fibre or prebiotics.
Finally, there are the polysaccharides, long chains of monosaccharides bound together in different ways to form substances such as starch and cellulose. Starch, the most common carbohydrate eaten by people, consists of many thousands of glucose molecules all joined together. It is generally broken down into glucose in the gut during digestion and is absorbed in the small intestine. Importantly, different types of starch are digested at different speeds and to differing degrees. These are grouped into three; the rapidly digested starch; slowly digested starch; and resistant starch that is broken down minimally in the small intestine and instead travels through to the large intestine where it is either used as a food by the bacteria of the microbiota or else, is ejected from the body in the faeces. By contrast none of the cellulose that is eaten is broken down and all of it passes into the large intestine where it is either used a food by the bacteria of the microbiome or ejected from the body in the faeces. This together with the resistant starch, this forms the bulk of the insoluble fibre or roughage, an essential element in a healthy diet.
The Glycaemic index and glycaemic load
The amount and form of the carbohydrates in the diet is a critical determinant of health. Sadly, the modern western diet usually provides very large quantities of simple monosaccharides contained in fizzy drinks, sweets, biscuits, cakes and even most fruit juices also rapidly digested starches such as white bread, peeled potatoes, white rice flesh and maize. Eating these forms of carbohydrate causes rapid rises in blood glucose levels and the foods are said to have a high glycaemic index and high levels of blood glucose after eating called a high glycaemic load. Increases in blood glucose trigger rises in the secretion of insulin – one of the hormones in control of food storage. A major action of Insulin is to enable glucose to be taken up into cells, particularly muscle cells and liver cells, a process that reduces the levels of glucose in the blood. However, because there is some latency in the feedback loop between blood glucose levels and insulin secretion, if blood glucose rises fast, increases in insulin lag somewhat behind with the result that even after the action of insulin has started to lower blood glucose, insulin is still being produced and secreted into the blood by the pancreas.
This delay means that insulin continues to be present and act even after the levels of blood glucose have fallen to normal or even below normal, causing a ‘rebound’ dip in blood glucose levels a couple of hours after eating. This dip is experienced by ones brain as lethargy and hunger – feelings that all too often cause people to reach for another high sugar high glycaemic index snack….. so the cycle repeats itself. This is not good, particularly because high levels of blood glucose and the high insulin levels gradually reduce the sensitivity of the insulin receptors that unless addressed, gradually leads to the development of diabetes.
The metabolism of excess fructose is different but arguably even more damaging to health. Fructose that is added into sweet fizzy drinks, confectionaries, cakes, breakfast cereals and a host of other foods, now constitutes about 10% of an average American’s diet – and not much less for your average European. Fructose is metabolised exclusively in the liver through a slightly different metabolic pathway to that of glucose. Critically, the fructose metabolic pathway side steps the rate limiting step whereby cellular energy levels feedback to slow or stop glucose metabolism. This means that the body can continue to metabolise large amounts of fructose with no feedback control – a situation that can very easily lead to uncontrolled fat synthesis in the liver. This brings me to another major problem with a high glycaemic load diet – excess fat synthesis and storage
Another major negative result of diets with a high glycaemic index and load is that excess monosaccharides must be stored somewhere. In small amounts they are temporarily (and healthily) stored in the liver and muscles as glycogen a short-term storage product that is converted into energy when needed in-between meals. However, when they are in excess and their production is continuous, they cause the build-up of fat, both in the form of body fat particularly around the abdomen thighs and arms and more sinisterly in the form of fatty deposits inside the arteries. This process leads to obesity and cardiovascular disease, including heart attacks, heart failure and strokes.
There are multiple other mechanisms involved in the metabolism of carbohydrates and multiple other negative effects of high glycaemic index and load diets such as chronic inflammation, but to make this introduction manageable I’ll introduce these in later posts.
Fat metabolism and the dietary guidelines around fat intake are a particular area of nutrition that is undergoing a profound reassessment and remains somewhat confusing. The historic view has been that high fat intakes are always undesirable and associated with obesity and cardiovascular disease. This view was based in part on a few studies that appeared to show associations between fat intake and cardiovascular disease together with a common-sense assumption that as a gram of fat is twice as high in energy (calories) as a gram of carbohydrates or protein and obesity is primarily due to an imbalance between energy intake and energy expenditure, high fat diets were likely to cause obesity.
Underpinning this thinking was the very clear association between high blood cholesterol and the risk of cardiovascular disease and the fact that the lesions that cause “hardening of the arteries” (technically known as atherosclerosis) are largely made up of cholesterol. In the late 20th century, atherosclerosis was the number one killer of men and women in developed western countries and when I trained as a doctor in the 1980s, the message was very clear: dietary fat and cholesterol are bad and cause cardiovascular disease and obesity – full stop!
However, over the last 20 years this view has been increasingly challenged and there is now substantial evidence that higher dietary fat intakes are not necessarily associated with higher levels of obesity and cardiovascular disease and may in some instances be protective. Critically, it is now clear that the levels of blood cholesterol are extremely tightly regulated through complex mechanisms and that dietary cholesterol has very little effect on the level of cholesterol in the blood or on the risk of cardiovascular disease.
LDL and HDL
These changes are starting to enter everyday understanding with the concept of “good” and “bad” fats, wherein the so-called good fats, more accurately called High Density Lipoproteins (HDL) are associated with a reduced risk of heart disease and the bad fats, Very Low Density Lipoproteins (VLDL), Intermediate-Density Lipoprotein (IDL) and Low Density Lipoproteins (LDL), are associated with increased levels of obesity and cardiovascular disease. So, it’s not the cholesterol per se that’s bad, (cholesterol is in fact an essential building block for health tissue, hormones and for fat digestion) – it is the form the cholesterol is in.
Fat synthesis in the body
Central to this new understanding of fat metabolism is the fact that much of the fat circulating in the general blood circulation is not the same fat as is eaten in the diet. The fats in the general circulation, particular the LDL are generally synthesised in the liver and this synthesis is tightly regulated by many factors other than dietary fat intake. Importantly, a diet with a high glycaemic index and load pushes the synthesis of these fats as the high blood glucose content that this type of diet causes must be stored – and is stored in the form of fatty tissue spread around the body. The LDL is carrier molecules taking this excess glucose (in the form of fat) to the tissues for storage. Unfortunately, high LDL levels in the blood (combined with oxidative damage see later) means that on route, some of the cholesterol that they are transporting sticks to the walls of the blood vessels (endothelium). This is an important reason why foods with a high glycaemic index lead to poor blood fat profiles with high LDL, heart disease and metabolic syndrome.
Fat breakdown in the body
By contrast, as a result of exercise or during periods of fasting, the body must use its fat stores. This mechanism largely entails HDL which mops up any LDL cholesterol and cholesterol released from fatty tissue and transports it back to the liver and other active tissue for use in metabolism. This is an important reason why exercise and intermittent fasting exert such a positive effect on metabolic health.
The changing dietary advice on fat and cholesterol
Blood cholesterol levels are still considered to be a very reliable marker of cardiovascular risk but the dietary and lifestyle advice on how to lower blood cholesterol has changed. Cholesterol in foods such as eggs is no longer considered to be bad for you and some fats, especially polyunsaturated fats rich in omega 3 and monounsaturated fats such as olive oil are now known to improve blood fat profiles and be protective against heart disease. Although most nutritionists still believe that saturated fats should be eaten only in moderation, they are no longer thought to be the main drivers of cardiovascular disease and instead the focus of prevention has fallen on reducing blood glucose peaks through eating a wholefood diet rich in fibre and low in simple sugars and with a low glycaemic index and load.
The earlier section on carbohydrates focused on those carbohydrates that are readily digested and metabolised in the body. In this section I want to briefly discuss those carbohydrates that are not easily digested and instead, pass through the small intestine into the relatively unchanged large intestine. These carbohydrates are often lumped together under the label “dietary fibre”. The group consists of many different substances ranging from monosaccharides such as sorbitol found in fruits such as aronia berries, multiple different oligosaccharides found in fruits (and human breast milk for example) and polysaccharides such as starches that are resistant to the action of human digestive enzymes; and also Beta-glucans a polysaccharide found in large quantities in oats, fungi, and seaweeds.
Fibre is divided into two groups, soluble fibre that dissolves in water and insoluble fibre that doesn’t. A healthy diet needs substantial quantities of both; insoluble fibre to provide bulk to the intestinal contents and allow their easy passage through the intestine plus rapid expulsion; and soluble fibre to feed and encourage a broad diversity in the microbiota.
Gut health and the microbiota
Having a healthy gut (intestine) is critical in protecting the structure and function of the intestine and in the promotion of health, vitality, and longevity. Sadly, in the western world, the structure and function of the gut are constantly under attack by the pro-inflammatory modern diet that is high in sugar and saturated fat and low in fibre. The damage that this diet does to the intestine underpins many of the negative impacts on health overall.
It is widely understood that the intestine must absorb nutrients and that this is essential to life itself. What is less well understood, are the multiple other functions that the gut must play that are equally important to a healthy life. The gut must efficiently foster the billions of helpful bacteria that form the microbiota, protect the body from attack by harmful organisms, block the absorption of toxins, prime the immune system to recognise pathogens and excrete some of the waste products of metabolism. All of these functions are closely linked to health and in particular, metabolic health.
The gut microbiota, the multitude of microorganisms (more than 100 trillion organisms) that live in your gastrointestinal tract, is central to much of this. Research indicates that the composition and health of these microbes is an absolute pre-requisite for both physical and even mental health through a vast array of mechanisms. This is all extremely new and the critical importance of the microbiota has only been extensively researched for less than 20 years. It is not an exaggeration to say that the importance of this new “organ” in developing our understanding of health and disease rivals that of the discovery of the function of the heart 500 years ago. Research into this area is very new and emerging concepts such as the “gut-brain” axis, the bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive aspects of the brain with intestinal functions, are only just beginning to be understood. What is clear however, is the that the composition and health of the microbiota has a profound effect on metabolic health and a disrupted microbiota is closely associated with metabolic syndrome especially diabetes and obesity.
Anabolism, catabolism and fasting
In very simple terms, the body is either storing energy and building tissue (anabolism) or breaking down its tissue and burning its energy stores (catabolism). The modern western lifestyle with constant snacking and multiple meals, means that most of the time people are undergoing anabolism, with raised levels of glucose and ‘bad fats’ in the blood, increasing fat stores in both the body fat but also in the liver. As described in the carbohydrate section above, this also means that there is circulating insulin preventing the breakdown of fatty tissue and preventing weight loss. Importantly, the prolonged presence of insulin, especially when accompanied with spikes of high insulin levels after food with a high glycaemic index and load (for example sweet drinks, chocolate, biscuits, cake, white bread) gradually reduces the sensitivity of the insulin receptors on muscle, fat and liver cells to insulin – a condition called insulin resistance that is one of the core features of diabetes and metabolic syndrome.
Conversely, when you have not eaten for several hours, the body enters a catabolic phase. During catabolism, there is no circulating insulin and instead, the hormone glucagon starts to break down energy stores. Initially these are mainly the glycogen stored in the liver, but progressively as fasting continues, fat in fatty tissue (and the liver) is broken down to provide energy for the body to function. At this stage the levels of bad fats in the blood decrease and the levels of the good fats (HDL) start to increase, allowing the body to clean LDL-cholesterol from the circulation.
Another major change in nutritional science is the understanding that the control of body weight is far more complex than a simple balance between calories (energy) in and calories used. There are multiple regulatory mechanisms in the body that exist to control body weight involving a range of hormones such as ghrelin, glucagon, insulin and leptin, the hypothalamus in the brain, the sympathetic nervous system and the microbiota. These all work together to balance energy intake, energy expenditure and energy stored. It takes a long time to gradually dial up the setting on the body’s internal weight thermostat to a steady state that allows for an increased level of body fat. Likewise, it takes a long time and much hunger and hardship to try to re-set this thermostat through calorie restricted diets. The complexity of this system and the difficulty and time taken to re-set, is reflected in the fact that only 1 in 5 calorie restriction diets achieves long term weight reductions continuing beyond 1 year – largely as a result in feedback mechanisms increasing appetite in response to decreasing body weight and body fat stores.
The good news is that there are small easy ways to implement changes that you can make to re-set the system. These changes focus on altering the stimuli provided to the various hormones affecting metabolism, particularly insulin, ghrelin, leptin and glucagon. They can be achieved and in fact, must be achieved, without excess calorie restriction, continual hunger or rapid weight loss.
THE POWER OF POLYPHENOLS
One of the few things that practically all nutritionists agree on, is that fruit, especially berries are good for you. What few people realise however, is just quite how good for you fruit actually is. A study published in 2010 in the prestigious New England Journal of Medicine, one of the world’s the leading medical journals, estimated that of all the identifiable risk factors that they studied, a low fruit intake is the third most important risk factor for all ill health, exceeding in importance obesity, high blood glucose, physical inactivity, high salt, and alcohol intakes as a risk factor for both ill health (morbidity) and death (mortality).
In common with most vegetables, fruit has several beneficial constituents; vitamins, minerals, soluble fibre and polyphenols. All fruit is good for you. However, some fruits are better for you than others and berries have been widely shown to have strong health-giving properties as outlined above. A key element in this is that berries generally contain large quantities of polyphenols, often above and beyond those found in other fruits. Aronia berries in particular are an exceptional source of polyphenols – one of the highest of any fruits or vegetable and that is why Aronia Ireland is developing a range of Aronia based health products. Much more on this later, but before that I want to provide you with some basic information about polyphenols; an introduction on what they are and what they do.
Polyphenols are protective chemical compounds that occur in plants and act as a plant’s defence and resilience mechanism, fighting off predators, preventing disease and protecting plants from environmental stress. When consumed by humans as part of their diet, they perform the same function – effectively transferring the plant’s exceptional protection mechanisms to humans for improved health.
The impact of polyphenols on health is dramatic and several powerful prospective multi-year cohort studies have indicated that high polyphenol intakes are associated with dramatic decreases in the risk of mortality – by dramatic the findings suggest a 35% in all-cause mortality and a 50% reduction in cardiovascular related mortality. To my knowledge there is no pharmaceutical drug that comes anywhere near to having such major impacts on mortality rates.
Although the results of these cohort studies can only provide an indication of associations rather than direct causality, there are many physiological reasons for believing that polyphenols do indeed cause such major reduction in mortality. In the section below I’ll provide an introduction to some of those physiological effects.
Antioxidants and anti-inflammatories
You have probably have heard of Antioxidants which describe the activity of molecules that fight the damaging effects of free radicals in your body. Free radicals (although essential for some aspects of metabolism) are compounds that cause harm if their levels become too high or they occur in the wrong places. They’re linked to multiple illnesses, including diabetes, heart and vascular disease, cancer and even dementia – diseases which typically also involve some form of inflammation. The process of ageing itself is associated with free radical damage and as a result, ever increasing levels of chronic inflammation.
Your body has its own antioxidant defences that keep these potentially harmful compounds in balance and prevent damage to the vital building blocks of your cells such as DNA, proteins, carbohydrates, and lipids. However to work properly, these defences require that your diet provides the critical compounds these protective systems need in order to function optimally. This is where polyphenols come in. They are not only exceptionally powerful antioxidants that can detoxify free radicals directly but they also control and reduce chronic inflammation through multiple mechanisms, for example by modifying the cascade of inflammatory molecules (the cytokine system) that initiate inflammation. In later articles I will go into more detail on the role of polyphenols in the reduction of chronic inflammation and antioxidants. For now, suffice to say, that you’ve heard of antioxidants or anti-inflammatories, but may not have known that polyphenols are both!
Polyphenols, gut health and the microbiota
Recent studies have shown that polyphenols in the diet have a complex two-way interaction with the gut microbiota. The presence of polyphenols in the intestine helps cultivate a healthy microbiota by inhibiting the growth of harmful (pathogenic) bacteria and stimulating the growth and development of beneficial bacteria. At the same time, the action of the beneficial bacteria in the microbiota increases the absorption of polyphenols and their availability for use in the body.
Closely associated with this is the positive impact that polyphenols have in maintaining the structure and function of the gut wall, specifically the intestinal mucosa – the membrane that lines the inside of the gut. Having a healthy and structurally sound gut mucosa is vital as in addition to efficiently absorbing nutrients, the gut mucosa must stop the entry of toxins into the blood and lymphatic circulations, particularly toxins produced by bacteria – the so called endo-toxins. If these toxins are allowed to enter the body, they trigger multiple negative reactions, many of which directly promote chronic inflammation that in turns promotes to metabolic syndrome and all the negative health impacts that entail. Polyphenols achieve these benefits directly through their ability to act as antioxidants, detoxify free radicals and block inflammation as well as through their positive effects on the microbiota. The net result of all these actions is to increase the thickness of the gut wall and decrease its permeability to toxins. I will go into more detail of the relationship between polyphenols and gut health in later articles, suffice to say for now that polyphenols provide powerful and positive benefits to improve composition and health of the microbiota and the integrity and proper function of the gut.
Polyphenols and Carbohydrate metabolism
Polyphenols improve how your body metabolises carbohydrates through many different mechanisms, some with direct effects on carbohydrate digestion and metabolism and some with indirect effects that down the line, modify carbohydrate metabolism. Some of the most important direct mechanisms are:
- slowing the enzymatic breakdown of carbohydrates in the digestive tract;
- decreasing the absorption of glucose through the wall of the small intestine;
- stimulating insulin secretion in the pancreas;
- decreasing glucose release from the liver and increasing the sensitivity of insulin receptors on liver, fat and muscle cells.
These effects all help to lower blood glucose levels that peak after eating – essentially decreasing the glycaemic index and glycaemic load of your diet. In this way, they directly help prevent the development of insulin resistance, the most important cause of metabolic syndrome.
Some examples of indirect mechanisms through which polyphenols protect metabolic health include:
- improving the barrier function of the lining of the intestine
- decreasing the absorption of endotoxins through the intestinal lining;
- improving the composition of the gut microbiota;
- helping inhibit the activity of inflammatory cytokines;
- protection of the specialised cells in the pancreas that produce insulin
I am convinced that a high intake of polyphenols is an important part of a healthy diet – helping to protect your metabolism from the deleterious effects of excess carbohydrates in your diet and in so doing, maintaining metabolic health and helping to prevent the development and progression of metabolic syndrome.
Polyphenols, fat metabolism and cardiovascular health
Closely associated with their effects on carbohydrate metabolism, polyphenols also modify fat metabolism in many beneficial ways. In the above section I described how they act to decrease the peaks of blood glucose after eating. This directly reduces the synthesis of LDL by the liver, thereby improving blood fat profiles and reducing the risks of atherosclerosis and heart disease. The beneficial changes polyphenols make to the composition of the microbiota also helps to directly reduce blood cholesterol.
A healthy microbiota promoted by polyphenols contains multiple species of bacteria with many Bifidobacterium and Lactobacillus that exert a very powerful effect on regulating cholesterol metabolism. They do this by two main mechanisms; breaking up the cholesterol rich bile acids secreted into the gut by the liver, into forms that cannot be reabsorbed back into the body, therefore ensuring their excretion – and converting dietary fibre into Short Chain Fatty Acids that directly block cholesterol synthesis. As the quantity of cholesterol secreted as bile acids greatly exceeds the amount of cholesterol eaten, these mechanisms to stop its reabsorption play a major role in lowering blood cholesterol levels.
The role of polyphenols in maintaining the structure and function of the gut wall discussed above, also helps reduce the body’s exposure to the endotoxins that damage the lining of the blood vessels. This is important as any damage to the lining of blood vessels encourages cholesterol to stick and starts the formation cholesterol rich plaques a critical part of the pathogenesis for cardiovascular disease. This protection is further strengthened by the direct antioxidant benefits that polyphenols exert to reduce oxidative damage to the endothelial lining of the blood vessels caused by any endotoxins that may get through.
As with the other sections, I intend this post to be an introduction to the role of polyphenols in improving fat metabolism and in further articles I will go into more details with references.
Polyphenols and weight control
Increasing the polyphenols in diet is an important aid to controlling weight. Their effect on carbohydrate metabolism discussed above helps reduce the conversion of glucose and fructose to fat. In addition, polyphenols have been shown to directly increase the oxidation of fat, increase sensitivity to insulin and leptin, as well as altering the expression of key genes involved in the storage and utilisation of body fat. As a result, there is a strong association between dietary polyphenol intake and reductions in levels of obesity in both animal models and people. These are relatively new findings with profound implications for weight control – and the topic is gaining increased scientific interest.
Sources of polyphenols
Traditionally, a high polyphenol intake has been achieved by eating foods such as nuts, fruits, vegetables, plant seasoning, spices, and virgin olive oil and even the odd glass of red wine or cup of coffee. However, ensuring a high polyphenol intake with a modern, often highly processed diet is often difficult, time consuming and expensive. This is where berries come in and as I said earlier, if there is one thing that nutritionists agree on, it is the importance of berries in a healthy diet.
Almost all berries have high concentrations of polyphenols but we at Aronia Ireland have picked aronia berries because these berries not only have the highest polyphenol content of any berry, fruit or vegetable, but much of their polyphenol consists of flavonoids, a class of polyphenols that has a particularly strong evidence base attesting to its efficacy in the prevention of cardiovascular disease. This combination means that only a small amount of our aronia berry-juice or our aronia powders as part of your daily diet, can deliver a large total polyphenol dose containing a high proportion of flavonoids.
In this initial long article I have tried to give an overview of a wide range of issues that I consider to be important in relation to health, vitality and longevity. Hopefully it has provided at least some of you with more insight into why nutritional advice changes overtime – and that these changes and even apparent U-turns in advice, are not a reason to ignore or distrust nutritional advice but are the result of rapidly expanding knowledge of what is an extremely complicated subject. In future discussions, I will try to provide further data on how diet relates to health and, how the polyphenol compounds, found in many plants and particularly in berries, have massive potential to improve health and vitality at both an individual and global scale.
Ultimately my aim is to encourage people to at least try out small changes in their diet and lifestyles for themselves as I am convinced that the positive and noticeable benefits that they will bring in health and vitality will then inspire them to make those small changes a permanent feature in a new healthier life. As they say, “the proof of the pudding is in the eating” – especially if it contains lots of berries!
Dr Steve Collins, MBE MD DSc MBBS,