Healthy Ageing

“Let your food be medicine and your medicine be food”, Hippocrates, 400BC.

The diet has always played an important role in health but even though research has come a long way in proving its validity, it still remains somewhat of an enigma given the lack of substantive evidence.

Along with the World Health Organisation (WHO), many governments are heavily promoting healthier eating to combat unhealthy aging.

Humans are now certainly living longer but are succumbing to a vast array of possibly avoidable illnesses in their twilight years. This factor is costly and also undesirable for both the individual and the nation that must pay for the ever-growing healthcare bill. Industrialised nations are struggling in the fight against cancer, cardiovascular disease, Type II diabetes, osteoporosis, dementia and gastrointestinal problems. All these age-related illnesses may be all or in part directly related to nutritional factors (Nicolas et al., 2001: 88).

If you are lucky enough to make it to old age you may notice the deterioration of your body, this is caused by a combination of forces, comprising of genetic, environmental and lifestyle factors, including diet.

There is a vast chasm of difference between how people age; some leap into old age with good mental acuity and physical prowess, whereas others hobble into their golden years plagued by discomfort and disease (Arking, 2006: 220).

The estimated maximum lifespan for a human is 120years but most fall short by about 40-50years

This article examines why humans age focusing on the influence of dietary factors. It examines both the positive and negative aspects of how the diet impacts health and longevity, specifically concentrating on current research on the nutrients and foods that may prevent, promote or initiate disease, it will argue that diet can prolong life and promote health. The free radical theory of ageing and caloric restricted diets will be examined, as both are implicated in current theories for life extension through dietary manipulation. Finally, the most common diseases associated with ageing are discussed, they include cardiovascular disease (CVD), cancer, stroke and type II diabetes as they are connected with poor dietary regimes and they are implicated as the major cause for millions of fatalities each year, in developed countries.

Improvements to sanitation, medical advances and the elimination of many of the once fatal infectious diseases equate to longer life spans in industrialised nations. But as humans’ age their bodies deteriorate as a result of genetic, environmental and lifestyle factors, including diet

Without nutrients humans would simply not survive.

Food is therefore a vital part of life and throughout life dietary choices can enhance or diminish the health of the body. The past 50years has seen a plethora of fad diets and wonder foods; it has seen the introduction of a multitude of commercial junk and fast foods; the highs and lows of dietary staples; and a huge increase in Type II diabetes, cancer, cardiovascular disease and obesity. Scientists and dieticians are still not cohesive on the perfect diet but certain truths have been extracted from the vast mound of information that is publicly available. Most governments have now implemented guidelines for healthy eating habits including the recommended daily allowances for macro and micronutrients. These guidelines are meant as a basic guide to the minimum and maximum amounts of nutrients people should consume to avoid deficiencies, excess and disease attributable to nutritional factors. Generally, these guidelines are to be followed throughout life so as to maintain the body adequately (British Nutrition foundation, 1996: 1-7)

The nutrients necessary to sustain human life are found in varying amounts in a wide variety of foods and it is advisable to consume a decent variety of food daily.

At the most basic level, good eating habits include; eating three balanced meals per day, eating high amounts of fresh fruit and vegetables (including legumes), low amounts of saturated fats, limited alcohol, salt and refined sugar and adequate fluid intake. To this basic list, it is possible to get more specific depending on age, sex and specific needs (National Health and Medical Research Council, 1999: xx-xxiv). The next section will discuss theories of aging and how the diet can influence the ageing process. It will specifically concentrate on free radical theory and calorie restriction in the quest for longevity.

The Ageing Process

Ageing is a complex process that has baffled mankind for centuries. Many theories attempt to explain why humans’ age but still there is no definitive answer. These theories come under two main headings, that is programmed and unprogrammed theories of ageing (Wong, 2001: 41).

When examining these theories collectively it is possible to see that the human body is ruled by certain inbuilt biological mechanisms that predispose the body to an inevitable death. It is possible to see that overtime these mechanisms may be unduly sped up by the accumulation of or damage from environmental pollutants, including dietary factors, that interfere with homeostasis, leading to senescence on both a cellular and organismal level. Nutritional implications feature in many of the unprogrammed theories of ageing that suggest environmental impacts on the body promote ageing, e.g., damage to DNA and cells by free radicals and cross-linking (Jones et al, 2006: 48-64).

Free radical Theory and antioxidants

At the cutting edge of gerontology is free radical theory. This theory contributes to many theories of ageing, including telomere theory, gene-mutation theory, cross-linkage theory and stress protein theory as the free radicals may instigate these changes. Free radical theory is based on the argument that molecules called free radicals cause damage to macromolecules (such as lipids, proteins and DNA). The free radicals will react with these molecules including DNA and protein that is in cells and when they do so, they oxidise and damage those molecules and give rise to mutations and abnormalities that cause them to be dysfunctional, this non-specific damage results in the changes observed in aging. Free radicals are cellular chemicals containing unpaired electrons which are formed as by-products of various normal cellular processes involving interactions with oxygen (Spence, 1995: 20).

Free radicals are triggered by a considerable range of endogenous and exogenous factors such as, exposure to X-rays, tobacco smoke, air pollutants, microbial infections, industrial chemicals, intensive exercise and dietary factors. The dietary factors include additives, smoked foods, pickled foods, alcohol, preservatives, stale food, artificial sweeteners and generally those foods that are difficult to digest and assimilate. These factors feature as triggers/causes for gene mutation theory, cross linkage theory and stress protein theory as well contributing to cellular accumulation theory and whole body theories of ageing (DiGiovanna, 1994: 29) (Spence, 1995: 18-19) (Jones et al., 2006: 51-56) (Kenton, 1985: 35). Telomere theory, a programmed theory of ageing, is currently playing a key role in anti-cancer and anti-ageing therapies. It has been found that an increase in oxidative stress, caused by free radicals, accelerates the rate of telomere shortening due to the accumulation of single strand breaks in telomeric DNA. Thus when examining telomere theory it is evident that if free radicals damage or hasten shortening of telomeres, that this will contribute to cellular senescence and possibly organismal aging (Ahmed et al., 2001: 1105) (Masoro et al, 2006: 344).

For a long time scientists have known that people that have diets rich in fruits and vegetables have a lower incidence of diseases associated with free radical damage, that is heart disease, diabetes, certain types of cancer and dementia.

These aforementioned diseases happen to be the foremost killers in developed countries (Selle, 2003: 50). The reason diets high in fruits and vegetables play a role in preventing these diseases is that they contain substances known as antioxidants. These compounds work against the negative effects of free radicals as they provide a protective effect to cells by mopping up free radicals and reducing their effects. Antioxidants include substances such as vitamin A, C and E, CoEnzyme Q10, selenium, beta-carotene and zinc. Antioxidants can be an important factor in increasing human beings’ functional life span or by increasing healthy longevity (Selle, 2003: 50). From this information, it is therefore clear to see both the positive and negative effects the diet can have on free radicals, some foods protect the body against their harmful damage whilst others promote or cause their activity.

Calorie restriction, Obesity and Longevity

Modern living has witnessed the rise of overeating and inactivity and as a result there has seen the rise of the plethora of diseases that go hand in hand with it.

Obesity, Type II diabetes, cardiovascular disease, some cancers, GIT disturbances and many other diseases may all be linked with overnutrition, this in turn is related to glucose intolerance which is related to accelerated ageing and disease (Arking, 2006: 222). In the USA, 45% of those aged 65-74years have severely impaired glucose tolerance this is a staggering figure but explains the rapid increase in Type II diabetes and cardiovascular disease sufferers. Glucose homeostasis is sustained by the insulin-mediated uptake of glucose by the peripheral tissues. When this is no longer efficient, the result is an elevated blood sugar level. In severe cases the person may develop Type II diabetes. Before this condition is developed elevated blood sugar levels may do serious damage on both a cellular and organismal level, thus contributing to the ageing process and disease (Arking, 2006: 222)

Healthy elderly individuals generally demonstrate an overall superior glucose tolerance.

When examining populations where there is a high density of healthy elderly people, such as in Okinawa (Japan), Soviet Georgia, Ecuador, Pakistan and some Mediterranean countries it is evident that these individuals are generally slim, do not over eat/calorie restricted diets and maintain healthy eating regimes and exercise(Arking, 2006: 220).

Increasing evidence points to caloric restriction as an effective method of healthy life extension. Caloric restriction significantly alters the body build, various indices of cardiovascular health, key indices of the glucoregulatory system and one measure of oxidative damage. It is becoming progressively more evident that a reduction of caloric intake is important in prolonging lifespan as long as the calories that are consumed are of a high quality, that is nutrient dense (high in antioxidants, adequate intake of complex carbohydrates, proteins and mono & polyunsaturated fats and low in saturated fats, salt and alcohol) (Arking, 2006: 220-223) (Masoro et al, 2006: 65) (Sinclair et al, 2006: 33-34)

Although widely available, diets are often lacking in the essential nutrients, this lack often morphs into increased susceptibility to disease and the premature ageing of the body. Vitamins and minerals are essential to life and if they are lacking for prolonged periods deficiency signs and symptoms will occur and if left unattended will develop into more chronic or serious diseases (Arking, 2006: 226). The following section will discuss the main conditions associated with diet and ageing, focusing on cardiovascular disease, cancer and diabetes.

Diseases of Ageing

With ageing, certain conditions and diseases are common, these include, pernicious anaemia, osteoporosis, immune system dysfunction, constipation, diverticular disease, certain cancers, cardiovascular disease and Type II Diabetes.

Out of the top ten leading causes of death in the United States four are directly related to the diet, including the top three, which account for two-thirds of the nations deaths per year. The perpetrators responsible for the untimely death of millions every year are cardiovascular disease (CVD), cancer (some types), strokes and diabetes (Whitney & Rolfes, 2002: 603).

Cardiovascular Disease

CVD is the leading cause of death around the developed world. The consequences of CVD are usually heart disease and strokes, that is, the first and third leading causes of death, in the United States. The most common form of cardiovascular disease is coronary heart disease (CHD). CHD usually involves atherosclerosis and hypertension and both are directly attributable to dietary factors, namely a diet high in saturated fats (Kraus et al, 1995: 1795) (Whitney & Rolfes, 2002: 605).

The most commonly reported CHD condition is high blood pressure. Risk of CHD is known to be positively associated with total blood cholesterol and low-density lipoprotein (LDL) and negatively correlated with high-density lipoprotein (HDL). Dietary related risk factors for CHD are abnormal blood lipids, hypertension, insulin resistance and obesity (Whitney & Rolfes, 2002: 605-7). A number of dietary recommendations are noted to reduce risk factors for CHD. That is, reduce low-density lipoprotein (LDL) cholesterol; maintain a healthy body weight; limit intake of saturated fats, total fats and dietary cholesterol.

The American Heart Association further recommends consuming a healthy diet consisting of a variety of fruits, vegetables, whole grains, fish, legumes, poultry and lean meats.

They also recommend that saturated fats, trans fatty acid, salt and alcohol should be reduced or avoided (Reddy & Katan, 2004: 168) (Whitney & Rolfes, 2002: 609).

Essential fatty acids and regular physical activity should be encouraged. As plasma cholesterol is often more harmful if it has undergone oxidation, antioxidants are important in the diet, selenium, vitamin E, carotene, etc may protect against heart disease therefore high intake of fruits, vegetables, nuts and seeds which are high in antioxidants are beneficial against CHD. Epidemiological studies also suggest a relative deficiency of dietary potassium may also explain increases in the risk of hypertension and therefore should be added in low amounts to the diet (Whitney & Rolfes, 2002: 609) (Tortora & Grabowski, 2000: 733)

Cancer

Cancer ranks second in the leading causes of death in the US. Many types of cancer exist, each with their own aetiology but there has been strong evidence that supports the link between the development of some cancers and the diet. Dietary constituents can be both preventative (Antipromoters) and causative (initiators), while others may promote a cancer that has already developed (promoters) (Whitney & Rolfes, 2002: 618).

Cancer initiators found in the diet are commonly known as carcinogens or carcinogenic food. The amount of known carcinogens increases daily but this area still lacks evidence, however some widely known carcinogens include some food additives, smoked foods, pickled foods, alcohol, preservatives, artificial sweeteners, etc. The extent to which diet contributes to cancers and the exact mechanism of action is unknown but it is estimated that diet may be linked with up to a third of all cases of cancer. Cancer promoters accelerate the development of cancer once it has already been initiated. Studies suggest that certain dietary fats eaten in excess may promote cancer, in part by contributing to obesity. More specifically, linoleic acid, the omega-6 fatty acid in vegetable oils, has been implicated in enhancing cancer development in some animals. Antipromoters are those foods that are protective against cancer (Whitney & Rolfes, 2002: 618).

Dietary recommendations to reduce the risk of cancer are to incorporate a plant rich diet; maintain a healthy weight and be physically active; reduce intake of alcohol, salt and saturated fats; prepare and store food safely and to reduce or eliminate processed, smoked and pickled foods (Whitney & Rolfes, 2002: 619).

Many epidemiological studies have demonstrated the link between increased consumption of antioxidants and the decreased incidence of cancer, therefore diets rich in fruits and vegetables, may promote lower rates of cancer. This may be due to the fibre, phytochemical and antioxidant content of these foods (Whitney & Rolfes, 2002: 618).

Diabetes

Ranking sixth among the leading causes of death in the US, Diabetes Mellitus also underlies, or contributes to a variety of other major diseases, including heart disease and stroke.

In fact, people with diabetes are twice as likely to develop these cardiovascular problems as those without diabetes (Whitney & Rolfes, 2002: 619). The predominant type of diabetes is diabetes type II (90-95% of all cases) and generally develops in those over 40years but is increasingly found in younger individuals. Although the exact cause remains unknown, high blood glucose and insulin resistance are the trademarks of this disorder. Once diabetes is established there may be complications affecting the micro and macro blood vessels and the nerves.

Nutritional intervention is extremely important in the prevention and treatment of diabetes and importance is placed on balancing blood sugar levels, weight loss and physical activity (Whitney & Rolfes, 2002: 623).

Although genetics and environmental factors also play a part in the development of these conditions, dietary factors seem to be crucial in their prevention and development. Healthy eating regimes combined with physical activity from an early age will possibly reduce the likelihood of developing these common diseases in later life (Lipski, 1996: 14). Each of the conditions mentioned had very similar preventative measures and in fact they mirror general healthy eating and lifestyle guidelines. It must be remembered that one cannot isolate any of the parts that make the whole, lifestyle along with emotional variables will invariably influence the health status of an individual and their susceptibility to certain disease. Diet can be manipulated for the benefit of the individual taking into account all other factors. Once an individual has reached old age either diseased or not it is necessary to continue modifying and correcting the diet according to their needs in order to maximise the potential life can offer (Nicolas, 2001:88).

Conclusion

It is not difficult to see that diet is crucial to our health, wellbeing and longevity.

This article examined issues concerning why humans age with a focus on the influence of dietary factors and the possibilities of life extension. This information was studied with regard to the free radical theory of ageing and caloric restriction as these theories are implicated in prolonging life through dietary manipulation.

The outcome of this information was that diets high in fruits and vegetables and low in saturated fats, alcohol and salt were beneficial whereas exposure to high amounts of environmental pollutants and poor diets were detrimental to health and promoted ageing and disease. The protective factor found in fruits and vegetables is due to high amounts of antioxidants which proved protective against diseases commonly associated with free radical damage, such as cardiovascular disease, diabetes type II and cancer. It was also found that caloric restricted diets were beneficial against the same diseases, once the diet is nutrient dense. The main diseases associated with ageing are correlated with bad eating regimes that include diets high in sugar, animal/saturated fats, salt and alcohol while lacking in fruits and vegetables.

Prevention, is most definitely, better than cure and put very simply, if one were to follow a diet that is high in antioxidants, low in saturated fats, animal foods, salt, alcohol and junk foods, one may find they may live to be a ripe old healthy age, so long as fate and good genes are on their side.

Reference List

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