Abstract
This study intends to study the effects of dieting on risk factors for Type 2 Diabetes. The overall objective of this research was to investigate and explore evidence and possible resolutions based on published literature concerning diet and lifestyle, and their impact to risk factors for Type 2 Diabetes and the prevention thereof. With the different studies on healthy lifestyle and the development of Type 2 Diabetes, recommendations for the prevention of this disease will be provided.
This study will utilize studies that are focused on understanding nutritional intervention, whether experimental or epidemiological, in the prevention of risk factors that can have an impact to Type 2 Diabetes, to provide disease-specific recommendations. Long term studies on the subject are primary resources used in creating the recommendations to be used for the study’s strength and credibility.
Several cohort studies and clinical experimental trials across different status - high, middle and low - of countries are used for the purpose of creating recommendations for the dietary and lifestyle based prevention of type 2 diabetes. Studies utilized will include: Pima Indian Study, Finnish Diabetes Prevention Study, Iowa Women's Health Study, the study on United States Physicians (male), and the US Diabetes Prevention Program. These studies will form central to the analysis of the study and in the creation of recommendations that will be relevant to the different settings and levels of income. This means that the study will be inclusive and useful to the different income-level of countries.
The study shows that there is clear evidence on the decrease of diabetes occurrence among adults who live a healthy lifestyle and are physically active. Risks of diabetes decrease with the maintenance of a normal body mass index among adults who lose weight. Development of Type 2 Diabetes increases with the presence of abdominal obesity, low physical activity, adult overweight and obesity, and material diabetes. Intake of saturated fats with the retardation of the intrauterine growth contributes to the increase of risks in the development of Type 2 Diabetes; while non-starch polysaccharide is a contributor to the reduction of risk factors in the development of Type 2 Diabetes. Intake of dietary foods with omega 3 fatty acids, practice of breastfeeding, and absorption of low glycaemic index foods can help to provide protection against Type 2 Diabetes.
As evidenced by the cohort studies and clinical experimental trials, possible recommendations for the prevention of the development of Type 2 Diabetes include maintenance or attainment of a normal body mass index (BMI); physical activity of the person; intake of healthy and dietary foods that are risk in omega 3 fatty acids and the reduced intake of saturated fats. Type 2 Diabetes is not a disease that is not preventable. With the aid of proper dieting, risk factors of Type 2 Diabetes are reduced and controlled to avoid their impact to the overall health condition of the person.
Literature Review
In a study conducted by O'Dea, Spargo & Akerman (1980) on the effect on Paleolithic diet on 13 healthy Australian Aborigines, they noted that metabolic effects of the diet on the human physical condition. Based on the study, glucose levels were not directly affected by the dietary program being used to these subjects considering that they didn't have diabetes. In fact, the elevated insertion of glucose did not normalize when the subjects reverted to the traditional and healthy lifestyle that they had. However, in a separate study of O'Dea (1984), he noted that there is a reduction of weight loss by 10% and the decrease of glucose levels together with the triglycerides and insulin with the sample of Type 2 Diabetes patients that followed the Paleolithic diet.
Frasetto et al. (2009) also tried to study the metabolic risk factors for cardiovascular diseases with the focus on Diabetes. In this uncontrolled experiment, they found that sedentary subjects who received dietary intervention were able to exhibit a reduction of blood pressure, improvement of arterial sensitivity, and the reduction of the presence of plasma insulin; and the clear reduction of the cholesterol level and triglycerides. This study provides evidence on the impact of dietary intervention on the reduction of insulin secretion, glucose tolerance, and lipid profiles of the person as the weight of the person is maintained. Frasetto et al. (2009) concluded that there should be no connection between weight loss and the occurrence of Type 2 Diabetes or other cardiovascular diseases.
Moreover, on the study conducted by Lindeberg et al. (2007 with the use of a controlled setup among 29 patients (which have ischemic heart disease or the presence of Type 2 Diabetes), they found improvement of the glucose tolerance after the intervention of Paleolithic or Mediterranean diet. Both dietary practices are focused on the intake of fruits, vegetables, whole grains, and low-fat products. Based on the study, while there is a significant improvement on glucose levels of a person, the weight of the person remains the same, thus proving further the non-correlative relationship of weight and Type 2 Diabetes as provided by the reports of Frasetto et al. (2009). Furthermore, it should be noted that between the two types of dietary practices, the most effective is Paleolithic which shows significant results compared to that of Mediterranean diet.
The study of Frasetto et al (2009) and Lindeberg et al. (2007) was also conducted by Osterdahl et al. (2008). In the study of uncontrolled subjects within 3 weeks of Paleolithic diet among 14 subjects, they found out that there were significant improvements in terms of body mass index, weight of the person, and waist circumference. In this study, there is a significant relationship between weight and the practice of Paleolithic diet. The same study provides a relationship between the systolic blood pressure of the person and plasminogen inhibitor. To note, the study is limited only to the relationship and impact of the diet on the weight of the person, but it did not report the relationship of the diet to diabetes or of the weight to diabetes.
In the study conducted by Montonen et al. (2005) they were able to identify two dietary patterns. First, the prudent dietary pattern - a mind of diet that is rich in vegetables and fruits - is associated with the reduction of risk factors in the occurrence of Type 2 Diabetes. On the other hand, the conservative pattern - a kind of diet that is rich in while milk, potatoes, butter and red meat - is associated with the increase of risk factors in the occurrence of Type 2 Diabetes. Based on the study conducted, the patterns are more observable among individuals with high body mass index, nonsmokers, older persons, and women.
The study of Montonen et al. (2005) provides evidence to the previous study of van Dam et al. (2002). In the Health Professionals Follow-Up Study, the Western and prudent dietary patterns are used. The Western dietary pattern is of processed meats, refined grains, high-fat products, and French fries. It was found out that those who followed the prudent dietary pattern reported reduction of risks in the occurrence of Type 2 Diabetes, while those who utilized the Western dietary pattern reported higher incidence of Type 2 Diabetes. In the cross sectional study conducted by Williams et al. (2000) they noted the inverse relationship between the occurrence of Type 2 Diabetes and the intake of vegetables, fruits, and low consumption of processed meat. A Canadian study also provided evidence on the relationship of intake of canned eat, canned fruit, chocolate, fries, and meat and that of the prevalence of type 2 Diabetes (Gittelsohn et al., 1998). They noted that those people who are more on unhealthy kinds of foods are more likely to develop Type 2 Diabetes. The Western dietary pattern is associated with the rise of plasma insuliun level, which is a precursor to the onset of Type 2 Diabetes. In the same manner, the intake of fatty foods, cereal fiber, and unsaturated fat can boost the potential development of Type 2 Diabetes.
The complicated interactions of food nutrients affect the way food impact of the body of the person. Based on the studies conducted by researchers, vegetables and fruits are associated with the reduction of risks in developing Type 2 Diabetes. Vegetables and fruits have preventive effects due to the presence of the antioxidants that protect the body from the disease (Knekt, 1999). It should be noted that magnesium is already established a major contributor to the prevention of type 2 Diabetes occurrence. Magnesium can stop insulin secretion as it encourages the development of insulin resistance in the blood of the person. In the same manner, the increase level of vitamins E & C with the direct attenuation of folic acid and beta carotene is also a major factor on how fruits and vegetables can keep the body from developing Type 2 Diabetes. These nutrients interact with each other for the purpose of stopping the secretion of insulin and protecting the body from the development of Type 2 Diabetes.
The prevalence of Type 2 Diabetes can be traced to irreversible factors that are already established as facts. Race and ethnicity of the person is a major factor in the development of Type 2 Diabetes. In the study conducted in Singapore in 1992, it was found out that the Chinese men and women were more likely to develop type 2 Diabetes at 8.5% of possibility (Tan et al., 1999). On the other hand, 13.3% of Asian Indians and Malays showed that prevalence of diabetes. In a cross-sectional study of Mather et al. (1998) they found out stark difference on the prevalence of diabetes among Europeans, South Asians and Africans. They found that out the Europeans are more likely to develop type 2 Diabetes compared with Asians. This is further confirmed by the study of James et al, (2001) on the differences of the body fat distribution among individuals as determined by their races and ethnicities.
Aside from race or ethnicity, another irreversible factor to the development of Type 2 Diabetes is familiar aggregation. The risk of having type 2 diabetes increases twice or six-fold if a parent or a sibling of a person has the disease. However, this is not a definitive factor because familiar aggregation may even occur without the impact of genetic factors. The environment and the lifestyle that two people share may contribute to the incidence of the disease. Nonetheless, according to Barnett et al. (1981) twins may have higher incidence of developing type 2 diabetes if one has the disease. The importance of genetics in the study of diabetes is shown by the relationship of ethnicity or race and the prevalence of Type 2 Diabetes occurrence. This means that when people share genetic mix-up, they may also share the same vulnerability to certain types of diseases. Lastly, another irreversible factor is age or gender. While there is a small gap or difference of prevalence or incidence rate of type 2 Diabetes between genders or among age brackets, it should be noted that the difference among women and men, or among age brackets can also be traced to the physical activity that they or do the foods that they intake.
Studies on the development of diabetes are also quick to mention physical inactivity as a major player in the development of the disease. The Nurses' Health Study showed that women who were more active or who exercised regularly have lower incidence of Type 2 Diabetes as adjusted to their age probability (Manson et al., 1991). The result showed more significance to people who have parents who are diabetic, or those who have ethnicity that is susceptible to the disease. This is also true with the study among male physicians. Male physicians who are physically active though they have higher body mass index are less likely to develop Type 2 Diabetes (Manson et al., 1992).
There are several risk factors associated with the development of Type 2 Diabetes. The management of these factors can either increase or reduce the prevalence of Type 2 Diabetes. Foremost, obesity has been studied as a major factor in the development of type 2 Diabetes. In the study conducted by Knowler et al. (1981) on the link between diabetes and obesity, they found a positive relationship between these two factors. The increase of obesity problems as faced by several countries is also proportional to the increase prevalence of Type 2 Diabetes. In the study of Knowler et al. (1981) they noted that the incidence of Type 2 Diabetes increases among people with higher BMI compared to those with lower BMI, even among older people wherein incidence of Type 2 Diabetes increase due to the age bracket. Furthermore, the study noted that even among Pima Indians who are very susceptible to type 2 Diabetes, the incidence rate also decreases among non-obese individuals. However, Knowler et al. (1981) also acknowledged that there are several other factors contributing to the rise of prevalence because the probability of Type 2 Diabetes development also increases among individuals whose parents have Type 2 Diabetes or just regular diabetes.
In the Nurses’ Health Study, researchers found out that individuals of European descent have higher risk of diabetes development even if granted that the BMI is within normal (Colditz et al., 1990). According to James et al. (2001), having the same BMI level, Asian individuals have lower incidence rate of Type 2 Diabetes because of the proportion of body fat compared with those in the Western regions of the world. While the study tried to point out that there are different links of obesity and diabetes, it should be noted that there are no clear research on the differences of fat levels and BMI. The established fact of several studies is that obesity level increases the possibility development of type 2 Diabetes; while lower body mass index decreases the possibility of developing the said disease. (But this is not confirmed or supported by the studies cited earlier in this literature review.)
Several studies proved that amount of fat and its quality can have an impact on the modification of glucose tolerance and the secretion of insulin (Hu et al., 2001). It is important to note that polyunsaturated is the most destructive type of fat that enters the body as mentioned. The increased content of high fat in the body can result to the reduction of glucose tolerance due to the consequent reduction of insulin that binds with receptors, the impairment of the transport of glucose, the reduction of glycogen synthase proportion, and the triglycerides accumulation in the skeletal muscles of the person (Storlien et al., 1991). Fat can stop the transport of glucose, thereby increasing the level of glucose in the body. It can also trigger the large secretion of insulin as the body’s adaptive behavior toward the presence of glucose. The low activity of the body in using available glucose that is stored in the body due to food intake results to the increase of incidence of diabetes.
The study conducted by Feskens et al. (1995) showed that intake of high saturated fat can result to higher risk of IGT and higher insulin levels, and higher fasting glucose. With the proportions of saturated fats in the muscle phopholipids, there is also a high risk of insulin levels to shoot up while the sensitivity of the same goes down, thus providing a good condition for the development of type 2 Diabetes. It should be noted in the study conducted, intake of high vegetable fat can result to the reduction of risks in developing Type 2 Diabetes as associated with lower fasting glucose, increased level of insulin sensitivity, and lower risk of IGT. With regards to monounsaturated fats, studies reveal different results. While it is part of unsaturated fats family, most of these fats are derived from saturated fat sources such as meat and dairy products. This creates the confusion as the effect of monounsaturated fats to the risk of developing Type 2 Diabetes. It could have been that the saturated fats in the sources of these monounsaturated fats are the culprit for the development of Type 2 Diabetes as associated with monounsaturated fats.
In the study conducted by Barnard et al. (2006) on how low-fat vegan diet can improve glycemic control and cardiovascular risk factors through a clinical trial of individuals with type 2 Diabetes, they noted that 40% of the vegan group and 26% of the ADA group subjects have seen a reduction of diabetes medications intake. In the same manner, the body weight or body mass index of those who are in the vegan group and ADA group also dropped significantly; it is correlated with the reduction of medications among Type 2 Diabetes respondents. Even if respondents did not alter their medications, they were able to see a drop of 21.2% of their cholesterol level.
Krentz & Bailey (2005) noted that the level of reduction in the medication of vegan group respondents showed comparable result as with the oral diabetes drugs. Both the vegan and ADA diets showed significant results as evidenced by the reduction of body mass index, the reduction of lipid concentrations and albumin excretions. The vegan diet affects the insulin sensitivity of the person. It is influenced by the reduction of dietary energy density and the intake of energy of the person. In the same manner, the reduction of total fat intake also results to the increase of insulin sensitivity and low-glycemic index.
An important part of the study conducted by Barnard et al. (2006) is the role played by dietary fiber in the vegan diet to the glycemic index. Dietary fiber influences the post-prandial responses of glucose and insulin. Glycemic index is the elicited response of 50g carbohydrate compared to that of 50g of glucose or white bread. By definition, it is the response of post-prandial glucose after consumption of carbohydrate. In the early 1970s, several studies have tried to examine the effects of dietary fiber to the prevention or maintenance of several diseases including Type 2 Diabetes. Succeeding studies have tried to point out that lack of dietary fiber results to the development of Type 2 Diabetes while there is an inverse correlative importance between insulin levels and the fiber intake of the person.
Aside from dietary fiber factors to the reduction of risk factors in the development of type 2 Diabetes, research shows that patients with type 1 diabetes experienced high level of oxidative stress. According to Kraus et al. (2000), vitamin E can help to reduce the oxidative stress that type 1 Diabetes sufferers’ experience. Studies conducted by Salonen et al. (1995) and Reunanen et al. (1998) in Finland showed the correlative importance between the level of Vitamin E in the blood of the person and the risk of developing type 2 Diabetes. The study revealed that with the low plasma level of Vitamin E results to the 3.9 multiplication ris of developing the Type 2 Diabetes. The study reported that 39% of the risk in developing Type 2 Diabetes is reduced with the intake of Vitamin E. This means that people who eat quality foods with higher Vitamin E nutrients are less likely to develop Type 2 Diabetes compared to those don’t eat foods high with Vitamin E. While nutritionists and researchers agreed that the relationship must be investigated, there is already sufficient evidence on the impact of Vitamin E in the reduction of risk factors in developing type 2 Diabetes.
Furthermore, studies also reveal the relationship between intake of alcohol and the incidence rate of developing Type 2 Diabetes. Results of the Nurses' Health Study showed that there is a significant reduction of diabetes among women with alcohol intake. In a sense, there is a strong relationship between alcohol consumption and the body mass index of the person (Stampfer, 1988). Among male physicians, the study revealed that with those who drink alcohol twice or four times a week, there is a low incidence of developing Type 2 Diabetes compared to non drinkers. It is important to note that while the studies revealed strong relationship with the reduction of risks and incidence rate of type 2 diabetes among men; there is a small percentage of relationship among women. This can be traced to the differences of body or physical make up of women and men, but there is still a need to further expand the study for a better correlation.
Over the years, most developing countries have seen significant onset of Type 2 Diabetes among teenagers. This implies that the burden of the community and the country is to protect young citizens from the lifetime disease. Continuing researches are conducted across several countries to examine the impact of dietary intervention in the reduction of the incidence rate of developing Type 2 Diabetes. With the results of these studies, further knowledge will be known regarding the risk factors of the disease.
References
Barnard, N.D. (2005). “The effects of a low-fat, plant-based dietary intervention on body weight,
metabolism, and insulin sensitivity.” Am J Med118:991–997, 2005
Colditz, G.A. (1990). “Weight as a risk factor for clinical diabetes in women.” American Journal
of Epidemiology 1990; 132: 501–13
Feskens, E.M. (1995). “Dietary factors determining diabetes and impaired glucose tolerance. A
20-year follow-up of the Finnish and Dutch cohorts of the Seven Countries Study.” Diabetes Care 1995; 18: 1104–12.
Jenkins, D.J. (2003). “Effects of a dietary portfolio on cholesterol-lowering foods vs lovastatin
on serum lipids and C-reactive protein.” JAMA290:502–510, 2003
Knowler W.C. et al. (1990). “Diabetes Mellitus in the Pima Indians: incidence, risk factors and
pathogenesis.” Diabetes-Metabolism Reviews 1990; 6: 1–27.
Manson, J.E. et al. (1991). "Physical activity and incidence of non-insulin-dependent
diabetes mellitus in women." Lancet 1991; 338: 774–8
Mather. H.M. (1998). “Mortality and morbidity from diabetes in South Asians and Europeans
11-year follow-up of the Southall.” Diabetes Survey, London, UK. Diabetic Medicine 1998; 15:53–9.
Montonen, J. et al. (2005). “Dietary Patterns and the Incidence of Type 2 Diabetes.” American
Journal of Epidemiology.
Rassmussen, O.W. (1993). "Effects on blood pressure, glucose, and lipid levels of a high-
fat diet compared with a high-carbohydrate diet in NIDDM." Diabetes Care 1993; 16: 1565–71.
Reunanen, A. (1998). “Serum antioxidants and risk of non-insulin dependent diabetes
mellitus.” European Journal of Clinical Nutrition 1998; 52: 89–93
Stampfer, M.J. (1988). “A prospective study of moderate alcohol drinking and risk of diabetes in
women.” American Journal of Epidemiology 1988; 128: 549–58
Storlien L.H. (1996). “Dietary fats and insulin action.” Diabetologia1996; 39: 621–31.
Tan C.E. et al. (1999). “Prevalence of diabetes and ethnic differences in cardiovascular risk
factors. The 1992 Singapore National Health Survey.” Diabetes Care 1999; 22: 241–7.
