Dietary guidelines for good health

Introduction

According to the United States Dietary Guideline Committee (2005), a healthy diet is the best weapons to fight several diseases affecting many people in the society today. Good nutrition helps in the prevention of heart and blood vessel disease which in extension contributes to prevention of other diseases, including some forms of cancer, renal disease and osteoporosis. These chronic diseases account for the majority of the morbidity and mortality in the population. In order to prevent this, it is important to highlight and provide the public with scientifically based dietary guidelines.

Dietary guidelines for good health

1. Eat a variety of foods

American Heart Association (AHA) (2008) strongly endorses consumption of a variety of foods and believes that all dietary recommendations should enable individuals to adopt eating patterns consistent with their own lifestyles and that will supply the calories, protein, essential fatty acids, carbohydrates, vitamins, minerals, and fiber needed for good health. This pattern can be achieved by eating foods from all the food groups, including fruits and vegetables; nonfat and low-fat dairy products; whole-grain breads, cereals, pasta, starchy vegetables, and beans; and lean meat, skinless poultry, and fish. The AHA recommends that healthy individuals obtain an adequate nutrient intake from foods eaten in variety, balance, and moderation. Vitamin and mineral supplements are not a substitute for a balanced and nutritious diet designed to emphasize intake of fruits, vegetables, and whole-grain foods. Excessive intake of calories, sugar, and salt should be avoided.

2. Choose a diet low in fat, saturated fatty acids, and cholesterol

AHA (2008) recommend the consumption of diet not more than 30% of total calories as fat with the aim of reducing saturated fatty acid intake and maintaining a healthy body weight.

Diets with very low total fat intake have been tested with favourable results in studies of persons at high risk, but such diets have not been demonstrated to be of value for the general population and may have adverse consequences, including potential nutrient deficiencies in certain subgroups such as children, pregnant women, and the elderly. For this reason, the AHA endorses the recommendation of the World Health Organization for a lower limit of 15% of calories as total fat.  Moreover, the AHA recommends that for the general population, the level of fat intake in the diet should be guided by emphasis on adequate consumption of fruits, vegetables, and grains; a healthy weight goal; and, as described below, dietary intake of saturated fatty acids and cholesterol appropriate to individual risk for CHD (Adebayo & Ibiso, 2010).

Njoku, Onyia and Okeke (2009) stated that the AHA emphasizes restriction of saturated fatty acid intake because this is the strongest dietary determinant of plasma LDL cholesterol levels. Different saturated fatty acids have varying abilities to raise blood cholesterol. Total plasma and LDL cholesterol levels are mainly affected by lauric (12 carbon atoms), myristic (14 carbon atoms), and palmitic (16 carbon atoms) acids. Reduced intake of these cholesterol-raising saturated fatty acids has resulted in a reduction in plasma LDL cholesterol levels in well-controlled dietary studies. Short-chain (less than 10 carbon atoms) fatty acids and stearic acid (18 carbon atoms) have little effect on cholesterol levels.

Currently the AHA recommendation for the general population is that less than 10% of total calories come from saturated fatty acids. Equations developed from carefully controlled clinical studies indicate that reducing saturated fat intake from the current average intake of 12% to 14% of calories can lead to an average reduction of 3% to 5% in CHD risk in the population as a whole. There is, however, inter-individual variation in plasma LDL cholesterol response to reduced intake of saturated fatty acids, partially influenced by genetic factors. For this reason and also because of varying CHD risk status, population-wide guidelines do not address the specific needs of all individuals. In particular, persons with elevated LDL cholesterol levels that are responsive to diet can benefit from even greater limitation of dietary saturated fatty acids, such as 7% or less of total calories. Specific dietary guidelines for persons at higher risk have been developed by the AHA and the Expert Panel of the National Cholesterol Education Program.  Because foods contain fatty acids in varying types and amounts, it is not practical to design an eating pattern that selectively eliminates or replaces one fatty acid with another. For example, food labels list total fat by category. For the purpose of designing an eating pattern, all saturated fatty acids are considered equivalent (Njoku, Onyia & Okeke, 2009).

According to Mustapha (2008), reduction in caloric intake resulting from limitation of total saturated fatty acids may be beneficial for achieving and maintaining a healthy body weight. When it is appropriate to reduce plasma lipid and lipoprotein levels while maintaining caloric intake, saturated fatty acids in the diet can be replaced by either polyunsaturated or monounsaturated fatty acids, carbohydrates, or protein, all of which have differing effects on plasma serum lipids and lipoproteins. High intakes of omega-6 polyunsaturated fatty acids, however, have been reported to increase risk of formation of gallstones. In addition, results of animal studies suggest that high intake of polyunsaturated fatty acids (more than 10% of calories) may promote cancer. The AHA currently recommends that intake of omega-6 fatty acids be no more than 10% of total calories. Omega-3 polyunsaturated fatty acids, derived primarily from fish, can also be substituted for dietary saturated fatty acids and as discussed below may have beneficial effects beyond those associated with lowering LDL cholesterol levels.

In recent years there has been an interest in monounsaturated fatty acids as a suitable replacement for saturated fatty acids. Although their net effect on serum lipids and lipoproteins is not much different from that of polyunsaturated fatty acids, they may have some advantages. Unlike polyunsaturates, monounsaturates are not as susceptible to oxidation, which may play a role in atherogenesis. The AHA therefore recommends a monounsaturated fatty acid intake in the range of 10% to 15% of total calories (National Cholesterol Education Program, 2010).

Another factor deserving attention is the use of trans fatty acids. Trans fatty acids found primarily in hydrogenated vegetable oils tend to raise cholesterol levels relative to their nonhydrogenated counterparts. This increase appears to be less than occurs with similar amounts of saturated animal fat or highly saturated vegetable oils, eg, coconut and palm kernel oils. Among the few data available, analyses using plasma or tissue levels of trans fatty acids as a measure of intake suggest that CHD risk is associated with trans fatty acids derived from animal products but not with those from hydrogenation of oils. In addition, there is no clear dose-response effect for trans fatty acid intake and CHD risk. Based on this limited information, the AHA recommends limiting trans fatty acid intake, for example, by substituting soft margarine for hard. The AHA also encourages the food industry to develop more products with reduced trans fatty acid content.

Dietary cholesterol can increase plasma and LDL cholesterol levels and in epidemiological studies has been shown to be related to CHD risk independent of its effects on blood cholesterol levels. When compared with the effects of saturated fatty acids, the effects of dietary cholesterol on LDL cholesterol levels are weaker but can be substantial in some individuals. As with intake of saturated fatty acids, there is considerable inter-individual variation in response to dietary cholesterol, which should be considered when making individual dietary recommendations. Currently the AHA recommends that dietary cholesterol intake be less than 300 mg/d.

Choose a diet with plenty of vegetables, fruits, and whole-grain products.

These foods should contribute the majority of daily energy intake—between 55% and 60% of total calories. Fruits, vegetables, whole grains, and legumes provide important vitamins, minerals, fiber, and complex carbohydrates as part of a diet moderate in total fat and low in saturated fat content.

Diets high in unrefined carbohydrates also tend to be high in both soluble and insoluble fiber. Foods rich in soluble fiber, including oats, barley, beans, soy products, guar gum, and pectin found in apples, cranberries, currants, and gooseberries can help maximize a reduction in plasma total and LDL cholesterol levels as part of a fat-modified diet. Total dietary fiber intake of 25 to 30 g/d from foods, not supplements, will help ensure an eating pattern high in complex carbohydrates and low in fat (Bell, Hectorn, Reynolds & Hunninghake, 2009).

4. Choose a diet moderate in sugar

The AHA encourages consumption of complex carbohydrates in the form of grains, vegetables, and legumes. Sugar intake has not been directly related to risk for cardiovascular disease, but diets high in refined carbohydrates are often high in calories and low in complex carbohydrates, fiber, and essential vitamins and minerals.

5. Use salt and sodium in moderation.

The AHA recommends that the general public consume no more than 6 grams of sodium chloride per day. This recommendation is based on the evidence for an association between dietary sodium chloride intake and blood pressure derived from a substantial number of epidemiological observations and clinical trials of salt restriction (Tang, 2011).

Results of therapeutic trials of sodium chloride restriction in hypertensive individuals also document modest but significant reductions in blood pressure. However, there is considerable variation among blood pressure responses to sodium chloride restriction, and there is no simple, reliable test to accurately predict salt sensitivity. Although there is general agreement in the scientific community that salt restriction can improve blood pressure in hypertensive individuals, there are no clear data that allow definition of a desirable upper limit for salt intake. In the United States most current estimates of average sodium chloride intake range from 7.5 to 10.0 g/d. The AHA has elected to support the recommendation of the US Dietary Guideline Committee to limit sodium chloride intake to 6 g/d.

However, slightly higher intakes (6.0 to 7.5 g/d) have not been demonstrated to increase cardiovascular risk or raise blood pressure in normotensive persons without other cardiovascular risk factors. The recommended guideline is an admittedly arbitrary recommendation for avoiding excessive salt intake rather than an attempt to impose low salt intake (Tang, 2011).

Based on the totality of the evidence, the AHA has concluded that the recommendation that the general public limit daily sodium chloride intake to 6 g/d is prudent and safe, will not restrict intake of other nutrients, and may have a significant impact on prevention of cardiovascular disease. Reduced sodium intake should be only one component of a comprehensive nutritional approach to blood pressure lowering, which should also include prevention and treatment of obesity, limitation of alcohol intake, and strategies that ensure adequate intake of potassium, magnesium, and calcium.

6. Drink alcoholic beverage in moderation

Incidence of heart disease in those who consume moderate amounts of alcohol (an average of 1 to 2 drinks per day for men and l drink per day for women) is lower than that in non-drinkers. However, with increased consumption of alcohol, there are increased public health dangers, such as alcoholism, hypertension, obesity, stroke, cardiomyopathy, a number of cancers, liver disease, accidents, suicides, and foetal alcohol syndrome. In addition, some persons with an inherited predisposition to a variety of metabolic conditions, such as hypertriglyceridemia, pancreatitis, and porphyria should not consume alcohol at all. For the person beginning to drink alcohol, alcohol addiction and alcoholism is a real threat, heightened by a familial predisposition to alcoholism. In consideration of these risks, the AHA concludes that it is not advisable to issue guidelines to the general population that may lead some persons to increase their intake of alcohol or start drinking if they do not already do so. The advisability of consuming alcohol in moderation (no more than 2 drinks per day) is best determined in consultation with the individual’s primary care physician (Klatsky, Armstrong & Friedman, 2012).

7. Balance food intake with physical activity

Loss of excess weight and long-term maintenance of a healthy weight can improve blood lipid levels and blood pressure and reduce risk for heart disease, the most common form of diabetes, stroke, and certain cancers (Stunkard, 2006). In many individuals with increased abdominal or visceral fat, even modest weight reduction may result in improvement in many metabolic coronary heart diseases (CHD) risk factors, particularly those associated with insulin resistance, including low high-density lipoprotein (HDL) level, elevated triglyceride level, and small dense low-density lipoprotein (LDL) (Blackburn, 2010). Successful long-term maintenance of a healthy body weight can be promoted by regular physical activity in conjunction with a diet that is limited in calories, particularly those derived from fat, and relatively rich in complex carbohydrates and fiber (Blair, 2007).

Importance of following these dietary guidelines

There are many reasons to follow these dietary guidelines:

Balancing of Calories

• Enjoy your foods, but eat less.
• Avoid oversize portions
• Prevent and or reduce overweight and obesity through healthy eating and physical activity.
• Control your total calorie intake to manage your weight. For people who are overweight or obese, this means eating fewer calories from food and drinks.
• Increase your physical activity and reduce the time you are not moving.
• Prevention of some disease condition. To prevent some disease condition, the Dietary Guidelines for Americans recommended eating lots of fruits, vegetables, whole grains and low fat or non fat dairy products. It further emphasised on the following:
• Balancing the food intake with your activity to reach and stay at a healthy weight.
• Limiting foods high in cholesterol, sugar, sodium, fats. Some of the diseases are hypertension and renal/kidney failure.

Management of some disease conditions

To maintain and manage some disease condition, a healthy diet may improve or maintain optimal health by eating enough calories, but not too many during each stage of life – childhood, adolescent, adulthood, pregnancy, breastfeeding and old age.

Implementation of dietary guidelines

1. Make half your plate of fruit and vegetables.
2. Switch to fat free or low fat (1%) milk.
3. Eat different vegetables especially dark green, red and orange vegetables, beans and peas. Eat more vegetables and fruits. Eat at least half of all grains as whole grains, replacing refined grains with whole grain.
4. Eat more fat free or low fat milk products such as yogurt, cheese or fortified soy beverages.
5. Eat different protein foods such as seafood, lean meat and poultry, egg, beans and peas, soy products and unsalted nuts and seeds.
6. Replace protein foods that are higher in solid fats with choices that are lower in solid fats and calories and or sources of oil. Replace some meat and poultry with seafood. Use oil to replace solid fats, like butter where possible. Choose foods that provide more potassium, dietary fibre, calcium and vitamin D. these foods include vegetables, fruits, whole grains, milk and milk products.

Conclusion/recommendations

A healthy eating habit is important in guaranteeing a healthy lifestyle; free from diseases and complications. In order to achieve this, one must make a conscious effort in making dietary decision by sticking to healthy food habit and avoiding diet that can pose dangers to their health and also balancing this healthy habit with adequate and appropriate physical activities.

References

Adebayo, J. & Ibiso, M. (2010). Can lifestyle changes reverse coronary heart disease? The Lifestyle Heart Trial. Lancet. 336:129-133.

American Heart Association (2008). Diet and Heart Disease. New York, NY: AHA.

Bell, L.P.; Hectorn, K.J.; Reynolds, H. & Hunninghake, D.B. (2009). Cholesterol-effects of soluble-fiber cereals as part of a prudent diet for patients with mild to moderate hypercholesterolemia. Am J Clin Nutr. 52,1020-1026.

Blackburn, G (2010). Effect of degree of weight loss on health benefits. Obes Res. 3(suppl 2),211-216.

Blair, S.N. (2007). Evidence for success of exercise in weight loss and control. Ann Intern Med.119,702-706.

Klatsky, A.L.; Armstrong, M.A. & Friedman, G.D.(2012). Alcohol and mortality. Ann Intern Med. 117,646-654.

Mustapha, M. (2008). Polyunsaturated fatty acids result in greater cholesterol lowering and less triacylglycerol elevation than do monounsaturated fatty acids in dose-response comparison in a multiracial study group. Am J Clin Nutr. 62,392-402.

National Cholesterol Education Program (2010). Second report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel II). Circulation. 89,1333-1445.

Njoku, C. Onyia, N. & Okeke, M. (2009). Quantitative effects of dietary fat on serum cholesterol in man. Am J Clin Nutr. 17,281-295.

Stunkard, A.J. (2006). Current views on obesity. Am J Med.100:230-236.

Tang, Y.C. (2011). Relation of electrolytes to blood pressure in men: the Yi people study. Hypertension. 17,378-385.

United States Dietary Guideline Committee (2005). Nutrition and Your Health: Dietary Guidelines for Americans (4th ed.) Home & Garden Bulletin 232.