The concept of a healthy diet is constantly evolving, reflecting our growing understanding of how various foods, essential nutrients, and other food components affect health and disease. A wealth of evidence indicates that consuming certain nutrients, food groups, or overall dietary patterns positively influences health and helps prevent common non-communicable diseases (NCDs).
Introduction
This article explores the numerous benefits of adopting a healthy diet, drawing upon scientific evidence and expert recommendations. It examines how a healthy diet can contribute to overall well-being, disease prevention, and improved quality of life.
Greater consumption of health-promoting foods and limited intake of unhealthier options are intrinsic to the eating habits of certain regional diets such as the Mediterranean diet or have been constructed as part of dietary patterns designed to reduce disease risk, such as the Dietary Approaches to Stop Hypertension (DASH) or Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets. In comparison with a more traditional Western diet, these healthier alternatives are higher in plant-based foods, including fresh fruits and vegetables, whole grains, legumes, seeds, and nuts and lower in animal-based foods, particularly fatty and processed meats.
Defining a Healthy Diet
A healthy diet is one in which macronutrients are consumed in appropriate proportions to support energetic and physiologic needs without excess intake while also providing sufficient micronutrients and hydration to meet the physiologic needs of the body. Macronutrients (i.e., carbohydrates, proteins, and fats) provide the energy necessary for the cellular processes required for daily functioning.
Macronutrients: The Building Blocks
- Carbohydrates: The primary source of energy, found abundantly in grains, fruits, legumes, and vegetables. Whole grains are preferred over processed grains due to their higher fiber and micronutrient content. Meta-analyses have linked increased whole-grain intake to a reduced risk of coronary heart disease, stroke, cardiovascular disease, and cancer, as well as to the decreased risk of mortality due to any cause, cardiovascular disease, cancer, respiratory disease, diabetes, and infectious disease.
- Proteins: Provide energy and amino acids, essential for bodily functions. Dietary proteins come from animal (meat, dairy, fish, and eggs) and plant (legumes, soya products, grains, nuts, and seeds) sources. Adequate protein intake is vital for maintaining lean body mass, especially in older adults, preventing age-related muscle loss, preserving bone mass, and reducing fracture risk.
- Fats: Essential for cell structure and energy. Dietary fats include monounsaturated, polyunsaturated, saturated, and trans fats. Unsaturated fats are linked to reduced cardiovascular and mortality risks, while trans fats and, to a lesser extent, saturated fats have negative health impacts. Omega-3 and omega-6 fatty acids are essential and must be obtained from dietary sources. Omega-3 fatty acids, particularly EPA and DHA, have potential health benefits, including cardioprotection, preventing cognitive decline, reducing inflammation, sustaining muscle mass, and improving systemic insulin resistance.
Micronutrients: The Vital Regulators
Although required in trace amounts compared with macronutrients, micronutrients are necessary for normal growth, metabolism, physiologic functioning, and cellular integrity. The shift from whole foods to processed, refined foods has reduced the micronutrient quality of the modern Western diet. Vitamin and mineral inadequacies have been implicated in cellular aging and late-onset disease, as scarcity drives chronic metabolic disruption.
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Hydration: The Body's Foundation
Water is the principal component of the body, constituting the majority of lean body mass and total body weight. Water not only provides hydration but also carries micronutrients, including trace elements and electrolytes. Drinking water may supply as much as 20% of the daily recommended intake of calcium and magnesium.
Health Benefits of a Nutritious Diet
Following a healthy diet has many benefits, including building strong bones, protecting the heart, preventing disease, and boosting mood. A healthy diet typically includes nutrient-dense foods from all the major food groups, including lean proteins, whole grains, healthy fats, and fruits and vegetables of many colors.
Preventing Non-Communicable Diseases (NCDs)
Non-communicable diseases (NCDs) such as cardiovascular disease, cancer, chronic respiratory diseases, diabetes, obesity, and cognitive impairment are among the leading causes of death and disability throughout the world, affecting populations in developed as well as developing countries. Dietary choices, for example, contribute to the risk for developing hypertension, hypercholesterolemia, overweight/obesity, and inflammation, which in turn increase the risk for diseases that are associated with significant morbidity and mortality, including cardiovascular disease, diabetes, and cancer.
The World Health Organization (WHO) includes strategies for addressing unhealthy diet patterns among its initiatives directed at reducing behavioral risk factors; the other components comprise physical inactivity, tobacco use, and harmful alcohol use. Dietary changes recommended by WHO include balancing energy intake, limiting saturated and trans fats and shifting toward consumption of unsaturated fats, increasing intake of fruits and vegetables, and limiting the intake of sugar and salt.
Supporting Heart Health
The foods people eat can reduce their blood pressure and help keep their hearts healthy. The DASH diet, or the Dietary Approaches to Stop Hypertension diet, includes plenty of heart-healthy foods. The program recommends:
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- eating plenty of vegetables, fruits, and whole grains
- choosing fat-free or low fat dairy products, fish, poultry, beans, and nuts
- limiting saturated and trans fat intake, such as fatty meats and full-fat dairy products
- limiting drinks and foods that contain added sugars
- restricting sodium intake to less than 2,300 milligrams per day - ideally 1,500 mg daily - and increasing consumption of potassium, magnesium, and calcium
Limiting certain types of fats can also improve heart health. For instance, eliminating trans fats reduces low-density lipoprotein (LDL) cholesterol levels. This type of cholesterol causes plaque to collect within the arteries, increasing the risk of a heart attack and stroke.
Reducing Cancer Risk
The American Institute for Cancer Research recommends a diet rich in a variety of fruits and vegetables, whole grains, and beans to support overall health and potentially reduce the risk of developing cancer. Some people believe that antioxidants in these foods play a key role in preventing cancer. However, according to the National Cancer Institute, while laboratory and animal studies link certain antioxidants to a reduced incidence of free radical damage due to cancer, human trials remain inconclusive. Indeed, doctors advise against using these dietary supplements without consulting them first. Having obesity may increase a person’s risk of developing cancer and result in less favorable outcomes. Maintaining a moderate weight may reduce these risks.
Boosting Mood and Mental Health
Some evidence suggests a close relationship between diet and mood. According to a 2020 study, diet can affect several factors which, in turn, may impact a person’s mood. These include blood glucose levels, immune activation, and the gut microbiome. The researchers also found that certain diets, such as the Mediterranean diet, may be linked to better mental health. The opposite is true for diets with high amounts of red meat, processed foods, and high fat foods.
Maintaining Cognitive Function
A healthy diet may help maintain cognition and brain health. The following diets incorporate many of these elements and are associated with a lower risk of cognitive decline and dementia: Mediterranean diet, Nordic diet, DASH diet, MIND diet.
Managing Weight
Maintaining a moderate weight can help reduce the risk of chronic health issues. A person who has more weight or obesity may be at risk of developing certain conditions, including coronary heart disease, type 2 diabetes, osteoarthritis, stroke, hypertension, certain mental health conditions, and some cancers. Many healthy foods, including vegetables, fruits, and beans, are lower in calories than most processed foods. Maintaining a healthy diet can help people stay within their daily limits without monitoring their calorie intake.
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Preventing and Managing Diabetes
A healthy diet may help a person with diabetes: manage their blood glucose levels, keep their blood pressure within target ranges, keep their cholesterol within target ranges, prevent or delay complications of diabetes, and maintain a moderate weight. People with diabetes must limit their intake of foods with added sugar and salt. They should also consider avoiding fried foods high in saturated and trans fats.
Strengthening Bones and Teeth
A diet with adequate calcium and magnesium is important for strong bones and teeth. Keeping the bones healthy can minimize the risk of bone issues later in life, such as osteoporosis. Dairy products, kale, broccoli, and canned fish with bones are good sources of calcium. Food manufacturers often fortify cereals, tofu, and plant-based milk with calcium. Magnesium is abundant in many foods, and some of the best sources include green leafy vegetables, nuts, seeds, and whole grains.
Improving Sleep Quality
Eating lots of processed foods that are low in fiber and high in saturated fats can interfere with deep sleep. That’s the stage of sleep that allows you to feel your best when you wake up. For a better night’s sleep, get plenty of fiber from vegetables, fruits, and whole grains. Choose low-fat protein sources. And go for foods that are high in B vitamins, which may help regulate melatonin, the sleep hormone.
Enhancing Eye Health
Eating foods rich in vitamins C and E, zinc, lutein, zeaxanthin and omega-3 fatty acids can be good for your eyes. You can lower your risk of serious eye conditions that can cause blindness, such as age-related macular degeneration and cataracts.
Reducing Inflammation and Arthritis Symptoms
The Mediterranean diet offers plenty of anti-inflammatory foods. They are rich in antioxidants and vitamins that can help ease joint pain and improve other symptoms of arthritis. Those include fatty fish rich in omega 3s (like salmon), unsalted nuts and seeds, and beans.
Healthy Dietary Patterns: Examples
Based on our understanding of nutritional requirements and their likely health impacts as described above, healthy dietary patterns can be generally described as those that are rich in health-promoting foods, including plant-based foods, fresh fruits and vegetables, antioxidants, soya, nuts, and sources of omega-3 fatty acids, and low in saturated fats and trans fats, animal-derived proteins, and added/refined sugars. Patterns such as these are naturally occurring in certain regions of the world and rooted in local/regional tradition and food sources, as is the case for the traditional Mediterranean and Asian diets.
The Mediterranean Diet
The Mediterranean diet is based on components of the traditional dietary patterns of Euro-Mediterranean countries and encompasses not only the types of foods consumed and their relative contributions to daily nutrient intake, but also an approach to eating that is cognizant of how foods are sourced (e.g., sustainability and eco-friendliness), cooked, and eaten, as well as lifestyle considerations such as engaging in regular physical activity, getting adequate rest, and participating in fellowship when preparing and sharing meals. The primary basis of daily meals in the Mediterranean diet is cereals such as whole-grain bread, pastas, couscous, and other unrefined grains that are rich in fiber and a variety of fruits and vegetables of different colors and textures that are high in micronutrients, fiber, and phytochemicals. Dairy products, preferably low-fat yogurt, cheese, or other fermented dairy products, are recommended daily in moderation as a source of calcium, which is needed for bone and heart health. Olive oil serves as the primary source of dietary lipids and is supplemented with olives, nuts, and seeds. Water (1.5-2.0 L/day or ~8 glasses) is recommended as the main source of hydration, whereas wine and other fermented alcoholic beverages are generally permitted in moderation, to be consumed with meals. Fish, white meat, and eggs are the primary sources of protein; red meat and processed meats are consumed less frequently and in smaller portions.
Research has revealed beneficial effects of the Mediterranean diet on a number of NCDs and related health measures, including cardiovascular and cerebrovascular disease, cancer, glycemic control, and cognitive function. Substudies have also shown that, compared with a low-fat control diet, the Mediterranean diet supplemented with olive oil or nuts is associated with a 30% reduced risk of major cardiovascular risk events and reductions in systolic blood pressure (SBP) and diastolic blood pressure (DBP) of 5.8-7.3 mmHg and 3.3-3.4 mmHg, respectively. Greater intake of polyphenols (phytochemicals found in fruits, vegetables, tea, olive oil, and wine) correlated with a 36% reduced risk of hypertension and improvements in inflammatory biomarkers related to atherosclerosis, as well as in high-density lipoprotein cholesterol (HDL-C).
The DASH Diet
The DASH diet derives its name from the Dietary Approaches to Stop Hypertension study, which evaluated the influence of dietary patterns on blood pressure. Patients who consumed a diet that was rich in fruits, vegetables, and low-fat dairy and that included a reduced amount of saturated and total fat and cholesterol experienced significantly greater reductions in blood pressure than patients who consumed a control diet that was similar in composition to a typical American diet or a diet rich in fruits and vegetables with a reduced amount of snacks and sweets.
Practical Advice for Maintaining a Healthy Diet
- Fruit and vegetables: Eating at least 400 g, or five portions, of fruit and vegetables per day reduces the risk of NCDs and helps to ensure an adequate daily intake of dietary fibre.
- Fats: Reducing the amount of total fat intake to less than 30% of total energy intake helps to prevent unhealthy weight gain in the adult population. Also, the risk of developing NCDs is lowered by reducing saturated fats to less than 10% of total energy intake, reducing trans-fats to less than 1% of total energy intake, and replacing both saturated fats and trans-fats with unsaturated fats - in particular, with polyunsaturated fats.
- Salt, sodium and potassium: Reducing salt intake to the recommended level of less than 5 g per day could prevent 1.7 million deaths each year. Intake of potassium can be increased by consuming fresh fruit and vegetables.
- Sugars: In both adults and children, the intake of free sugars should be reduced to less than 10% of total energy intake. A reduction to less than 5% of total energy intake would provide additional health benefits.
Addressing Barriers to Accessing Healthy Foods
There are barriers to, and disparities in, the accessibility and availability of foods that support healthy dietary patterns. Distance to grocery stores and lack of transportation are barriers that can inhibit access to healthy food options. Predominantly Black and Hispanic neighborhoods have fewer large chain supermarkets than predominantly White and non-Hispanic neighborhoods. Lack of access to foods that support healthy dietary patterns may have a greater impact on members of racial/ethnic minority communities, residents of low-income communities, and those living in rural areas, especially older adults, due to the other social and environmental determinants they tend to face. Affordability also influences access to foods that support healthy dietary patterns. Low-income groups tend to rely on foods that are cheap and convenient to access but are often low in nutrients. Improving access to foods that support healthy dietary patterns is one method for addressing health disparities and population health.
Strategies for Promoting Healthy Diets
Diet evolves over time, being influenced by many social and economic factors that interact in a complex manner to shape individual dietary patterns. balanced and healthy diet - requires the involvement of multiple sectors and stakeholders, including government, and the public and private sectors. Governments have a central role in creating a healthy food environment that enables people to adopt and maintain healthy dietary practices. Effective actions by policy-makers to create a healthy food environment include the following:
- Creating coherence in national policies and investment plans - including trade, food and agricultural policies - to promote a healthy diet and protect public health
- Promoting appropriate infant and young child feeding practices