Dr Bhuvaneshwari Shankar
Changes in dietary patterns can lead to changes in NCDs rates and health gains unmatched by any other interventions.
Non-communicable diseases (NCDs), together with injuries and violence, are now causing about 60% of the deaths worldwide. The five major NCDs are heart disease, stroke, cancer, chronic respiratory diseases and diabetes. There is strong scientific evidence that healthy diet and adequate physical activity (i.e. 30 minutes of moderate intensity physical activity, 5 days per week) play an important role in the prevention of these diseases. It is not only the adult lifestyle that determines the risk level of chronic diseases. Diet and nutrition throughout the life cycle affects the later health outcomes.
The industrial revolution in the last 200 years has introduced radical changes in methods of foodproduction, processing, storage, and distribution. Economic development together with recent technological innovations and modern marketing techniques have modified dietary preferences, and consequently, led to major changes in the composition of diet.The accelerating factors for the rapid transition include globalization, e.g. exposure to the global mass media, shift in occupational structure including the trend from labour-intensive occupations and leisure time activities toward more capital-intensive, less strenuous work and leisure.
Eating habits and dietary intakes are changing rapidly. Substantial increases in the intakes of fats, refined sugars and salt have led to imbalanced nutrition and overnutrition. At the same time chronic diseases are becoming more common while undernutrition as a public health problem still persists in many parts of the world. Changes in dietary patterns can lead to changes in NCDs rates and health gains unmatched by any other interventions.
The role of diet in the aetiology of most NCDs is extremely important. The shift towards refined foods and meat and dairy products (what has been termed the “nutrition transition) is increasingly occurring with resultant rises in obesity and NCDs.
Consuming predominantly plant-based diets reduces the risk of developing obesity, diabetes, cardiovascular diseases, and some forms of cancer. Plant-based diets are high in vegetables and fruits, whole grains, pulses, nuts and seeds, and have only modest amounts of meat and dairy. These diets help to achieve and maintain a healthy weight, reduce blood pressure, and are also rich in sources of dietary fibre (which protects against colorectal cancer).
Whole grains and fibre
Whole grains and fibre have a protective effect against NCDs due to their bulky texture which ensures a limited time period within the digestive system, inhibiting development of tumours and malignant transformation. In addition, whole grains are rich in nutrients and phytochemicals. Whole grains can contribute to maintaining normal weight by being relatively low in energy density. A number of epidemiological studies have shown that whole grains are protective against cancer, CVD, diabetes and obesity.
Fruit and vegetables
Fruits and vegetables have a high content of vitamins, minerals, antioxidants and phytochemicals and play a positive role in preventing CVD, Diabetes and specific cancer types. Fruit and non-starchy vegetables are also very low in energy-density; contributing with increased satiety to maintain normal weight. It is likely that particular vegetables and fruits, including cruciferous vegetables such as cabbage and broccoli, and many fruits or vegetables that are rich in folate, also protect from developing cancers of the colon and rectum, mouth, pharynx, larynx and oesophagus. It is important to ensure a wide variety of fruits and vegetables are included in meals as they are rich in different vitamins and minerals. Low fat cooking methods such as steaming or grilling can be used to retain maximum nutrients.
Red and processed meat
Eating red and processed meat increases risk of developing colorectal cancer. Red meat and highly processed meats i.e. meats which have been smoked, salted or added preservatives are convincingly associated with increased risk of NCDs especially CVD and several cancers. Red meats are together with dairy products the main source of saturated fat in the diet, and have negative effects on blood cholesterol levels. Red meats might also strain the digestive system by staying in the body longer time. Diets high in meat and dairy also increase blood pressure.
Lean meat and poultry with visible fat and skin removed are high in iron and can be included in the diet. Fish should be included regularly, particularly oily fish high in omega 3 fatty acids such as salmon and sardines. Low fat cooking methods such as grilling, poaching, dry frying or steaming can be utilized to minimize extra fat added during the cooking process.
Fats can have both harmful and protective effects against NCDs depending on the source and type of fat. Poly- and monounsaturated fats are generally viewed as having protective effects against NCD especially CVD, while trans and saturated fats have negative effects.
Polyunsaturated, monounsaturated fatty acids from fish and plant sources exert protective effects by lowering the harmful and total blood cholesterol. This group includes the essential omega 3 and 6 fats which improve blood flow, stabilize blood sugar levels and inhibit inflammation and plaque formation in the arteries.
Trans and saturated fatty acids mostly originating from animal sources and partially hydrogenated vegetable oils increase risk of NCDs by causing high levels of the harmful type of cholesterol. They stay in blood stream for longer resulting in higher fasting insulin concentrations and lower insulin sensitivity. Trans fats are not essential in the human diet. Trans fat increases the risk of CVD and abdominal fat distribution; recent research suggests that the most efficient improvements in risk of CVD are seen by replacing trans fat with polyunsaturated fat as opposed to eliminating trans fat.
Sugar and high energy density foods
Sugar contributes to the energy-density of foods and contains no essential nutrients (i.e. “empty calories) and increases the risk of weight gain. Sugar is not causally related to CVD or cancer, however high sugar consumption is increasingly linked to obesity and Type 2 Diabetes. Most international recommendations, suggest that sugar should not exceed more than 10 % of total energy intake. Diets high in energy-dense, highly-processed foods and refined starches and/or sugary beverages contribute to overweight and obesity.
Dairy products are generally seen as a good source of essential nutrients vitamin A and calcium. However, dairy products, together with red meat are the primary dietary source of saturated fat. There is some evidence suggesting that milk probably protect against some cancers. Dairy products high in saturated fat are furthermore convincingly linked to NCDs. To reduce fat and calories it is best to choose low fat or fat free varieties.
Higher sodium/salt intake is a major risk factor for elevated blood pressure and cardiovascular diseases, and probably stomach cancer. Salt and salt-preserved foods are related to increased blood pressure, cholesterol levels and risk of cancer.
Overall nutrient intake adequacy improves with an increasing variety of foods.Consumption of vegetables and fruit, the amount and quality of fat ingested, and the intake of salt are the most important elements of the dietary prevention of both cardiovascular diseases and cancers. Maintaining normal weight and adequate physical activity throughout the life span are the most effective ways of preventing diabetes and many other chronic diseases.Diet, together withphysical activity, plays a major role in combating the emergence ofNCDs.
“We are what we eat is a common refrain and reflects the great importance of food and diet.