Diet Suffix In Diabetes

By JYOTI BALANI

If the estimated prevalence of diabetes mellitus worldwide in the year 2025 is going to be 300 million, India may have the maximum number -- nearly 85 million.

The cornerstone of therapy in diabetes is a lifestyle that centres around diet -- this may be supplemented by oral agents, or insulin. However, it should be emphasised that modification of dietary practices cannot work effectively in isolation. It has to be combined with lifestyle changes and augmentation of physical mobility.

Obesity produces a state of insulin resistance and compensatory hyperinsulinaemia. This leads to frank glucose intolerance, or diabetes. Hence, individuals with a family history of diabetes and obesity should be assessed routinely for the presence of carbohydrate intolerance and also encouraged to maintain desirable body weight. Approximately 80 per cent of patients with non-insulin dependent diabetes [NIDDM] are overweight. Hence, much dietary effort needs to be directed to achieve caloric reduction.

Blood glucose usually returns to normal as weight loss occurs in the obese diabetic patient. Weight loss also improves hypertension, hypertriglyceridaemia and hypercholesteraemia. In genetically susceptible individuals, data suggest that the degree of obesity, duration of obesity and specific distribution of excess body fat are associated with the development of NIDDM.

Diet For Diabetics

The American Diabetes Association has now abandoned its earlier approach of providing “Exchange” lists of major foods. Today, there is no one “diabetic'” diet. The recommended diet can only be defined as a dietary prescription based on nutritional assessment and treatment goals. Medical nutrition therapy for people with diabetes should be individualised with consideration given to eating habits and other lifestyle factors. Flexibility in use of ordinary foods is important for both patients and their families.

Caloric Content

The first decision in prescribing a diabetic diet is the caloric content of the diet, based on the need to gain or maintain current weight or, most universally, lose weight. Caloric recommendations from the Food and Nutrition Board for adults carrying out average activity is about 36 Kcal/kg for men and 34 Kcal/kg for women. Also, moderate caloric restriction of 500-1,000 Kcal below daily requirements may be optimal in producing a gradual, sustained weight loss.

Proteins

The minimal protein requirement for good nutrition is about 0.9 gm/kg body weight/day, and the acceptable range is 1.0-1.5 gm/kg/day [12-20 per cent of total calories]. The intake of proteins should be mainly in the form of vegetables, proteins [dal, legumes], and a small quantity of animal protein [skimmed milk, yoghurt, fish etc.,]. In patients with diabetic nephropathy, the protein content should be limited to 0.8 gm/kg/day, i.e., about ten per cent of the total calories, as it may slow down the progression of nephropathy. Vegetable proteins are anionic and tend to reduce albuminuria; they are useful in cases of diabetic nephropathy.

Reduction Of Fats

A restriction of fat is usually recommended, if weight loss is desired, because of the high energy content of fat relative to proteins and carbohydrates. An average recommendation for non-obese patients and those without hyperlipidaemia is that fat should make up 30 per cent or less of total calories, with less than 10 per cent as saturated fat. In hypercholesteraemic subjects, saturated fat should be lowered to less than seven per cent of calories; cholesterol level should be below 180 mg.

Saturated fat and n-6 polyunsaturated fat activate the production of arachidonic acid and consequently cytokines, which are potent vasoconstrictors and platelet aggregators. Excess of n-6 polyunsaturates are highly thrombogenic, immunogenic and proinflammatory. Metabolism of n-3 fat, on the other hand, leads to metabolites such as prostacyclin. The n-6/n-3 ratio of 4:1 prevents the tonic effects of n-6 polyunsaturated fat. Hence, the use of n-3 fat is desirable in a diabetic diet.

Fish oils are a rich source of n-3 fat. Monounsaturates have a salutory effect on lipid profile. They reduce levels of LDL ["bad"] cholesterol, triglycerides and VLDL cholesterol. Animal fats like dairy products, butter, ghee, and hydrogenated fats [vanaspati] are about 50 per cent saturated. They should be avoided. Some vegetable oils like coconut oil are over 90 per cent saturated. They should not be used.

Trans-Fatty Acids

Trans-unsaturated fatty acids have been demonstrated to cause an increase in total cholesterol, LDL cholesterol, and a fall in HDL ["good"] cholesterol. Natural sources of trans-fatty acids are mainly milk, butter, ghee and animal fats [beef and pork] which contain about five per cent trans-fatty acids. Much larger amounts of trans-fatty acids are found in manufactured products such as margarine, partially hydrogenated oils and fats used for deep frying and shortening. Deep frying also increases the percentage of transmonosaturated fat. This provides the rationale for avoiding hydrogenated oils [vanaspati], ghee, butter, red meat and fried foods.

Carbohydrates

After the protein and fat are chosen, the remaining calories are assigned to carbohydrates. The use of sucrose as a taste additive in mixed meals in a small quantity [up to five per cent of carbohydrate calorie intake] is acceptable in patients who are lean and do not have carbohydrate-aggravated hyperlipidaemia. Increasing the fibre content of the diet may be helpful. This could be made available from whole grains, pulses, green vegetables and fruits. However, use of purified fibre supplements is not recommended.

Anti-oxidants

Oxidant stress has now been implicated both in the causation of diabetes and the genesis of its complications like retinopathy and diabetic glomerulopathy. It has also been implicated in causing peripheral insulin resistance in Type-2 diabetes. Free radicals oxidise LDL and oxidised LDL is a potent atherogenic substance -- it has been linked to accelerated macroangiopathy.

Hence, foods like fruits, vegetables, spices and condiments, green tea and sprouts which are abundant sources of anti-oxidants must be included in a diabetic diet. Yellow vegetables such as carrots, tomatoes, pumpkin and fruits, such as papaya, are rich sources of beta-carotene. Sprouts are rich in vitamin E. Vitamin C is abundant in citrus fruits and guava. Minerals dissolve in cooking water; hence, vegetables should be steamed or cooked in microwave, instead of boiling. The absorption of iron in legumes, whole grains and green vegetables is better when a food high in vitamin C [i.e., orange juice; or, supplements] is taken at the same time.

Distribution Of Calories

The distribution of calories in the day is also very important, especially if hypoglycaemia has to be avoided in insulin-dependent patients. A typical pattern might include 20 per cent of the total for breakfast, 35 per cent for lunch, 30 per cent for dinner, and 15 per cent as a late evening feed. Often a mild morning and mid-afternoon snack are necessary as well. Vigorous adherence to diet is required in patients of NIDDM -- more so, in individuals who have not been treated with exogenous insulin, since their endogenous insulin reserve is limited, and they cannot respond to the increased demand produced by excess calories.

Exercise & Diabetes

The American Association of Clinical Endocrinologists [AACE] strongly advocates exercise along with appropriate diet in diabetic patients. Its bottom line is -- good healthy diet and good physical activity.