Dietary fat (lipids) provide energy and essential fatty acids for various functions in the body. Lipids are divided into four groups comprising of fatty acids, glycerides, non-glyceride lipids, and complex lipids. A mixture of triglycerides, small proportions of phospholipids, glycolipids, monoacylglycerols, diacylglycerols and unsaponifiable fraction are collectively called non-glyceride lipids. Fatty acids which are the building blocks of various lipids are classified into saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs).
Functions of fatty acids
Fatty acids exist in the bloodstream, in cells and tissues of the human body. The impact on the health and biological activities in the body vary according to the different types of fatty acids. In general we can say that fatty acids are used in a number of ways, like energy sources in the absence of glucose and provide efficient neural communication. Fatty acids are an important part of cell membranes and influence membrane fluidity as well as lipid protein interactions. Fatty acid activities influence cell and tissue metabolism and are essential for the function, and responsiveness of hormonal and other cells signals. They also regulate the production of bioactive lipid mediators. Fatty acids are important for the development of the central nervous system. They have an impact on diet-related non-communicable diseases (DR-NCD), namely, coronary heart disease (CHD), diabetes and cancers. During pregnancy fatty acids play an important role in the development of the infant’s brain, retina and growth tissues which the foetus can get only from the mother.
Non-glyceride components provide nutrition and promote health
- The non-glyceride components of fats from animal foods contain cholesterol and fat soluble vitamins A, E, D
- Plant foods and vegetable oils have fat soluble vitamins, E, D, K and carotenoids, plant sterols and a wide range of other chemical compounds
- Plant sterols as well as unique non-glyceride components like oryzanols and sesame lignans lower LDL cholesterol in the blood
- Vitamin E, carotenoids, sesame lignans, oryzanols and phenols have antioxidant effects
The hypocholesterolemic (low levels of cholesterol in the blood) and antioxidant effects is better with a combination of non-glyceride lipid components. Therefore, taking plant sterols and other non-glyceride components from natural plant foods and vegetable oils could provide an additional dietary means that could prevent and correct dyslipidemia (large amounts of lipids) and increase the antioxidant potential of human diets.
The total fat intake in Indian diet comes from these sources
- small amount of fat is present in each and every item of food (invisible fat)
- fat in processed and ready to eat foods (hidden fat)
- vegetable oil, ghee, butter and vanasapati used for cooking (visible fat)
Fats are an integral component of foods (invisible fat)
- Edible plant foods have a low content of fat and saturated fatty acids (SFAs) except nuts and oilseeds and are fairly good sources of MUFAs and PUFAs.
- In most cereals, millets, legumes and pulses fat content ranges between 1.5-3 percent while maize, bajra, bengal gram and soyabean have higher content
- In cereals, millets and most oilseeds, linoleic acid (LA) is the major fatty acid whereas pulses / legumes, green leafy vegetables, some oilseeds (soyabean, rapeseed/mustard, perilla seed and flaxseed) and fenugreek are good sources of both LA and alpha-linolenic acid (ALA)
- Animal foods like fatty dairy products like butter, ghee, whole milk, cream, fatty cheese and fatty meats provide cholesterol, high amounts of SFAs and are a natural source of Trans fatty acids (TFAs) (5 % of total fatty acids).
- Lean meats have fairly high content long-chain polyunsaturated fatty acids (LC PUFAs). The meats of animals that graze on grass and in the wild contain less fat, SFAs and higher LC Omega-3 PUFAs as compared to meats of those animals that are captivity fed on grain based rations.
- Poultry meat contains less fat and cholesterol but appreciable amounts of PUFAs including LC PUFAs.
- Egg has high cholesterol but is a good source of LA, ALA and docosahexaenoic acid (DHA).
- Fish has less fat, SFAs and cholesterol and is a good source of LC omega-3 PUFAs. The fat content and relative contents of eicosapentaenoic acid (EPA) and DHA vary in fish and other sea foods. The total quantity of invisible fat and its fatty acid composition depend on the kind of diet eaten
Vegetable oil used in cooking is the major source of visible fat consumed and others are vanaspati and ghee. India has a wide range of edible vegetable oils (groundnut, rapeseed/mustard, soybean, sunflower, sesame, safflower, rice bran, cottonseed and linseed). The type of vegetable oil consumed varies from one part of the country to the other. Vanasapati (PHVO) is used in Haryana, Punjab, Himachal Pradesh, and Uttar Pradesh as cooking medium. In most parts of the country, vanasapati is used as a substitute for ghee in Indian sweets and savoury foods. It is also used in preparing commercially fried, processed, ready-to-eat, packaged, frozen, premixed foods and street foods. In recent years the health claims have affected the choice of cooking oil(s) in the urban population. The relative proportions of fatty acids are known to vary in different visible fats. Depending on the percentage of various fatty acids, fats and oils can be grouped as oils containing:
i) high SFAs
ii) high MUFAs
iii) low (less than 20%), medium (20-40%) or high (more than 40-70%) LA
iv) both LA and ALA
The traditional rape-mustard seed oils contain 50% erucic acid. There are many concerns about the negative effects of erucic acid which led to the development of low / zero erucic acid rapeseed variety and the oil is sold as canola oil. Butter, ghee, coconut oil and palm kernel oils are rich sources of short and medium chain SFAs. Partial hydrogenation of vegetable oils results in the formation of several trans isomers. During refining of vegetable oils, deodorization step contributes to formation of trans isomers, the contents should be less than 1% of total fatty acids. PHVO like vanasapati, bakery fats and margarines are the main modifiable source of TFAs in Indian diets.
Fat intake in Indians
The total fat intake in the Indian population is income dependent and therefore highly skewed, the intake being low among rural and urban poor income groups. Diet surveys by the National Nutrition Monitoring Bureau show that daily intake of visible fats in rural India ranges from 6-22g and the median is 13g of consumption per unit. The intake of total fat and PUFAs calculated by putting together the total fats and contents of LA and ALA from cereals, millets, pulses/legumes and milk and any one vegetable oil (median 13 g/consumption unit ) shows that diets of the rural population (including children, pregnant and lactating women) provides less than14 % total fat calories. Depending on the type of vegetable oils consumed, the levels of LA range between 3 to 7%E. Efforts to increase the dietary levels of total fat and Omega-3 PUFAs in the rural population would contribute to lifelong health and wellbeing.
In the urban middle and upper income groups the daily intake of visible fat ranges between 22-45grms per day and total fat in their diets furnish 20-33%E. Studies on plasma lipid fatty acid compositions in urban upper middle income groups have shown that a large proportion of Indian subjects have inadequate omega -3 PUFA nutritional status. To provide fat quality consistent with good health, it is necessary to increase omega-3 PUFAs in the diets of the urban segments.
Recommended intake of dietary fats for Indians
The ICMR recommendations for dietary fats in Indians have been revised taking into account
- the latest recommendations of the FAO and WHO
- total fat, individual fatty acids and health promoting non-glyceride components
- sources of dietary fats in Indians
- availability of fat
The recommendations are directed towards meeting the requirements for optimal foetal and infant growth and development, combating chronic energy deficiency (children and adults) and DR-NCD in adults.
NOTE: The guidelines and recommendations in the article and the table below are as per Indian Council of Medical Research (ICMR) criteria.
Recommendations for dietary fat intake in Indians
|Physical activity||Minimum level of Total fat|
|Fat from foods other than visible fats ͩ %E||Visible Fat ᵍ|
|Adult Man||Sedentary|| |
|Adult Woman||Sedentary|| |
|Infants||0-6 months||40-60||Human milk ͥ|
|7-24 months||35ᵇ||10 ͨ||25||25|
|Children||3-6 years|| |
a This has been referenced by ICMR from FAO/WHO Expert Consultation on Fats and Fatty Acids in Human Nutrition
b gradually reduce depending on physical activity
c Human milk /infant formula+ complementary foods
d if higher than 10%E, visible fat requirement proportionately reduces
g cooking oils, butter, ghee and margarine
i infant formulae/ milk substitutes should mimic contents of fat and fatty acids in human milk including arachidonic and docosahexaenoic acid.