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Palm oil use and compatibility in India

Bagepalli S. Narasinga Rao

Abstract

India is experiencing a shortage of edible oils that may increase in years to come. To meet this challenge, palm oil is being considered as a potential new source of oil owing to the high productivity of the oil palm. Besides importing palm oil for the present, indigenous production by cultivating the oil palm has been initiated as a long-term measure.

When a new edible oil is introduced, people have to be assured of its safety and nutritional quality. Besides ensuring that palm oil meets essential fatty acid (EFA) requirements, concern about its atherogenic potential due to its saturated fat content has to be allayed. The habitual low-fat Indian diet based on cereals and pulses contains invisible fats amounting to 25 g per day, but it provides two-thirds of EFA requirements. Increased consumption of fat in the form of palm oil should therefore not pose a problem to the requirements since the oil contains about 10% of n-6, 18:2 linoleic acid. Although categorized as a saturated fat, palm oil does not raise blood cholesterol, unlike other fats such as coconut oil. Unrefined crude palm oil, which is rich in ß-carotene, is also of special interest as it can be used to prevent vitamin A deficiency, which is widespread In India.

Owing to its technical characteristics, palm oil can be used in domestic cooking as well as in the foodprocessing industry for the manufacture of vanaspati and margarine, and as a specialty fat in the bakery and confectionery industries.

Edible oil supply and demand in India

Vegetable oils are the main source of dietary fat in India. The country is fortunate in having a wide range of sources of edible oils, the most important being groundnuts, mustard seed, and rapeseed, which together account for approximately 60% of the supply (table 1). The current annual production of edible oils from all sources, amounting to 4.8 million tons, is nevertheless inadequate to meet the demand, with the shortfall estimated to be on the order of a million tons, and this gap is bound to widen in years to come.

The current availability of edible oil per capita is about 15 g per day, which may be adequate to meet minimum nutritional needs [2]. However, the shortage in relation to the amount needed to meet the level of intake of visible oil or fat recommended as desirable by nutrition experts, 25 g per day [2], is much larger, namely 2.2 million tons.

Dietary fat intake in India is highly skewed and varies widely among different groups depending on socio-economic status (table 2) and the region of the country. It is reported that a mere 5% of the affluent population consumes nearly 30% of the available fat [3]. Visible fat intake among the bulk of the population in the lower socio-economic groups in both rural and urban areas is quite low, the daily intake per person being less than 10 g. It is fortunate that the habitual diets of these people, based as they are on cereals and legumes, provide nearly 25 g of invisible fat per day that is rich in polyunsaturated fatty acids [4].

Concerted efforts have been made to boost the productivity of the traditional oil seeds so as to improve the supply of edible oils, and significant improvements in the yields of rape, mustard, and other seeds have been achieved in recent years. However, these efforts are inadequate to meet fully the shortage in the country at present and in the future, and therefore alternative sources have to be sought.

The potential of palm oil in meeting demand

In view of the high productivity of the oil palm and palm oil's availability and competitive cost, it is considered a potential new source to meet the increasing demand for edible oil. Large quantities have been imported since the mid-1980s; annual imports reached a little over a million tons a few years ago, but more recently they have fallen back to about 300,000 tons.

TABLE 1. Estimated annual supply and demand of edible oils in India, 1989-1990

Source: Ref. 1.

TABLE 2. Dietary fat intake by socio-economic group in India

Computed from dietary intake data of the National Nutrition Monitoring Bureau, ICMR.

a. Rural incomes in rupees per month.

There are also plans to encourage the cultivation of oil palms in favourable regions of the country in order to produce the oil locally. Several areas have been identified as suitable [5], and large-scale cultivation was initiated in several states (Andhra Pradesh, Karnataka, and Kerala) a few years back. The first indigenously produced and processed palm oil is likely to be introduced into the market in 1993 or 1994, and quantities are expected to increase progressively in years to come. In the interim, however, significant quantities may still have to be imported to meet the needs.

The palm oil already imported has helped the population to become accustomed to this previously unfamiliar oil. There are wide regional and individual differences in preference for the type of edible oil consumed. In recent years, however, the availability of highly refined and double-refined oils has largely eliminated such preferences, and now oils are chosen mainly for their physical, chemical, and cooking properties and their nutritional quality, availability, and cost. In view of this trend, the introduction of palm oil with its good nutritional and cooking qualities may not pose much problem, and it is likely to play an important role in the economy. However, people need to be assured of its safety and nutritional advantages.

The nutrition and health impact of palm oil

Since palm oil will only supplement the traditional edible oils, its nutritional and health impact will be different from what it would be if it completely replaced a traditional oil. Therefore it needs to be examined in relation to other oils and the composition of the habitual diets, both of which can modify its impact.

Two major considerations are its capacity to meet the essential fatty acid requirements of the major segment of the population whose current level of fat consumption is low, and the health implications of its saturated fat content when it is consumed at higher levels by the affluent in relation to the risk of atherosclerosis and cardiovascular diseases. Several minor components of palm oil also have considerable potential health significance: Carotenoids and tocols can act as antioxidants, with various beneficial effects, and in particular the high ß-carotene content in neutralized crude palm oil can be used to advantage to meet the vitamin A needs of India's population and to prevent the widely prevalent vitamin A deficiency.

Palm oil as a source of essential fatty acids

Most of the vegetable oils traditionally consumed in India have a high content of the essential fatty acid (EFA) linoleic acid, ranging from 22% to 75%.

TABLE 3. Minimum daily intake of different edible oils needed to meet the EFA requirement for an Indian adult

Based on a cereal and legume diet of 2,400 kcal per person per day, with 25 g of invisible fat providing 2 en% of EFA and the edible oil to provide an additional 1 en% of EFA (linoleic acid).

They can easily meet the EFA requirements of the population even at low levels of fat intake [2]. Can palm oil, with only 10% linoleic acid, also meet the requirements if used as the sole source of visible fat?

Fortunately, nearly two-thirds of the EFA requirements are already met by the invisible fat in the habitual diets of the Indian people based on cereals and legumes [2, 4, 6]. As already noted, cereals, pulses, and vegetables contribute nearly 25 g of invisible fat per person a day, with one-third of its fatty acid content being linoleic acid. Such diets can contribute nearly 2 en% (2% of total energy) of EFA, with another 1 en% to be provided by visible fats. The daily intake of different oils needed to meet the additional EFA adult requirement is given in table 3. A daily intake of 5-10 g of most of the traditional oils other than coconut oil can satisfy the requirement for an adult on a cereal- and legume-based diet. If palm oil were the only source of visible fat, an intake of 27 g per day, or 10 en% of the diet, would be necessary to meet the requirement. On the other hand, if palm oil is used together with other edible oils, except coconut oil, a daily intake of a smaller amount (say, 10 g) will suffice.

The adequacy of palm oil as the sole source of visible fat to meet EFA requirements with a cereal- and legume-based diet has been demonstrated in rats [7]. When growing rats were fed palm olein at a level of 5% in their diet, there was no evidence of deficiency in their plasma EFA profile. Rats fed coconut oil at the same level showed EFA deficiency. On a casein-based semisynthetic diet, rats fed palm oil exhibited a marginally inadequate EFA status.

Recent studies on the effect of palm oil on the long-chain EFA (LC-EFA) content of membrane lipids in both humans and animals [8] indicate that the capacity of palm oil as a sole source of fat, with only 10% linoleic acid, to meet EFA requirements may be due to a more efficient conversion of the linoleic acid originating from palm oil to LC-EFA in the body. The LC-EFA content of plasma phospholipids and platelets in human volunteers fed palm oil was comparable to that when the subjects were fed groundnut oil with 30% linoleic acid. Similar observations have been reported in studies comparing the fatty acid composition of membrane lipids in rats fed palm oil with those fed groundnut [7, 9], safflower [9], or sunflower-seed oil [10]; the LC-EFA content of tissues in those fed palm oil was comparable to that in those fed safflower or sunflower-seed oil with high levels of EFA (table 4). These preliminary observations on the greater efficiency of conversion of linoleic acid in palm oil to LC-EFA need to be confirmed by more detailed studies in human subjects, perhaps with the use of stable isotopes.

TABLE 4. Long-chain EFA composition of phospholipids in rats fed palm oil and other edible oils

Values are mean ± SEM.

a. Plasma phospholipids.
b. Total phospholipids.
c. Platelet phospholipids.

TABLE 5. Effects of introducing palm oil on the fatty acid profile of the national supply of edible oil

SFA = saturated fatty acids.
MUFA = mono-unsaturated fatty acids.
PUFA = polyunsaturated fatty acids.
P:S = polyunsaturated to saturated.

TABLE 6. Linoleic acid intake of different socio-economic groups in India if the visible fat in their diets were replaced with palm oil

The effect on the weighted average linoleic acid content of India's edible oil pool of introducing palm oil on a large scale, say 1-2 million tons a year, to meet the edible oil shortage is shown in table 5. Even with 2 million tons of palm oil, the linoleic acid content of the pool would be reduced only from 28% to 23%, which would not have a significant impact on the EFA intake of the population.

The effect on the total EFA content (visible + invisible) of the diets of various socioeconomic groups of replacing currently consumed oils entirely with palm oil is shown in table 6. Consuming palm oil as the sole edible oil would not compromise the EFA intake of any of the groups; the total EFA intake would remain at 4.4-5.7 en%, which is more than adequate to meet requirements. Thus it is evident that the introduction of palm oil in India will not have any adverse effect on the EFA status of the population.

Possible effects on hypercholesterolaemia and cardiovascular disease

Since palm oil has a high percentage of saturated fatty acids (50%), principally palmitic acid, and lower levels of polyunsaturated fatty acids (PUFA; 10%), with a polyunsaturated to saturated (P:S) ratio of 0.2, it is reasonable to be concerned about whether it has a hypercholesterolaemic potential like that of other saturated fats of either animal origin (butter, tallow, lard) or vegetable origin (coconut, hydrogenated vegetable fats); in some Western countries it is viewed as a saturated tropical oil with a potential for causing cardiovascular disease. It must be pointed out in the first place, however, that the potential of any dietary saturated fat for causing hypercholesterolaemia is particularly related to the level of its consumption. Only when they are consumed at high levels are saturated fats an important risk factor in hypercholesterolaemia and cardiovascular disease [11]. At low levels of consumption, such as prevail among the bulk of the Indian population, that kind of risk may not apply even though there may be a risk in affluent populations with a high fat intake.

Furthermore, the hypercholesterolaemic risk of consuming high levels of palm oil has been investigated extensively in experimental animals and in human subjects in various countries with different types of diets, and all these studies have established that palm oil does not behave like a saturated fat in its effects on blood cholesterol or blood clotting, as might be anticipated from its fatty acid composition [12-14]. In some of the studies, palm oil was compared with other saturated fats such as coconut oil or animal fats such as butter, lard, or tallow and, unlike them, did not raise blood cholesterol either in humans or in animals. In some studies, in fact, it not only reduced blood cholesterol [15] but also demonstrated an antithrombotic effect [16].

Among the factors contributing to the exceptional character of palm oil in not raising blood cholesterol or promoting blood clotting may be the following:

>> The main saturated fatty acid in palm oil, palmitic acid, is considered less hypercholesterolaemic than the short-chain fatty acids present in other saturated fats such as coconut oil and animal fats. Palm oil contains few short-chain fatty acids such as lauric and myristic acids.
>> Palm oil, like many other vegetable oils, is rich in the mono-unsaturated fatty acid (MUFA) oleic acid (40 % ), which has recently been shown to have a hypocholesterolaemic influence [17].
>> In the triglyceride molecules of palm oil, palmitic acid predominantly occupies the a position and the unsaturated fatty acids the ß position (75%). It is reported that saturated fatty acids such as palmitic acid and stearic acid are more hypercholesterolaemic when they are in the ß position in the triglyceride molecule, as in lard and coconut oil, than in the a position, and this positional arrangement has been considered a factor responsible for the absence of a hypercholesterolaemic effect in palm oil [18,19].
>> In one study palm oil fed to experimental animals produced a balance of eicosanoids, a thromboxane:prostacyclin ratio, that favoured an anti-aggregatory tendency [9, 20].
>> The vitamin E tocotrienols present in palm oil are known to reduce circulating cholesterol concentrations in humans [21, 22]. This effect is attributed to a dose-dependent inhibition by tocotrienols of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase [23, 24] thus inhibiting the in vivo synthesis of cholesterol in the liver and thereby lowering serum cholesterol, particularly of the low-density lipoprotein (LDL) fraction.

In assessing the possible impact of palm oil in India in relation to its atherogenic and cardiovascular disease potential, three important factors have to be taken into account:

Level of fat intake

The risk of hypercholesterolaemia and consequent cardiovascular complications is high only when fat intake exceeds 30% [11]. As pointed out earlier, the fat intake of the bulk of the Indian population does not exceed 10 en%, and consumption of palm oil at this level, even as the sole source of fat, should pose little risk of cardiovascular disease. Even among the affluent, who constitute less than 10% of the population and whose fat intake may equal or exceed 30 en% (80-100 g per day), the consumption of palm oil as the principal fat should pose little risk on the basis of recent findings [15]. In addition, typical Indian diets contain significant amounts of invisible fats rich in PUFA, high dietary fibre [25], and other hypocholesterolaemic factors like spices.

Invisible fat with high PUFA content

According to current concepts [20, 25] the influence of high fat intake on cardiovascular status depends on the fatty acid profile and the P:S ratio, both of which can be modified by fatty acids contributed by invisible dietary fat. The effect of exclusive palm oil consumption on the P:S ratios of the diets of different socio-economic groups with different levels of fat intake is shown in table 7. The net effect of invisible fat on the overall fatty acid profile of a diet containing palm oil is to reduce the proportion of saturated fatty acids and to increase the proportion of PUFA and the P:S ratio. The P:S ratio in the low-income groups remains above 0.5, which is considered desirable.

The potential effect of consuming palm oil as the source of visible fat on the composite fatty acid profile and P:S ratio in the high-income group is shown in table 8. Palm oil would have a limited influence on the fatty acid profile of the total diet, and the P:S ratio would remain at 0.4. However, if instead of palm oil other saturated fats such as coconut oil or vanaspati were consumed, the P:S ratio would decline to 0.2, which is known to be associated with the risk of hypercholesterolaemia. Since palm oil is not likely to be consumed exclusively but only in combination with other traditional edible oils with high PUFA, the dietary fatty acid profile and P:S ratio can be expected to be much less affected.

TABLE 7. Effect of various oils as the sole source of visible fat on the P:S ratios of the diets of different socio-economic groups

a. Hydrogenated vegetable oil.

TABLE 8. Effect of different oils on the dietary fatty acid profile and P:S ratio in the high-income group

Dietary fat intake: invisible, 46 g per day: total, 95 g per day.

As shown in table 5, even with the introduction of 2 million tons of palm oil annually, the overall fatty acid profile of the country's edible oil pool would not be greatly affected, and the P:S ratio would remain nearly 1.0.

Blood lipid values

The effect of palm oil consumption on blood fatty lipid values in a group of middle-income volunteers has been investigated [8]. Employing a crossover design, 12 adult men on a lactovegetarian diet (2,400 kcal per day) were fed either palm oil or groundnut oil at a level to provide about 30% of total dietary fat calories. The results indicated that consumption of palm oil as the sole source of visible fat at a level of 30 en% total fat calories did not adversely influence either the content of blood lipids or the aggregability of whole blood or platelets. The effect of a palm oil-enriched diet on blood lipid values was comparable to that observed for the groundnut oil diet.

Nutrition and health benefits of minor components of palm oil

Palm oil contains several minor chemical components in its unsaponifiable fraction (table 9), of which carotenoids and tocols (tocopherols and tocotrienols) are important. These two components can act as powerful antioxidants. In addition, carotenes can serve as a source of provitamin A in meeting the vitamin A needs of the population, which is of particular interest in India to combat widespread vitamin A deficiency. The presence of carotenes and tocotrienols, which distinguish palm oil from other edible oils, is a major factor in its nutritional superiority, offering special nutrition and health benefits that are not obtainable from other edible oils currently in use.

TABLE 9. Minor components in crude palm oil

Carotenes

Crude palm oil is the richest natural source of carotenoids, with a content varying from 500 to 700 µg per gram (table 10). Unfortunately, the carotenes are completely destroyed during the processing of refined palm oil, so that it is of no value in preventing vitamin A deficiency [25].

Vitamin A deficiency is widespread in India because of the low intake of carotene-rich fruits and vegetables that are the main sources of provitamin A. Currently 1,162 µg of [carotene is available per person per day from all food sources, meeting only 50% of the estimated requirement [26] (table 11). The introduction of crude palm oil could help to meet the shortage; a daily intake of 3 g of red palm oil per capita should make up the deficit (1,200 µg). That would require 870,000 (or approximately 1 million) tons a year to cover the entire population's provitamin A requirements.

Since all carotenes are lost during the refining of palm oil by the present process, a technological innovation is needed to avoid such loss. Some simple processes have been developed to retain most of the ß-carotenes [29], but the unpleasant odour of such treated red palm oil remains a problem.

A recent seminar emphasized the importance of red palm oil as a source of §-carotene to combat vitamin A deficiency, particularly among women and children [27]. A programme of action and research to prevent the disorder in children by introducing red palm oil through a supplementary feeding programme was initiated by the Nutrition Foundation of India with the support of UNICEF and FAO. Studies have also been carried out at the National Institute of Nutrition to establish the safety and acceptability of red palm oil and the stability of its carotenes under different methods of cooking [28].

TABLE 10. Crude palm oil as a source of ß-carotene (provitamin A)

TABLE 11. ß-carotene economy in India

Tocopherols and tocotrienols

Palm oil, like other vegetable oils, contains tocols that can act as natural biological antioxidants. However, it is distinct in that it contains a high level of tocotrienols as well as tocopherols. The latter are commonly present in many other vegetable oils, but not tocotrienols. It is also interesting that palm oil has a high tocol content despite its low level of PUFA. In other vegetable oils, the tocopherol content is usually directly related to that of PUFA; the higher the level of PUFA, the higher that of tocols.

Tocols have a number of health-promoting biological functions. Together with carotenoids, they act as antioxidants to protect tissues and membranes from free radical damage [30] and to prevent lung and oral cancers and the damaging effects of environmental toxins. The tocotrienols in palm oil have beneficial effects on blood cholesterol and platelet aggregation. This potential source of antioxidants will augment the low antioxidant potential of Indian diets.

Uses of palm oil as food

Blending with other edible oils

Besides being marketed for use by itself as a liquid oil, palm oil can be promoted for blending with other edible oils and for use in the food-processing industry. Because of its moderately low linoleic acid content it is admirably suited for blending with oils with a high PUFA content-for example, soy-bean, safflower-seed, sesame-seed, and sunflower-seed. Although high-PUFA oils were advocated in the past as hypocholesterolaemic, it is now realized that they may not be desirable as they can lead to oxidative damage and the formation of free radicals, which may be potential carcinogens. During frying, high PUFA oils cause the formation of undesirable polymerized compounds. An intake of linoleic acid (PUFA) exceeding 10% of total energy is no longer recommended [11].

An ideal edible oil is one in which the ratio of saturated, mono-unsaturated, and polyunsaturated fatty acids is close to 1:1:1 [11]. By blending palm oil with high-PUFA oils in proper proportions, one can achieve such a ratio. Blending palm oil with soy-bean and rapeseed oils will also help to reduce the high linolenic acid content of the latter to a more acceptable level. The quality of the oils can also be improved in terms of other characteristics such as storage stability, heat stability, and cloud points by blending.

Some examples of possible blends are given in table 12. All of them have an S:M:P ratio close to 1:1:1, but their other characteristics such as stability will have to be studied.

Other food uses

Palm oil lends itself to a wide range of food uses both in the domestic kitchen and in the food industry [31]. It can be profitably used in the food-processing industry, thus releasing other oils for conventional uses.

Frying

Palm oil with its moderate linoleic acid content, very low linolenic acid content, and high levels of natural antioxidants is admirably suited for direct use in most frying operations, and this is its major use worldwide. It does not undergo much oxidative damage at a temperature of 180°C, unlike other vegetable oils with a high linoleic acid content. It can be used for frying domestically, in restaurants, and in snack-food manufacturing.

TABLE 12. Fatty acid profiles of blends of palm oil with other edible oils

Vanaspati

The production of vanaspati (hydrogenated vegetable oil) is the major industrial use of vegetable oils in India. Current production is around 800,000 tons a year. Substituting palm oil could release a significant quantity of conventional vegetable oils for other use. Palm oil has certain advantages for this purpose, such as the fact that it does not need hydrogenation. Research is needed to determine the maximum quantity of palm oil that can be used without modifying the characteristics of the vanaspati, and technical guidelines will have to be developed.

Margarine

Palm oil and palm kernel oil are highly suitable for manufacturing margarine. Palm oil with ß-carotene can help to produce margarines that are naturally coloured. This is of special interest in India, where the artificial colouring of margarine is prohibited. These margarines can be used at the table as well as in the baking industry.

Miscellaneous

Palm oil has been widely used as a bakery shortening, in confectionery, in dairy products such as filled milk and ice cream, and in coffee whiteners. In some of these applications, it can be a substitute for cocoa butter, saving on the use of imported cocoa butter.

The Indian Nutrition Advisory Committee on Palm Oil has recommended several projects to promote the use of palm oil in the food industry, particularly in the manufacture of vanaspati and margarine.

Conclusion

A wider use of palm oil, obtainable at a lower market cost than other edible oils, would offer distinct advantages in India, both in alleviating the shortage of edible oils and in providing health benefits, especially as a rich source of provitamin A and of nutritional antioxidants. It would in particular be in the country's interest to carry out further research on the applicability of palm oil in feeding programmes for children and women.

Improved technologies for refining palm oil without destroying its provitamin A value, as current methods do, are needed, however, because processed crude palm oil or red palm oil is likely to encounter consumer resistance because of its colour and odour.

Strong consumer-oriented market research is needed before the presently available products can be marketed adequately. Some of the resistance to crude palm oil or red palm oil may be overcome by promoting it as a health food; encouraging its use in curries and pickles, which have strong natural colour and flavour; substituting it for tumeric, which is normally used as a colouring spice in Indian cooking; and blending it with other edible oils to reduce the intensity of colour. Blending can also help to promote the consumption of palm oil by providing additional ways of using it.

The use of palm oil can be advocated as a response to the inadequate supply of domestic edible oils without fear of any compromise on the nutritional health of the people.

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