Online edition of Daily News - Lakehouse Newspapers Compiled and coordinated by Edward Arambewala
There is the need to clarify issues relating to intake of coconut fats and health, more particularly for populations that still depend on coconut fats for much of their fat intake.
This paper describes the metabolism of coconut fats and its potential benefits, and attempts to highlight its benefits to remove certain misconceptions regarding its use.
Coconut consumption and lipid patterns in Sri Lanka
A recent study has shown that in Sri Lanka, whereas 91 per cent of the poor still consume coconut as their main source of fat, only 70 per cent of those earning more than Rs. 5,000 use coconut oil.
The amount of coconut consumed is less than 5 years ago for 75 per cent of those surveyed. Thus study also found that one of the reasons for reduced coconut consumption was a misconception that coconut fats are bad. The misconception has arisen due to the fact that coconut fat is mainly saturated fat, and saturated fats are synonymous with atherosclerosis, ischaemic heart disease and cerebrovascular disease.
There remains the question whether coconut fats have actions other than those in relation to lipid hypothesis of atherosclerosis, ischaemic heart disease and cerebrovascular disease which need to be considered when answering the above question. Ischemic heart disease
To answer that, one would have to first look at coconut consumption and possible relationship to the prevalence of ischaemic heart disease and cerebrovascular disease in Sri Lanka. Kaunitz states that the Demographic Yearbook of the United Nations (1978) reported that Sri Lanka has the lowest death rate from ischaemic heart disease.
Sri Lanka was quoted as being the only country giving reliable data where coconut oil is the main dietary fat. This was at a time when average coconut consumption was around 130 nuts/person/year.
On the other hand, according to Abeywardena, the incidence of ischaemic heart disease and cerebrovascular disease in Sri Lanka is increasing at an alarming rate and is similar to that of the developed world. Central Bank of Sri Lanka reports show that the coconut consumption has now declined to around 100-110 nuts/person/year.
Are coconut fats the culprit
Under the circumstances, are coconut fats the culprit or have they been given a bad name simply by virtue of its fat being greater than 90 per cent saturated fat?
Epidemiologic studies both in Sri Lanka and elsewhere, have failed to clearly establish a relationship between coconut fats, atherosclerosis and ischaemic heart disease.
The classic study by Prior among Pacific islanders whose diet contained large amounts of coconut showed a low prevalence of heart disease, cancer, diabetes and arthritis.
Mendis has attributed this to a 'protective effect' of omega-3 fatty acids from the fish these people ate. Other, more recent studies on small population samples have failed to establish a clear link between consumption of coconut products and atherosclerosis, ischaemic heart disease and cerebrovascular disease.
Case control studies comparing the diet of patients with ischaemic heart disease and controls have come out both for and against a causative role for coconut fats. Coconut fats and lipids
The possible role of coconut fats in disturbances of lipid metabolism is also not well established. Many allopathic medical practitioners seem to think that, as coconut fats are saturated, they elevate plasma lipids in the same manner as the saturated fats from animal sources.
Adding to the misconception is the fact that many of the animal studies on the role of coconut fats in lipid metabolism have used hydrogenated coconut oil. This is an unnatural form of coconut oil that is purposely altered to make it completely devoid of any essential fatty acids.
The conclusion that can be drawn from such animal research is that feeding hydrogenated coconut oil devoid of essential fatty acids enhances the formation of atherosclerosis markers. However, coconut oil, unlike much of the soybean and corn oil consumed both here and abroad, is free of hydrogenated fat and hence transfatty acids.
In human feeding studies, coconut fats without doubt elevate high density lipoprotein (HDL) cholesterol. The effect on total cholesterol and low density lipoprotein (LDL) cholesterol is probably neutral. It is also possible that women may react differently to men when fed a coconut diet.
A Sri Lankan study found that the risk of coronary heart disease as assessed by the body mass index, ratios of total cholesterol to HDL-cholesterol, and LDL-cholesterol to HDL-cholesterol, was significantly lower in subjects in rural areas, who were agricultural workers with a high degree of physical activity, subsisting on a diet consisting mainly of plant food, despite a higher consumption of coconut, a saturated fat.
This study also suggest that hyperlipidaemia is more common among urban dwellers than among the rural population. This difference was attributed to lower fruit, vegetable and fibre content in the diet and lower physical activity among the urban population. Yet from Peiris' study we know the rural poor consume more coconut than city dwellers.
Abeywardena has proposed that a low fat diet with predominantly coconut fat may lead to the 'metabolic syndrome' and thus be associated with the increasing prevalence of ischaemic heart disease and cerebrovascular disease. However, this needs to be proven by good epidemiologic studies.
Virgin coconut oil when fed to rats is reported to lower lipid levels in serum and tissues, and LDL oxidation.
This property of virgin coconut oil is attributed to the biologically active polyphenol components present in the oil. Other studies have shown that consumption of a solid fat rich in lauric acid gives a more favourable serum lipoprotein pattern than consumption of partially hydrogenated soybean oil rich in trans-fatty acids.
Other effects of coconut oil
What of the claim that coconut fats decrease platelet adhesiveness? Hard data are not readily available. A 1993 study comparing a high fat diet (50 per cent of total energy) to a low fat diet (20 per cent) suggested that the high fat diet might increase blood thrombogenicity by virtue of augmented postprandial activation of factor VII. A more recent 2003 study showed that a lesser increase in FVIIa occurred after the consumption of saturated fats, than after unsaturated test fats.
Others have attempted to study the effects of individual fatty acids on whole blood aggregation and concluded that compared to oleic acid, lauric, myristic or palmitic acids do not effect in vitro whole blood aggregation induced by collagen ADP-induced aggregation.
Compared to a high unsaturated fat or high polyunsaturated fat diet, a coconut oil-based diet lowers postprandial t-PA antigen concentration, and this may favourably affect the fibrinolytic system and the Lp (a) concentration.
What of other benefits that may accrue from eating coconut oil? Many readers may not be aware of the close similarity among the medium chain triglycerides in coconut fats, human breast milk and the secretion of sebaceous glands, all rich in lauric acid.
Monolaurin and even lauric acid have been shown to be bactericidal, particularly against Helicobater pylori, Vibrio cholerae, Salmonella typhi, Shigella sonnei and enterotoxigenic Escheichia coli. coconut oil also helps the body to increase absorption of calcium and magnesium ions.
It has been suggested that coconut oil is used to supplement treatment of rickets in poorly developed countries, alongside infant formulae supplemented with these inorganic ions.
No work has been done with coconut fats per se. However, it is interesting to speculate whether monolaurin and lauric acid released by pre-gastric lipase may contribute to the reported low incidence of Helicobacter pylori infection in Sri Lanka compared to other South Asian countries.
Current understanding based on the effect of dietary lipid manipulation upon immune system function indicates that fatty acids are involved in the modulation of the immune response through complex pathways.
The problem with many animal studies is that they use hydrogenated coconut oil. One study where non-hydrogenated coconut oil was used showed that lipopolysaccharide-stimulated TNF-alpha production by macrophages decreased with increasing unsaturated fatty acid content of the diet."