Healthy oils: beyond trans fats
The link between trans fatty-acid consumption and increased risk of cardiovascular disease has changed the oil industry irrevocably. Mark J Tallon, PhD, investigates the current — and next — trans fatty-acid replacements
Trans fatty acids (TFAs) arise as a result of the hydrogenation processes. Early concerns that high intakes of TFA may increase the risk of coronary heart disease have been strengthened by recent studies.1 Further, there is evidence beyond that of cardiovascular dangers extending to foetal and neonatal growth and development.2 Given these adverse consequences, it is shameful that government organisations, such as the Food Standard Agency (FSA) in the UK, have not changed their labelling guidelines to come into line with those highlighting TFA content in foods, such as the FDA in the US.3
The attention on TFA negatives is leading consumers to healthier alternatives. In 2006, we had a whole host of health-promoting oils that provided food technologists with oil characteristics to blend into almost any food. The following studies provide a brief overview of healthy TFA replacements.
Obtained from a tropical plant, palm oil (Elaesis guineensis) is a form of edible vegetable oil and the second most widely produced edible oil, after soybean oil.4 In recent times there has been a growing research interest in palm oil, one of the major edible plant oils in tropical countries, because of the link between dietary fats and coronary heart disease.5
The purpose of a recently published study was to test if replacing TFAs by palmitic acid in margarine results in unfavourable effects on blood lipids.6 In this study authors compared the effects of margarines with palm oil (PALM-margarine), based on partially hydrogenated soybean oil (TRANS-margarine), and a margarine with a high content of polyunsaturated fatty acids (PUFA-margarine) in 27 young women for 17 days.
There were no significant differences in total cholesterol, LDL cholesterol and apoB between the TRANS- and the PALM-diet. However, HDL cholesterol and apoA-I were significantly higher on the PALM-diet compared to the TRANS-diet while the ratio of LDL- to HDL-cholesterol was lower, although not significantly on the PALM-diet.
The results from this suggest that, compared to partially hydrogenated soybean oil, dietary palm oil may have a more favourable effect on the fibrinolytic system, which breaks down cross-linked fibres to avoid excessive thrombosis/blood clots. From a nutritional point of view, palmitic acid from palm oil may be a reasonable alternative to trans fatty acids from partially hydrogenated soybean oil in margarine if the aim is to avoid TFAs.
Obesity and DAG
According to the American Obesity Association, approximately 127 million adults in the US are overweight, 60 million obese, and nine million severely obese.7 As such, the possibility of using a food-grade oil to ameliorate this social disease is intriguing.
In a recent study from the Department of Pediatrics at the Fussa Hospital, Japan, researchers investigated the effect of DAG oil as part of dietetic therapy in obese children.8 The participants were 11 male and female obese children who were under treatment at the outpatient clinic (four boys, seven girls, 7-17 years old). Daily-use cooking oil was changed to DAG oil, and the effects on abdominal fat areas, adipocytokines and serum lipids were investigated.
The total and subcutaneous fat areas significantly decreased following five months of DAG oil ingestion. Leptin was significantly lower than the initial level after ingestion of DAG oil. This study is one of the first to demonstrate that the ingestion of DAG oil decreased both the abdominal fat and leptin in obese children, suggesting that DAG oil prevents obesity in children as well as in adults.
Dual benefits of EPA
The control of energy in exercising and diabetic populations is of great importance in relation to physiological function. For those involved in competitive sports, particularly endurance sports, sparing muscle and liver glycogen (the body's glucose store) is vital to extending the capacity to keep exercising. In diabetics, the ability to transport blood glucose into tissues is also of great importance to avoid hyper- and hypoglycaemic responses.
In a study carried out at Oslo University College, Norway, researchers investigated the chronic effects of eicosapentaenoic acid (EPA) on fatty acid and glucose metabolism in human skeletal muscle cells. 9 In an in vitro study using cultured muscle cells, glucose transport and oxidation were shown to increase two-fold in EPA-treated muscle. Low concentrations of EPA also increased fatty acid and glucose uptake. Moreover, GLUT1 (the glucose transporter on muscle cells) expression was increased 2.5-fold by EPA. These data show that chronic exposure of muscle tissue to EPA promotes increased uptake and oxidation of glucose despite a markedly increased fatty acid uptake, and as such may provide benefits for diabetic populations.
The application of this message could be to enhance fuel utilisation from lipids during endurance sports, thereby sparing vital muscle-glycogen stores. For diabetics, treatment with EPA may aid in controlling blood-glucose levels, which may decrease the incidence of adverse consequences related to the diabetic condition.
Fighting deficiency: A global challenge
Vitamin A deficiency causes the drying out and scarring of the outer eye. Corneal scarring is the world's most common cause of childhood blindness. Almost 250,000 children have been blinded by vitamin A deficiency and a further 100 million are at risk.10 There are many solutions to this, but a cost-effective and natural remedy may come in the form of food oils.
Vitamin A (VA) deficiency is widespread in sub-Saharan Africa, and school-age children are a vulnerable group. In Burkina Faso, a nation within west Africa, the production and consumption of red palm oil (RPO) is being promoted as a food supplement for VA. A recent study assessed the impact on serum retinol by adding RPO to school lunch in two test zones of Burkina Faso.11 During one school year, 15ml RPO was added to individual meals three times a week across 24 schools and eight controls. Serum retinol was measured at baseline and 12 months later. The rate of low serum retinol went from 46.1 to 17.1 per cent in the VA capsule group and from 40.4 to 14.9 per cent in the RPO group.
In conclusion, the authors commented that RPO given regularly in small amounts appears highly effective in the reduction of VA deficiency. The largest effects are seen in those with the greatest deficiencies.
The market for 'trans-free oil' is now rapidly expanding and in some cases is outstripping demand. As such, US farmers are expected to plant some 750,000 acres of low-linolenic soybeans in 2007, as demand for the higher-stability, low-linolenic soybean oil outstrips supplies. As food manufacturers begin providing oils with a healthier nutritional profile, sources such as virgin oil, red palm seed oil, canola oil, tall oil and echium oil will proliferate the mainstream, making it just a little more difficult and competitive to keep a solid grip on these important oils.
Mark J Tallon, PhD, is chief science officer of OxygeniX, a London-based consultancy firm specialising in claims substantiation, product development and technical writing. www.oxygenix.com
Dr Tallon is also co-founder of Cr-Technologies, a raw-ingredients supplier. www.cr-technologies.net Respond: [email protected]
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5. No Author. Malaysian Oil Palm Statistics 2005. Malaysian Palm Oil Board and Council.
6. Lichtenstein AH, et al. Novel soybean oils with different fatty acid profiles alter cardiovascular disease risk factors in moderately hyperlipidemic subjects. Am J Clin Nutr 2006;84(3):497-504.
7. CDC, National Center for Health Statistics, National Health and Nutrition Examination Survey. Health, United States. 2002.
8. Matsuyama T, et al. Effects of diacylglycerol oil on adiposity in obese children: initial communication. J Pediatr Endocrinol Metab 2006;19(6):795-804.
9. Aas V, et al. Eicosapentaenoic acid (20:5 n-3) increases fatty acid and glucose uptake in cultured human skeletal muscle cells. J Lipid Res 2006;47(2):366-74.
10. UNICEF. The 2006 State of the World's Children: excluded and invisible. 2006.
11. Zeba AN, et al. The positive impact of red palm oil in school meals on vitamin A status: study in Burkina Faso. Nutr J 2006;5:17.