In a review article in this month's issue of British Nutrition Foundation's Nutrition Bulletin(31, 104-110), Professor Ian Givens of Reading University's Nutritional Sciences Research Unit argues that fortification of most commonly-consumed foods could impact incidence of several serious illnesses, including cardiovascular disease.
The current recommended intake of very long-chain omega-3 polyunsaturated fatty acids (PUFA) in the UK is 450mg per day. Yet on the basis of food consumption surveys, researchers estimate that the current mean intake amongst adults is only 282 mg per day, of which EPA and DHA contribute 244mg.
Omega-3 has been studied extensively for its potential to decrease the risk of cardiovascular disease. According to the British Heart Foundation, cardiovascular disease caused 39 per cent of deaths in the UK in 2002 - just under 238,000 people.
The cost of treating heart disease is costing the UK economy £29bn (€42.5bn) a year, according to recent research from the University of Oxford, accounting for a fifth of the National Health Service budget.
Since only about 27 per cent of adults actually eat any oily fish, and that alpha linolenic acid, from plant sources like flaxseed, are poorly converted in humans, Givens said there is a need to review current dietary sources of these fatty acids.
“If successful and accepted by the consumer, this could prove to be a major advance in the health of the nation,” said Givens.
In particular, he drew attention to the “significant impact on progression of conditions such as cardiovascular disease.”
Consumption of fish has seriously declined over the past 50 years in the UK. In the early 1950s mean consumption was around 230g per week, and it reached an all time low of around 130g in the late 1970s. It has since recovered slightly, to just under 150g.
The overall decrease is due to falling consumption of white fish rather than oil rich fish, however, and the average oily fish-eater now consumes an average of 194g per week.
But it still remains that less than a third of adults presently eats any oily fish at all.
Most meats do contain small amounts of omega-3, but these are just a fraction of the levels found in fish. For instance poultry contains 0.15mg/g EPA and 0.35mg/g DHA, compared to 7.8mg/g and 10.6mg/g respectively for oil fish. Bacon and ham contain just 0.0362mg/g and 0.0463mg/g.
Given that current Western eating habits are meat-heavy, Givens looked at the potential impact on intake for raising omega-3 levels in popular meats. Poultry came out on top in terms of intake per person per week (374g): If EPA was raised to 0.60mg/g and DHA to 0.80mg/g, poultry could contribute to 74.8mg omega-3 per person per day.
Givens wrote: “…Other useful contributions could be provided by eggs [54.3mg] and full-fat cheese [24.2mg], although the contributions fro liquid milk and other meats are likely to be modest based on current food consumption data.”
Some concern has been raised recently in opposition to fish oil being used in animal derivatives and animal feeds, most notably from The Vegetarian Society, on the grounds that it may lead to vegetarians inadvertently consuming fish.
Givens also considers the sustainability issues over continuing and increasing levels of fish-derived omega-3 in other food products due to over-fishing.
Other concerns are that the efficiency of incorporating omega-3 from the diet into edible tissue is low, that dietary fish oils in animal feed may give rise to higher levels of unhealthy trans fats in food from these animals, and that the oxidative stability of foods may be affected, which may impair smell and taste.
To work around these issues, he says that further work on the potential of industrially produced microalgae as dietary sources of omega-3 seem warranted.
Moreover, if current research into genetic modification of plants to synthesis DHA and EPA from their shorter chain precursors yields results and is accepted by consumers, “this could prove to be a major breakthrough”.
In 2004 the European market for the omega-3 was valued at US$194 million (around €160 million), more than three-quarters of which was generated by marine oils. Algae-derived products by the likes of Nutrinova and Martek Biosciences made up 19 per cent of the market.
