The 14-year study, led by Dr. Yasuyuki Nakamura at Shiga University of Medical Science, tracked 5,186 women, finding that those who consumed one or more eggs a day were more likely to die than women who ate one or two eggs a week.
"Limiting egg consumption may have some health benefits, at least in women in geographic areas where egg consumption makes a relatively large contribution to total dietary cholesterol intake," concluded the researchers in a paper published in the July edition of the American Journal of Clinical Nutrition.
Mixed messages about egg consumption and the role cholesterol - found in high levels in egg yolks - have plagued sales for the egg industry over the last decade. Only recently, sales have started to pick up on the back of the popular low-carb Atkins diet, which promotes an increase in protein consumption. A recent report from Mintel showed that while volume egg sales in the UK rose by some 10 per cent between 1999 and 2003, value sales increased by double this amount, at 23 per cent, due to consumers trading up to premium egg varieties and helped by consumer education campaigns to try to dispel myths that consumers should not eat more than three eggs per week.
But studies such as the latest Japanese research could impact an already vulnerable market. "Experts say that the results of the study are misleading because just as many women died in the group who ate the least amount of eggs as did among those who ate the most eggs," retorted the American Egg Board in a statement released yesterday.
Branding the research as 'sloppy' and 'misleading' the egg board added that the study on eggs and mortality "is not scientifically sound because the subset of women studied was too small to deliver accurate data".
While the egg industry is benefiting from decent sales growth, food makers have been hit by a rise in egg yolk prices linked to the outbreak of avian flu earlier this year in Asia that severely impacted the global poultry industry. In the last 12 months, food firms have seen a 20-30 per cent rise in liquid egg prices. Yolk prices rose from about £1,700/tonne last summer to £2,250 in the last quarter of 2003 and are around £1,850 today, although stability is in sight with prices starting to level out.
Yolk products - usually mixed with salt or sugar to increase shelf life - are used principally in mayonnaise, sauces and ice cream. The British Egg Information Service estimates that total production in the UK is around 8,800 tonnes per annum with a current value in the region of £16.3 million.
On the back of the price hikes for egg yolks, Cargill-owned starch and derivatives firm Cerestar has seen a boost in sales for its emulsifying starches.
"Customer interest has been further heightened since egg yolk prices began to rise a year ago, and more price rises are expected, so the starches solution is becoming even more attractive as a cost-saving route," said Mark Wastijn, of Cerestar Food & Pharma Specialties Europe, quoting the firm's C*EmTex 12688 for cold processed mayonnaise and C*EmTex 06369 for hot processing.
Studies suggesting consumers should cut back on egg consumption, such as the Nakamura-led research, can only lift such sales.
But the Japanese findings contradict a recent study published last month that found eating an egg a day does not impact the cholesterol particles in the blood most likely to cause heart disease.
The study, supported by the American Egg Board, measured the influence of a high-cholesterol diet, based on daily egg consumption, on the atherogenicity, or potential to lead to heart disease, of low-density lipoprotein (LDL) particles.
"We found that the dietary cholesterol in eggs does raise the LDL-1 and LDL-2 fractions but it does not impact the small, dense LDL-3 through LDL-7 particles that are the greatest threat for cardiovascular disease risk," explained Maria Luz Fernandez from the University of Connecticut.
"We also found that that egg cholesterol did not impact the small, dense LDL particles among a sub-set of participants who were genetically predisposed to being most sensitive to dietary cholesterol," she added.
But according to the Nakamura study, women who ate an egg a day were 22 per cent more likely to die of any cause compared with those who ate only a couple of eggs per week - regardless of factors such as age, smoking habits and body weight. Those who ate two or more eggs a day showed a still higher death risk, but only a small number of women fell into that category.
The researchers studied data on nearly 9,300 men and women who in 1980 completed lifestyle surveys, which included questions on how frequently they ate various foods. Participants' blood pressure, cholesterol levels and other health indicators were measured at the start of the study, and deaths were tracked over the next 14 years.
Full findings are published in the American Journal of Clinical Nutrition, Vol. 80, No. 1, 58-63, July 2004.