ANALYSIS - Two news items this week from the medical research world have put the poultry industry back in the firing line again as links have been made to negative impacts on human health: one links egg consumption to heart disease and another suggests that a whole range of human health problems could be put down to antibiotic use in farm animals. On a more positive note, dairy products were more commonly associated with foodborne Campylobacter infections than those from poultry in a new US study.
The first involved a study from Western University in Canada, published recently in Atherosclerosis, which has linked egg yolk consumption and atherosclerosis.
Research led by Dr David Spence shows that eating egg yolks accelerates atherosclerosis in a manner similar to smoking cigarettes. Surveying more than 1,200 patients, he and his team found regular consumption of egg yolks is about two-thirds as bad as smoking when it comes to increased build-up of carotid plaque, a risk factor for stroke and heart attack.
The study has received critical attention from the egg industries of other countries.
From the US, the Egg Nutrition Center and American Egg Board have commented that the results of the Canadian study "are surprising and contradict more than 40 years of research demonstrating that healthy adults can enjoy eggs without significantly impacting their risk of heart disease".
Mitch Kanter, PhD, Executive Director of the Egg Nutrition Center, added: "While eggs provide many nutrients and make an important contribution to overall diet quality, they are often accompanied by foods high in saturated fat and calories. These pairings were not taken into consideration in the Atherosclerosis study."
The agencies added that Western University carried out an observational study, which is not designed to measure causality. Further, the researchers did not adjust for lifestyle habits including smoking and exercise patterns, waist circumference, intake of saturated fat, alcohol, or foods commonly eaten with eggs like high-fat meats and other high-fat side dishes.
Australia's Egg Nutrition Council concurred with the US agencies' response, describing the Canadian study claims as 'weak', highlighting the important variables that were not measured, such as total dietary intake and physical activity level.
The British Egg Information Service has also questioned the conclusion of the Canadian research, saying it is not clear if the alleged link is causal or an unrelated association.
In the second health-related story of the week, researchers at New York University School of Medicine say that antibiotics used in livestock production could have widespread clinical implications, potentially affecting everything from nutrient metabolism to obesity in children.
Ilseung Cho, MD, MS, and colleagues set out to reveal how antibiotics used in farm animals act on the body, hypothesizing that low doses of the drugs may alter the composition and function of the bacteria in the gut. The resulting study, appearing this week ahead of print in Nature, confirmed their theory about the gut microbiome, the term used to refer to the community of bacteria that lives in the stomach, and raises new questions about how manipulating it can impact metabolism and disease in the body.
The researchers administered STAT to normal mice and observed that the mice receiving antibiotics developed increased fat mass and percent body fat. After about six weeks, the mice that received antibiotics had gained about 10 to 15 per cent more fat mass than the mice that did not receive antibiotics. The researchers also noted that bone density was significantly increased in STAT mice early in development and that particular hormones related to metabolism were affected by antibiotic exposure, as well.
Dr Cho commented that the scientific community is only now beginning to understand just how complex the microbiome is and how it affects health and disease. With a better understanding about the interactions between the microbiome and hosts and how these interactions can be manipulated, he and his colleagues believe the finding has the potential to affect a wide array of conditions ranging from childhood obesity to metabolic syndrome in adults.
There was one positive food-related story for the poultry industry. Campylobacter is a bacterium often linked to poultry in cases of food poisoning but dairy products were more commonly associated with infection than those from poultry in a new study. Looking at common source outbreaks of Campylobacter infection in the US between 1997 and 2008, Centers for Disease Research and Prevention researchers found that that Campylobacter is a common but decreasing cause of foodborne infections. Foodborne transmission was reported in 86 per cent of outbreaks; dairy products, poultry and produce were implicated in 29 per cent, 11 per cent and five per cent, respectively, of the food-related cases.
And finally, UK supermarket, Morrisons, reports it is working with its British poultry suppliers to develop an information pack aimed at helping them tackle the impact of wet litter on bird health and performance.