Naturalized Health Article Directory - Food Allergies

When testing for food allergies, allergists often ask about family history. If your parents have food allergies, the chances are higher that you too will have them. Problem is, not everyone who reports a food allergy actually has one. A study in Annals of Allergy, Asthma and Immunology, the scientific publication of the American College of Allergy, Asthma and Immunology (ACAAI) reports only 28 percent of parents of kids with food allergies tested positive to the foods to which they reported allergies.

A sensitivity to a food can be indicated in a skin prick test or a blood test, but does not always show a true allergy unless there has been a previous reaction to the food. "Parents of kids with food allergies had a higher rate of positive blood and skin tests to foods than the general population," said allergist Melanie Makhija, MD, MSc, ACAAI member and co-lead author. "But of the 2,477 parents, only 28 percent of those who self-reported a food allergy actually tested positive. This tells us that either people haven't been tested and are assuming an allergy from a previous reaction to a food, or they haven't been tested properly and may not truly have an allergy.

Allergy testing, including blood and skin prick testing, is not always reliable; there are a lot of false positives." Parents of children with food allergies were recruited from local hospital clinics and community settings. To be eligible, families had to have a child with a food allergy. In response to the questionnaire, 13.7 percent of parents reported having a food allergy. Of that group, only 28 percent tested positive to the food to which they reported being allergic.

Previous studies have focused on the general adult population," said allergist Rachel Robison, MD, study co-lead author. "While we found positive test results were more common in parents of kids with food allergies, the actual levels in the blood for the foods were quite low. Low positives in allergy testing are more likely to be false positives This points to the importance of proper testing for any kind of allergy, but particularly food allergies. Interestingly, we also found that of the parents who reported no food allergy, 14 percent had positive tests to peanut and sesame, for example." According to ACAAI, skin tests may reveal sensitization, but being sensitized to an allergen doesn't mean you are allergic. Oral food challenges remain the gold standard for allergy testing and are considered very accurate for diagnosing allergies. An allergy blood test alone is not as accurate. Food allergy tests aren't able to predict future risk for someone who has never eaten the food before.

Diabetes and Obesity - What We Really Know

Social and economic factors have led to a dramatic rise in type 2 diabetes and obesity around the world. In a review in Science, Mark McCarthy, professor at the University of Oxford, UK, and Paul Franks, professor at Lund University, Sweden, examine the knowledge of the actual causes and the interplay between genetics and lifestyle factors.

By studying how our genes express themselves in response to environmental factors and changes in lifestyle, we will better understand how health recommendations and treatments can be tailored to each individual.

"Environmental factors that disturb cellular and physiological processes and have an effect on the individual's predisposition to diseases, such as type 2 diabetes, are likely to do so through active, and reactive, modulation of genome function. There is a compelling rationale behind this concept, but the details about how these processes work remain poorly defined," says Paul Franks.

"However, there is emerging evidence that epigenomic changes such as DNA methylation and histone modifications, which affect the ways in which genes are transcribed and translated into proteins, are important features of these processes," he continues.

Previous research has largely focused on dietary components and which diet would be best to lower the risk of obesity and type 2 diabetes, but so far there is no clear evidence from epidemiological or clinical trial data that a specific diet is optimal for long-term weight-loss or lowering the risk of diabetes. Some types of dietary fat may be harmful while others may in fact be protective. The researchers also concluded that the widely established view that vitamin D supplementation lowers blood sugar levels and the risk of type 2 diabetes is unlikely to be accurate.

In recent years, there has been an explosion of interest in the role of the gut microbiome in the development of type 2 diabetes and obesity.

"Several studies have detected differences in the composition of the gut microbiome between healthy people and those with obesity and type 2 diabetes, but the cause and effect remain unclear," says Mark McCarthy, and continues:

"In addition, both high and low birth weight have been linked to type 2 diabetes later in life. It seems as if these associations reflect the complex interplay of genetic variation in both the foetus and the mother, along with the impact of the intrauterine environment."

The major challenge is getting closer to a mechanistic understanding of why type 2 diabetes and obesity occur and why they have become so much more common in the last 40-50 years.

"We have only a superficial understanding of that. It often gets blamed on our western lifestyle but the specific components of modern life that are most damaging remain unclear. We also know that this occurs on the background of hundreds of genetic differences that influence predisposition. The genetic findings are increasingly allowing us to understand the mechanisms involved, and to start to connect the genetic and environmental contributions," says Mark McCarthy.

Nutritional Supplements Could Prevent Thousands Of Preterm Births

Sophisticated analyses of two clinical trials -- one in the U.S. and the other in the Australia -- suggest that thousands of early preterm births -- those at or before 34 weeks' gestation -- could be prevented if pregnant women took daily docosahexaenoic acid (DHA) supplements.

The randomized controlled trials in which pregnant women took daily DHA supplements independently found statistically significant reductions in early preterm birth. The statistical model examined low-, moderate- and high-risk births from mothers supplemented with DHA during pregnancy as compared to placebo controls. The researchers estimated that more than 106,000 high-risk early preterm births could be avoided in the U.S. and about 1,100 could be prevented in Australia each year if pregnant women took daily supplements of the omega fatty acid.

Infants born very preterm often require lifesaving treatments and longer hospitalizations at birth and are at increased risk for additional hospitalizations in the first year of life -- and that is in the developed world. Further, these infants are at risk for serious disability or death the earlier they are born, said Susan Carlson, A.J. Rice Professor of Nutrition at the University of Kansas Medical Center, who co-directed the U.S. study with John Colombo, KU professor of psychology and director of the Life Span Institute.

"At present there is no effective method to prevent spontaneous early preterm birth," Carlson said. "Our recent studies suggest that DHA could be a promising agent for reducing this critical public health problem."

Both the KUDOS (Kansas DHA Outcome Study), directed by Carlson and Colombo, and the DOMinO (DHA to Optimize Mother Infant Outcome) study directed by Maria Makrides, professor of human nutrition and Healthy Mothers, Babies and Children theme leader for the South Australian Health & Medical Research Institute, and Robert Gibson, professor of functional food science at the University of Adelaide, saw a small overall increase in gestation length, but this increase was found to be related to a decrease in deliveries at higher risk for early preterm birth.

DHA (docosahexaenoic acid) occurs naturally in cell membranes with the highest levels in brain cells, but levels can be increased by diet or supplements. An infant obtains DHA from his or her mother in utero and postnatally from human milk, but the amount received depends upon the mother's DHA status, Carlson said.

"U.S. women typically consume less DHA than women in most of the developed world," Carlson said. "The intake of DHA is both the U.S. and Australia is well below that reported by Japanese women."

By using the results of DOMinO and KUDOS, the researchers in both studies found that early preterm births could be reduced to only 1.3 percent in Australia or 1.5 percent of births in the U.S. in demographically similar populations.

"These percentages are remarkably similar and may reflect the lowest rate of spontaneous early preterm birth that can be achieved in any population," Carlson said.