Celiac In The News
Posted 09 October 2004 - 07:27 AM
Cracking the code: Genetics reshapes medicine
When food turns toxic
ILLNESS MAKES EVERYDAY GROCERY ITEMS OFF-LIMITS
By April Lynch
Hungry and tired after a high school tennis match, Kelly McKenna raids the family kitchen. Her little sister, Laura, pulls out a few snacks, combing through a pantry designed just for the two girls.
In this stash of teenage-friendly food, there are no everyday crackers, commonplace cookies or most of the wheat-filled fare found in American cupboards. The pasta is made from rice flour, as is the brownie mix. The sisters grab a bag of corn chips and dig into a bowl of guacamole.
Kelly and Laura choose their food specifically for their bodies because they know what's in their genes. The girls have celiac disease, a genetic digestive illness that turns wheat and other grains into a gut-destroying poison.
By letting genetic knowledge guide their meals, the sisters avoid pain, anemia and malnutrition. As gene-based medicine develops, more people will be able to join Kelly and Laura in crafting their best possible personal diet.
This blend of genetics and food, known as nutritional genomics or nutrigenomics, is gradually changing everything from shopping habits to heart disease research. ``You are what you eat'' is evolving into ``eat for who you are.''
Food-related conditions as common as lactose intolerance start in the genes, scientists have learned, and can be treated by controlling what a person eats. In other cases, food choices can trigger genetic responses that flare into high cholesterol, cancer or other serious illnesses.
Ultimately, scientists hope to give people their own personalized food pyramids, steering them toward an individual menu plan for their health.
``This can help us design better drugs, better nutrition, and understand diseases better,'' said Wasyl Malyj, co-principal of a leading U.S. nutrigenomic research center at the University of California-Davis. ``We'll be able to tune our nutrition in ways we can't right now.''
Until the emergence of gene-based medicine, nutrition rarely got such sophisticated scrutiny. Dietary advice usually comes in very general terms -- calcium from dairy products is good, lots of fat is bad, sugar is unhealthy.
But genetic research has revealed plenty of exceptions to those rules. Lactose intolerance, a gene-based condition, requires many people to look beyond milk to get calcium. Some people, genetically prone to cholesterol trouble, suffer more from the effects of dietary fat. In people prone to diabetes, sugar isn't just unhealthy -- it can be deadly.
In researching celiac disease, scientists have uncovered how genes turn some of the world's most common foods into poison.
Celiac patients carry at least one gene that leaves their bodies unable to tolerate gluten, a protein in wheat, rye and barley. Gluten is found in everything from bread and soy sauce to bottled salad dressings and candy.
Some people with celiac genes may never have a problem. But in others, the immune system mistakenly identifies gluten as an intruder and attacks it in ways that damage the lining of the small intestine.
The intestinal damage limits the body's ability to absorb nutrients and often causes painful abdominal bloating. Patients with the condition, also called celiac sprue, usually lose weight. Their hair can fall out. Many are thin, anemic and perpetually tired. If not diagnosed, celiac disease can eventually stunt growth, weaken bones or trigger cancer.
Kelly, 17, who lives in Woodside, discovered her condition in November after a long bout of unexplained illness. She was so thin and anemic that her doctors asked whether she was anorexic.
``They talked to me like it was all in my head,'' Kelly said. ``I knew it was real.''
After her mother, Molly, did her own research on Kelly's symptoms and pushed for celiac disease tests, Laura was tested and diagnosed as well.
``I would out-eat my dad, but I was still this big,'' said Laura, 13, holding out a slender pinkie finger. ``They'd wonder where it was all going.''
Researchers are using their understanding of the genetic underpinnings of celiac disease to develop treatments. In the process, they say, they are also uncovering wider links between genes and nutrition.
``We are learning some very interesting and important things about the interplay between genetics, nutrition and health,'' said Chaitan Khosla, a chemistry professor at Stanford University who started doing celiac research when his wife and son were diagnosed with the condition.
He heads the Palo Alto-based Celiac Sprue Research Foundation, which is researching a celiac disease treatment. While there is currently no way to fix the genes that drive celiac disease, the foundation is getting ready to start tests on a pill that would help celiac patients tolerate gluten.
``I have become a lot more tuned in to things that used to just fly by me before,'' Khosla said. ``When someone tells me her daughter can't tolerate strawberries, and neither can she, I don't dismiss it the way I used to. I ask lots of questions, wanting to know more.''
At UC-Davis, doctors and scientists are already looking beyond individual nutritional diseases.
The university's nutrigenomics center, a combined effort among UC-Davis, federal scientists and researchers from Children's Hospital Oakland Research Institute, is funded by $6.5 million in federal grants. Racial differences in genes, diet and health form a key focus of the group's work. The center is also probing broader genetic factors linked to some of the country's most common health problems, such as heart disease and high cholesterol.
Millions of Americans have high cholesterol, but not everyone develops it the same way. Scientists already know that some people's cholesterol shoots up if they eat certain types of fat. Dr. Ronald Krauss, an East Bay scientist and cholesterol specialist affiliated with the center, is studying another genetic type -- people with cholesterol problems triggered by a low-fat, high-carbohydrate diet.
Krauss emphasizes that this trait isn't found in everyone, and he doesn't push wide use of the low-carbohydrate diets so popular in recent years. What his findings do make clear, he said, is that there is no one correct cholesterol-limiting diet for everybody.
``No one should expect all individuals to respond in a given way to any set of dietary recommendations,'' Krauss said. ``That expectation is a thing of the past.''
But neither, he said, should people expect to hear about genomics from their nutritionist in the near future. What people are more likely to see in their doctor's office is a growing range of genetic tests that can pinpoint specific nutrition-related diseases.
New genetic tests are available for lactose intolerance and celiac disease. Doctors who specialize in intestinal illness say they are especially interested in the celiac test, as the condition can be difficult to diagnose.
The condition is believed to affect as many as one out of every 150 people -- about 2 million Americans in all. For reasons doctors still don't understand, it can flare up suddenly in people who never had symptoms before.
To get a solid diagnosis, most patients have to undergo blood tests and intestinal biopsies. If a diagnosis is positive, relatives then need testing. Some are turning to genetic screening to try to avoid a biopsy of their own. The genetic test, which uses a blood sample, looks for genetic variations found in almost all celiac patients.
If relatives of a celiac patient don't have the variation, they will rarely develop celiac disease. Those with the variation need further testing and monitoring.
The test, offered by San Diego-based Prometheus Laboratories, costs $440. Results take about four days. Insurance sometimes covers it, Prometheus spokeswoman Beth Kriegel said.
The test has limits. A celiac gene is no guarantee a person will develop the disease. For now, that leaves genetics as just one part of pinpointing the illness and choosing a healthy diet.
``With some of these tests, you have to be careful how you interpret the results,'' said Dr. Eric Sibley, a pediatric gastrointestinal doctor and researcher at Lucile Salter Packard Children's Hospital at Stanford. ``You may not want to drop something from your diet just because of one genetic test.''
Still, those wondering about their genes and food welcome any glimpse into the code that shapes them. As a precaution, Kelly and Laura's younger brother, Michael, will undergo the celiac genetic test.
``He has been fine,'' their mother, Molly, said. ``But it would be good to know more.''
The girls, in the meantime, say they are happy to follow their genes when they eat. They miss pizza. But they have learned to scrutinize food labels and cookbooks. Kelly has created videos to educate medical students about celiac disease. The sisters have ready answers for people who misunderstand their careful choices and ask whether they aren't too young to count carbs.
And they eat well, knowing that the food they reach for truly blends with their bodies.
``I was so sick before,'' said Kelly, digging into a salad topped with cheese and olives. ``I'm so happy to know that this works. It would be cool for everyone to know this much.''
Contact April Lynch at firstname.lastname@example.org or (408) 920-5539
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Posted 09 October 2004 - 01:23 PM
gluten-free since January 2004
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