If you are planning to get pregnant, don't go on a diet.

That's the recommendation of John Challis, a U of T specialist in fetal health development (and vice-president, research). In a groundbreaking study published in 2003 in Science, Challis and colleagues in Australia and New Zealand found that even modest diet restrictions around conception can result in premature deliveries.

"Babies born prematurely have less opportunity for their lungs and organs to develop in utero in preparation for life outside the womb," says Challis, former scientific director of the Institute of Human Development, Child and Youth Health of the Canadian Institutes of Health Research.

About 40 per cent of all premature births are "idiopathic" - meaning that the cause for the pre-term birth is unknown. The research team found that, in sheep studies, a sizeable proportion of these idiopathic births can be linked to maternal undernutrition before conception.

"Even modest restrictions in diet around the time of conception could have far-reaching consequences. This period can impact the development of the baby's pituitary and adrenal glands and may well affect the other organs."

Challis and his colleagues are now seeking to determine the critical period of undernutrition, the impact of different types of diets and restricted foods and exactly how much weight loss can trigger premature births. - Maria Saros Leung

Flaxseed is already well known for its ability to fight a range of ailments - from stomach problems to cardiovascular disease. Now, nutritional sciences professor Lilian Thompson is producing evidence that flaxseed helps fight breast cancer.

Thompson is one of the world's experts on the pluses of flaxseed and other plant foods. "We have always known that plant foods are beneficial to health," she says. "But I am interested in just what it is in the plants that promotes health."

So she turned her attention to "lignans" - plant chemicals that are similar to the female hormone estrogen.

Other researchers found vegetarians have high concentrations of lignans in their urine, while breast cancer patients have low concentrations. "This indicated that maybe lignans could protect against breast cancer," says Thompson. "But we didn't know how much of the lignans were present in foods."

To find out, Thompson screened 66 plant foods normally found in the vegetarian diet and discovered that flaxseed contains 75 to 800 times more lignans than most of the foods. She then tested flaxseed on carcinogen-treated rats, immuno-deficient mice with human tumours and, more recently, breast cancer patients. But flaxseed has many chemical compounds, so Thompson isolated the lignans from the flaxseed and also tested them.

With each subject group, breast cancer tumours were reduced in size, sometimes by as much as 50 per cent. And metastasis - the spread of cancer through the body - was also reduced.

"Our idea is that the lignans interfere with estrogen, which promotes tumour growth," says Thompson. She has also found that the lignans work in harmony with anti-estrogen cancer drugs, unlike soy, which seems to negate the work of drugs in some studies.

Thompson isn't finished. "We have only tested a small number of human patients, so we need to repeat the research with more. And we are interested in seeing if the lignans are made part of a baby's diet and continued through childhood, whether they can fight breast cancer when the children become adults." - Paul Fraumeni

Enthusiasts of today's fad diets would have you believe that carbohydrates are public enemy number one. But are these abundant and affordable staple foods really that bad for you?

Not according to Thomas Wolever, who says carbohydrates not only taste good, they are good for you - especially if you have type II diabetes.

The professor and acting chair of Nutritional Sciences is one of the world's foremost researchers of the glycaemic index (GI), the system that ranks carbohydrates based on how they impact blood glucose levels. White breads and sugary breakfast cereals, which elevate blood glucose rapidly and cause insulin levels to spike, score high on the GI. However, foods such as oats and legumes that release glucose slowly have low GI ratings.

"People get diabetes because they don't secrete enough insulin," says Wolever. "We found that a lower GI diet actually improves insulin secretion."

Low GI foods such as grainy breads, pasta, long grain rice, bulgur and tabuleh, are healthy choices. Still, Wolever cautions anyone who looks to the GI as a magical treatment for weight loss.

"Low GI foods fit in with a proper approach to weight loss. But I am much more confident in saying that a low GI helps people with diabetes. There is much more evidence to support that over weight loss." - MSL

Memory loss, disorientation and inability to reason or perform routine tasks are the well-known flags of Alzheimer's. But beyond cognitive deterioration, there lurks another threat for sufferers of this mysterious disease.

"People with Alzheimer's are at extremely high risk for malnutrition," says Carol Greenwood, a professor of Nutritional Sciences who is also cross-appointed at the Baycrest Centre for Geriatric Care, where she is looking at how the disease affects appetite responses and food intake.

"We are finding tremendous shifts of food intake patterns that we feel contribute to malnutrition," she explains. Greenwood has found that patients with advanced Alzheimer's have stimulated appetites in the morning and depressed appetites later in the day. "We are looking at different types of interventions and trying to understand how Alzheimer's impacts appetite response and food intake."

Ensuring that people with Alzheimer's get adequate nutrition is critical for staving off infections, skin wounds and dehydration. "One of the biggest problems for people in the later stages of Alzheimer's is swallowing," explains Greenwood. "At that point, we have to thicken their fluids so they can safely swallow. It's very difficult to maintain hydration once someone is at this stage.

"At the advanced stage of Alzheimer's, you are less concerned with disease progression and more concerned about dealing with a host of problems - and malnutrition is one of the most serious." - MSL

Few of us are unfamiliar with the rejuvenating powers of a cup of coffee first thing in the morning. And that welcome surge of caffeine has some folks returning to the coffee pot several times a day. But how much is too much?

While some health experts say everyone should limit caffeine intake to avoid illnesses such as heart disease, Ahmed El-Sohemy takes a more individual approach. An expert in nutrigenomics, this 32-year-old assistant professor of nutritional sciences and Canada Research Chair in Nutrigenomics is investigating the interaction between diet and genes to better understand the range of responses our bodies have to the foods we consume.

Along with researchers at Harvard, El-Sohemy is studying the genetic make-up of a group of coffee drinkers in Costa Rica, a country where per capita coffee consumption is among the highest in the world. The team identified a sequence variation in a gene that has long been known to metabolize caffeine, which led to the discovery that some people have a "high metabolism" version of this gene while others have a "low metabolism" version.

"For people who are slow metabolizers, the amount of caffeine that lingers in the system is much greater," says El-Sohemy. "So one cup of coffee for them might be the equivalent of four cups for the fast metabolizers."

El-Sohemy's research program extends beyond caffeine to include studies of the beneficial effects of green tea on bone health and the genetic basis for food preferences.

"The current one-size-fits-all model clearly doesn't work, so I think it's important to identify the exceptions to a given rule," El-Sohemy insists. "This approach gives us a better assessment of exposure and risk - and will ultimately help us make more personalized dietary recommendations." - Althea Blackburn-Evans