Folic acid given to mother rats protects offspring from colon cancer

ScienceDaily (May 26, 2011) — Folic acid supplements given to pregnant and breast-feeding rats reduced the rate of colon cancer in their offspring by 64 per cent, a new study has found.

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The research, led by Dr. Young-in Kim, a gastroenterologist at St. Michael's Hospital, adds to the growing but sometimes contradictory evidence that folic acid supplementation during pregnancy and lactation can increase or decrease the development or progression of some pediatric malignancies and common cancers in their offspring in adulthood.

For example, a separate study by Kim published in February found the daughters of rats who were given folic acid supplements before conception, during pregnancy and while breast-feeding have breast cancer rates twice as high as other rats who were not given the supplements. They also had more tumours and developed them at a faster rate.

Kim said these studies collectively suggest that folic acid may have drastically different effects on cancer development in different organs, that specific organs may have different needs for folate, its natural form, or metabolize it differently. He said more studies, including human studies, were needed.

Kim's new study, published in Gut, an international journal in gastroenterology, is the first to find that folic acid supplements at the level ingested by North American women of childbearing age "significantly protects against the development of colorectal cancer in the offspring."

Folate is known to help make DNA and help it replicate.

"It appears that giving folic acid during pregnancy and lactation reduces DNA damage and suppresses the proliferation of cells in the colon," Kim said. "It actually increases the stability of the DNA and this might be one of the mechanisms of how folic acid in utero may protect against colon cancer."

The amount of folic acid to which fetuses are exposed has increased dramatically in North America in the past decade. Natural folate is found in grains and dark, leafy vegetables. Women are routinely advised to take folic acid supplements before becoming pregnant and while pregnant to prevent neural tube birth defects such as spina bifida.

Since 1998, the Canadian and U.S. governments have required food manufacturers to add folic acid to white flour, enriched pasta and cornmeal products as a way of ensuring women receive enough of the B vitamin. In addition, up to 40 per cent of North Americans take folic acid supplements for possible but as yet unproven health benefits.

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Sun protects against childhood asthma

ScienceDaily (May 19, 2011) — Vitamin D, which is primarily absorbed from the sun, plays a role in protection against childhood asthma. Now, a new study led by Valencian researchers has shown that children who live in colder, wetter cities are at greater risk of suffering from this respiratory problem, since there are fewer hours of sunlight in such places.

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"Prolonged exposure to the sun can cause cancer, but it's also dangerous to avoid it. There has to be a balance between the pros and cons," says Alberto Arnedo-Pena, an epidemiologist at the Public Health Centre in Castellón and lead author of the research, which is part of the International Study of Asthma and Allergies in Childhood (ISAAC), led by Luis García Marcos of the University of Murcia.

In fact, 90% of our vitamin D is synthesised through exposure to the sun. This vitamin, which can be found in various cell receptors, is usually found at lower levels in people with asthma. The study results show that there is a higher prevalence of this illness among children in wetter places with less sun (northern Spain).

The research, carried out on more than 45,000 children and teenagers from nine Spanish cities and published in the International Journal of Biometeorology, shows that climatic conditions, above all solar radiation, can in many cases explain the high geographical variation in the prevalence of asthma in Spain.

"Although we need more studies on this issue -- this hypothesis is not even five years old -- it is clear that an average level of sun exposure is important for the assimilation of vitamin D, a compound that is extremely important in preventing illnesses such as asthma, tuberculosis and other infectious diseases," stresses Arnedo-Pena.

The solar vitamin

In northern countries (where there are fewer hours of sunshine than in the Mediterranean), the advice is to spend 20 to 30 minutes' in the sun each day, although not at times within the highest risk period (from noon to 4pm). For now, no similar advice exists in Spain.

Once the benefits of sun exposure are understood, it can be seen that there is a problem in countries at latitudes higher than 40º north, where it is not possible to absorb enough vitamin D during the winter months. "People in these countries should take supplements to ensure they are not at risk," the researcher concludes.

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