Tiny hearts may have big problems with complementary medicine

Giving supplement such as herbs, vitamins, and other natural health products to children taking Warfarin for congenital heart defects could increase their risk of clots, bleeding, and other complications, nurse practitioner Mary Bauman and Dr. Patti Massicotte told the 2008 Canadian Cardiovascular Congress, co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

"We just assume these products are safe because they are 'natural' and don't require a prescription," says Heart and Stroke Foundation-funded researcher Dr. Massicotte. "The problem is that the anticoagulant action of Warfarin is unpredictable on its own, so adding dietary supplements to that can be a challenge. Sometimes that product is the straw that breaks the camel's back and could push children into high risk situations."

She says that many marketed supplements can cause changes in the blood and shouldn't be taken with Warfarin, but there is little research on drug interactions with these kinds of products. "There is no standardization of the active ingredient per capsule or tablet between companies and it is this variation - especially in combination products - that provides the greatest challenge," she says.

Some of the most common natural health products taken by the children in the study included chamomile, lemon, fennel, and green tea. Multivitamins and minerals were also high on the list, which, Dr. Massicotte warns, can be a problem if they contain vitamin K - a vitamin that enhances clotting and could make Warfarin less effective.

Ms. Bauman, the creator of the Pediatric Outpatient Anticoagulation Clinic in Edmonton, Alberta has been working with Dr. Massicotte to see how many children are taking natural health products. They looked at 67 questionnaires which surveyed children taking Warfarin.

Warfarin is an anticoagulant - also often called a blood thinner - that helps prevent blood clots from forming in the body. Blood thinners help reduce risk for heart attack, stroke, and blockages in the arteries and veins.

They found that 37 per cent of children with heart problems were taking some kind of dietary supplement and 22 per cent of their parents and 10 per cent of their healthy siblings were taking them as well. Yet, few parents informed their doctors about their children's use of natural health products - which can be dangerous for the child since an interaction could occur with their medication.

"It is interesting that only 10 per cent of siblings were taking these products," says Ms. Bauman. "Parents more commonly gave these products to their child with health challenges believing that these products are safe and may provide benefit. However, the opposite may be true as supplements have the potential to negatively influence prescriptive medical care."

The researchers say the main problem is that the children take these supplements inconsistently. That means their blood may be thicker on some days and thinner on others. This can make it difficult for doctors to prescribe the right amount of Warfarin to protect them from clotting, but not expose them to bleeding, Dr. Massicotte says.

"I think that the really important thing is for healthcare professionals to ask families whether or not they are taking natural health products and for what purposes," Ms. Bauman says. "And we need to do it in an open and non-judgemental way because people won't listen to you if you are going against their beliefs system. That may mean incorporating natural health products into the treatment and trying to do it the safest way possible."

Statements and conclusions of study authors are solely those of the study authors and do not necessarily reflect Foundation or CCS policy or position. The Heart and Stroke Foundation of Canada and the Canadian Cardiovascular Society make no representation or warranty as to their accuracy or reliability.

The Heart and Stroke Foundation (heartandstroke.ca), a volunteer-based health charity, leads in eliminating heart disease and stroke and reducing their impact through the advancement of research and its application, the promotion of healthy living, and advocacy.