Autoimmune Thyroid Disease

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Pregnancy supplements may trigger asthma in kids

with 4 comments

Another New Scientist article of interest to failsafers.

The same vitamins and supplements that mothers-to-be take to protect their kids from birth defects could predispose children and even grandchildren to asthma.

If mice studies are confirmed by studies in humans, expectant mums may need to strike a balance between amounts of supplements such as folate, which reduces the risk of spina bifida, and those that bring on asthma, says John Hollingsworth, a doctor who specialises in diseases of the respiratory system – pulmonology – at Duke University Medical Center in Durham, North Carolina. “A little could be helpful and a lot could be harmful,” he says.

He and his colleagues fed pregnant mice supplements including folate, vitamin B12 and zinc in doses roughly equivalent to those recommended for pregnant women. These chemicals turn down the expression of certain genes and mark the DNA of a developing embryo so that the effect is passed from generation to generation, a process known as epigenetics.

Mice who ate the supplement-rich diet delivered pups with some signs of asthma. Their lungs contained high levels of immune cells and proteins that predict asthma in humans compared with mice that ate a supplement-poor diet.

To future generations

When Hollingsworth’s team bred these pups on a normal diet, their offspring still showed some signs of asthma – an indication of epigenetics in action.

Indeed in a genome-wide search for genes epigenetically marked for lowered expression in the first generation of mice pups, the researchers turned up several genes important for harnessing the immune system. Mice completely lacking one such gene, called Runx3, develop spontaneous asthma, and the researchers suspect epigenetically reduced expression of the gene could have the same effect.

“It’s a nice mouse model, but it’s a mouse model,” says Rachel Miller, an allergist and pulmonologist at New York Presbyterian Hospital. She says that to prove that maternal supplements could predispose kids to asthma, researchers would need to closely track the diets of expectant mothers, as well as any asthma that develops in their children.

“I think it needs to be tied back with human disease,” agrees Hollingsworth. But if confirmed by such human studies, the link between dietary supplements and asthma might explain the mysterious rise of the disease in developed countries, where pregnant women are advised to take folate supplements.

However foods such as leafy greens, broccoli and nuts, also contain folate and can silence genes. Cigarette smoke makes the same epigenetic changes, and one retrospective study found that grandmothers who smoked while pregnant are more likely to have asthmatic grandchildren than non-smoking grannies.

“You are what you eat – or you are what your grandma eats,” Hollingsworth says.

Journal reference: Journal of Clinical Investigation, DOI: 10.1172/JCI134378 (in press)

Pregnancy supplements may trigger asthma in kids

Yes, there is such thing as too much of a vitamin. In fact, too many can vitamins damage the correct function of your immune system.

Although only a mouse study, this is the first significant evidence I have come across suggesting epigenetic factors could be involved in a food chemical intolerance related symptom. This theory makes a lot more sense to me than the usual speculation banded about over vitamin deficiencies causing epigenetic alterations. Food chemical intolerance would be much less common today, if it were correlated with vitamin deficiency. According to the hype (though not necessarily the reality), asthma is more common today.

Other genes that can accidentally be switched off by methylation include a handful of important genes designed to help the immune system detect and destroy cancer cells.

The same genes that predispose to asthma also predispose to eczema. I know of a lot of mothers who have given birth to babies with eczematous rashes in the last few years, including a several dedicated WAPF members.  They have followed WAPF advice to the letter, eating liver and other high folate and vitamin A sources during their pregnancy (vitamin A is also involved in gene methylation). Asthma takes a few years to develop, but usually appears between the ages of three and six. I feel sorry for those mothers, because they really thought they were doing right and now they have this possibility to look forward to.

Bipolar disorder, autism, ADHD and fibromyalgia are also more likely in individuals with asthma, possibly due to leukotriene overproduction or COX II inhibition – the science is at a very early stage here, but this is the main system salicylates act on.

I have been in a dilemma over what I should do if I should get pregnant. To supplement or not supplement? Folate makes me quite ill, and it makes my asthma and eczema worse. Perhaps I should be listening to my body instead of to yet more flaky medical/nutritional advice. Rhetorical question: how come medical authorities never test anything properly before they advise the population to do it, á la low fat diets, fibre, statins, thalidomide, resting babies on their faces, five-a-day…? Since when was mass experimentation on the populace an okay thing to do?

Written by alienrobotgirl

21 September, 2008 at 11:49 pm