Monday, January 17, 2011

Breast feeding: Personal genetics is in it’s infancy…

There is a lot in the new today about breast feeding – should it be exclusive for at least 6 months (WHO) or should it include some earlier introduction of solid foods (BMJ article)? A lot of the reporting is confusing the issue, claiming or implying that the BMJ authors are saying the 6 months is too long (and pointing out that they have been consultants to the baby food industry). The BMJ authors are not saying that, they simply say that it might be prudent to introduce gradually some solid foods, while still breast feeding before 6 months.

There is a useful account at the Marion Nestle blog and I left a comment there which I have expanded upon here. This could be an area where genetic testing can help – blanket advice is never the best for all but confusion (as we have now) is even worse. I blogged about celiac disease and genetic testing a while ago and part of the post addressed exactly the issue of breastfeeding and weaning.

...babies differ! Probably, very likely, one type of advice is not applicable to every situation, but we don't yet have much idea of how to select.

The choice here is not breastfeeding vs. infant formula, it should be made very clear that the evidence suggesting adding solid foods before 6 months does NOT also suggest stopping breastfeeding. Precisely the opposite. The ESPGHAN (European Society for Pediatric Gastroenterology, Hepatology, and Nutrition) issued some precise advice targeted especially at infants with possible celiac disease risk (i.e. a genetic predisposition): For further details see http://bit.ly/9xo8lt)

It is prudent to avoid both early (<4 months) and late (>or=7 months) introduction of gluten, and to introduce gluten gradually while the infant is still breast-fed, inasmuch as this may reduce the risk of celiac disease, type 1 diabetes mellitus, and wheat allergy.

Using genetics to give targeted advice is in it's infancy (excuse me!) - but could be useful in this case. If the universal advice were to suggest introducing solid foods between 4-6 months, there is a danger that it could lead to more frequent introduction actually before 4 months, which according to the evidence is even more risky for allergies and autoimmune diseases. So in this perspective the WHO advice could be considered to be wise, but there are exceptions.

I’m not so sure I understand the SACN logic though:

Currently available evidence on the timing of introduction of gluten into the infant diet and subsequent risk of coeliac disease and T1DM is insufficient to support recommendations about the appropriate timing of introduction of gluten into the infant diet for either the general population or high-risk sub-populations. However, there is evidence suggesting that not being breastfed at the time when gluten is introduced into the diet is associated with an increased risk of subsequently developing coeliac disease.

Source: Draft SACN/COT Statement on the Timing of Introduction of Gluten into the Infant’s Diet

I understand why earlier introduction of gluten may not be the best advice for the general population, but for high-risk sub-populations, I’m not so sure. The evidence is not water tight but that which does exist has been reproducible and indicates that 4-6 month introduction of gluten (while still breastfeeding) is the lower risk option. There are no studies that contradict this and none that suggest that there are more benefits than risks by waiting until after 6 months in high risk subpopulations. There are some clinical trials underway (e.g. PreventCD) which may help, but until then, the benefits and risks calculation suggests following the ESPGHAN advice, see above.

4 comments:

  1. Have you seen this http://www.analyticalarmadillo.co.uk/2011/01/starting-solids-facts-behind-todays.html interesting look at the paper. I cant seem to see a study that looks at exclusivity until 6 months and outcome, it seems to be mixed feeding and gluten LATER than 7 months

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  2. Many thanks for an interesting blog post. It was unfortunate that the BMJ article, which offered no new evidence and quoted very selectively from the literature, was featured on the front page of so many newspapers and in some cases with very misleading headlines.

    There is an interesting new study which was mentioned in The Times the other day which might eventually help to provide some answers. The article is behind The Times paywall:

    http://www.thetimes.co.uk/tto/health/child-health/article2877749.ece

    This new study is from an organisation called Eating about Tolerance and there is further information on their website:

    http://www.eatstudy.co.uk

    The 23andMe test already includes four SNPs associated with coeliac disease. I have the low-risk version of the one that is supposedly the most problematic. I am sure that the day will come when parents will be able to use results from genetic tests to decide on the best time to introduce solids and in particular foods associated with allergies. In the meantime, a lot more research is still required.

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  3. Thanks Debbie - the EAT trial looks interesting. The PreventCD trial is looking at adding small amounts of gluten during months 4-6, while still breast feeding and as the project implies, it is focussed on Coeliac disease rather than general allergies. There is also another clinical trial where they are looking at adding gluten at 6 or 12 months (don't know what evidence they used to select those time periods though).

    The 23andMe panel doesn't unfortunately allow you to determine whether you are HLA DQ2 or DQ8 which are the genotypes necessary for developing celiac - unless they have added extra tagging SNPs for the upgrade...I'm still waiting for my results!

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  4. It will be interesting to see the results from these trials in due course. It's good to see that some proper studies are being done.

    There's an extensive thread on coeliac disease in the 23andMe Forums which you might find of interest:

    https://www.23andme.com/you/community/thread/460

    23andMe have said they will begin loading data today and over the next few days. They apparently have "many thousands of data-sets to load". You should start getting results soon. It will be interesting to know what extras you get with the new chip. I held off upgrading. I'm not too sure that I want to sign up for a subscription and also I would have had to pay the expensive courier charges to send them a new DNA sample. I don't know why they can't use ordinary post like everyone else!

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