FADS2 Gene Linked to Higher IQ in Breastfed Children

FADS2 Gene Linked to Higher IQ in Breastfed Children

by Dr. Hsien-Hsien Lei
Posted November 6, 2007 in DNA in General

breastfeeding symbol

Big headlines this morning:

  • Breastfeeding leads to higher IQ in babies with the right gene
  • Common gene determines if breast is best
  • Breast-feeding link to higher IQ
  • Mental Abilities: Gene Found to Play Role in Benefits of Breast Milk
  • Gene ‘links breastfeeding to IQ’
  • Breastfeeding is good – if it’s in the genes
  • Breastfeeding’s IQ boost may depend on genes
  • The gene that turns breast-milk into brain food

It appears that children with one variant of the FADS2 gene see an average improvement of seven points on IQ tests if they’re breastfed as compared to formula-fed children. Children who do not have that variant do not see a corresponding increase in their IQ from breastfeeding.

The FADS2 gene encodes for an enzyme that is involved in fatty acid metabolism. So, people with the variant of FADS2 linked to higher IQ may be more efficient at utilizing fatty acids for brain development. The good news: 90% of the population carries the variant of FADS2 linked to higher IQ so chances are, your child will benefit from breastfeeding.

Hold on a minute.

Regardless of its effects on IQ, BREASTFEEDING IS STILL GOOD FOR YOUR BABY! Ounce for ounce, breast milk contains better fats, protein, carbohydrates, immune boosters, vitamins, minerals, enzymes, and hormones than formula. (Comparison of Human Milk and Formula, AskDrSears.com)

This is not to say that all breast milk is created equal or that all children are able to glean equal amounts of nutrition and benefit from breast milk. In 2005, researchers at Wake Forest University School of Medicine found that two genes, ApoA4 and ApoE, help to determine the amount of docosahexaenoic acid (DHA) and total fat in the breast milk mothers produce.

DHA is an omega-3 fat that is critical in the development of the brain and eye. DHA deficiency is believed to play a role in autism, attention deficit hyperactivity disorder, and learning disabilities. Mothers who carry the 347S variant of ApoA4 produce 40% more DHA in their breast milk than women with the more common (347T) version

Mothers carrying the E4 variant of the ApoE gene were found to have 40 to 75% less total fat in their breast milk and would thus provide less calories per ounce. This finding, however, didn’t concern me much. It is well understood that babies are capable of self-regulating the amount of calories they ingest. For mothers whose breast milk has a lower caloric content, their babies would most likely compensate by drinking more. And it is usually obvious if a baby is not getting enough calories because they look and act unwell.

breastfeeding motherIs genetic testing for breastfeeding efficiency in mother and child somewhere in our future?

Dr. Richard B. Weinbert:

…in the future, similar genetic testing may help identify women who need to modify their diet or take supplements to maximize the nutritional value of their breast milk.

Shouldn’t or can’t we all modify our diet and take supplements regardless of our genotype? Breastfeeding is one of the most controversial subjects among parents today. A mother’s health and nutritional status are often called into question if her baby does not thrive. While I believe that each family has the right to choose between breast milk and formula, I’m afraid that once a mother’s genetic make-up is known, it will be one more reason to blame her for inadequate breast milk. Similarly, if a child’s FADS2 status were known, would some mothers choose to use formula instead of breastfeed even though there are a myriad of positive benefits to breast milk besides just a boost in intelligence?

I am proud to say that my son has never had a drop of formula. He was breastfed for several years (yes, that’s right – years). While I’m confident it benefited him physiologically, I also know that it benefited us emotionally.

If you need breastfeeding support or general breastfeeding information, visit Angela White at Breastfeeding 1-2-3.

HT: Kathy

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Comment by Ricardo Vidal

I also noticed this story on my radar and happened to follow some other blog posts related to it.
I’d like to add to this great post you’ve put together, a short quote about IQ tests that I found on Brian Clegg’s blog at NN

A single number [IQ], based on a very selective set of tests, simply can’t indicate a level of something as complex as intelligence. Yes, it’s correlated to aspects of academic achievement – but then a fair amount of academic achievement is really just a measure of how good you are at passing tests too.

Rick, As I always tell people, passing tests and doing well academically are all just part of the big game of life. And IQ is just one part of learning how to play ball.

Comment by Sara Subscribed to comments via email

Thanks for this thorough and informative post, Hsien! Great job bringing a lot of info together. :)

Thanks, Sara! Breastfeeding is one of those topics I could go on for ages about so this was relatively short and under control. haha

Comment by Krissy Poopyhands Subscribed to comments via email

Ah. It’s so hard, isn’t it? This is one of those topics that when I read about it it comes up and there are automatic feelings of being attacked. I’m at my desk cringing.

Your experience was not my experience. I know that your experience was best for your family, and that’s great.

(Comments wont nest below this level)

Yup. As I said in my post, every family makes the choice that’s best for them. But I don’t understand people who want to argue the benefits of formula vs breast milk from a scientific point of view. It’s like bugging me about eating white bread and not wheat. I know wheat bread is healthier but I like the taste of white bread! (Lame example but I think you know what I mean.)

Comment by Krissy Poopyhands Subscribed to comments via email

I totally get it. I guess what people are usually arguing is “how better?”, also “how long?”, “how much?”.

I dunno. I totally understand what you’re talking about, but it comes with a side plate of such a huge, heaping, stinking pile of booby guilt no matter which side you’re on. And that’s not new, my mom had the same experience.



Krissy, Have I never told you that I have ceased to feel guilty about anything? My motto in life is: “Do what you want.” Pretty much what people end up doing anyway regardless. :P

Comment by Krissy Poopyhands Subscribed to comments via email

This is because you’z a smart cookie.


[...] geneticist’s take on this news, read the clear explanation offered by Dr. Hsien-Hsien Lei at Eye on DNA. advantages of breastfeeding, breast milk, breastfeeding, health of the baby, lactation, [...]


FYI for everyone, DNA Network member Chris Della Vedova has more on this study of FADS2, higher IQ, and breastfeeding.


Comment by Pender Subscribed to comments via email

“While I believe that each family has the right to choose between breast milk and formula”

WHY? At some point, the benefits to the child outweigh the costs to the mother, and we may do well to require it. Boosting one’s IQ by half of a standard deviation is an enormous difference — for perspective, it is 25% of the difference between normal and retarded by the modern measure (and 50% according to the old measure). Does each family also have the right to malnourish the child?

Hi Pender, Thanks for the comment but what totalitarian society do you come from? Next thing you know we’ll be banning fatty foods….

Comment by Pender Subscribed to comments via email

Hi Dr. Lei (and Sara, commenting below),

I guess I phrased it in a pretty inflammatory way, but the question, it seems to me, is whether abstaining from breast-feeding *should* be a right. Our conception of rights changes all the time. Once, beating your child with a switch when he misbehaved was seen as a right, but now that same act can (correctly, in my opinion) get you in trouble with the law!

So what determines whether something is or isn’t a right? I think it has to be a weighing of the costs and benefits. If the overall benefits to society of declaring something a right outweigh the overall costs, then it should be a right. If the overall costs to society of declaring something a right outweigh the overall benefits, then it should not be a right.

I agree that we have always considered it a right to feed a child with formula instead of breast milk. But something new has come to light: there is a much greater benefit to breast-feeding (and thus, a much greater cost to leaving the choice between formula and breast-feeding as an individual right) than we previously thought. So it is natural, I think, to reevaluate whether the choice should remain a right.

I don’t think it is OBVIOUS that breast feeding should now be mandatory, and I did not mean to imply that it definitely should. But I do think it’s a serious question. How much of a benefit to breast feeding must there be — or alternatively, how much of a cost to NOT breast feeding must there be — before we are willing to make it mandatory?

The fact that it is the woman’s body is significant but not dispositive, in my view. It means that mandating breast feeding is a much greater intrusion into a woman’s autonomy. But there are other cases where that intrusion is nevertheless mandated precisely because the benefits to it are so high. As one example, it is illegal for a doctor to prescribe certain acne medication while a woman is pregnant or planning to get pregnant because the medication can cause serious birth defects. Third-trimester abortions are illegal. I don’t know the state of the law, but I would not be surprised if many people would agree that abstaining from serious alcohol consumption while pregnant is also at least morally mandatory.

So the relevant argument, it seems to me, is whether a difference of 7 IQ points is great enough to warrant intruding on a woman’s autonomy. Maybe it is; maybe it isn’t; but I think it’s facile to invoke a woman’s autonomy and assume the discussion closed.

(Comments wont nest below this level)
Comment by Krissy Poopyhands Subscribed to comments via email

The term ‘7 IQ points’ is subjective in and of itself. What does that really translate to in future ability, quality of life, benefit to society? What about the kids who’s bodies can’t metabolize the breastmilk properly? Or the moms who produce enough in quantity but not quality?

Internment camps for the lot, I suppose, so they don’t infect the super-geniuses with their inferior milk IQ.

I have to tell you, it makes those of us who tried like hell and couldn’t do it feel all warm and fuzzy that we’re beeing lumped in with child abusers.



Hi Pender, Thanks for coming back to explain your argument. There is no question that I’m an ardent supporter of breastfeeding BUT there are many factors that go into play when it comes to IQ, including measurement error and confounding variables. These results are by no means conclusive.

On the other hand, you’re right that we do draw the line in the name of public health although alternatives are often available. When it comes to breastfeeding, formula does do the job and at some point, perhaps breast milk banks may fill the need if it’s only fatty acids we’re after. As I pointed out in my post, however, there are many wonderful reasons to support breastfeeding.

Comment by Pender Subscribed to comments via email


IQ is not subjective. The difference that 7 points is likely to make is precisely measurable in terms of things like education, longevity, happiness, divorce rate, religiosity, and even certain political views. Certainly, nothing is guaranteed in the individual case — but that’s also true of things like fetal alcohol syndrome, and yet we’re still comfortable making women lay off the booze while they’re pregnant.

My intent was not to make you feel guilty, and of course you shouldn’t. If you could not breast-feed, it’s not your fault and that’s really the end of the issue, morally.

As for your comments about internment camps, I’m not quite sure what to say. Obviously I advocated nothing of the kind, and I’m a little bit annoyed that you would resort to such a cheap and inflammatory mischaracterization.

Dr. Lei,

I wasn’t aware that these results were any more subject to measurement error or confounding variables than any other study. I assumed it was a controlled long-term study of a large and well-chosen sample. If not, obviously the reliability of its results are diminished accordingly.

But if you mean that 7 IQ points is a sufficiently small difference to overall IQ that we can discount it, then I disagree. It’s half of a standard deviation. As the article says, that’s enough to put an otherwise average person into the top third of IQ. And as I said, it’s 25% of the difference between normal and retarded. It’s a big, big deal.

In any case, I join you in hoping for the arrival of equivalent alternatives. Perhaps whatever the special sauce is can be added to formula for the same effect. Failing that, breast milk banks sound like a great idea. I have particular interest in these alternatives, since I’m a gay guy who may someday want children, and the prospect of hiring or convincing a woman to breast feed the children is a daunting one. (Krissy, perhaps you can take comfort in that: whatever physical difficulties your family encountered in bearing or nursing children, they’re nothing compared to mine! :)


Pender, First of all, measurements of IQ are controversial to say the least then you have to factor in a person’s genetic make-up and response to breast milk as well as the composition of breast milk that is offered. That’s two variables right there. So even if a person were primed to gain the most from breast milk doesn’t mean s/he is going to get the best quality. And 7 IQ points may be the difference between being normal and retarded but it is also the difference between normal and Sharon Stone (actually, she may be even more points above the mean). I think I might prefer to be normal…not saying I am or not or whatever….

Comment by Pender Subscribed to comments via email

Measurements of IQ are controversial like Galileo was controversial in the days of the Inquisition. The science itself is very much one-sidedly in support of the concept, and indeed psychometric testing is possibly the single most robust achievement of psychology as an academic discipline. Many people would prefer that it did not exist, that we are truly all created equal, etc., but that does not make it reality.

True, not everyone has this FADS2 thingy that responds well to breast milk. But 90% do. That’s a damn good success rate. I don’t know what the issue with breast milk composition is, but I assume that is already taken into account by the 7 IQ points figure — i.e. if only half of mothers’ breast milk has the effect, then to get to 7 IQ points, it must have a 14-point effect the lucky half of the time.

Imagine a dose of lead poisoning that causes a 7-point average IQ reduction in 90% of all exposures to children. Would you be as willing to write that off as the breast milk effect because the other 10% of exposures have no effect?


Pender, Even assuming measurements of IQ are accurate (which I think is subject to debate), they’re one dimensional! No guarantees that society would see great improvements and advances if we were able to up the average IQ of the population by 7 points. In fact, I’d venture to say not much would change because relative differences would remain AND the effects of socioeconomic factors would still be highly influential.

Also, there is no way FADS2 is the only gene influencing intelligence so to focus on that and breastfeeding would be missing the forest for the trees. The effects of FADS2 and breastmilk composition aren’t yes/no dichotomies, they’re continuous variables.

In some sense, what we’re talking about here is totally pointless. It is universally agreed that breastmilk IS the better alternative and every country emphasizes its important. What you seem to want to do is to FORCE women to breastfeed and that just isn’t going to happen. Just like you can’t force women to stop smoking and drinking during pregnancy even though everyone knows you damn well shouldn’t be doing it.

Comment by Pender Subscribed to comments via email

“Pender, Even assuming measurements of IQ are accurate (which I think is subject to debate), they’re one dimensional! No guarantees that society would see great improvements and advances if we were able to up the average IQ of the population by 7 points. In fact, I’d venture to say not much would change because relative differences would remain AND the effects of socioeconomic factors would still be highly influential.”

Dr. Lei, I really respect you, but this argument flies in the face of modern science. Nearly every declarative statement in this paragraph is factually incorrect. IQ is extremely influential in all kinds of areas and has all of the implications that you claim it does not. The correlations are precisely measurable, and IQ has greater predictive ability of many things (e.g. job performance) than ANY OTHER VARIABLE we can isolate (including, e.g., job experience, interviewing ability, and education).

“In some sense, what we’re talking about here is totally pointless.”

I agree with this. As Half Sigma posted below, it turns out that the study is dubious at best.

Comment by Sara Subscribed to comments via email


I am curious to know at which point a woman’s breasts no longer belong to her. And here I thought we women were autonomous beings…silly me!

Comment by Lia

OK, what are these “cases where that intrusion is nevertheless mandated precisely because the benefits to it are so high.”?

This is about optional extras, not about redefining deprivation or malnourishment! Extra possible benefits for your child, regardless of whether or not you can supply them. You’re proposing that it’s OK to invade the bodily integrity of others, against their will, to accomplish this?

Maybe compulsory breastfeeding is no big deal to you – no more than wearing high heels every day, as you see it. Hey, can’t we all just live with that? But it is a step in the wrong direction to argue for it against someone’s will.

If your child needed a blood transfusion, you could probably hope to supply that. The line is crossed when court orders are proposed to order anyone to donate blood, by law, to anyone. What if US athletes could do better with a shot of my blood?
Hey, I don’t think so, guys. I’m a volunteer here.

It only adds insult to point out that you’ll never be the subject of any such court order, but you’d quite like to debate how desirable it would be to apply it to others.

Do you see where we’re going with this?
Put it like this; how would you feel about me proposing invasive & prolonged genetic testing for you, before you’re allowed to father any children? What if permission were denied? Do you see now how objectionable it sounds to others? I would never propose such a thing, because that would be wrong for society. I hope you can see why I think so.

I admire you, Pender for being so frank about your situation and future hopes & plans.

But you do realise that parenthood is not like buying a car?

Good parents love & accept a child as is, on delivery. If you father a child, there are no guarantees what kind of parent you’ll be. All the successful movers in the world can’t compensate for a parent who would love them more if they could just upgrade them a little, tweak a gene here, speed up their performance …

All this says to the child, loud & clear, is that you prefer your dream of a different child – who is not actually them. It says that they are unacceptable to at least one other adult in the world. You’re a bright guy. Why on earth shouldn’t your child be fine as he or she is?

Naturally you may want the best for your child or children. That hardly means that you only want the best child? Would you reject them? Are you unprepared for your child being less than average, less than well, less than perfect? They’ll likely be the best thing that ever happened to you, and you’ll probably be a great father, but not if you pre-judge them. I guess that’s worth equal consideration, and right now, while you can sleep nights! Not when you’re dog-tired & annoyed by the reality of a baby, seriously.

Besides, a high IQ, don’t forget, is not only socially abnormal, but it generally doesn’t spell financial success. If it does, it might well be at the high cost of a stressful career which leaves no time for family. Which is what you would not want, right?

Best of luck in the future. I mean that.

Comment by Pender Subscribed to comments via email

First of all, this whole debate is moot — not because mandatory breast-feeding will never happen, but because, as Half Sigma posted below, the study seems to be completely unsound.

But if, as a counterfactual thought experiment, we assume its results are true, then I do not see why you are so fast to dismiss the possibility of mandatory breastfeeding. I do not think it is necessarily the right result, but I also do not see why it is necessarily the wrong result.

True, we think of invasions of the body as particularly offensive to our rights. Certainly, there is a presumption against them. But we still go there from time to time when the stakes are high! We MANDATE immunization for children to attend public schools. We MANDATE the extraction of certain forensic evidence in certain criminal proceedings when it is safe. When you get pulled over for drunk driving, we MANDATE either a breathalyzer or urine sample. Why do we mandate these things? Because the benefits of doing so far outweighs the costs.

Okay, let’s take your example about blood transfusions. You’re right, we don’t demand them even if a parent could easily and safely give one and it would save the child’s life. But we SHOULD! It’s outrageous that a dependent child would die because of his mother’s stupid decision when it’s so easy to see what the correct decision is! Imagine the things you would think of a mother whose screaming child died slowly on a hospital table because she didn’t want to give a transfusion. There is no reason to tolerate that kind of abject immorality when it is so easy to fix.

Parenting comes with certain obligations. If you insist on feeding your child a vegan diet and he dies of malnutrition, you could well be tried for second degree murder. In fact, this past summer, the NYTimes ran an article about exactly that. If you leave your child in a crib all day, every day, throwing food in and scooping out poop from time to time, you will be tried for all kinds of abusive treatment if you are ever caught. That means the law quite rightly applies a POSITIVE OBLIGATION to take care of your child.

As to your last point, high IQ is a good thing. You are empirically wrong when you say that “it generally doesn’t spell financial success.” See http://en.wikipedia.org/wiki/IQ#Income . And no, high IQ is definitely a good thing. It predicts good school performance (”The correlation between IQ scores and grades is about .50 . . . [or] 25% of the variance. . . . . Correlations between IQ scores and total years of education are about .55, implying that differences in psychometric intelligence account for about 30% of the outcome variance.”), job performance (”the validity of cognitive ability for entry-level jobs is 0.54, larger than any other measure including job try-out (0.44), experience (0.18), interview (0.14), age (−0.01), education (0.10), and biographical inventory (0.37). This implies that, across a wide range of occupations, intelligence test performance accounts for some 29% of the variance in job performance.”), income, and non-criminality.

How can you seriously argue this last point? Do you really think you’d be no worse off if you were made half a standard deviation stupider? Sure, one of the doors opened by high intelligence is the ability to get a lucrative but “stressful career which leaves no time for family,” but it also opens the door to a lucrative career that earns more money for the SAME number of hours. And your implication that a legitimate way to prevent a child from making a career choice that you don’t like is to make him too stupid for anyone to offer him the choice… well, I think it’s downright pathological.

Best of luck to you too, and of course none of this is personal. I do think it would benefit us all to recognize (1) that rights are really social calculations of costs and benefits and are that they are open to revision when new data comes to light, and (2) that intelligence is a very real phenomenon with incredibly important social implications that will not go away if we pretend that they do not exist.

Comment by Half Sigma

The breastfeeding-IQ link is more junk science that I debunked at my blog:



[...] from an improved IQ compared to formula-fed infants. Hsien-Hsien Lei took this one step further at Eye on DNA, exhaulting the known health benefits of breastfeeding, genetically influenced or otherwise. Also [...]


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