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Breast-Feeding the Microbiome (newyorker.com)
123 points by anthotny on July 25, 2016 | hide | past | favorite | 51 comments

> “We got eighty litres, collected over two years, from someone random at Stanford University, who said, ‘I have all this milk. Do you guys want it?’ ”

Wow... that's quite an amount. So human milk doesn't "expire"? Why does cow milk expire then, and what exactly is expiry in the context of milk?

It is frozen. This can be done for cow milk as well. It changes the taste of cow's milk and (probably) changes the taste of breast milk.

It's not commonly done for cow's milk because (1) fresh milk is usually readily available and (2) adults will complain about the taste.

With breast milk, the supply is more limited and an infant won't tell you the taste is off (but they might refuse to drink it!).

From my short (3 month experience) , refrigerated milk will take on a "soapy" smell and flavor. From what I've read, this is due to the enzyme lipase and can be removed by heating the milk. My baby will sometimes refuse to drink it at first but then I guess hunger takes over and she downs the whole thing.

My kids as babies has all sorts of reason to refuse my wife's milk for all sorts of reasons, not that we could ever be certain what it was but it seemed somedays they didn't like what she ate that day, if it was pumped and stored and reheated the temperature wasn't precisely right, etc.

But yeah, in the end when that's all that's on the menu... hunger takes over :-)

heating before freezing might kill lipase activity, but heating after thawing won't turn soap back into fat

This only occurs for a minority of women.

Seems obvious in retrospect. Wonder if the freezing adversely affects anything? Probably not.

The freezing process of breastmilk does destroy some of the nutrients, making it less nutritious than an infant feeding directly on breast.

They say to only keep frozen breast milk for up to 3 months though.

I think this has more to do with residential freezers being opened/closed regularly, and doing defrost cycles.

"They" are talking about milk for human consumption, not milk for research being kept in -40C freezers.

That's it? We had a chest freezer full of the stuff within two months of my daughter's arrival.

Was that on purpose? Milk production waxes and wanes on demand.

I imagine pumping without consideration for that causes over-production (and the desire to pump more to relieve the 'pressure').

Cow's milk from the store expires in the manner it does due to the processing. Raw milk eventually turns into yogurt, but is still consumable (and delicious, imo).

I'd say they froze the milk in question though, just thought I'd mention it.

The reason pasteurized milk spoils instead of turning into yogurt is the same reason why making yogurt from unprocessed milk is a really bad idea. Milk turns into yogurt instead of curd because of a symbiotic relationship between two bacteria which are added to milk after it has been processed. These bacteria are usually already present in raw milk but we wipe them out so that all of the really nasty stuff doesn't survive (aka botulism and a host of other bacteria that produce toxins).

I've seen very conflicting information when it comes to how dangerous unprocessed milk actually is. Many people argue that the ultra-bad bacteria is a result of the processing itself (homogenization of milk from hundreds of cows in a single vat, unsanitary conditions for animals, udder sores producing infectious discharge).

I'm not saying you're wrong, but my wife and I get our milk from a single cow. It's tested for harmful bacteria bi-monthly and we wash our own containers beforehand. Do we run a greater risk than purchasing pasteurized milk from the supermarket? Probably, but the flavor and nutrition make it worth it for us.

Additionally, the raw yogurt eventually does turn to curd if put in an environment > ~50 degrees F. If you strain it through a cheesecloth, you have a very soft cream cheese. We don't make a habit out of doing that though -- leaving milk out overnight seems like a bad idea regardless of the source.

Well, apparently "many people" don't have a basic understanding of biology. The pasteurization process kills all but the thermophilic bacteria which is why you need to culture pasteurized milk. Only one of the two bacteria needed to make yogurt can withstand the process and the rest of the survivors are incapable of out competing our immune system because they are adapted to an entirely different environment. It doesn't matter how many cows produced a batch of milk as long as the temperature is high enough to kill the non-thermophilic microbes. When it comes to food poisoning and regulated dairy products, the vast majority of contaminations are from the bacteria Staphylococcus aureus, which is so common it can be found on the skin of almost any human being and is easily transfered after pasteurization. A staph infection is peanuts compared to the "ultra-bad" bacteria like Clostridium botulinum which produces a toxin that is fatal at a concentration on the order of nanograms of toxin per kilogram of body mass (and it certainly can't survive the high temperatures of pasteurization).

Raw milk isn't actually banned in most of the developed world. The EU, for example, has non-binding rules that allow vendors to sell raw milk as long as it is done at a small scale, like your case, where the animals are tested often and the scale of the operation doesn't endanger the health of the average consumer. In most EU countries you can "time share" or own a cow that provides raw milk for your household but you can't openly sell it at a supermarket. Countries like France, where raw milk is culturally preferred (something like 20% of cheeses in France are made from raw milk), have a much much higher incidence of food poisoning from dairy than any of the countries where milk is always pasteurized.

I love raw milk and miss it dearly since I moved to the United States but there is nearly a century of evidence that raw milk at commercial scale is an unacceptable risk to public health. So much so that there isn't a single country in the developed world that doesn't strictly regulate raw milk products and all of them do so for public safety reasons.

Botulism spores can survive much higher temps than those used for pasteurization. This is why there's a risk for botulism for home-canned goods that aren't acidic enough. If you're water bath canning, that's pretty much 212F (or less due to altitude). Pressure canning at 15PSI can get up to around 240F, which the minimum temp to kill botulism.

In the past I have done the family milk cow/goat thing, as well as canning, natural fermentation, and cheese-making. So I've done some reading on the topics. I sorely miss raw jersey milk on a daily basis. That stuff is wonderful.

Botulism isn't a problem as long as the incipient yoghurt is exposed to oxygen and contains plenty of other micro-organisms: c. botulinum is anærobic and easily out-competed by lactobacillus.

There are spores of c. botulinum everywhere, but they don't normally cause a problem unless there's a deoxygenated environment (e.g. in the core of a sausage — Latin botulus, hence the name).

The trouble with poorly-canned goods is that they are not exposed to oxygen, other micro-organisms have been killed off, but c. botulinum has survived: that's a perfect breeding ground for the stuff.

So ... does this mean we are going to see yogurt with "B. Infantis"? Or is this a infant-only symbiotic strain? Curious.

Probably not yogurt, but I have run across several probiotics with this particular bacteria present in it. Additionally I have read that yogurt for the most part is pretty useless as a probiotic as your stomach acid kills most of the bacteria in it (also, many yogurts have little live culture in it).

Yoghurt as a probiotic is bad simply because it doesn't contain the right mix of gut bacteria. Typically it's a lactobacillus strain, which is present in our gut, but it's only 1 of millions of strains.

It's not bad, it's insufficient.

But in the stomach, it is my understanding that the bacteria in yogurt can help process the sugars in milk, thus avoiding an excess of sugars in the gut, which might upset the balance of the intestinal flora.


> Every mammal mother produces complex sugars called oligosaccharides, but human moth­ers, for some reason, churn out an exceptional variety: so far, scientists have identified more than two hundred human milk oligosaccharides, or H.M.O.s.

The second part is very suspicious or at least misleading. I guess that chimpanzees and bonobos have a similar milk composition.

> A study recently published in the Journal of Proteome Research details how human milk has a stunning 1,606 different protein types essential for newborn growth - a cocktail of many key nutrients that other mammals' milk does not boast. By comparison, the mother's milk of rhesus macaque monkeys - one of humanity's closest primitive relatives - boasts only 518 key proteins.


1,606 different protein types essential for newborn growth

I read that as "if the baby doesn't get all 1,606 of this proteins, it won't develop normally."

That sounds like a ridiculous statement.

It might be, but that's orthogonal to the point I was making, which was "yep actually human breastmilk is significantly different to chimpanzees".

Maybe. A chimpanzee is much closer to a human than a monkey, which already had ~500 of the ~1600 proteins.

I found a handy graph of the primate family: http://www.nature.com/nrg/journal/v15/n5/fig_tab/nrg3707_F1....

> The time of separation of the human lineage from the rhesus macaque lineage is dated at 28–25 million years ago, whereas the human and chimpanzee lineages are believed to have diverged ~9–5 million years ago.

I don't understand why HN is so obsessed with gut bacteria.

I don't oppose posting it, I just don't understand the fascination.

I suspect, from my own anecdata, it's because a great many of us in the field have had gut issues. A lot of us lead lifestyles that aren't necessarily the greatest (although I feel overall that old adage is changing for the better rapidly) and have a deep interest in fixing the problem. Plus, knowing how things work, biological, electrical, whatever.. it all fits the hacker ethos

Is that your "gut feeling"?

Finding shortcuts is literally hacking. Let's shortcut our way to good health by reading Wikipedia instead of seeing a doctor. Okay then

No one should entrust their health solely to a doctor. It is like entrusting our life to technical support, which half the time is terrible.

No, not instead of as in "never see a doctor" but rather as trying to be smart about things you can do yourself. For example:

Healthier lifestyle: do you need to consult a doctor to decide to cut down smoking or even stop it? (No) Start exercising? (Most likely, no, thise few who need will likely know.) Changing your diet? (No, unless you are doing something very special.)

Picking up some basic skills also means you can treat smaller issues yourself. I keep iodine solution, painkillers, and wrapping bandages for smaller sprains readily available at home. Leave antibiotica, wounds beyond scratches (could have been infected by tetanus or other nasty stuff) to the professionals.

Well, it's literally seen as a medical revolution.

"There is increasing evidence that the microbiome and its output (our interactome) touch many, if not most, pathways that affect health, disease, and aging. It is reasonable to propose that the composition of the microbiome and its activities are involved in most, if not all, of the biological processes that constitute human health and disease, as we proceed through our own life cycle"


Don't get too ahead of yourself. Sure we have a lot of evidence that your microbiome is important in things like C. difficile infection, but I've only seen very tenuous evidence supporting any impact on things like aging.

Not to say it might be discovered in the future. But it also stands a good chance of being a dead end.

> Don't get too ahead of yourself.

That quote about aging is from Blaser:


It's a relatively new field of medicine, with some compelling evidence that it might help. Importantly, the microbiome is very amenable to manipulation - directed and undirected. There's very much a prospect for being able to design the microbiome - something that's logically appealing to the mindset of many people who post on HN.

There's evidence that gut flora have a hand in many diseases including obesity, Crohn's, depression, etc. We know so little about it, as is the case with many of the details of our body's daily functions.

Our gut bacteria is the interested party - not our brains. Microbiomes are really excited to finally be getting some press for all their hard work.

Because gut issues have been implicated in a whole lot of common maladies, but the precise nature of the interactions of gut bacteria and their human hosts has yet to be determined, making it very intellectually intriguing. Especially for those of us with chronic conditions that are finally starting to see treatment success with carefully targeted probiotics or fecal transplants.

We are exploring and learning to hack the most complicated system we are aware of. Even the smallest component is truly remarkable.

Because the paleo- and keto-eating HN master race are curious about answers to the question "why would anyone eat anything else?"

Having cured all of the physical injuries that one would encounter from having an active lifestyle (knee injuries, head trauma, etc.) we now have more time to focus on things that are more esoteric and only manifest in subtle ways. Cancer, autism, etc. are the problems of the first world, industrialized, and coddled demographic that a site with this title would have.

Well, it's literally seen as a medical revolution. "There is increasing evidence that the microbiome and its output (our interactome) touch many, if not most, pathways that affect health, disease, and aging. It is reasonable to propose that the composition of the microbiome and its activities are involved in most, if not all, of the biological processes that constitute human health and disease, as we proceed through our own life cycle" http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4191014/

Regarding the Microbiome, I'm currently reading Rodney Dietert's "The Human Superorganism: How the Microbiome Is Revolutionizing the Pursuit of a Healthy Life". I haven't finished it yet, but it's been a great read so far.


Why did you post this a second time under another account?


Nice catch!

Another good book on the subject is "The Good Gut: Taking Control of Your Weight, Your Mood, and Your Long-term Health"


Regarding the Microbiome, I'm currently reading Rodney Dietert's "The Human Superorganism: How the Microbiome Is Revolutionizing the Pursuit of a Healthy Life". I haven't finished it yet, but it's been a great read so far. [https://www.amazon.com/dp/1101983906]

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