Don't tell me they found Tyrannosaurus rex meat again!

It seems that some scientists are still claiming they can find bits of dinosaur meat clinging to the fossilized bones of ancient dinosaurs. Don’t sharpen your dinner knives yet.

I thought this story, which first appeared in 2007, had died long ago, but it has just reappeared. Before I get to that, though, let me explain the original claims. Back in the late 2000’s, a couple of paleontologists managed to publish two articles in the journal Science claiming they had found traces of original dinosaur proteins in 68-million-year-old Tyrannosaurus rex fossils, and in an even older 80-million-year-old fossil from another dinosaur, a hadrosaur.

This would have been shocking news if it was true, but alas, it wasn’t (even if Jurassic Park fans wished otherwise). Organic material survives only a very short time after an animal dies, usually just a few years. Bones and teeth can last far longer, though. Scientists have extracted DNA from the bones of Neandertals and cave bears that are over 50,000 years old, which is pretty extraordinary.

But 68 million years is far, far longer than 50,000 years. Those fossils are one thousand times older than bones from Neandertals.

But maybe proteins can last longer than DNA? Well, perhaps, but not that long. The oldest known protein fragment, which was preserved in an exceptionally cold environment, is about 3 million years old. The T. rex fossils studied in the Science paper were found in a warm climate, where any proteins must have degraded far more quickly.

I wrote about this way back in 2008, expressing my disappointment with the journal and explaining some of the problems. Nature ran a news story about the controversy as well.

But wait, you’re probably thinking, that T. rex study was published in a prestigious journal, so how can it be wrong? Well, what seemed to happen was this: one of the editors at Science back in 2007 simply believed the study, or maybe he just wanted to believe it, so he ignored the reviewers. How do I know this? Well, when the first paper appeared, in 2007, two of the scientific reviewers, both experts in the field, contacted me to tell me that they had both recommended rejecting the paper, but the editor went ahead with publication anyway. (They contacted me because I had published papers in Science before, and they wanted my advice on what they could do.)

My guess is that the Science editor wanted to get headlines along the lines of “T. rex tasted like chicken.” (To explain: the tiny fragments of protein that the first paper found appeared to be similar to proteins from birds.) The editor got exactly that, in stories that ran in the Washington Post, the New York Times, Smithsonian Mazazine, and elsewhere back in 2007 and 2008.

After the original T. rex paper appeared, at least two letters were sent to Science explaining why it was wrong. Science published them as a “technical comments,” which weren’t nearly as prominent as the original paper.

That letters gave far more plausible explanations for the data from the paper: first, one letter explained that it was very likely that the tiny, tiny trace of chicken-like protein was simply contamination from a modern bird, maybe as benign as someone’s turkey sandwich. That letter also pointed out that the supposed T. rex protein appeared to be modern in origin, because it lacked the signs of aging that an ancient protein fragment should have. (The details are very technical; follow the link if you want to learn more.) The other letter pointed out errors in the statistical analysis, pointing out that the result could easily be a statistical artifact.

A later paper, published independently, re-analyzed the T. rex data itself and found that the sample appeared to contain “common laboratory contaminants, soil bacteria, and bird-like hemoglobin and collagen.” In other words, no ancient proteins at all.

I should note that the experiments used to detect the dinosaur proteins, using a technology called mass spectrometry, are notoriously plagued by contaminants. Even a tiny trace of a modern bird in the mass spectrometry lab (e.g., someone eating a turkey sandwich) is liable to produce a few protein fragments that show up in the experiment. Scientists at the time pointed out that the very same lab had done experiments using ostrich bones around the same time as the dinosaur fossils.

And if that wasn’t enough, yet another published paper argued that the “soft matter” found in some fossils by the paleontologists was likely to be a bacterial biofilm. Fossils, I should explain, are highly porous, and it’s easy to imagine how bacterial could infiltrate them over the millenia.

In fact, you don’t have to imagine that at all: another scientific paper from 2019, published in the journal eLife, described finding “an abundant microbial community” in dinosaur fossils.

All of this skepticism did not deter the original scientists. It was less than two years before they’d published a second report (also in Science, with the same editor) claiming that they’d found similar proteins in another, even older dinosaur fossil, an 80-million-year-old hadrosaur.

And yes, the paleontologists continued to insist that they found “soft matter” that must have originated from the original dinosaurs. Dinosaur meat! The highly regarded CBS news program 60 Minutes was so impressed that they aired an entire segment on this finding:

Alas, there’s just no way that fossils contain any soft matter from 62 million years ago. It was likely just bacteria. But we can’t let that get in the way of a good story.

So how long can animal proteins survive? In temperate regions (such as those where the T. rex fossils were found), most organic matter decays in a few decades. If the animal happens to die in a very cold place, and its body is encased in ice, it seems that some organic material can survive up to one million years, and possibly even longer. Cool! (Pun intended.)

But the T. rex fossils from the original Science study were found in temperate climates. They were not frozen in deep permafrost or ice, and the original organic material was almost certainly long gone many millions of years ago.

I thought this story was dead, but apparently I was wrong: a small cadre of scientists continues to believe that dinosaur fossils–which are made entirely of stone, not bones–contain detectable traces of the original dinosaur proteins. Unbeknownst to me (because I wasn’t following it), another paper appeared in 2017 that claimed to find signs of dinosaur proteins in a 195-million-year-old fossil, more than twice as old as the previously reported claims.

Astounding, if true. And just this month, a chemistry professor at MIT reported that he has the explanation for how these proteins survived so long. This finding, though, is more about how the chemical bonds in collagen–the protein that bones are built upon–are exceptionally stable. That’s interesting, but it doesn’t at all prove that collagen can last for nearly 200 million years.

So count me as deeply skeptical. The science of dinosaur “meat” has from the beginning been fraught with wishful thinking. Multiple papers appeared refuting the original claims, and none of those were effectively rebutted; it seems they were just ignored by scientists who preferred a more fanciful story. I wish it were otherwise, but fossilized bones from Tyrannosaurus rex and other dinosaurs lost any traces of the original organic material eons ago.

The Hayflick Limit: why humans can't live forever

 A scientific legend, Leonard Hayflick, passed away at the beginning of August. Most non-scientists probably don’t recognize his name, but he made a remarkable discovery in the early 1960s. Back then, while doing experiments on human cells, he and a colleague, Paul Moorhead, discovered that our cells can only divide a limited number of times.

This discovery, although made at the level of an individual cell, has a dramatic implication: humans cannot live forever.

What Hayflick discovered was that after 40 to 60 rounds of splitting in two, cells simply won’t divide any more. At that point, they enter a phase called senescence, and they eventually die. The number of divisions that a cell can go through is now known as the “Hayflick limit.”

Prior to Hayflick’s experiments, many scientists believed that cells could divide forever. After all, every cell in our body comes from one original cell, and that cell came from our parents, and from their parents before that, and so on back through the ages. So it stood to reason that cells could continue to divide without limit. What’s more, in the early 20th century, Alexis Carrel (a Nobel laureate) claimed to have grown cells in his labs that continued to divide for decades, with no sign of decline.

(Aside: Jan Witkowski explained in an article back in 1980 that it was likely that Carrel’s seemingly immortal cells had been quietly replenished, without Carrel’s knowledge, by members of his lab who were eager to keep the boss happy.)

Back to the Hayflick limit: because all of our organs are destined to wear out, our bodies will simply die unless we can intervene and restore cells to their youthful state. That would require technology that has not yet been invented. Hayflick himself estimated that the limit of the human lifespan is 125 years.

Hayflick’s limit raised an intriguing puzzle: how does a tiny, microscopic cell keep track of how many times it has divided? In other words, how can a cell know how old it is? Don’t all of our cells have identical DNA? Hayflick himself didn’t have a solution for this, but a few decades later, others figured it out.

The answer to this cellular “clock” puzzle resides, it turns out, in our DNA. More specifically, it depends on the DNA sequences at the very ends of our chromosomes, which are called telomeres.

Telomeres don’t really do anything, and they appear very simple: they consist of a long stretch of six DNA bases, TTAGGG, repeated hundreds of times, end-to-end. All our chromosomes end with telomeres, on both ends.

So here’s the thing: when a cell divides, it has to copy all of its chromosomes. The mechanism for copying isn’t quite perfect, and it can’t go all the way to the end of the chromosome, so the new copy is a little bit shorter. The telomere gets shorter! Fortunately, we have a special enzyme, called telomerase, that fixes this problem by adding a few extra copies of TTAGGG to the end of each chromosome, restoring the proper length. Problem solved, right?

Well, no. Telomerase doesn’t work perfectly, and chromosomes sometimes do get a bit shorter each time they divide. When the chromosomes get too short, the cell can’t divide any more, and it eventually dies.

And yes, scientists have explored the question of whether telomere length might be the key to longevity. No one has figured out a way to keep telomeres long, and it’s not clear that would help anyway. On the contrary, as my Hopkins colleague Mary Armanios reported in a study last year, long telomeres might help individual cells stick around, but they don’t seem to prevent aging.

Does the Hayflick limit mean we really can’t live forever? Well, not necessarily. Some types of stem cells can produce “fresh” cells that could, in theory, replenish our old cells. Perhaps some day we’ll have the technology to replace our organs with new ones, possibly grown in a lab, that will have the youth and energy of a 20-year-old. But without replacing our parts, we are destined to wear out, even if we manage to avoid cancer, infections, and the many other perils that humans face.

Leonard Hayflick made it to 96, a ripe old age by today’s standards. It would have been fitting if he’d reached 125, the limit that he estimated, but no human has ever done that. Yet.

Can you use the gut microbiome to diagnose autism? I think not

Last week, the New York Times published a story claiming that we might be able to use the gut microbiome to diagnose autism. The Times story was based on a just-published scientific paper that claimed the same thing.

This report set off all my skeptical alarm bells. My initial reaction was “oh no, more bad science around autism.” For one thing, as most scientists studying autism are aware, the modern anti-vaccine movement started with a scientific paper, back in 1998, that claimed, falsely, that childhood vaccines caused autism. That paper in The Lancet was later shown to be fraudulent and was eventually retracted, but not before a huge amount of damage was done. Its lead author, Andrew Wakefield, went on to become a hero to the anti-vaccine movement, and he continues to promote anti-vaccine misinformation to this day.

The new paper (from the journal Nature Microbiology) is not making outrageous claims like that, nor was the New York Times. However, anyone claiming autism is caused by microbes in the gut should know that the notorious Lancet study was based on a hypothesis about a “leaky gut,” a hypothesis that was discredited long ago. (I don’t want to give it any credibility, but that hypothesis held that virus particles in some vaccines somehow “leaked” from the gut and made their way to the brain. It was nonsense at the time and still is.) That’s one reason why the suggestion that microbes in the gut might cause autism (or even be used to diagnose it) raises so many alarm bells.

I’ve now looked at the study, and frankly I don’t believe a word of it. Let me be clear, though: I’m not trying to prove scientifically that the study is wrong, which would require many months of effort and a much more detail than I can put into a column anyway. Fortunately, though, there’s an earlier study that did that job for me, which I’ll get to below.

However, the science behind this study is closely related to my own work, so I feel pretty comfortable offering my opinion. So what did the authors do?

Well, as the new study explains, they collected poop (”faecal samples”) from 1,627 children, some of whom had been diagnosed with autism and some who hadn’t, and they sequenced DNA from the poop. Then they looked for bacteria, viruses, and other microbes in the DNA sequence data.

That’s right: the “gut microbiome,” is really just a polite term for bacteria that live in the intestines and the colon, some of which come out in poop. Of course, some bacteria in poop might come from the food that a person ate, but mostly these are so-called gut bacteria.

I’ve been involved in many studies like this myself, so I’ve seen that these experiments yield hundreds of different species from every sample. The data sets are very complex, and a widespread problem in the field is that these data are often misinterpreted. In the Nature Microbiology paper, the authors took these very complex data sets and fed them to a machine learning program, and voila! The AI program was able to do a pretty good job (far from perfect, I should note) identifying the autistic children, based on the melange of microbes in their poop.

Right. I don’t believe any of this, as I wrote above. Why not? Well, first of all, machine learning programs are really good at telling apart two sets of subjects (such as children with and without autism) if you give them enough data. It sometimes turns out that the learning programs are keying in on irrelevant features that the scientists didn’t intend.

For example, this 2021 paper looked at over 400 studies that used machine learning to predict Covid-19, all of which had claimed some success, and found that all of the studies were essentially useless “due to methodological flaws and/or underlying biases.” Of course, the gut microbiome study wasn’t one of those, and some machine learning experiments do work, but we should be very skeptical.

Another reason for skepticism is that the new paper doesn’t even try to tell us what the machine learning models actually learned–it just treats the programs as a “black box” that we should trust.

Perhaps the biggest flaw in the study of autism and children’s gut microbiota is this: children with autism tend to be finicky eaters, and their parents try all sorts of diets in the hope that they can at least alleviate the symptoms of autism with food. There are countless websites–many of them scams, unfortunately–claiming that special diets can help these children. Why is this important? Because a special diet will alter your gut microbiome, sometimes quite significantly.

Thus even if the machine learning models in the new study are correct, the causality almost certainly goes the other way: children with autism might have a different microbiome because they’re eating different foods. Thus it’s autism that indirectly affects the microbiome. Unfortunately, both the New York Times and the scientific paper suggested the opposite.

Now on to that earlier scientific paper I mentioned above. It turns out 3 years ago, a group of researchers in Australia published a major study in the journal Cell that addressed precisely the problem I just pointed out. In that study, the scientists collected and sequenced poop from 247 children both with and without autism. They found “negligible direct associations between ASD [autism spectrum disorder] and the gut microbiome.“

On the contrary, the authors warned: “microbiome differences in ASD may reflect dietary preferences ... and we caution against claims that the microbiome has a driving role in ASD.”

In other words, three years ago a study in a major scientific journal found that there was no connection between autism and the contents of the gut microbiome. They went on to warn that if you see differences in the gut microbiome in autistic kids, those are caused by their diet, so don’t go claiming that the microbiome causes autism. The authors of the newer study, and the reporters at the New York Times, apparently decided otherwise.

So no, the gut microbiome can’t be used to diagnose autism.

RFK Jr. is a famous anti-vaxxer. How does this make him qualified for President?

I’ve written about the anti-vaccine movement and its many proponents more times than I can count. So why write about it again? Because one of them is running for President of the United States.

Robert Kennedy Jr. is famous for two things: first, he’s famous because he’s the son of a former Senator and the nephew of a former president. His father, Robert Kennedy Sr., served as Attorney General under President John Kennedy and then as a US Senator. Tragically, both JFK and RFK were assassinated in the 1960s, and RFK might very well have been elected president in 1968, as he was leading the Democratic field when he was killed.

Having a politician as one’s father does not qualify anyone for office, although many children of politicians use their famous name to win elections. That’s clearly what RFK Jr. is now hoping for.

But what RFK Jr. is really famous for now, and for the past 20 years, is something entirely different. As I wrote nearly a decade ago, Kennedy is obsessed with the notion that vaccines cause autism. He’s particularly obsessed with the thoroughly discredited idea that thimerosal, a preservative used in some vaccines, causes autism.

His efforts to convince people of the harms of vaccines landed Kennedy in the number two position on the infamous list of “The Disinformation Dozen,” This list, created by the Center for Countering Digital Hate, contains “the twelve anti-vaxxers who are responsible for almost two-thirds of anti‑vaccine content circulating on social media platforms.” Yes, this is what RFK Jr. has been focusing his energy on, at least until he decided to run for President.

Ten years ago, Kennedy published an entire book on this topic, called “Thimerosal: Let the Science Speak,” and he promoted it both in the press and in the halls of Congress. He had personal meetings with then-U.S. Senator Barbara Mikulski and Sen. Bernie Sanders to try to convince them to take action based on his claims. Why is it that a scientifically unqualified anti-vaccine advocate got a private audience with two U.S. Senators? Because he’s a Kennedy.

RFK Jr. gives hundreds of speeches a year, and up until the early 2000s, he spoke mostly on environmental issues. I heard one or two of his interviews during that era, and he was quite convincing. His usual argument was that large corporations were engaged in some kind of conspiracy to damage the environment so that they could increase their profits. That made sense to me!

But then he found the thimerosal issue and went completely off the rails. One example was a Salon.com and Rolling Stone article (jointly published in both magazines) that he wrote in 2005, which claimed not only that thimerosal-containing vaccines cause autism, but that “the government” knew about it and had been covering it up. Kennedy wrote that

“The story of how government health agencies colluded with Big Pharma to hide the risks of thimerosal from the public is a chilling case study of institutional arrogance, power and greed.” [quote from RFK Jr.]

Alarming-sounding stuff. The article was full of dramatic claims like this one. The only problem was, all of them were false.

To explain, let’s review what thimerosal is and why it has probably saved many lives. There was never a conspiracy because there was nothing to hide.

Thimerosal is a preservative that was used in many vaccines for decades. Why? Well, as I’ve explained before, early vaccines (back in the pre-WWII era) were administered from multi-dose bottles, in which bacteria would sometimes grow. In one particularly disastrous incident in 1928, 12 children in Australia died from staph infections after receiving the diptheria vaccine from the same multi-dose bottle. After the introduction of thimerosal, bacterial infections caused by vaccination virtually disappeared.

Why the panic from RFK Jr. and others about thimerosal? Well, it’s a mercury-based preservative, and RFK assumed (wrongly) that the tiny amounts of ethylmercury in vaccines caused autism or other neurological problems. One problem with this idea is that ethylmercury is very different from environmental mercury, which is called methylmercury and which can indeed be toxic. Ethylmercury is cleared from the body far more quickly–and the minuscule amounts in vaccines have never been shown to cause any harm.

But many anti-vaxxers, especially RFK Jr., have continued to spread alarming stories about vaccines (particularly through Children’s Health Defense, an organization founded by Kennedy), and a disturbing number of parents have withheld vaccines from their children because they didn’t know who to believe.

In the late 2000's, in an effort to address the concerns of anti-vaccine alarmists, a special U.S. vaccine court conducted three lengthy hearings in which the anti-vax advocates were asked to present their best cases. One of the cases focused specifically on the question: does thimerosal in vaccines cause autism? In that case, the judge concluded:

“The numerous medical studies concerning the issue of whether thimerosal causes autism, performed by medical scientists worldwide, have come down strongly against the petitioners’ contentions. Considering all of the evidence, I find that the petitioners have failed to demonstrate that thimerosal-containing vaccines can contribute to the causation of autism.”

As a lawyer, Kennedy should have been able to understand this. The science agrees with the court: in study after study, scientists found no link between thimerosal and autism or any other kind of neurological disorder. That should have been the end of the matter, but of course it wasn’t.

Furthermore, as RFK Jr knows, thimerosal was removed from childhood vaccines in the U.S. over 20 years ago, and the rate of autism diagnosis continued to rise after that. This fact alone contradicts his major claim: if thimerosal was fueling an autism epidemic, then cases should have declined after vaccines stopped including it.

What was shocking to me, the first time I heard Kennedy talk about thimerosal in vaccines, was how absolutely certain he was. He came across as a man who remained utterly convinced that vaccines cause autism, despite the mountain of evidence against him.

After RFK Jr.'s Salon article appeared, scientists responded quickly and convincingly, pointing out its numerous flaws and distortions. Salon tried to fix the problem, issuing five corrections before throwing up their hands and removing the article entirely from their website. Rolling Stone also took down the article. Salon’s editor-in-chief wrote an apology, saying

“I regret we didn’t move on this more quickly, as evidence continued to emerge debunking the vaccines and autism link. But continued revelations of the flaws and even fraud tainting the science behind the connection make taking down the story the right thing to do .”

Kennedy has steadfastly refused to admit any errors, ever. When I wrote about him in the past, his website still displayed the original Salon article, without even the small corrections that Salon.com had made. (That website, robertfkennedyjr.com, no longer exists now that he’s running for President.)

Kennedy also published another anti-vaccine book just last year, titled “Vax-Unvax: Let the Science Speak.” (In case you didn’t notice, Kennedy has zero credentials to write a book about vaccine science, but that has never slowed him down.) And in case there’s any doubt about his leanings, early in 2024 Kennedy hired Del Bigtree, a “top anti-vaccine activist,” as his campaign communications director.

By ignoring the scientific evidence that shows that thimerosal and vaccines have no link to autism, Robert Kennedy placed himself firmly in the camp of conspiracy theorists and cranks. He’s also demonstrated breathtaking arrogance. He believes that despite his lack of scientific training, he knows the truth that every scientist who’s studied this issue has missed.

Even worse, Kennedy has used his fame to spread anti-vaccine misinformation, which grew far worse during COVID. Though I doubt he will listen to me (he’s ignored everyone else), Kennedy needs to take a hard look at the harm he’s causing to defenseless children, the elderly, and cancer patients, and anyone else with a weak or compromised immune system.

When I heard Kennedy talk about environmental topics, where I agreed with him, I was impressed by his passion and his seeming command of the issues. But having heard him speak about thimerosal and vaccines, I now realize that he’s a dangerous ideologue, willing to distort the truth so thoroughly that he can’t be trusted on any topic, even ones where I agree with him. His campaign for President, although certainly doomed to fail, is likely to increase the spread of his harmful anti-vaccine tropes.

Finally, I couldn’t help but notice that the bio on RFK Jr’s campaign’s website makes no mention of his anti-vaccine activism, even though it’s been his top priority for the past 20 years, and it’s the main reason he has the visibility he has today. It does mention “his nonprofit, Children’s Health Defense” but doesn’t say that the primary work of that nonprofit is to spread scary misinformation about vaccines. I’m just guessing here, but it appears that some of his campaign advisers have decided that being a famous anti-vaxxer might not be the best qualification for President.

Update, May 28, 2024: Since this story was published on May 27, RFK Jr. has been contacted for comment.  

Hormone replacement therapy is beneficial and safe, it turns out

 

A new study that just appeared in the Journal of the American Medical Association has some good news for women who take estrogen replacement therapy.

To jump to the punch line: estrogen therapy helps to alleviate hot flashes and other symptoms of menopause, and it carries little risk. And even better news: the study also reported that estrogen-only therapy might actually decrease the risk of breast cancer.

Why does this matter? Because about 20 years ago, millions of women stopped taking estrogen, even if it was helping them, because of a report that hormone replacement therapy might increase (not decrease) the risk of breast cancer.

These latest results come from the long-running Women’s Health Initiative, a National Institutes of Health-funded study of more than 160,000 women who were given various hormone therapies and then followed for up to 20 years. The WHI was responsible, somewhat notoriously, for the cancer scare in 2002, when the NIH reported–without consulting many of the scientists leading the study–that hormone replacement therapy increased the risk of breast cancer. This was wrong, as I explained in this column a few years ago, but as a result, many women stopped taking estrogen, and physicians stopped recommending it.

The confusion stemmed from the use of two different types of hormone therapy: (1) estrogen alone, or (2) estrogen plus progestin. The increased risk occurred solely in the combination therapy group (estrogen plus progestin), and not in the estrogen-only group. Despite this crucial difference, the WHI halted the studies of both treatments in 2002, and their press releases didn’t fully explain the difference.

And yet, as Dr. Robert Langer explained in 2017, the WHI trial of estrogen alone (without progestin) continued to track its subjects, and in 2004 that study reported that estrogen-only therapy led to a reduction in breast cancer, and a reduction in coronary heart disease as well.

(Aside: the Women’s Health Initiative website boasts that their 2002 report contains “revolutionary findings about combined hormone therapy,” emphasizing only the harm. I couldn’t find any comparable highlight describing the benefits of estrogen-only therapy.)

The new study, which appeared in JAMA on May 1, confirms several earlier studies that have reported a cancer benefit for estrogen therapy. In addition to its beneficial effects on menopause symptoms (which are widely acknowledged), the new study found that, after an average of 10.7 years, “rates of breast cancer were significantly lower in the CEE group [estrogen only] compared with the placebo group (HR, 0.77).” That HR value means that women who took estrogen had a 23% reduction in their risk of breast cancer.

Further supporting these findings is a 2022 study from NIH, available as a preprint in medRxiv here, which found that women taking estrogen only, compared to no hormones at all, had “significant risk reductions for all study cancers, breast, lung, endometrial, colorectal and ovarian” as well as a 20% reduction in mortality. The 2022 NIH study also found, similarly to the 2002 findings from WHI, that when estrogen was combined with progestin, the risk of breast cancer increased.

And there’s more. This 2012 study out of Denmark studied women who received estrogen-only therapy for 10 years starting in the early 1990s. They then followed these women for another 16 years, and found that women taking estrogen had a lower risk of heart attack, heart failure, or death–and no increased risk of cancer.

(As another aside: the new JAMA paper also reported results on a completely separate study of calcium plus vitamin D. They found that taking supplemental calcium+D didn’t provide any benefit in reducing the risk of bone fractures, confirming what I wrote in a recent column, here.)

So what’s the bottom line? We now have a raft of evidence showing that for post-menopausal women, estrogen therapy can offer significant benefits not only in treating hot flashes and other “bothersome menopausal symptoms” (to quote JAMA), but also in reducing the risk of some types of cancer. In contrast, hormone replacement therapies that use progestin, which is commonly used in birth control pills, might increase the risk of cancer and should be avoided.

As with most medical treatments, the true picture is complicated, but millions of women today might benefit from estrogen therapy. If you think you might be one of them, talk to your physician.