I’m often asked what my opinion
about a diet or disease is.
Who cares what my or anyone else’s opinion is.
All we should care about is what the science says.
What does the best available balance of evidence
Published in the peer- reviewed medical literature
have to say right now?
Welcome to the Nutrition Facts Podcast,
I’m your host, Dr. Michael Greger.
Did you know that by age 50 about half of all men and women
will experience hair loss?
The majority of age-related hair loss is genetic,
but even identical twins can have dramatically different heads of hair
based on their diet and lifestyle.
In our first story, we look at whether biotin or zinc supplements
have any role in preventing hair loss.
“Studies show that by age 50, approximately half of men and women
will experience hair loss.”
No, it’s not caused by washing your hair too much,
or brushing your hair too little, two of the many myths out there.
The majority of hair loss with age is genetic
for both women and men, in the case of this study.
Based on twin studies, the heritability of baldness in men
is 79 percent, meaning about 80 percent of the differences
in hair loss between men is genetically determined.
But that still leaves some wiggle room.
Even if you have identical twins, identical twin sisters
in this case with the same DNA, one can have more hair loss
than the other thanks to Increased stress,
increased smoking, having more children,
or having a history of high blood pressure or cancer.
Smoking can contribute to the development of both
male and female pattern baldness because of the genotoxic compounds
in cigarettes may damage the DNA in hair follicles
and cause microvascular poisoning in the base of the follicle.
Other toxic agents associated with hair loss include mercury,
because it seems to concentrate about 250-fold in growing scalp hair.
In fact, maybe the reason Shakespeare started losing his hair
was due to mercury poisoning from syphilis treatment.
Thankfully doctors don’t give people mercury anymore.
These days, as the CDC points out,
mercury mainly enters the body through seafood consumption.
So, doctors should consider screening for mercury toxicity
when they see hair loss, since there’s something we can do about it.
Instructing patients to reduce fish intake and repeat blood tests
could offer relief of symptoms and uncover dietary habits
that may be a source of heavy metal-induced hair loss.
Though admittedly, sometimes heavy metal can lead to too much hair.
What about nutrient deficiencies as a cause of hair loss?
After bariatric surgery, the most frequent nutrient deficiency symptom
is hair loss, but that’s because they’ve had their anatomy
rearranged to cause malabsorption on purpose.
In general, there is little evidence to suggest that vitamin
and mineral supplementation benefits people
unless they are actually deficient.
For example, we’ve known for centuries that scurvy,
severe vitamin C deficiency, can cause hair loss,
but once you have enough vitamin C such that
our gums aren’t bleeding, there’s no data correlating
vitamin C levels and hair loss once you have
a certain baseline sufficiency of vitamin C.
It’s also a myth that supplements containing zinc
will increase hair growth, unless you have zinc deficiency,
like if you’re an alcoholic or something.
But if you have normal zinc levels in your blood, taking more zinc
won’t help, and in fact can have negative side effects.
It’s the same thing with taking iron supplements.
The most common ingredient in top-selling hair loss products
is vitamin B7, also known as biotin.
Yes, biotin deﬁciency causes hair loss,
but there are no evidence-based data
that supplementing biotin promotes hair growth.
And severe biotin deﬁciency in healthy individuals eating
a normal diet has never been reported,
but if you eat raw egg whites, you can acquire a biotin deﬁciency
since there are these compounds that attach to biotin
and prevent it from being absorbed.
But other than rare deficiency syndromes,
it’s a myth that biotin supplements increase hair growth.
But hey, why not just have the attitude "can’t hurt, might help?”
Because of the lack of regulatory oversight
of the supplement industry and, in the case of biotin,
interference with lab tests.
Many dietary supplements promoted for hair health
contain biotin levels up to 650 times
the recommended daily intake of biotin.
And excess biotin in the blood can play haywire on a bunch
of different blood tests, including thyroid function,
other hormone tests including pregnancy),
and the test they do to see if you’ve had a heart attack,
so it could potentially even be life or death
And in terms of poor regulation, as I’ve done tons of videos about,
there are all sorts of supplement manufacturer shenanigans.
For example, this outbreak in which hundreds suffered
selenium toxicity because they had an oopsie
and put 200 times the dose and so it ended up causing hair loss.
And the same thing can happen with getting too much vitamin A.
Next up, we look at the pros and cons
of the drugs finasteride and minoxidil for hair loss.
“Any consumer looking on the Internet for a treatment
for hair loss is exposed to a multitude of remedies.”
However, we only have good evidence for efficacy for the
FDA-approved drugs, finasteride, sold as Propecia,
and minoxidil, sold as Rogaine.
It’s considered a myth that all the patented hair-loss supplements
on the market will increase hair growth.
And they may actually be more expensive, with over-the-counter supplement
regimens costing up to more than a thousand dollars a year,
whereas the drugs may only be one to three hundred dollars.
The drugs can help but can cause side-effects.
The Propecia can diminish libido and cause sexual disfunction,
while the topical Minoxidil can cause itching.
To understand why there are so many hormonal side-effects
for Propecia like impotence, testicular pain, and breast enlargement,
you have to understand how the drug works.
Androgens, male hormones like testosterone,
are the principal drivers of hair growth in both men and women.
We know this from studies a half century ago
that show that castration of men stopped hair loss.
Why exactly were they being castrated?
Due to eugenics laws in the United States,
when mentally handicapped persons were castrated
or had their tubes tied against their will.
So-called retarded persons were routinely sterilized
without their consent or knowledge and we,
the United States of America, was the first country to introduce
eugenic laws, which were later upheld by the US Supreme Court.
In the 1930s, a vocal proponent complained that
“The Germans are beating us at our own game.”
Anyway, testosterone is the primary androgen circulating in the blood
and can be converted to dihydrotestosterone,
which is even more powerful by an enzyme called 5-alpha reductase.
That’s the enzyme that's blocked by Propecia,
so it inhibits the souping up of testosterone.
That’s why women are not supposed to take it
since it could femininize male fetuses;
whereas for men it has the sexual side effects
like erectile dysfunction, which can affect men for years.
It’s something the drug companies had to disclose for the last decade:
“a difﬁculty in achieving an erection
that continues after stopping the medication,”
side effects that may even be permanent.
Up to 20 percent of subjects reporting persistent sexual dysfunction
for six or more years after stopping the drug,
suggesting the possibility that it may never go away.
What we think might be happening is that the drug
may actually structurally change the part of your brain
responsible for sexual function.
And indeed, though blood levels of hormones in users
with persistent effects appear normal.
If you do a spinal tap and look at the cerebrospinal fluid surrounding their brains,
neurosteroid levels do appear to end up being altered.
So, it's "recommended that prescribers of ﬁnasteride,
as well as potential users, be aware of the potential serious
long-term risks of a medication used for a cosmetic purpose.”
To date, no new interventions are used routinely
in the treatment of male or female pattern baldness.
Given the side-effects of the current drug options,
there is a need for alternative treatments.
So, what about foods? Things we could eat to combat hair loss.
That’s exactly what we’re going to explore next.
Androgenic or androgenetic alopecia, also known as
male or female pattern hair loss, is one of the most common
chronic problems seen by dermatologists.
Wait, so it’s called male pattern hair loss
and female pattern hair loss?
Yeah, in men they call it male pattern hair loss,
and in women they call it female pattern hair loss.
Okay. Either way, it is characterized by progressive hair loss,
predominantly of the central scalp.
I’ve talked about hair loss supplements.
I’ve talked about hair loss drugs.
What about foods for hair loss?
What role might diet play in the treatment of hair loss?
Human experiments with fecal transplants offer a clue to how powerful
our microbiome is, with reports of improvements in hair loss
after a fecal slurry made from freshly passed stools from a donor
was administered into another person’s colon, and not just by a little.
A totally bald guy starts growing back hair a few months
after a fecal transplant and a little over a year later,
check it out, completely regrown.
The moral of the story is not to drink brown smoothies,
but to keep your good gut bugs happy.
Population studies have found that male pattern baldness
is associated with poor sleeping habits
and the consumption of meat and junk food;
whereas protective associations were found
for the consumption of raw vegetables, fresh herbs,
as well as the frequent consumption of soymilk.
Drinking soy beverages on a weekly basis was associated
with 62 percent lower odds of moderate to severe hair loss,
raising the possibility that there may be
compounds in plants that may be protective.
Complementary and alternative medicine treatments
“boast the ability to ’cure’ hair loss ‘safely’
with ‘less side effects’ than conventional medicine.
However, it is important...to look beyond the overarching claims
and marketing to critically review the literature.”
For example, many studies have little relevance
because the evidence was obtained on shaved rodents.
Hey, let’s smear shaved mice with bee venom.
And even when they do clinical studies on actual people,
sometime there’s no placebo control; so, you have no idea
if the food had anything to do with it.
But there has been a randomized double-blind, placebo-controlled study
of compounds in hot peppers and soy,
showing significantly higher promotion of hair growth.
Here are some before-and-after pictures of both men and women.
Okay, but what kind of doses were they using?
6 mg of capsaicin a day and 75 milligrams of isoflavones.
Okay, what does that translate out to in real food?
You can get 6 mg of capsaicin in just a quarter
of a fresh jalapeno pepper a day. That sounds pretty doable.
And you can get 75 mg of isoflavones
eating ¾ of a cup of tempeh or just straight soybeans.
Soy nuts are even more concentrated,
dry roasted soybeans,
but given the formation of advanced glycation end-products
in high fat/high protein foods at high temperatures, I’d suggest
avoiding routinely eating roasted or toasted nuts, seeds, or soy.
There’s also been a randomized, double-blind,
placebo-controlled trial of pumpkin seed oil.
Where did they get that idea?
In 2009, a study out of South Korea found that randomizing men
with BPH—enlarged prostate glands— to just 320 mg of pumpkin seed oil
a day (that’s about 16th of a teaspoon, so just a few drops a day)
improved urinary flow rates.
Urinary flow continued to kink off and decline in the control group,
but those taking the equivalent of just like eating two
single pumpkin seeds a day saw a significant improvement.
That would seem to be an anti-androgen effect,
so maybe it would help with hair loss.
It seems to work in mice when used topically,
but what about in people just eating pumpkin seeds.
It couldn’t hurt.
Sadly, we often throw away pumpkin seeds, squash seeds,
or watermelon seeds, and they actually have
a rich repertoire of nutrition.
But you don’t know if they actually work for hair loss,
until you put it to the test.
In a study, 76 men with male pattern baldness received
400 mg of pumpkin seed oil a day hidden in capsules,
or they took capsules instead of the placebo for a few months.
Again, that’s only like eating two pumpkin seeds a day,
maybe two and a half pumpkin seeds.
They measured scalp hair growth with all sorts of objective
and subjective measures, and... after 24 weeks of treatment,
self-rated improvement and satisfaction scores
in the actual pumpkin seed oil group was higher,
and they objectively had more hair, a 40 percent increase
in hair counts compared to only 10 percent in the placebo group.
In the pumpkin group, 95 percent remained either unchanged or improved,
whereas in the control group more than 90 percent
remained unchanged or worsened.
Given such a pronounced effect might we be worried
about sexual side-effects?
They looked before and after at an index of erectile dysfunction
and found no evidence of adverse effects.
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please go to the Nutrition Facts Podcast landing page.
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