Let’s say you really need to find reliable information
about the best diet for high blood pressure,
or heart disease, or diabetes.
Where do you go?
Do you go to a website sponsored by Big Pharma
that wants to sell you pills to fix your problem?
Or, do you want to treat the cause?
Welcome to the Nutrition Facts Podcast
with the latest peer- reviewed research
on the best ways to eat healthy and live longer.
Today we take a close look at the mighty power
of vitamin C.
And we start with the risks and benefits
of using vitamin C for depression and anxiety.
“Emerging evidence suggests that higher daily intake of ﬁber-rich
fruits and vegetables is associated with lower incidences of anxiety
in adults and at the same time, greater happiness, higher life
satisfaction, and greater emotional well-being.”
So, “persuading people to consume more fruits and vegetables
may not only benefit their physical health in the long-run,
but also their mental well-being in the short-run.”
Fruit consumption, for example, has protective association
with leading killers like heart disease, stroke, diabetes,
and cancer, as well as depression. The question is why?
Several different mechanisms have been proposed.
For example, it may be the antioxidants and anti-inflammatory
properties of produce, scavenging the free radicals that are
involved in some of the inflammation associated with depression.
If that’s the case, what about just taking vitamin C supplements?
The brain has some of the highest levels of vitamin C in the body;
so, the thought is if we take extra vitamin C,
it may have some sort of therapeutic role in brain diseases,
especially given that it’s not just an antioxidant,
but also has other critical functions in the brain such as
helping to build neurotransmitters like dopamine.
But you don’t know whether it actually helps,
until you... put it to the test.
One study found a beneficial effect of adding vitamin C as an
adjunct treatment to an antidepressant, while another study
found no benefit from vitamin C supplementation.
So, there are mixed results for vitamin C and depression.
Here’s another study that found no benefit when it came to
depression, but those randomized to vitamin C instead of
placebo pills did show a significant decrease in anxiety level.
And this wasn’t only seen in this study.
The effects of oral vitamin C supplementation
on anxiety in students:
a double-blind, randomized, placebo-controlled trial.
High school students were given 500mg a day or placebo.
500mg of vitamin C is about what you’d find
in five oranges, four yellow kiwifruit or guavas,
or one and a half yellow bell peppers.
Within just two weeks, the vitamin C reduced anxiety compared to
placebo, along with providing a significant drop in heart rate.
Given these data showing vitamin C may have
anxiety-reducing effect, researchers sought to find out
if only a single dose could acutely affect emotional states.
And indeed, within only two hours of taking some C,
subjects experienced a significant drop in anxiety
compared to placebo, though only among those
who started out the most anxious in the first place.
As a bonus, vitamin C supplementation may lower
your blood pressure a few points, but whole fruits
and vegetables can do the same thing and may even
do it better for those who need it the most.
As I’ve shown previously, even just adding two servings
of fruits and vegetables a day can have psychological
well-being benefits within only two weeks.
And you won’t be put at risk of kidney stones like you would
with vitamin C supplements, though that appears to be
only a problem in men.
Here’s a fun fact.
There are now experiments that can show
how much vitamin C our body absorbs and excretes.
Here’s the story.
For many years, the RDA, the recommended daily allowance
for vitamins, was just based on preventing deficiency,
with a margin of safety,
but the miniscule amount of vitamin C, for example, needed to avoid scurvy
is not necessarily the ideal intake for optimal health.
So what might be the optimal intake of vitamin C?
Let's ask the body. How might we do that?
By seeing how much the body absorbs and excretes.
If you swallow 15 mg of vitamin C, which is what you would get
eating about a quarter of an orange, your body sucks up nearly 90% of it.
But if you take a supplement containing 1,250 mg,
your body seems to realize that's too much, and so clamps down on absorption
at the intestinal lining level, and you end up absorbing less than half.
So by doing experiments where you slowly ratchet up the intake
you can see when the body starts to say, OK, that's enough,
and that magic level of intake appears to be about 200 mg a day.
When you take up to 200 a day your body sucks it all up,
but above that your body tries to block further absorption
suggesting our intestinal vitamin C transport mechanisms have evolved
to fully absorb up to about 200 mg of vitamin C a day.
In addition, vitamin C is reabsorbed in our kidneys back into our bloodstream
to maintain our vitamin C blood levels up at around 70 or 80 micromoles per liter.
Which is what you reach at a vitamin C intake of about 200 mg a day.
So even if you take 10 times as much vitamin C supplements,
you know, 2000 mg a day, your body will just pee and poop it out
to keep your blood levels in that narrow range.
So based on these kind of data,
one might propose that 200 mg is the optimal daily intake of vitamin C.
You can confirm using disease data.
At what daily intake of vitamin C is there the lowest stroke risk, for example?
Apparently at about 200 mg a day.
While dietary vitamin C intake was associated with lower stroke risk,
vitamin C supplements were not,
which is consistent with the overall body of evidence
showing that antioxidant supplements in general
don't seem to protect against heart attacks or strokes.
But wait...
Can you get all up to an intake of 200 mg a day without taking supplements?
No problem.
Single servings of fruits and vegetables may have about 50 mg each,
so a measly 5 servings of fruits and veggies a day
could get you to ideal blood levels.
Finally today, what can we conclude
about the role of IV vitamin C after 33 years of trials
involving more than 1,500 patients?
Studies in the 70s showed an extraordinary survival gain
in terminal cancer patients with vitamin C,
a simple, relatively nontoxic therapy,
and so no wonder it got a lot of attention
especially when reported by a world-renowned scientist,
Linus Pauling,
but studies like this in the 1980s found no such benefit
and so alas they were left with the inevitable conclusion
that the apparent positive results
in the original study were the product of bias
rather than treatment effectiveness.
In the 90s though, an alternative explanation arose.
The disappointing 80s research only used oral vitamin C,
whereas the apparently successful 70s experiments
also gave vitamin C intravenously
and we didn’t realize until the 90s
that the same dose given IV can lead to dramatically
higher levels in the blood stream
than if taken orally,
So maybe high dose vitamin C does help in terminal cancer,
but maybe only when given intravenously.
Encouraging case reports continue to be published.
Here there was a regression, remission and cure
documented in individual cases of advanced kidney cancer,
bladder cancer, and lymphoma.
But that’s three success stories out of how many?
If it was three out of a hundred,
or even three out of a thousand...well okay,
if the treatment is sufficiently nontoxic,
but there’s evidence that IV vitamin C
is widely used in the alternative medicine world,
as in 86% of practitioners surveyed.
Just those 172 practitioners alone
treated about 10,000 patients a year
And you ask the manufacturers,
and they’re selling hundreds of thousands of vials
of this stuff in the U.S.
Now it’s not all being used for cancer,
but presumably at least thousands of cancer patients are being treated
every year with IV vitamin C, making the publication
of three remarkable case reports seem less impressive.
So no matter how amazing these cases seemed,
it’s possible the cancers just spontaneously regressed
all on their own and it was just a coincidence
that it happened after they were given vitamin C.
To know for sure you have to put it to the test.
To date there have been some small pilot studies,
and the results so far have been disappointing.
The good news is that even insane doses of IV vitamin C
seem remarkably safe,
but failed in this study of two dozen patients
to demonstrate anticancer activity.
Similar small studies have been published
all the way through to the present
with tantalizing but inconclusive results.
What we do know is that the present state of cancer treatment
is unsatisfactory.
People have this perception that chemotherapy
will significantly enhance their chances for a cure,
but put all our cancer-killing chemo together
and the overall contribution to 5-year survival
is on the order of 2%.
All those side-effects for 2.1%,
at a cost of maybe $100,000 per patient per year.
So it may be worth looking deeper into therapies
like IV vitamin C.
However, the lack of financial reward,
since vitamin C can’t be patented and sold for $100,000,
and bias against alternative medicine
could dissuade conventional investigators and funding agencies
from seriously considering this approach.
So decades later what can we conclude?
After trials which have included at least 1,600 patients
over 33 years, we have to conclude...
that we still don't know
whether Vitamin C has any clinically significant antitumor activity.
Although there is currently no definitive evidence of benefit,
the Mayo Clinic randomized controlled trials
did not negate the potential benefit based on what we now know
about oral versus IV routes of administration.
So we’re kind of back to square one,
does it work or not?
There are highly polarized views on both sides,
but everyone’s working off the same incomplete data.
What we need are carefully controlled clinical trials.
The question is, what do we do until then?
If it was completely nontoxic, then one could argue-
what have you got to lose?
But it’s not; it’s only relatively nontoxic.
For example, there have been rare but serious cases
of kidney injury reported.
After all, if it’s so safe,
why did our bodies evolve
to so tightly control against excess absorption?
It can also be expensive and time-consuming.
Each infusion can cost 1 to 2 hundred dollars out of pocket,
since insurance doesn't pay for it.
which can be quite a boon for alternative medicine practitioners.
About 90% of the millions of doses of vitamin C
being dispensed are in for-profit arrangements,
so there’s financial pressures pushing in both directions,
for and against this treatment.
Given the relative safety and expense, though,
if controlled studies even find a small benefit,
it would be worthwhile.
And if they don’t, okay, fine, the vitamin C question
can be put to rest once and for all.
But in cancer treatment we don’t have the luxury
of jettisoning possibly effective relatively nontoxic treatments.
We should revisit promising avenues,
without prejudice, and with open minds.
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please go to the Nutrition Facts Podcast landing page.
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plus, links to all of the sources we cite to each of these topics.
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