I am generally
skeptical of vitamin claims outside the two naturals that obviously need
monitoring. That is vitamin C and
vitamin D. The mega dose arguments for C
are pretty clear and convincing with direct benefits for damaged arteries. After that you are surely playing with fire.
The best solution is to
actively enrich your diet as much as possible in a pro vegan direction to get
the maximum of the welcome phytochemicals.
This also helps to avoid local mineral deficiencies. Organic is clearly better also.
The point is that diet
is your best friend and you have to become an expert because what is on the
shelf is ignorance and appetite gaming to distort your diet.
The problem with taking
too many vitamins
17
October 2013
Millions
of people swear by vitamin supplements. But many are wasting their time and
some could even be harming themselves, argues Dr Chris van Tulleken.
In
November 1912 a party of three men and 16 dogs set out from a remote base in
eastern Antarctica to explore a series of crevasses many hundreds of miles
away.
Three
months later just one of the men returned. His name was Douglas Mawson. His
skin was peeling off and his hair was falling out. He had lost almost half his
body weight. He recounted what Sir Edmund Hillary described as "the
greatest story of lone survival in the history of polar exploration".
A
month into their journey, one of the team, along with the tent, most of the
provisions and six dogs plunged into a crevasse, never to be seen again. Mawson
and the other surviving member, Xavier Mertz, started to return to base,
surviving in part by eating the remaining dogs. After a few weeks Mertz
developed stomach pains and diarrhoea. Then his skin started to peel off and
his hair fell out. He died incontinent and delirious a few days later.
Mawson
suffered similar symptoms. With the kind of understatement typical of his
generation of polar explorers he described the skin of the soles of his feet
peeling off: "The sight of my feet gave me quite a shock, for the
thickened skin of the soles had separated in each case as a complete layer...
The new skin underneath was very much abraded and raw."
It
was the suffering of early explorers and sailors that motivated the first
studies of vitamins and their deficiency diseases.
At
first sight Mawson's story seems to be another such tale - starvation combined
with a lack of some vital nutrient. In fact, Mawson's description of his
symptoms is an almost textbook description of vitamin A overdose - probably
from eating dog liver. As little as 100g of husky liver could give a hungry
explorer a fatal dose.
Mawson
lived to the decent age of 76 but in his story we find the cautionary tale for
our times - vitamins can be very bad for you.
This
piece is about what we have learned about vitamin supplements in the last few
years - if you are healthy, and you live in a country like the UK, taking
multi-vitamins and high-dose antioxidants may shorten your life.
For
most of us, for most of the time, they're unhealthy. "Argh!" I hear
you say, "I spend loads of money on them and the claims on the packet are
really persuasive. Everything, from my full head of hair to my sex life,
depends on them!"
I
want to get into this in a bit more detail because the vitamin companies
certainly don't agree with me. So why do we believe they're useful and why do
we take them?
Vitamins
are essential for life, and there are groups of people even in the UK who
benefit from specific supplementation, but general unsupervised vitamin
pill-popping is more than just a waste of money. The problem is that we all
feel very warm and fuzzy about vitamins because, firstly, the tales of
deficiency are so horrific, secondly, we read breakfast cereal packs and
thirdly, a double-Nobel laureate called Linus Pauling liked vitamin C in vast,
vast doses.
All
this is packaged by the people now selling us vitamins over the counter into
that most beguiling of all logical falsehoods - if a little is good, then more
must be better.
Now
I knew the names of the most obscure vitamins long before medical school
because I have always had a fondness for the kind of multicoloured,
artificially flavoured breakfast cereals that are marketed using a combination
of unlikely cartoon animals and claims of being "vitamin and
mineral-enriched".
And
it has to be said that this vitamin and mineral enrichment of staple food has
been one of the most effective public health interventions in history. It
continues to save countless lives per year even in Europe.
So,
while you shouldn't eat dog liver in Antarctica, vitamin A deficiency hugely
increases the risk of blindness and death in children with measles and
diarrhoea in developing countries. So the World Health Organization recommends
a very strict amount and cautions that higher doses can cause birth defects in
early pregnancy among other problems.
So
vitamins do make a huge difference to life expectancy in some circumstances,
which is persuasive, and the breakfast propaganda catches us in our most
vulnerable, bleary-eyed, early morning state, hinting to us that these vitamins
have some sort of catch-all, beneficial effect on our lives, that will
transform us into the healthy, energetic beautiful people/cartoon creatures
portrayed on the cereal box.
These
things contribute to a general ideal of healthfulness of vitamins. And then
there's Linus Pauling.
Whether
or not you've heard of him, Linus Pauling is a major influence on vitamin and
nutrient culture. It's almost impossible to imagine someone with more authority
and credibility. He won two Nobel prizes and was, by all accounts, a genuinely
good bloke. He wrote a book in 1970 saying that high doses of vitamin C could
be effective in combating flu, cancer, cardiovascular disease, infections and
degenerative problems.
He
took immense quantities himself, hundreds of times the required amount, and
lived to a ripe old age surrounded by many great grandchildren. He was the
poster boy for mega-dosing of vitamins and this contributed to the growth of an
industry supported by the belief that supplementation of these molecules in our
diet is beneficial in almost every way imaginable.
But
rather than taking one man's word for it, however credible, it's worth looking
at the results of studies that look at what happens to people who take these
supplements for long periods of time.
Looking
at any one individual study won't be very revealing to answer the question of
whether vitamin supplementation is good for you. They're densely scientific and
the conflicts of interest can be very hard to spot.
For
the answer you have to turn to what are called "systematic review papers".
This is where independent scientists gather up all the available data and
re-analyse it to answer big questions.
Here's
what a couple of them say:
"We
found no evidence to support antioxidant supplements for primary or secondary
prevention [of diseases of any kind]. Beta-carotene and vitamin E seem to
increase mortality, and so may higher doses of vitamin A. Antioxidant
supplements need to be considered as medicinal products and should undergo
sufficient evaluation before marketing". (See references below).
Just
to be clear - "increase mortality" - that means they're killing you.
These are powerfully bioactive compounds but they're not regulated in the same
way as drugs. Whatever you think about the regulation there should surely be a
warning on the pack if there's data saying they're bad for us.
The
next question is - why are they bad for us? It's very hard to pick apart the
data, partly because vitamins are a fabulously diverse group of chemicals.
I'm
going to include what people normally refer to as minerals under the heading of
vitamins. They're required in the diet not for energy, but as chemical partners
for the enzymes involved in the body's metabolism - cell production, tissue
repair, and other vital processes.
Their
functions are understood largely by their deficiency diseases so we're not
exactly sure of precisely what they all do or how they interact. Antioxidants
provide a nice example. They soak up the very toxic, chemically-reactive
by-products of metabolism called free radicals. These free radicals, left
unchecked, can cause damage to DNA and may be linked to cancer.
Your
cells are full of antioxidants but surely taking more would be better? Right?
Keep those cancer causing radicals under control? Well, unfortunately, your
body's immune system fights infections by using free radicals to kill bugs.
Exactly what effect huge quantities of extra antioxidants could have on this is
not clear but it's easy to imagine that it might not be good and you could get
more infections.
Vitamin
A is linked to increasing lung cancer in smokers. Excess zinc is linked to
reduced immune function. Long-term excessive intake of manganese is linked to
muscle and nerve disorders in older people. Niacin in excess has been linked to
cell damage. And so on.
And
it gets more complicated still when you start mixing everything up in one
tablet. For example, different minerals compete for absorption. If you take
large quantities of calcium you won't be able to absorb your iron. If you take
large quantities of iron you won't be able to absorb zinc. If you take vitamin
C you'll reduce your copper level.
So
it's not just that taking lots of one thing is not good for you, it's that it
may cause a dangerous reduction in something else even if you are also
supplementing that. To work out the optimal ratios is all but impossible
although some manufactures claim to have worked it out.
So
when are supplements recommended? The National Institute for Health and
Clinical Excellence (NICE) recommends certain supplements for some groups of
people who are at risk of deficiency, including:
Folic
acid for all women thinking of having a baby and pregnant women up to week 12
of the pregnancy.
Vitamin
D for all pregnant and breastfeeding women, children aged six months to five
years, people aged 65 and over and for people who are not exposed to much sun,
for example people who cover up their skin for cultural reasons, or people who
are housebound for long periods of time.
Finally
a supplement containing vitamins A, C and D is recommended for all children
aged six months to four years. This is a precaution because growing children
may not get enough, especially those not eating a varied diet, such as fussy
eaters.
Your
GP may also recommend supplements if you need them for a medical condition. If you decide to take
supplements, stick to within the RDA, unless you've had guidance from a
state-registered dietician or clinical nutritionist to exceed the dose. If
you've got questions about dosage levels, consult a state-registered dietician
or clinical nutritionist.
The
tales of deficiency combined with the success of enrichment programmes mean
that it's easy to make that leap of logic that if a little is good then more
must be better.
And
if you read my
article last week on
water you'll see where this is going. I could do this every week. The same
article. Substitute water for vitamins/probiotics/antibiotics. Don't trust the
science done by the people who are trying to sell them to you and don't assume
that if some is good more must be better.
It's
like beer. Or coffee. Or computer games. Goldilocks was right about things
needing to be just right.
References:
Bjelakovic
G, Nikolova D, Simonetti RG, Gluud C. Antioxidant supplements for preventing
gastro-intestinal cancers, , 2004
Bjelakovic
G, Nikolova D, Gluud C, Antioxidant supplements to prevent mortality, The
Journal of the American Medical Association, 2013
Bjelakovic
G, Nikolova D, Gluud LL, Simonetti RG, Gluud C, Antioxidant supplements for
prevention of mortality in healthy participants and patients with various
diseases, Cochrane Database of Systematic Reviews, 2012
Chris
van Tulleken is on Twitter: @doctorChrisVT
Vitamin
A needed for good vision, healthy skin and growth; found in green and
yellow vegetables and dairy products. Deficiency can cause night blindness,
xerophthalmia (lack of tears) and ultimately blindness as a result of corneal
damage
Vitamin
B needed for healthy skin, and helping body release energy; found in
bread, milk and eggs
Vitamin
B12 needed for red blood cells; found in meat, milk and fish
Vitamin
C - needed for healthy skin, cell protection and iron absorption; found in
fruit and vegetables
Vitamin
D - needed for strong teeth and bones; found in margarine and oily fish
Vitamin
E - needed for cell protection; found in nuts, seeds and cereals
Vitamin
K - needed for blood clotting; found in green vegetables and cereals
1 comment:
What are the odds of any of us subsisting on husky liver? Nutrition is so routinely demonized while "maim-scream" medicine kills hundreds of thousands to millions each year (see Gary Null, Carolyn Dean - 'Death by Modern Medicine). Let's teach people to eat whole foods and judiciously supplement -- and stop all the taxpayer subsidies for processed foods and specious drugs! Thanks for posting this.
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