Vitamins: which ones you REALLY need and why


Confused about which vitamins to take or if you should take any at all? You are not alone. Scottish GP Dr Malcolm Kendrick is a family GP who specialises in heart health. He is also an author, a speaker, sceptic and maverick. 

Dr Malcolm Kendrick

He also knows a lot more than many cardiologists know when it comes to the real causes of heart disease. And he knows more than many doctors about the effects of diet on heart and overall health. And about vitamins.

Kendrick meant to write this blog about stress, mental health and heart health. But people keep asking him about vitamin supplements.

Below, he tells you what to take – and why the pharmaceutical industry is so keen to persuade you not to take vitamins. You may be in for a big surprise. – Marika Sboros

By Malcolm Kendrick

I must say that I do like vitamins, I like the idea of them. And my mother did make me take vitamin C tablets every morning. So, perhaps she is to blame for my early age mental programming.

However, there is very little good evidence that any vitamin supplement is beneficial. In large part, this is because there are not huge profits to be made from selling vitamins as they cannot be patented.

If a company did a major clinical trial on vitamin K and found that it saved lives, there would be nothing to stop anyone else selling vitamin K, whilst claiming the newly discovered health benefits for themselves. The company that took the financial risk and funded the trials would be unable to recoup any research costs.

Another factor in play here is that the pharmaceutical industry is doing its level best to attack vitamins as damaging and dangerous. The industry is lobbying madly to have vitamin supplements banned.

Once they achieve this state of Nirvana, they can then invent new synthetic vitamins. They can patent them and sell them back to us as hugely inflated prices, making massive profits.

I just made that bit up, but I wouldn’t put it past them. What they are more likely to do is to add vitamins to various other drugs to extend patent life. As Merck attempted to do with statins and niacin – and failed.

Another of the problems in trying to get a handle on the potential benefits of vitamins is that it can be very unclear what the optimal dose, or blood levels, might be. This, I believe is because of the way that doctors first discovered vitamins.

Click here to read: Statins: attacks on doctors reveal ‘smoking guns’ on side effects?

Over many hundreds of years, they noticed that some diseases occurred when “something” was missing from the diet. Scurvy was the first of these diseases they documented. In 1753 a Scottish surgeon first proposed that lemons and limes could prevent and/or cure the condition.

Obviously, he had no idea what it was in the limes and lemons that did the trick.

Doctors identified other diseases such as pellagra and rickets as being due to a lack of a substance, of some sort. They coined the term for these missing substances “vital amines”. Shortened to vitamins.

Genesis of vitamins

It took some time before researchers isolated the vitamins themselves. The first was vitamin B1, in 1910, the last was vitamin B12 in 1948.

Scientists generally accept that there are 13 vitamins and many of them are B vitamins of one sort or another. However, in my opinion, there are only 12. And Vitamin D is really a hormone.

I think people only classified vitamin D as a vitamin because no one knew that the body could synthesise it in the skin, from sunlight. Whilst people lived mainly outside, there was no vitamin D deficiency. It was only when the industrial revolution started, and people began to live and work indoors that rickets, (bent malformed bones) became an epidemic. A lack of vitamin D in the diet was identified as the cause.

Thus, Vitamin D looked and acted like a dietary vitamin deficiency. But it was not actually a dietary vitamin deficiency. Or at least only in part.

Click here to read: You need 5-a-day fruit and veg? No you don’t!

To prevent rickets, parents gave their children milk. Unfortunately, we are now seeing rickets again, because darker-skinned Muslim women now fully cover up their skin, and some of them are becoming severely vitamin D depleted.

(Editor’s note: Kendrick has added an addendum on the benefits of magnesium supplementation.)

The reason for this ramble is to make the general point that researchers only identified vitamins when they identified major, immediate, and potentially life-threatening illness. Which meant that the first task was the find the dose, or blood level, that prevented things like scurvy and rickets and pellagra.

At the time researchers were not looking for longer-term effects, eg, prevention of CVD (cardiovascular disease), cancer, or suchlike. Which means that there is no recommended daily allowance that takes optimal health into account.

I sometimes think of the recommended daily intake (RDI) of vitamins as being just enough to keep you alive, but no more. A bit like having a houseplant that is small and shrivelled. But if you give it some form of plant feed, it bursts into vigorous growth and is far healthier.

Unfortunately, because we have these hallowed recommended daily intakes, the medical profession views vitamins as very simple things. You give the vitamin, make sure it gets above a baseline level in the blood, and that’s that. Nothing to see here, move along.

B Vitamins

But if we look at just vitamin B12, the reference range (normal range), is all over the place. In the UK is set at 110 – 900ng/l (It is higher in some regions). In the US is it between 200 – 900ng/l, and in Japan 500 – 1300ng/l. With a level of 110 in Japan and the US, doctors would immediately give you additional B12. However, in the UK they would ignore you. “Your level is fine, go away.”

I have seen many patients who strongly believe that they need additional Vitamin B12 injections, as they feel tired, depressed and suchlike. The NHS simply ignores, unless they have a level below 110. Perhaps I should advise them to emigrate to Japan.

An additional problem with vitamin B12 is that the synthetic Vitamin B12 normally used is called hydroxocobalamin. The body then converts this into the active form, methylcobalamin. However, some people cannot metabolise into methylcobalamin and need methylcobalamin injections. Which they cannot get on the NHS. Jolly good.

Yes, the more you look into the area, the more complicated, and frustrating, it gets.

Vitamin D, aka the ‘sunshine’ vitamin

sunVitamin D is the vitamin most in the news at present. The debate and arguments about vitamin D are becoming quite vitriolic. Some doctors refuse to believe that anyone has a true vitamin D deficiency. Others think that the entire population needs to be dosed with added vitamin D during the winter months. I am very much in the latter group.

Click here to read: Vitamin D: sunshine vitamin or snake oil for pseudo-disease?

For example, researchers have only recently discovered that vitamin D has potent anti-cancer effects and may reduce the risk of CVD. What level of vitamin D would you need to provide these benefits? Almost certainly a much higher level than that required to prevent rickets.

Have researchers ever established this level? No. What about the risk of developing thin bones in old age? No.

Even more recently, a low level of vitamin D has been associated with a much higher level of hospital admission with acute asthma. What level would you need to prevent this happening? No idea. As the potential benefits of vitamin D continue to pile up, the minimum blood level remains unchanged and, it seems, unchangeable.

Folate, another B Vitamin

Moving to folate which, despite its name, is another B vitamin. Folate is known to be essential to prevent neural tube defects in the unborn child and to produce red blood cells and suchlike. Again, researchers have established the doses to stop these things happening.

However, a recent study in Cambridge has shown that B vitamins, including folate, have significant benefits in reducing homocysteine levels. And if you give them in high doses, way above those currently recommended, they may delay, or even prevent, Alzheimer’s disease and reduce, or prevent brain shrinkage.

So, what is the correct dose of folate? Enough to stop neural tube defects, or anaemia, or enough to stop Alzheimer’s?

Vitamin K

Can vitamin K prevent atherosclerotic plaques from becoming calcified? Who knows, they have never tested the correct formulation. Can vitamin C reduce the risk of CVD? Who knows? It was tested once in humans, at the wrong dose – at least the wrong dose according to Linus Pauling.

We haven’t the faintest clue about the correct doses, and blood levels of vitamins, required to achieve optimal health. What I do know is that you can take far more than the recommended daily dosage with no problems whatsoever. Vitamins are almost entirely safe. In the US, in 2010, for example, not a single person died from taking a vitamin.

On the other hand, you may be interested to read about the total burden of damage and deaths due to correctly prescribed pharmaceuticals. Here, from Harvard University:

“Few know that systematic reviews of hospital charts found that even properly prescribed drugs (aside from misprescribing, overdosing, or self-prescribing) cause about 1.9 million hospitalizations a year. Another 840,000 hospitalized patients are given drugs that cause serious adverse reactions for a total of 2.74 million serious adverse drug reactions.

” About 128,000 people die from drugs prescribed to them. This makes prescription drugs a major health risk, ranking 4th with stroke as a leading cause of death. The European Commission estimates that adverse reactions from prescription drugs cause 200,000 deaths; so together, about 328,000 patients in the U.S. and Europe die from prescription drugs each year. The FDA does not acknowledge these facts and instead gathers a small fraction of the cases.

Zero deaths, versus 328,000 per year. If I were truly looking for something dangerous to ban, it sure as hell would not be vitamins.

Tips on what to take

So, which vitamins would I recommend taking? My own view is, take vitamin D in the winter, vitamin C always, along with thiamine and Vitamin K2. About five to 10 times recommended daily intake should be fine.

What of other supplements, such as magnesium, co-enzyme Q10, potassium, L-arginine, L-carnitine, Omega-3 fatty acids, and suchlike. Well, I am keen on potassium, very keen. I first noted research associating higher potassium consumption with significantly reduced mortality in the Scottish heart health study.

As for magnesium. Experts increasingly recognise magnesium as a major health issue that can greatly increase the risk of sudden cardiac death. I now routinely test patients for magnesium levels. As does the rest of the health service, which has belatedly woken up to the importance of this chemical. Magnesium deficiency can also trigger atrial fibrillation (AF) which, in turn, vastly increases the risk of stroke.

But I feel I am running away with myself a bit. I need to stop, and take stock. The last thing I want people to do is to worry too much about the levels of this and that in the blood.

Magnesium and potassium

Magnesium level deficiency for example. This is almost unknown if you do not take an acid-lowering drug such as omeprazole, or lansoprazole (both proton pump inhibitors (PPIs)). Unless you are taking one of these or any other “zoles” long term, you are extremely unlikely to be magnesium deficient.

As for potassium, get some lo-salt (a mixture of potassium and sodium chloride), or eat lots of broccoli and bananas, and you will be fine. Other vegetables are available.

What of Omega-3 fatty acids, the fabled fish oil. There is some good quality evidence that they can be good for you. And they seem to have beneficial effects on the conduction of electrical impulses in the heart. They are mildly anti-coagulant, a bit like aspirin with fewer downsides, such as causing blood loss from the stomach. They also have some benefits on brain function.

So, should you take an Omega-3 supplement? Easier, I think, to eat fish once a week. Sardines on toast is my favourite. But if you feel the need to buy Omega-3 supplements, go ahead. The only downside is cost.

A few years ago, a small company that wanted to create a combination pill to reduce the risk of CVD contacted me. They asked me to give them some medical input and support, which I did but they ran out of money. Before going bust, they did produce a few thousand tubs of Prokardia. A tablet that contained:

  • Vitamin K2 5µg
  • Thiamine 7mg
  • Folic acid 7µg
  • Potassium 50mg
  • Magnesium 50mg
  • L-arginine 600mg
  • L-carnitine  50mg
  • L-citrulline 7mg
  • Co-enzyme Q10 3mg

The L-arginine and L-citrulline on that list are “co-factors” for the production of nitric oxide (NO) in endothelial cells. Co-enzyme Q10 is something I have talked about at some length, and L-carnitine is an amino acid that has many benefits in cardiovascular health.

I would have added vitamin D and vitamin C to this list. But you can only get so much stuff in one tablet before it becomes a meal in itself.

I would have been more than happy to promote Prokardia as a supplement. It could do no harm and everything on that list was potentially beneficial for heart health. Unfortunately, Prokardia does not now exist. However, if you took these supplements, in these doses x4 (you were supposed to take four tablets a day) you would not go far wrong.

Having said all this, I do not want everyone to get too carried away with supplements. Eat good, natural foodstuffs and it should be possible to get everything you need in the diet. After all, that was what we were designed to do.

Our ancestors did not go around searching for potassium supplements, or L-citrulline. It was all right there, in the nearest woolly mammoth. All you needed to do was catch it.




  1. Malcolm Kendrick is always interesting and often funny. I’ve read his book ‘Doctoring Data’ twice and it’s a real eye opener for people who assume our medical systems are driven by logic or evidence.

  2. Dr K has made an addendum to his initial post, with more information about Mg.
    Maybe you could include it here also, or a link to it?

  3. Of course such ridiculous inundations of vitamin C are ‘bad’ for YOU…
    But 15 GRAMS of vitamin C per day did Linus little harm. He lived into his 90’s, not to be sneezed at and from all accounts, still in possession of ‘all his faculties’.
    Buying ascorbic acid / lysine & proline in bulk, and filling your own capsules will substantially reduce the cost of….
    – Your expensive urine.


    • that’s just it .. Linus didn’t recommend 15 gms per day. Google “linus vitamin c recommendation mg” and see just how crazy things become.

      • Better late than never… Just found this (again).
        Yes, Googling gives ‘Recommendations’ of 3 g per day for ‘Prevention’ – and over 6 g. for high-risk ‘Therapeautic’. All doses are ‘divided’ throughout the day.
        He also lists Lysine from 1 to 6g, and later Dr Rath added Proline to the list, in similar amounts.
        Not sure who included B3 (Niacin) Vit A and Vit E. Dosing of those 3 is not heroic.

        I understand Pauling started taking Vit C in his 60’s and usual figures for his personal use range from 12 to 15 grams. My own tolerance is around 25 g, and my current is 5 to 8g . Aim is to work up higher all round as two of my 5 CABGs are not as happy as I’d like.
        When Vetssay guinea pigs need 30 mg/kg per day, and apes etc will ingest around 4 to 5 g in their ‘greens’… a gram or two for us is not unreasonable.
        What IS ridiculous is the WHO saying we humans need the same as a 2kg, super- morbidly obese guinea pig! (60mg)

  4. Hmm, what a bunch of hand waving. I’m sceptical at least. Supplementary vitamins will never be banned whatever court cases are instigated. Though lawyers will get rich as a result, that’s a certainty. And the supplements industry will remain profitable even if they can’t stand at the same troughs as Big Pharma.

    “There is some good quality evidence that they can be good for you. ”

    There is also some decent evidence that most rich diet eating people don’t need most supplements most of the time. Too much vitamin C, say, as advocated by Nobel Prize winning Pauli, are, according to some “good quality evidence”, simply bad for you.

    Let me hand wave back and say that probably 99% of what’s spent on taking supplements is a waste of good money and time.

    • horseshit, you believe in myths inflicted by pharmaceutical cronies set up to fail not good quality evidence. Do try and convince us that you and your fake science creators of today are superior to the only 2 time unshared nobel prize winner in science ever to exist. No one can make an evidenced based argument against megadose vitamin c as the replication of the mythological adverse effects will never be verified independently nor do trials ever use adequate dose to cause anything other than lowering markers and risk factors.
      If you had functioning gulunolactone oxidase your body itself would produce 10 grams or more a day ascorbate and your leukocytes alone can take 7 grams them self at times, you are simply science illiterate.
      Your experts “quality evidence” are likely from the same folks that would of promoted cigarettes for a quick buck back in the day. The same types that use coal tar produced synthetic fake vitamin E in low doses for their vitamin E trials.

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