/ Health

Do vitamins and supplements make you healthier?

Lots of people take supplements to boost energy or keep joints healthy. But our investigation found that there’s a chance that they might not always have the health benefits you’d expect.

When we looked into the health claims on the packaging of certain supplements we found that the ‘key ingredient’ might not deliver on the health benefit you might gather from reading the label.

In fact, we found that a multivitamin you could pick up in any supermarket for a lower price could often do just as much good as a supplement designed for specific complaints.

Do you check the label?

Many people take supplements – and in our survey of 3,422 Which? members who do, cod liver oil and other fish oils were the most commonly used, with six out of ten of you taking them.

However, our investigation found that no special health claims can be made about cod liver oil at all – this might be surprising, especially as half of the people we surveyed think that it helps to support joints and cartilage.

In fact, the active ingredient in the tablet that’s contributing to your joint health is actually vitamin D – which is naturally present in cod liver oil, but can also be found in other cheaper multivitamins.

It was much the same story with co-enzyme Q10, taken by one in ten of those we surveyed. This is often promoted as an energy supplement, but this is often down to B vitamins in the tablets rather than the co-enzyme Q10 itself.

You’d have to squint to find out the vitamin ingredients on the back of the label of some supplements, as they aren’t always listed at the front. But it’s important to check and see exactly what it is that you’re taking.

Bad reactions to supplements

Some of you told us about problems you’ve had after taking supplements, like skin irritation after taking vitamin B6, and a laxative effect possibly caused by magnesium in a supplement.

But we found that there is no systematic way of recording these side effects and finding out how common they are. With no official reporting system that catalogues side effects or bad reactions to vitamins, unlike medicines or herbal supplements, it’s difficult to know what your risks are from taking these products.

So do you take vitamins and/or supplements, and if so, do you find them beneficial? And have you experienced a bad reaction to a supplement before?


The only vitamin we keep is Vitamin C 1000mg.

We take it for a few days at the first sign of a cold or if someone sneezes over us or when flying. I haven’t had a bad cold for at least 25 years when someone told me how good it was.

It is also stops cold sores developing if I take them immediately I feel my lip quivering.

I don’t think it is a good idea to take any of these supplements on a regular basis as there is plenty of information online to suggest they can upset the bodies balance.

But I definitely can’t eat 70 oranges that is supposed to be the equivalent of 1000mg of vitamin C so not a problem taking them just for a few days.


Hi alfa, the late American professor of chemistry , Linus Pauling originally recommended the use of vitamin C for the prevention of colds. If I recollect correctly this was in the 1960’s. More recent medical evidence does not support professor Pauling’s recommendation and GP’s certainly do not recommend it. A normal balanced diet contains plenty anyway. It is present both in veg. and fruit. As a retired GP I am not aware of any evidence that vitamin C can prevent cold sores. You may like to have a year without the supplement! ( Complete absence of vitamin C from the diet causes scurvy which can be lethal. Hence, in the past sailing ships on long sea voyages always carried a supply of apples).


Dave just a correction, the original cure that was introduced to the Royal Navy was not apples as they rotted quickly but LImes . Hence in deporting prisoners to Australia the prisoners/sailors were called Limy,s /limies in Australia taken up by the US at one time for English citizens.


Dave, if you read my post properly, I don’t take vitamin C on a regular basis. I probably take less than a dozen tablets in a year.

Next time you feel a cold coming on, try it and you might just get no more than a few sniffles.


Seems a very strange article to post on the day that it is announced that the Scottish Parliament is considering adding folic acid to flour.

I think we can quite reasonably take a view that as many foods are already incorporating vitamins and supplements by Government edict. The question is are there others that should be added or have we got the right amount from our current lifestyle and diet.

Many countries add Vitamin D to milk, lack of folic acid and birth defects has been known in the UK since 1985. There is no doubt there are dubious and contrary research results out there however I have no doubt that given 5-10 years we will be giving better advice and also advising that all peoples metabolism are different rather than realising on averages.


As you say, people differ. That’s why it makes sense to test people if a vitamin deficiency is suspected. If my memory you told us that you had arranged your own vitamin D testing, Dieseltaylor.

We all need vitamins for health but may get all we need from a decent diet. That’s my approach, and if I was concerned about my health I would arrange to be tested.

Although vitamins are essential, taking more than we need may not be beneficial and could be harmful. It frightens me to see the shelves of vitamins etc in the supermarkets.


Holland & Barratt , owned by theCarlyle Group are the largest UK seller of supplements and have made the Press this last week on “requesting” cost reductions from their suppliers.

“Holland and Barrett is being accused of squeezing small businesses after it sent a letter to suppliers demanding contributions to its investment plan. In a letter this month, seen by the BBC, the high street retailer says it wants a reduction of costs of at least 5% from all its suppliers. It also wants suppliers to pay for £3m worth of security tags and CCTV. ” BBC

Perhaps they are gearing up for a flotation later this year. Last year they made much: ” The firm, which is based in Nuneaton , saw sales rise by 11.7 per cent to £513.6million for the year ending September 2015, with profit before tax up by 12.2 per cent to £146million” Coventry Telegraph.
A very very good return on sales.

In the US this recent report from the NY DA might give pause for thought until one finds out are things different in the EU. As for those who like to buy from the US ……
“Of all the store-brand herbal products tested from these stores, only 21% turned up DNA from the plants listed on the products’ labels, while 79% of the results showed either no DNA related to the labeled content or turned up contamination from other plant material, including rice, beans, pine, citrus, asparagus, primrose, wheat, houseplant, wild carrot, and others.

For the testing, researchers obtained multiple samples of each of the six supplement types — Gingko Biloba, St. John’s Wort, Ginseng, Garlic, Echinacea, and Saw Palmetto — and tested each sample five times. In all 78 samples were tested 390 times.”


Overdose of vitamins = Vitamin A= doses over 10,000 IU can lead to hair loss ,diarrhea. dry skin,nausea,headaches ,it also increases the risk of birth defects — Vitamin B6 -over 400mg-problems walking ,numbness in hands/mouth –B3-liver damage,abnormal gastric ulceration (ulcers ) . Vitamin C (over 500 mg ) blocks vitamin -B12 . Vitamin E- more than 1000 IU – excessive bleeding (dangerous ! ) , high blood pressure ,fatigue, bad immune system action . Vitamin D-over 10,000 IU calcium deposits on kidneys ( VERY painful kidney stones ) high blood calcium -high cholesteral, HBP (Dangerous ) cacium deposits ALL over body . Iron- more than 25mg damage to Pancreas,liver,heat muscle (dangerous ) Calcium- more than 2000 mg -kidney damage, fatigue deposits on tissue . Zinc- more than 75 mg anemia, abdominal bleeding (dangerous ) impared immune function – premature births -still birth . Selenium – more than 750mcg- tooth decay, loss of nails ,yellow skin, diabetes (dangerous ) low immune system . Iodine- more than 2mg – it can SHUT down your thyroid gland Very dangerous ) heavy menstrual cycles and numerous smaller problems . ALL per day .


Reader View: Vitamins Healthy Or Harmful? Which February 2016

Dear Which,

As a which reader for many years, I was very disappointed with the poor quality of the article “vitamins: healthy or harmful?” which appeared in your February 2016 issue.

The main problems were:

1. The available evidence was heavily filtered to support a particular point of view.

2. Some of the advice given is many years out of date, and now considered contrary to good practice.

3. There were factual errors in some of the basic science.

Overall, I was very disappointed that Which chose to publish this.

Healthy Diet

There is very strong evidence that a poor diet and lack of exercise is responsible for around 80% of cancer and a similar proportion of heart disease. A good review of the evidence is given by the World Cancer Research Fund. (http://www.wcrf-uk.org/uk/preventing-cancer/ways-reduce-cancer-risk).

The high prevalence of cancer and heart disease is a strong indication that the majority of people do not have a healthy diet.

An excellent study on the population effects of diet, describing results for 50,000 people is contained within the book: “The China Study” by Colin Campbell.

The minimum vitamin RDA levels were developed many years ago to indicate the minimum levels of vitamins needed to prevent diseases such as scurvy and rickets. They RDA does not indicate the level of vitamins needed for a healthy lifestyle.

The article is correct in saying that increasing intake of vitamin D has a range of benefits. There is also extensive evidence for the benefits of other vitamins.


The phrase evidence is used in clinical circles to mean a variety of different things.

Pharmaceutical companies use the word evidence to refer to large-scale randomised controlled trials carried out on a univariate basis. There is considerable debate in the literature as to whether this approach is driven by science or economics.

Large-scale randomised controlled trials can only be carried out on drugs that will be sold at a high cost. There has at times been conflict between the NHS and the pharmaceutical industry for their refusal to carry out trials on cheaper drugs.

A large proportion of treatments delivered by health services worldwide has not been tested by large-scale randomised controlled trials.

Other forms of evidence include:
• small and medium scale clinical trials carried out on a univariate or multivariate basis
• population studies
• chemical pathway analysis

Health Risks

The article is correct in saying that high levels of vitamin A can be harmful.

The article is 20 years out of date in encouraging the reader to eat red meat. The evidence is now that this increases bowel cancer risk, and the recommendation is to minimise the consumption of red meat.

The article is 10 years out of date in encouraging the reader to eat dairy products. High levels of dairy products increase the risk of a variety of diseases. It is better to increase calcium intake from vegetables.

The article is correct in saying that people should take care when using any pharmaceutical or vitamin in conjunction with chemotherapy or warfarin therapy. There is always a risk of complications in the complex interactions that can occur. This does not however mean that the pharmaceutical or vitamin is harmful to a person who is not using chemotherapy or warfarin therapy.

Basic Science Errors

The statement that natural vitamins are the same as synthetic vitamins is basically wrong. Many complex biochemical molecules exist in multiple forms.

I enclose a quotation from Wikipedia:

“An isomer (/ˈaɪsəmər/; from Greek ἰσομερής, isomerès; isos = “equal”, méros = “part”) is a molecule with the same chemical formula as another molecule, but with a different chemical structure. That is, isomers contain the same number of atoms of each element, but have different arrangements of their atoms.[1][2] Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like positional isomers, cis-trans isomers and enantiomers, etc. (see chart below). There are two main forms of isomerism: structural isomerism and stereoisomerism (spatial isomerism).”

The biological action of any molecule in the body depends on both the chemical structure and the physical structure. Biological processes tend to produce a single isomer, i.e. a single physical shape. Chemical processes tend to produce multiple isomers. Different isomers have different biological properties.


Hello John,

Thanks for your feedback on the magazine article. I would like to explain where we got our information from.

We wanted to use sources that were as robust and reliable as possible. This included the Department of Health, the European Food Safety Authority, a report from the Expert Group on Vitamins and Minerals, and the NHS. We also consulted an NHS dietitian who could tell us what advice patients are routinely given.

We do keep up to date with the latest research, but base articles on information and advice from the most official sources we can find.

We quoted the RDAs of vitamins to allow readers to compare the relatively high levels of vitamins that may cause unwanted effects in someone who was taking many supplements. There is no need for RDAs to be seen as a daily target.

The information in the table on ‘Common vitamin deficiencies’ was intended to give background information on food sources of vitamins. We are certainly not recommending that readers eat a lot of red meat, as we are well aware of the research linking consumption of large amounts of red meat to bowel cancer risk.

Anyone with a known nutrient deficiency should, of course, be taking supplements as directed by their doctor.



I have fears that in a fast moving area of medical research Which? is actually on to a loser being a source of advice on these matters. As pointed out by others repeating strongly that ” good diet and you should be OK” and then links to parts relevant such as my copying of the NHS on Vitamin D would be a way to approach the matter.

This Conversation could be the basis of a simple intro to the subject followed by a nice CAWiki article which could give all the necessary links to the underlying resource, that could be pulled up by a subscriber instantly. I see Which? missing the boat with this article and interesting inputs, and the magazine article becoming difficult to find on the Which? site and of course as they are not up-dated increasingly of less value

Given the results in the US on bogus Vitamins and supplements that WOULD be a product testing role foe Which? to be active in. I realise that testing has cost implications however I do believe some of the continental consumer , and possible regulatory, bodies, may already cover this area.

It might be a consideration that testing them at all indicates a belief that they have value. to consumer which presents a policy decision. I actually do consider that some are beneficial for some people. Most particularly Vitamin D as we see rickets re-surfacing in the UK and more elderly people with increasingly limited ability to create Vitamin D through sunshine.

Eating fish works very well but is significantly more expensive than a 10p pill,


Interesting diesel – you do know that with the introduction of the NHS I being poor as **** was given daily ==cod liver oil +orange juice in 2 separate NHS bottles , my mother got it from a central distribution area precisely for combating the permanent symptoms of poverty your describe -rickets ,etc . I remember seeing people with “bandy legs ” because of starvation and poverty –and now its back which to me is damming for the government . Shares first -babies second in the UK . Not only is that back so is TB and other poverty diseases. Britain is one of the richest countries in the world but ,like the US now -its greed ,corruption graft and theft from the state done a bit more subtly here than the US but never the less still done . i could live with it but not at the expense of babies lives.