Will Vitamin D supplements protect me against colds and flu?

Vitamin D supplements are often combined with
calcium as a treatment for osteoporosis

No one likes getting respiratory tract infections such as colds. There is interesting news that a wide-ranging study shows that vitamin D supplements can reduce the risk of getting colds and flu, particularly in those with severe vitamin D deficiency.

This is encouraging, especially as it isn't based on a single small trial. However, it is worth repeating once piece of the report: '... 33 people would need to take vitamin D supplements to prevent one acute respiratory tract infection.' That's for ordinary folk - for those with severe deficiencies, it's only four people taking the supplement to get one prevention.

So there does seem to be an effect, particularly if you are in that deficient group. As we get most of our vitamin D from sunlight, that's most likely to be people who avoid exposure to the sun, or who live in countries with low levels of sunlight in winter.

Even so, it's best not to get too excited. Assuming your vitamin D levels are average, rather than extremely low, bear in mind that the chances are high that taking the supplement would not prevent you getting an acute infection. (The study doesn't not cover non-acute infections.) But this is one of the few examples suggesting that people who are generally healthy might benefit from vitamin supplements.

The study is published in the BMJ.

Can a garlic soup conquer colds and flu?

I was fascinated to see a post on Facebook relaying a claim that a soup made with 52 cloves of garlic can 'defeat colds, flu and even norovirus.' Leaving aside the possibility that this is because anyone consuming that much garlic will never get close enough to anyone else to catch anything, it seemed a claim that was worth putting under the Science for Life spotlight.

The claim is from a two-year-old article on a website called Complete Health and Happiness, which as a source, I admit, did rather get my dubiousness sensors tingling. However, I decided to take it at face value and see what the claim was based on.

The website gives as its source a 'recent and significant finding from Washington State University' and helpfully provides a link - but this takes the reader to another so-so looking site called PreventDisease. However, this at least appears to have a link to the research - but it turns out the link just goes to the home page of the respectable Journal of Microbial Chemotherapy. While I struggled to find the precise article, a search on Washington and garlic did throw up a number of papers such as this one which reports the impact of an active chemical from garlic on Scedosporium prolificans in vitro. Most of the work on garlic seems to be in vitro - effectively in a test tube - which makes it impossible to draw any conclusions from it for consuming garlic soup. Lots of substances destroy disease-causing microbes in a test tube (washing up liquid, for example), but that doesn't mean that they will help if you swallow them.

Other papers did cover experiments with mice and humans, though as yet these were very limited and not providing sufficient information to be practical. However, what all the papers have in common is that (like the antibiotics the original website refers to) they are dealing with bacteria. There is nothing whatever in them about viruses. And so, I'm afraid, that there is no evidence that this soup will defeat colds, flu and even norovirus.

Don't get me wrong - garlic is good for you and almost all of us could do to have more vegetables in our diet. But don't think that eating a soup will protect you from infection.

Sugary science

Sucrose - image from Wikipedia

It is well known that the cigarette companies were aware of the dangers of smoking long before the general public, yet spent large amounts of money on attempting to counter the science. Similarly, many of the oil companies have actively sponsored attacks on global warming. Now it appears there is a new bad guy on the block - the sugar industry.

It is only in the last few years that we have displaced some of our concern about fat in the diet to take on sugar as a dangerous substance to over-consume. And it's easy to assume that this awareness also took the sugar industry by surprise. But research undertaken by the University of California, San Francisco suggests that the US sugar giants were aware of the risks of sugar consumption as far back as the 1950s.

To make matters even worse, the paper tells us

Together with other recent analyses of sugar industry documents, our findings suggest the industry sponsored a research program in the 1960s and 1970s that successfully cast doubt about the hazards of sucrose while promoting fat as the dietary culprit in [coronary heart disease].

This is astounding if true. Not only was the risk from sugar played down, but it appears that the sugar industry used a distraction technique by overplaying the role of fat.

There's the possibility here of tobacco-style mass law suits. But what interests me more is whether or not US big business (Europeans do it as well, but not on the same scale) is still playing this kind of bait and switch game with our health. We know that the oil companies are still trying to play down climate change - but what about the food industry? Or pharmaceuticals?

I'm no enthusiast for conspiracy theories, but this kind of behaviour defies belief. Don't these people have children?

Is Manuka Honey great for the immune system?

We are constantly being bombarded with the latest celebrity fad, so I'm grateful to an email from Chelsea asking if Manuka honey is great for the immune system.

The quick answer - no.

This is a honey produced by bees exposed to pollen from the Manuka tree, mostly in New Zealand and Australia. It sold at incredibly high prices for honey - as much as £50 or more for a small jar.

Unfortunately, this is a classic case of assuming something that has a topical benefit - if you use it externally - will have a benefit if consumed. And as is usually the case, there is no link.

Honey in general has a mild anti-bacterial action (as do many substances - washing up liquid, for instance) - and there is reasonable evidence that Manuka honey is amongst the best at this. So applied appropriately to a wound (and I'm not recommending just slapping honey on), it can in principle have a positive effect (though there are many other, cheaper and more effective anti-bacterial agents).

When you eat it, though, it has no impact on your immune system. As discussed in Science for Life:

Your immune system is not a single part of your body but rather a vast network comprising physical barriers like your skin, white blood cells, various different organs and a whole range of complex chemicals with literally thousands of different roles. ‘Boosting’ it by simply eating something is a bit like hoping to redecorate your house by throwing a capsule of paint at the wall.

And in this case there is no evidence that the honey will be anything more than an incredibly expensive sweetener, adding unnecessary sugar to your diet. See the Cochrane report for details on use of honey in treating wounds.

Has it been proved that mobile phones (cellphones) cause cancer?

There has been a certain amount of panic in the news about data from a US National Toxicology Program study where rats were exposed to cellphone radiation and it has been claimed there was evidence of cancer being caused.

The quick answer is no, it hasn't been proved. There is no good evidence to say that mobile phones aren't safe. Keep using them!

There are far more studies suggesting no link at all - so immediately we have to take any findings with a pinch of salt. As is made clear in Science for Life, a single study is never enough to provide useful guidance as any study can be flawed, and it's important to take in the bigger picture. But also the actual findings of this study aren't as negative as the headlines suggest.

First, the study involved exposing rats (with much less brain shielding than humans) to 9 hours of phone radiation a day for the whole of their lives. That's a lot. No females developed any problems, but 3 per cent of the males developed brain cancer. However, experts have pointed out that the number of cancers was small enough to be a statistical occurrence. What's more, most rats were exposed to higher intensity radio waves than are allowed from a mobile phone - and stranger still, the rats that were exposed to the radio transmissions lived longer than a control group that wasn't exposed.

All this strongly indicates that there is nothing negative to be learned from this trial. See the NIH for details.

What is A2 milk?

In Science for Life, there's a chance to see the pros and cons of milk in terms of fat, sugar and calcium content. But some years ago there was a case made that a substance in milk called A1 beta casein could be a risk factor for diabetes and coronary heart disease. What made this interesting was that there was a variant of the protein, imaginatively called A2 beta casein, that didn't have the negative risk - and it was possible to produce milk that only had this variant of the protein, called 'A2 milk', which would be healthier for consumers.

Unfortunately, a detailed review by leading science journal Nature found that the diabetes study could not be duplicated with larger, better experiments, while the heart disease study was 'small, short, in an unsuitable animal model and had other design weaknesses' - which is pretty damning even before it fails to be backed up with better experiments. As is often the case with this kind of finding, all too often irresponsibly splashed across the newspapers, the original studies were too small, used bad statistics and simply don't tell us anything useful.

The Nature review calls the A1/A2 hypothesis 'ingenious' - and if it had been backed up it would have resulted in a major transformation of the milk industry. Unfortunately, however, the idea had no credible evidence to support it. Single, small trials are just not enough to do anything more than point out a direction for more in-depth work. In this case, the in-depth work - the stuff we need to listen to - showed that the A2 phenomenon to be unsupported.

Thanks to Professor Etienne van der Poel for bringing this to my attention.

Sugar tax

Brighton and Hove Council in the UK, teamed with Jamie Oliver, the chef and food campaigner, have announced that they are going to recommend a voluntary 10p 'health tax' on soft drinks with added sugar. 

While it's a good move, it doesn't go far enough. I suspect 10p isn't enough to make a huge difference- it probably should be something like 50p. But also it should be an all high sugar drinks - fruit smoothies for instance - not just those with added sugar. 

Are taller people more at risk of cancer?

Most of the newspapers have reported on a study from Sweden showing that taller people are more likely to get cancer. This follows an earlier study in 2011 which came up with similar results.

As a piece of news it isn't particularly helpful - if you are tall, there's not a lot you can do about it. But also it seems reasonably logical.

It's normal, in this kind of study, to factor out other potential contributory factors, such as being under/over weight, so effectively we are comparing like with like. If two people have the same body mass index and one is taller than the other, then the taller person will have more cells in their body. As cancer is, given similar environmental and genetic background, essentially a statistical disease, the more cells available, the more likely it is that there will be a cancerous cell or cells forming. So it doesn't seem entirely surprising as a result.

The figures show a relatively small difference, and like all such studies it is very difficult to be sure that everything else has been adequately controlled for. There does indeed seem to be a small increase in risk, but we are all subject to a whole host of risks that make us different to other people (diet, hereditary, environment, exercise, smoking etc.) so to worry about a small factor we have no control over seems unnecessary.

Would an obesity tax work?

In a comment piece in the i newspaper yesterday, Julia Hartley-Brewer made a plea for a tax on fatty foods and sugary drinks. She was clear about what needed to be done: 'Forget about a few pence on a litre of cola or a cheeseburger and fries, though. We need obesity taxes at 50 or 100 per cent to hike up the cost of the foods and drinks we should only be consuming as an occasional treat, not as part of our daily diet.'

Is this true? Would a tax work at all? A study of 'heath related food taxes' from Oxford University was supportive, though the results were based largely on modelling and controlled trials, as the first real health-related food tax in Denmark has not been running long enough to provide anything other than anecdotal evidence.

One specific piece of evidence comes from Ireland, where a 10% soft drinks tax, introduced in the 70s, intended to bring in revenue rather than improve health, saw an estimated 11% drop in consumption. Because of this, the report recommends a 20% tax on sweetened drinks (though interestingly not on sugary drinks like smoothies, which can contain more sugar than a cola). They also suggested putting VAT on unhealthy foods like chocolate biscuits, confectionary and soft drinks.

It seems likely that there would be some impact, but one cause for suspicion about the level of benefit is that there is already, in a sense, an 'unhealthy foods' tax if you compare the price of typical single chocolate bar with, say, a banana, which addresses many of the same desires for sweetness, is equally filling and is significantly healthier. The chocolate bar has the equivalent of a 4-500% price hike on the banana... and yet we still know which many of us pick up from choice.

How something with 6.8 per cent fat can be 'fat free'

As we've previously discovered, it's possible for food to contain more than 100 per cent of its ingredients according to a misleading industry regulation. Now we discover that it is possible for a substance that is 6.8% fat to be labelled fat free. Take a look at this label from Nestlé's instant cappucino product:

Yes it's 6.8 per cent fat - yet it is also labelled 'Fat Free'. This is too big a discrepancy to be a mistake, so there has to be an industry weasel mechanism to enable this apparent contradiction - and there is. Nestlé responded to a query by saying:

Hi Brian, in order to make a fat free claim a beverage should contain no more than 0.5g fat per 100 mls

So, leaving aside the fact that 0.5g per 100 millilitres isn't actually fat-free, the get-out clause is that the drink as consumed only contains 1.2g of fat, which with the volume of powder and 200 ml of water probably takes it down to 0.5g per 100 ml.

For me, this remains a dubious concept. The fact is that the product itself is certainly not fat free, so the label in the 'Good to know' box is confusing at best.

Retin-A and Retinol

There are two types of cosmetic 'science': magic and pharmaceutical.

The magic kind is where you take a substance that has value inside the body and use it in a way that can't deliver the same benefit. A good example is hyaluronic acid. This was original discovered as part of the gunk that fills eyeballs, and later was shown to be an important part of the matrix that supports cells in the body. The way it is generally sold is that it somehow replenishes this support function, plumping up skin. But this is a bit like saying that food gives you energy, so if you plaster food on your skin you should feel energised.

The good news about hyaluronic acid is that is a genuine humectant - it grabs water, so acts as a reasonable moisturiser - but no better than much cheaper substances like vaseline.

Products with a pharmaceutical background, on the other hand, certainly have an effect, but we have to recognize that all pharma comes with side effects, some of which can be worse than the condition treated. And they need to be used with care. Often the cosmetic industry gets round this by putting so little of an active substance in a product that it doesn't risk side effects, but equally produces very little in the way of results.

So we come to our topic, Retin-A, Retinol and various other names applied to chemical variants on Vitamin A. Retin-A is a brand name for tretinoin, aka retinoic acid, the carboxylic acid derivative of Vitamin A and has been a topical treatment for acne since the 1960s. In the 1980s it was accidentally discovered that it seemed to reduce the appearance of skin wrinkling. Since the original anecdotal benefits there has been some research suggesting positive results. It has since been sold as a skin treatment in the US, though is not widely available in this form elsewhere because of its pharmaceutical nature.

Weaker and more dilute forms turn up in commercial skin creams, often based on retinol, one of the animal forms of Vitamin A. In these cases there may be a small effect, but it certainly will be limited as the dosage is restricted to avoid the side effects. In the more concentrated form (Retin-A, Renova etc.) it can have make a more noticeable change, but can result in a number of side effects, most notably skin irritation and burning, dryness and increased sensitivity to sunlight. For some users this fades over time, for others it will come back each time the cream is used - and the product is only effective while in regular use.

Overall this seems a borderline product. It does have a genuine effect, but it is a pharmaceutical product with known side-effects being applied outside its intended use. As such, the negative aspects may outweigh the positive, and I have not been able to find any research on long-term impact, which may be another concern.

Links

• Hyaluronic acid - page 386

Can drinking tequila help you lose weight?

If I had £1 for every new story where [insert your favourite alcoholic drink] is shown to have some positive effect, I could retire immediately. And, surprise, surprise - this is yet another such story that has no basis whatsoever as far as the headline goes. But it does have one interesting possibility for an alternative to sugar.

All the press coverage comes up with statements like 'You won't believe why drinking tequila might actually help you lose weight,' or 'You won't feel so guilty after that extra shot.' To be clear. Tequila will definitely not help you lose weight, and even if the implied benefit were true, which it isn't, the dangerous impact of alcohol would far outweigh the benefit. In fact the research specifically points out that the beneficial substance this report is based on, of which more in a moment, is not found in tequila.

Hidden beneath the 'drink your way to weight loss' stories is a much more interesting possibility. The actual research, reported at an American Chemical Society meeting, showed that the agave plant, which happens to be the plant tequila is produced from, contains some very interesting sugars called agavins. Instead of the usual fruit sugar fructose, these sugars are fructans, which are effectively fructose polymers. The result of this different structure is that the sugars can't be used by the body and so don't have the negative impact of sugar. They even appear to somewhat reduce blood sugar levels - and they still give a sweet taste. Admittedly not as sweet as a conventional sugar, but still offering the hope of a sweetener that has few potential side effects (some people are intolerant to agavins) and no negative impact on blood sugar levels.

It should be noted that this was a trial on mice, and was funded by a food company and a company making agave products - but that doesn't necessarily mean that the research is dubious.

A really interesting story - but almost entirely hidden by the baloney about tequila being 'good for you.'

Links

• Artificial sweetners - page 9
• High fructose corn syrup
• Sugar - page 102

Balancing hormones

Thanks to reader Yuka for pointing out the wide range of products that are advertised to 'balance the hormones', particularly targeted at women consumers.

There are some parallels here with attempts to 'boost the immune system' (see page 301 in the book). We aren't talking about a simple system or individual entity that can somehow be put back in balance by taking a supplement.

Hormones comprise a vast range of signalling chemicals produced by various glands in the body to control different functions from digestion to sleep and the reproductive system. Various illnesses result in unusual hormone levels, and require proper medical treatment. But the idea that you can 'balance your hormones' by eating something seems more oriented to the ancient and baseless idea of your body having four humours that need to be kept in balance. There is no good scientific evidence for taking supplements to balance your hormones, nor any clear mechanism by which many recommended supplements could even have an influence on hormone levels.

There are many hormones and many products said to 'balance' them, but this article gives an example of some specific products claiming to be 'bioidentical hormones', recommended by their vendors as alternatives to hormone replacement therapy, and also said to improve quality of life. As the article makes clear (with proper testing to back it up) these products have serious potential problems.

Overall, then, if you suspect you have a hormonal problem, the last thing you want to do is self medicate. See your GP.

Vitamin B17, aka laetrile or amygdalin

Flipping through Facebook today I saw someone had shared a post titled 'Vitamin B17: the greatest cover-up in the history of cancer.' There's certainly a cover-up here, but not in the way that was intended by the author. Substances labelled 'Vitamin B17', 'laetrile' or 'amygdalin' (technically a slightly different compound) are sold as cancer cures that the pharmacological industry doesn't want you to know about. But they aren't anything of the sort.

Amygdalin is found in apricot pits, while laetrile is a synthetic compound which is similar in structure. Despite the 'vitamin B17' label it is frequently given, this is not a vitamin in any way, shape or form. Amygdalin, which enzymes can break down to give off the deadly hydrogen cyanide, was tested as a cancer treatment over 100 years ago and found both not to work and to be extremely toxic. Neither of these problems seem to have got in the way of those promoting it as a cure.

One of the reasons that laetrile continues to be rediscovered as a supposed cure is that it was heavily marketed by a self-styled doctor, Ernst Krebs who claimed that cancer was caused by a deficiency of 'vitamin B17.' For decades there have been attempts to make money from those suffering from cancer by promoting this unsubstantiated substance as a cure.

A thorough review of studies of the use of laetrile in the treatment of cancer made in 2011 concluded: The claims that laetrile or amygdalin have beneficial effects for cancer patients are not currently supported by sound clinical data. There is a considerable risk of serious adverse effects from cyanide poisoning after laetrile or amygdalin, especially after oral ingestion. The risk-benefit balance of laetrile or amygdalin as a treatment for cancer is therefore unambiguously negative.

Are microwave ovens dangerous?

At any one time there are a number of posts circulating on social media, or by chain emails, suggesting that microwave ovens present a danger to health. But is it true?

Generally speaking, the assaults on microwaves either suggest that the damage and de-nutrify food, or that the microwaves themselves are zapping us as we stand around the kitchen.

Let's take the food part first. It is certainly true that microwaving reduces nutritional value - but so does all cooking. On the whole, cooking in a microwave is more likely to retrain nutrients than using conventional means of cooking. Some of this is probably due to the reduced cooking time. Of course it's perfectly possible to cook vegetables for longer than usual in a microwave in a container with lots of water - and just like boiling vegetables excessively in conventional cooking, this is a great way to remove nutritional value. Like any other means of cooking, it's possible to microwave badly.

Another food claim is that microwaving produces carcinogens - again, this is a typical outcome of cooking, though unless you char your food, the amount of carcinogens produced is likely to be lower than the levels of natural carcinogens that are in food anyway. It is sensibly recommended that some plastics aren't used in microwaves, but this is because they melt, not because they give off nasty toxins.

How about the stray microwaves? Studies of undamaged microwaves have shown practically no leakage - well below safe levels. It is important to replace a microwave if door hinges etc. get damaged, but if your microwave is in good condition, the amount of microwaves that can leak from it is tiny and harmless. Those who don't like microwaves will always refer to them as 'radiation' because this sounds scary. They are indeed radiation, but only in the same sense that light, for instance, is radiation. We are not talking about nuclear radiation, but electromagnetic radiation - things like radio waves and light. 

Nothing that makes things hot is totally harmless. You can get burned from hot food in microwaves. Microwaves are susceptible to uneven cooking - so it's important that you make sure the turntable is working properly and that you stir food as required. And it is possible for some liquid microwaved foods and drinks to spurt when, say, a spoon is put in them - so care is important. You shouldn't leave a microwave in the charge of a five-year-old, any more than you should a conventional oven. But all the negative comments about microwaves beyond this simple safety requirement seem to come from a very small number of sources, some of which have a vested interest in selling 'radiation meters' etc., while those regarding microwaves as safe are proper scientists, engaging in well-reviewed scientific trials. 

LINKS

• Burned food - page 15

Can chocolate be good for you?

A new chocolate bar claims to 'help keep you happy and healthy every day' - can chocolate really be as good for you as this product claims?

Although we've a separate entry on chocolate, this claim seemed so dramatic that it was worth its own entry. The product in question is ohso and it's even packed in handy sets of seven, so you can eat it every day.

The chocolate's website, excruciatingly titled 'ohsolovesyourtummy.com', is a little short on facts. There is no nutritional information in the 'Nutritional Guide', for instance - I finally found them tucked away under a secondary heading, but what it didn't say was whether the list was for the 'added sugar' or 'no added sugar' variety. So far, the company has failed to respond to a request for more information. (And the site could do with a proof read, as it includes "Ingredient's" and "refferred to".)

So what are ohso's health claims?

• It's free from gluten and nuts and has 'no added dairy'. That's good if these cause you problems, though not difficult to find these days. For the vast majority of us, no health benefit.
• Has 63 kcal in the 'no added sugar' bar and 72 kcal in the others. Certainly not a scary amount of calories. So is this really low calorie chocolate? In fact it actually says 'We add no dairy, so each bar of ohso is 72 calories.' But it's not particularly the dairy that piles on the calories in chocolate. This is a small, 13.5g bar. The same amount of Cadbury's Dairy Milk, which I think it's fair to say no one, not even Cadbury, would consider healthy (and certainly does contain dairy) has, wait for it, 72 kcal in 13.5g. Exactly the same amount.
• It contains 'friendly bacteria', which survive passage through the gut 'three times better' than in a yoghurt drink. Sounds good. But just because bacteria survive the passage through the gut doesn't mean they stick around and do anything. And as the Probiotics section of Science for Life shows (see page 80), there are no proven benefits from consuming 'friendly bacteria' other than in some very specific medical conditions. 
• It's cholesterol free. So what? As you'll see in the Cholesterol section of the book (see page 28), it has been known for some time that eating cholesterol has no significant impact on our cholesterol levels.

Not a lot of health value there, then. I couldn't see it on the website, but many of the reviews of the product also contain that old chestnut that dark chocolate is 'packed with antioxidants'. How many times do we have to say this? We don't need to consume extra antioxidants - it doesn't add to our natural antioxidant level and with some supplements it has been shown to increase the risk of death.

What's particularly worrying is the way that the chocolate is packaged in 7s and is labelled as containing 'your optimal daily amount of "friendly bacteria"'. This seems to be encouraging people to eat chocolate every day and that can't be a good thing. The other thing to bear in mind is that you will paying £3.99 for under 100g of chocolate. As a comparison I took a look at a quality brand of chocolate (Green & Black's) at Waitrose, so you couldn't accuse me of skimping on price - £2.19 for 100g of their Maya Gold, around half as much.

As we say in our chocolate section, consumed in moderation chocolate is fine - and no one can doubt that it tastes good. But to suggest that chocolate can help keep you healthy stretches a point to breaking.

Brewer's yeast

Some health stores recommend brewer's yeast as a natural way of reducing cholesterol - but does it work, and is it safe?

Brewer's yeast, which is essentially a powdered fungus used in beer production, is one of the many wonder products you can find in a health food store. It is sold both as a way of getting B vitamins and chromium, and is sometimes claimed to reduce cholesterol. This claim is based on a number of studies - but the evidence is weak, with some studies showing no effect at all, and several centres of expertise suggest there is no basis for the claim.

What is certainly true is that where it has been suggested that brewer's yeast has a cholesterol reducing benefit, the product is being taken in doses of around 500mg a day (1-2 tablespoons in powdered form). One concern this raises is that this would result in receiving around 1,000% of the RNI of niacin ((the amount that is enough, or more than enough for 97% of the population), and there is good evidence that high doses of niacin can have negative effects. There are simpler ways to reduce cholesterol.

The other claimed benefits of brewer's yeast tend to be from the trace mineral chromium (for which there are various claims with mixed evidence) and a source of B vitamins, but as we make clear in the Vitamins and minerals section (page 111) a normal adult on a balanced diet should not need supplementation. By all means enjoy the brewer's yeast containing spreads like marmite or vegemite if you are in the 'love' camp - but it seems unlikely that it will provide much benefit as a supplement.

Niacin

Niacin, or vitamin B3 is added to white bread and cereals, and present in high doses in some supplements. But do we need this fortification?

As mentioned in the Vitamins and minerals section (page 111), vitamin B3, or niacin, is an essential micronutrient that supports the nervous system and is required for good skin. Deficiencies can result in weakness, loss of appetite, dermatitis, diarrhoea and, at the extreme, dementia. It is found in wholegrain products, peanuts, sesame seeds, fish and most meat.

You may have noticed that it is added to many breakfast cereals, and it is also added by law to white flour (and hence white bread) in the UK, as in the 1950s the government reacted to the new enthusiasm for white bread, which lacks some of the nutrients of the wholegrain equivalent. To be honest, the level in flour and bread isn't enough to make a huge difference - and these days few of us in developed countries lack niacin.

However, there is a concern about over-consumption of niacin in supplements. A young child, for instance, being given a multivitamin on top of a normal diet can end up with around 600% of their RNI (the amount that is enough, or more than enough for 97% of the population). And an adult taking a high dose of, say, brewer's yeast, could be on 1,000% of their RNI from that alone.

The reason this is a worry is that B3 is one of the vitamins that can cause problems in excess. At high levels it can cause skin flushes, rashes and at the extreme stomach bleeds and an increased risk of diabetes. Serious problems over and above the flushes are only likely to be caused by consumption well over 1,000% of RNI, but even so, this is a good example where unnecessary supplements can actually have a negative effect. And we particularly need to be careful with young children.

Vitamins aren't sweets and care needs to be taken with dosing, bearing in mind that most of us get a lot of vitamins already in our diet.

High fructose corn syrup

High fructose corn syrup is used as an alternative to sugar to sweeten some drinks, particularly in the US. It possesses no greater health risk than any other sugar - but do cut down on sugar!

This is one that is more of concern in the US than the UK, where it is unusual for high fructose corn syrup (or HFCS) to be used. The reason it tends to be used in the US is that it is cheaper than conventional sugar, apart from anything else because fructose, one of the two sugars in HFCS (the other is glucose), is sweeter than sucrose (the fructose/glucose combo in conventional sugar). This means that technically it is slightly healthier than sucrose, as you can use less HFCS than cane or beet sugar to get the same sweetness.

There is nothing magic about any of these sugars, and HFCS has less fructose concentration than, say, an apple or pear. And, to be absolutely certain, there has been plenty of good research done on HFCS which shows that there are no negative effects whatsoever, apart from the usual problems of sugar.

So that's it. It's yet another scare because HCFS sounds less 'natural' than cane or beet sugar. In the end it's the same stuff, but because fructose is sweeter than sucrose, you need less of it to get the same level of sweetness, so if you have a choice, you should go for the HCFS. Like all sugars, it's something we should consume in moderation. Like all sugars, almost all of us should consume less. But the dire warnings doing the rounds on social media making it a dietary bogeyman have no basis whatsoever.

LINKS

• Sugar - page 102

Copper bracelets for health

It's easy to find shops selling copper bracelets and other copper-based things to wear that it is claimed will help reduce chronic pain and swelling, reduce the impact of arthritis and more. But does it work?

Copper is a relatively common element that we need to consume in trace quantities for a number of functions of the body, but we get plenty of copper in our diet and an excess can result in liver damage and brain deterioration, so it's not something to take as a supplement without medical advice. But how about wearing it?

The immediate scientific response is to wonder how wearing a copper bracelet, say, could have any impact on pains in other parts of the body. One claim, for instance, is that the body can draw metal out of the bracelet to help with cartilage replacement. There is no mechanism by which this could happen - and even if copper was absorbed, it would do more harm than good. This seems little more than an appeal to magic.

A study was carried out in the UK in 2013 which reported that wearing copper bracelets had no impact on these problems, and that any perceived benefit from wearing copper was simply a placebo effect.

On a separate claim, it is just possible that copper compounds, appropriately applied, could have some antibacterial benefits - but it isn't enough to wear a piece of metallic copper, and there is no evidence as yet of a wearable product containing copper or copper compounds have such a benefit.

So by all means wear a copper bracelet if you think it looks nice - but don't expect it to make you healthier.