Coffee again

Image from Wikipedia

Yet again we've seen newspapers flooded with stories on diet and health - specifically that drinking coffee can reduce mortality rates by a small but significant amount.

The good news is that the two studies referenced are high quality, large scale studies. Admittedly one of them does not specify the dosage of coffee involved (for the other, 3-4 250ml cups a day seems to be it), and that same first study did not seem to control for many other lifestyle contributors - could the coffee drinkers have been more health-conscious in other aspects of their life, for example.

You can read an excellent summary of the details of the studies and find links to read the original studies if you wish at the Skeptical Raptor website.

Sugar, sugar

We all know these days that sugar is a problem in our diet, but there is huge confusion over what sensible limits are. Practically everyone seems to be confused by this - and I'm afraid this included me, when I wrote about sugar in Science for Life, because I didn't realise just how stupid the regulations and recommendations are (thanks to reader Clare Kendall for pointing out an error in the book, and Phil Langton from Bristol University for useful guidance).

Our food packaging in the UK is generally labelled with the quantity of sugar in the product. In 2015, the UK's Science Advisory Committee came up with a report recommending we reduce consumption to 5% of total dietary energy, which led to the figures of no more than 35g for a man and 25g for a woman. Now, it would only be sensible to make such a recommendation if, as I assumed, it matched the labelling - but it doesn't, making it practically meaningless. This is a recommendation for 'free sugar', where the labelling is the amount of total sugar. Free sugar is defined as 'all monosaccharides and disaccharides added to foods by the manufacturer, cook or consumer, plus sugars naturally present in honey, syrups and unsweetened fruit juices. Under this definition lactose (the sugar in milk) when naturally present in milk and milk products and the sugars contained within the cellular structure of foods (particularly fruits and vegetables) are excluded.' Got it?

There are two problems here. One (the one that confused me) is that it doesn't make any sense for your labelling legislation to require a different definition of sugar content to your recommendation for consumption. But the other is that limiting restrictions entirely to free sugars makes very little sense. For example, they treat all the sugar in orange juice as free sugar, but none of the sugar in an orange (say) as free sugar. However, when you eat an orange, you release a lot of the fruit juice in your mouth, assuming you don't swallow the segments whole. Why isn’t that free sugar? Clearly it is.

There is also a problem with lactose, the sugar in milk. Again, it’s not clear how much this should be counted, but it seems wildly illogical to simply ignore it. And downright weird to count it when it's added, but not when it's already there, as milk has no structural protection to prevent absorption, as there is in fruit.

As far as I can see from the document, there is not good evidence of the involvement of non-free sugars in diabetes, but equally there is not good evidence they are not involved (and nothing either way on heart conditions etc.) My suspicion is they didn't want to scare people off eating fruit and drinking milk because there are other nutrients in them that are good - but the result is a very confusing message.

I suspect the best thing is to cut down on all sugar, but of the sugar you do have, to make sure that it is accompanied by other beneficial nutrients. By all means drink milk (assuming no lactose intolerance) and eat fruit - they are good for you because of those nutrients - but don't consume too much. As mentioned in the book, it's sensible if more of your 5 (or 7 or 10) a day are vegetables rather than fruit. And I'd definitely stay away from smoothies and other very high sugar content drinks (Frappacinos, for instance) and foods mentioned in the book, except as occasional treats.

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.

Crispy roasties and burnt toast

There's been an outbreak of news stories about cancer risk from over-cooked starchy foods because of the production of substances called acrylamides. If your roasties, chips and toast, for instance, are too dark, we are told that they could increase your risk of cancer. This is not news - it's an idea that has been around for a long time and was covered in Science for Life. All that's new is that the Foods Standards Agency (FSA) has launched a campaign called Go for Gold encouraging us not to cook these starchy products too harshly and to leave them golden coloured. Bizarrely they are using that well known food science expert, Olympic medallist Denise Lewis to publicise the campaign (see what they've done - go for gold?), and the FSA wants us to cut back.

As mentioned in Science for Life, some studies do show a small potential increased risk of a handful of cancers, so there's no harm in avoiding really dark fried or grilled starchy foods, which is what I recommended. However, these studies are not definitive - in fact at the moment the general view is that there is no strong evidence of risk from acrylamides - and even if the risk does exist, it is small enough to happily still enjoy the crunchy bits of roast potatoes.

To put it into context, lots of things we eat may well produce a very small increase in risk of cancer. Things like, for instance, those killer foods orange juice and celery. We know for certain that alcohol has the biggest influence on cancer risk of anything we eat or drink, and coffee certainly has some small risk attached. But it the grand scheme of things, worrying about these small risks is like worrying about being struck by lightning or being in a fatal train crash. It can happen. It will happen to some people. And you don't want to stand on a high hill holding a metal pole in the air when there's thunder nearby. But life's too short to worry excessively.

You can read more on the statistical aspect here.

Acupuncture update

Science for Life has over two pages on acupuncture, concluding that it is primarily a placebo-based treatment with no other benefit, but with some evidence that it was effective in the treatment of lower back pain, a view that was, at the time, supported by a Cochrane review and the UK's NICE body, which authorises medical treatments.

However, the evidence has now been through a more thorough analysis, and NICE has changed its guidance to say that acupuncture should not be offered for that remaining area, lower back pain. It seems that the original NICE guidance was subject to a number of flaws and influenced by those with a reason to want acupuncture to be recognised by the NHS.

The weight of evidence now appears to be clear that the benefits of acupuncture, like many other alternative treatments, are solely those to be gained from the placebo effect. See this post by David Colquhoun for details of the problems with the earlier assessment and the new ruling.

The eating cholesterol blues

For some time now, the UK has dropped the recommendation that you should limit cholesterol intake, because there is no good evidence that consuming cholesterol has an impact on our blood cholesterol levels - which is why eggs are now considered good again. But it has taken a while longer for the US to catch up on this one. Now they have.

This was indirectly drawn to my attention as a result of a blog post comment. Back in 2009 I moaned about a radio ad featuring Gloria Hunniford in which the veteran presenter said 'A while ago I used to have high cholesterol,' (or words to that effect). I pointed out that saying 'A while ago I used to have...' was just repeating yourself. It should either be 'A while ago I had high cholesterol' or 'I used to have high cholesterol', but not both.

I've had a comment from Nicole Lascurain, the Assistant Marketing Manager of a US health firm pointing out that their website listed what '100% of your daily value of cholesterol looks like.' The page has various pictures of foods like friend chicken and cheese showing their cholesterol content, telling us that 'it's no secret that eating fatty foods raises your bad cholesterol levels'. Unfortunately, they're confusing cholesterol levels in the food with fat levels, which aren't the same thing. Yes, high fat levels, particularly transfats, push up your cholesterol levels, but eating cholesterol doesn't.

They based their 300mg a day limit on a genuine but out-of-date US standard. To quote the Scientific Report of the 2015 [US] Dietary Guidelines Advisory Committee:

Previously, the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 mg/day. The 2015 DGAC will not bring forward this recommendation because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol, consistent with the conclusions of the AHA/ACC report.

Simples!

Herbal medicine

Herbs have been used in all cultures as medicines and some have real medical benefits. but care has to be taken with herbal cures as they are poorly regulated.

In historical times, herbs played a major part in our medical treatment, though as early as the 17th century, when herbalist Nicholas Culpeper published his Complete Herbal, there was a debate between the proponents of herbal and chemical medicine. With a modern understanding of the active ingredients in herbs we can see that the distinction is artificial. Herbs are an effective source of chemicals that have an active effect on the human body, though often this effect is improved if the chemical agent is refined and modified.

So, for instance, willow bark, containing a chemical called salicylic acid, has been used to help reduce pains and fevers for at least 4,000 years. Unfortunately salicylic acid causes sharp stomach pains and can cause internal bleeding – so that relief came with a price. At the end of the 19th century, the German pharmaceutical company Bayer produced a painkiller called aspirin, which modified the active ingredient to the much less aggressive acetylsalicylic acid. The active ingredient of medical herbs has been repeatedly isolated and improved. Quinine for malaria, atropine and digitalis for the heart, for instance, all originated with herbal cures, but are much better and safer in their pure chemical form.

Herbal medicine has a strong presence in China, and there are herbal medicine stores on many of our high streets. Unfortunately, current herbal medicine still uses theories with no basis (such as employing a herb with the same shape as an organ of the body to treat that organ) and has rarely advanced. There are also well-documented dangers in taking herbal medicines at the same time as other medications. It is always worth checking with your doctor first.

The popular herbal treatment St John’s Wort, for instance, which has proved effective in helping with mild depression, has as many possible side effects as any prescription drug, from gastrointestinal pain to dizziness. It can cause serious problems with anti-HIV, anti-cancer drugs and contraceptive pills; plus it generally reduces the effectiveness of the transport mechanism carrying drugs into the bloodstream. Because of this it has been banned in France. You can’t assume that because a treatment is herbal it is safe in all circumstances.

Another significant problem with herbal treatments is that a herb rarely contains only one active ingredient – and it is almost impossible to give a well-controlled dose, as the amount of the chemical in a herb will vary from plant to plant. Where a prescription medicine will have isolated the useful chemical, in a herb you could be exposing yourself to a whole range of potentially unpleasant substances to get the beneficial one. But more worrying still is the reality that there is very little regulation of the quality of herbal medicines.

A major US study in 2013 analysed 44 processed herbal prod- ucts and 50 medicinal herbs from a range of suppliers. The results were shocking. Less than half of the products actually contained the labelled main ingredient. Nearly 60 per cent contained herbal species that weren’t listed on the ingredients. A third also contained fillers and contaminants that weren’t on the label. In three of the companies tested, none of the products contained what they said they did. In other studies, herbal medicines have been found to be contaminated with dangerous heavy metals and other extremely poisonous substances.

*UPDATE* In February 2015 the New York State attorney general's office accused four major US retailers of selling herbal supplements that were fraudulent and in some cases were contaminated with unlisted ingredients. These weren't backstreet herbalists, but Walmart, Walgreens, Target an GNC. Approximately four out of five products didn't contain any of the herbs on their labels. Many contained little more than rice and houseplants.

The products with non of the herb in included Gingko Biloba, St. John's Wort, Ginseng, Echinacea and Valerian Root. Typical fillers were rice, asparagus, wheat or grass and garlic, though oddly many of the samples actually claiming to be garlic had none in. This really emphasises how much you are at risk of getting anything but what you expect when buying herbal remedies.

So, while there are certainly benefits to some herbal remedies, the lack of a proper regulation and of a testing regime paralleling that used on conventional medication means that there will always be significant risks attached.

Screens and eyes

For as long as we’ve had televisions they have been accused of damaging our eyes – but now, with screens everywhere, what’s the true picture?

When I was young, older people were always telling us not to sit too close to the TV or to spend too much time watching it. Yet back then, we only had a fraction of the screen time that most of us experience today. You may well spend all day at work looking at a computer screen, then come home to spend the evening in front of the TV. And what were you doing in between these times? Looking at your phone or tablet.

In 2014 there was a scare story that overusing smartphones may damage the eyes. The concern was that the light from LED screens contains more blue/violet light than the natural light that best suits our eyes, and the higher energy blue/violet light can overload the sensors on the retina, increasing the risk of macular degeneration, a common cause of blindness.

The story particularly highlighted the risks from smartphone use, where the screen is held considerably closer to the eyes than a computer or TV screen and is often used in lower lighting condi- tions, where the dilated irises of our eyes allow more light in.

We have to approach this story with a little caution. There is no study showing that exposure to screens, even smartphones, causes eye problems – this is extrapolating from laboratory-based evidence that light in this region can cause damage to the type of cells used in the retina. So at the very most, this is a precautionary warning as yet.

What is certainly true is that our eyes don’t respond well to being focused as closely as a smartphone requires (TVs are usually positioned at a better distance) for long periods of time, and this can cause eye strain. Taking a break from screens for at least five minutes in each hour, and a few longer breaks during the day is highly recommended. Furthermore, regular screen users – which is pretty well all of us – should have regular check-ups with an optician.

UPDATE: In December 2014 a different study showed that people who read backlit screens in before going to sleep produced less of the hormone melatonin. This can make it harder to get to sleep, and in the long term, sleep deficiency can produce significant health problems. As yet the evidence is relatively limited - this was a very small study with just six people on each kind of book. However if you do have trouble getting to sleep, and you read from a screen for your bedtime reading it is worth switching to a paper book (or an e-ink reader like a basic Kindle that doesn't have a backlight) to see if it helps make sleep more easy. Ideally avoid close backlit screens (including phones and computers as well as tablets and backlit e-readers) for a couple of hours before trying to sleep. TVs don't seem to be a problem as we don't sit anywhere near as close, so the blue backlight is a relatively small part of our incoming light - and the generally darker coloured picture of video is better than the stark white of a page to read. If you have to use a backlit e-reader, try turning down the brightness.

Gluten

Gluten is a complex natural molecule that gives dough the stretchy, gooey texture that makes great bread. For most of us gluten is harmless, but a few are intolerant, and others believe a gluten-free diet would benefit us all. What’s the truth?

Between 1 and 2 per cent of the population is gluten or wheat intolerant. They get stomach pains, constipation and diarrhoea, most often because they have coeliac disease, a genetic disorder of the small intestine where the immune system gets it wrong and thinks that the gluten is attacking it, causing inflammation. Rather more people claim gluten intolerance than actually have it – for the rest it is a ‘nocebo’, the negative equivalent of a placebo effect, where believing something is bad for you causes pains with no physical cause.

There are simple tests that your GP can perform to check if you do have a genuine gluten intolerance. If this proves to be the case, then it’s a matter of ensuring that the diet is gluten-free, something that is increasingly easy with a wide range of gluten-free products available in the supermarket. In general, food should be fine as long as you avoid wheat, barley and rye. (Oats, while not a problem in themselves, are probably best avoided also as they are often contaminated with gluten from other grains.) Other cereals like maize and rice are fine.

There has been something of a fad diet of avoiding gluten – the kind of diet often endorsed by celebrities rather than experts – in those who don’t have a gluten intolerance, probably on the assumption that people must be intolerant because there is something toxic in the gluten and that avoiding gluten must be ‘good for digestive health’. In fact, it’s the reverse – people who are gluten intolerant have a mutation that makes them react badly to a harmless substance that is a normal part of our diet.

The general argument for a gluten-free diet if gluten doesn’t cause you problems is open to interpretation. Here’s nutritional therapist Deborah Thackery, quoted in the Morrison’s supermar- ket magazine:

Gluten doesn’t need to be in sausages or many other foods in which it is often present. There is growing evidence that gluten is difficult to digest and while we need protein, the right sort of fats and plenty of vitamins and minerals, we don’t need gluten. All of these nutrients can be found in other, non-gluten-containing foods.

This doesn’t make a lot of sense as dietary advice – after all, fibre is hard to digest, but it’s still good for you (see Fibre). All the evidence is that supermarkets are using ‘gluten-free’ rather as they do the ‘organic’ label: as a way to put a considerable mark-up on a product that doesn’t cost them much more to produce. Gluten-free products can be a rip-off. Trials have failed to demonstrate any health benefit to a gluten-free diet for those who aren’t intolerant, and it makes it significantly harder to get the fibre (and some vitamins) we all need. What’s more, many gluten-free products are higher in fat than their normal equivalents, as something has to be used as a substitute to give the textural contribution of gluten. So, a gluten-free diet is best avoided if you don’t have a medical reason to be on one.

A review published in November 2014 highlighted that those who aren't intolerant shouldn't avoid gluten, but should go for products made from whole grain cereals. The report concluded:

There is overwhelming evidence of clear health benefits of a whole grain based diets featuring store cupboard staples such as bread and cereal made from lightly processed wheat.  The benefits are increased where whole grains have undergone relatively little processing... the scientific evidence behind many of the most popular wheat and carbohydrate free diets turns out to be surprisingly thin and selectively used... Whole grain products are undoubtedly good for health and given their multiple beneficial aspects could easily be described as a super food. It might be possible to argue that they are superior to many other fruit and vegetable super foods since they have multiple modes of action and provide both short- and long-term health benefits.

The review was funded by the company that makes Weetabix, however it was undertaken by the University of Warwick, which points out that the 'company had no input into the conclusions of the research'. While clearly such research is beneficial to the manufacturer, there is no reason to suppose that the funding would bias the outcome.

Links:
• Fibre
• Placebo effect

Chocolate

For most of us chocolate is a wonderful treat – and as long as it’s consumed in moderation, it’s not a bad thing, either.

There is something very special about chocolate – and as long as we remember it is mostly fat, and treat it appropriately, it’s a confection that most of us can enjoy.

Some chocolatiers will tell you that the reason chocolate is so appealing is because of the tactile sensation of consuming it. Because it melts at the temperature of your mouth, the solid turns into a sensuous liquid on your tongue. And there is an element of truth in this. It is also the case that there are a range of active chemicals in chocolate that could influence our brains, and sugar has to be part of the attraction of the modern treat. But there seems little doubt that we also get a kick from a substance called theobromine.

This is a bitter tasting alkaloid, a term we often associate with drugs like morphine and natural poisons. Caffeine, nicotine, quinine and cocaine are all part of the alkaloid family, but none has the appeal of theobromine. A clue might come from the Greek origins of the name which approximate to ‘food of the gods.’ Theobromine is the compound that makes chocolate special. The main source in our diet is the cocoa tree. The seeds of this tree (misleadingly called cocoa beans) contain the fatty substance cocoa butter that is the main ingredient of chocolate.

Chocolate has been enjoyed as a drink in Central and South America for at least three thousand years, and has been popular in Europe since the seventeenth century. In its original form, the drink was bitter (it often had chillies added to give it more bite) – it was a European twist to add sugar and milk to make something closer to modern drinking chocolate. The familiar solid form didn’t arrive until the nineteenth century, which was also when theobromine was first discovered. The substance has similar effects on the brain to caffeine, which is probably why you will occasionally see it said (incorrectly) that chocolate contains caffeine. Theobromine can reduce sleepiness and in large quantities produces a jittery sensation. On the positive side it is a cough suppressant and can help reduce asthma symptoms.

Most of us have heard that chocolate is not good for dogs – and it is theobromine that is to blame. The darker the chocolate, the higher the concentration of theobromine, and the more dangerous it is. A small dog could be killed by as little as 50g of strong dark chocolate. Smaller doses will cause vomiting. This isn’t a problem limited to dogs, poisoning all mammals to some degree, though the speed at which theobromine is disposed of by the system differs from species to species. Cats are particularly sensitive to theobromine, but rarely eat chocolate because they don’t have sweet taste receptors and so don’t get the kick from sweets that humans (and dogs) do.

Theobromine is also poisonous to humans, though not to same the degree as dogs and shouldn’t cause concern. Almost everything is poisonous in a large enough dose (even water, for example) and toxicity is all about dosage. In the case of theobromine, humans have about three times the resistance per kilogram of bodyweight as does a dog, and are significantly heavier, so we are much less likely to be damaged by our treats. A dangerous dose for an adult human would involve eating more than 5kg of milk chocolate.

A number of health benefits have been claimed for chocolate, including reducing blood pressure, reducing stress, reducing diabetes risk and giving limited protection against bowel cancer. None of the trials that have come up with these results have been big enough or repeated sufficiently to be sure of the outcome. The effect on blood pressure was slight, the cancer results are only laboratory based and the stress test was poorly designed (and sponsored by a chocolate manufacturer). The diabetes results were based on compounds in chocolate called flavonoids, but the trial could not show if the flavonoids caused the benefits – and chocolate is not the best source of flavonoids (the study focussed mainly on berries and wine). Plus we know that excess sugar consumption, a major content of most chocolate products, makes diabetes more likely.

[NEW] A recent addition to the chocolate family is 'raw chocolate' which is being promoted as yet another superfood. What this means is that the cacao beans are not roasted as usual, but left outside in the sun to dry. It is claimed that this means there is less loss of nutrients and keeps more antioxidants. As we've seen elsewhere superfood claims are very dubious, and consuming excessive antioxidants seems to be bad for you - so given it has been suggested the raw process could increase the risk of bacterial contamination, there seems little reason to prefer raw chocolate. Eating chocolate for health doesn't make a lot of sense. A good balanced diet is the health part - chocolate is a fun excess.

Bearing in mind the high fat levels in chocolate, the balance of evidence is that that we can’t think of it as a healthy food, but rather one to enjoy in moderation.