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Good hydrations: how do drinks affect our health? Fruit juice, fizzy drinks, milk and health drinks

Shared from the New Scientist:  https://www.newscientist.com/round-up/good-hydrations/?cmpid=ILC|NSNS|2017-GLOBAL-inlinelink&utm_medium=ILC&utm_source=NSNS&utm_campaign=inlinelink

Good hydrations: Is fruit juice better than soda?

Fizzy pop is just candy in a can, and diet alternatives are full of nasties. Pure 100% fruit juice is best – or so we’re led to believe

Sugary drinks rot your teeth, and the more you drink, the more they will rot. Fizzy pop is generally assumed to be the worst. That is not because of dissolved CO2 – it is a myth that sparkling mineral water is any worse for your teeth than the plain variety – but because of the combination of sugar and common flavourings such as phosphoric acid.

Their high sugar content means squashes and sodas deliver a huge calorie hit without filling you up: one standard can of a drink like cola provides more than the recommended daily amount of “free” or added sugar. That piles in excess energy that we store as fat. Those who regularly imbibe sugary drinks are more likely to be overweight, regardless of income or ethnicity, and consuming a can of sweetened fizz or the equivalent a day increases the risk of type 2 diabetes by a quarter. Overall, this form of liquid sustenance has little to recommend it.

Diet sodas

So, if the main problem with sugary drinks is sugar, eliminate that and you eliminate the problem, right?

Not so fast. Some studies indicate that diet sodas help with weight loss, but others find a seemingly paradoxical association with weight gain. Mice consuming artificial sweeteners can even develop glucose intolerance, a precursor to type 2 diabetes.

It is tricky to pin down cause and effect in human studies, says Vasanti Malik, a nutrition scientist at Harvard University: people who are already overweight may be consuming diet drinks in an effort to lose weight, skewing the stats. And the animal studies have been criticised as unrealistic, with mice or rats in some experiments consuming quantities of sweeteners equivalent to us gobbling a few hundred tablets a day.

But there are plenty of reasons why low-calorie sweeteners might not always have their intended effect. One is psychology: you had a diet cola this afternoon, so you can have an ice cream this evening. Alternatively it could be that the intenseness of the artificial stuff, which can be 200 times as sweet as sugar, drives us to prefer sweet things, says Malik. Or perhaps sweeteners disrupt our gut bacteria, or our normal hormonal response to sugar intake. “As a result, the body doesn’t respond as well when real sugar is consumed,” says Susan Swithers at Purdue University in West Lafayette, Indiana, leading to weight gain.

The latest review concluded last year that choosing diet drinks over normal sugary drinks can contribute to weight loss. But the uncertainty should give us pause for thought, says Swithers. “The reality is that no one should be drinking a sweetened beverage every day, whether it’s regular soda or ‘diet’ soda,” she says. “It’s like candy in a can either way.”

Fruit juices

Pure fruit juice feels like a healthy alternative. It’s 100 per cent fruit, after all, and contains good stuff that fizzy drinks don’t, such as vitamins, minerals and antioxidants. The UK National Health Service says one small 150 millilitre glass of pure fruit juice counts towards your five-a-day.

But only one. Fruit juice is missing a lot that fruit has: the juice of one orange contains 0.4 grams of fibre, compared with 1.7 grams in an actual orange. And it is as sickly sweet as sweetened drinks. The World Health Organization recommends that the natural sugar in fruit juice should be lumped together with that added to food and sweetened drinks as free sugar, and advises strict limits on how much we should consume. Orange juice and Coca-Cola contain roughly the same amount, and some juices even more (see “Sugar to go”). That suggests pure fruit juices should carry the same health warnings as added-sugar drinks.

In truth, we don’t know whether fruit juices are better or worse for you than soda, says epidemiologist Nita Forouhi of the University of Cambridge: other lifestyle factors such as income, diet, smoking and exercise that may differ between habitual juice drinkers and habitual soda drinkers make it hard to draw watertight conclusions.

A review by Forouhi’s group and others in 2015 did conclude that added-sugar drinks, artificially sweetened drinks and fruit juices were all potentially associated with type 2 diabetes, but differing study designs mean the evidence for artificially sweetened drinks and fruit juices might be “subject to bias”. In other words, the jury’s still out.

Sports drinks

Sports drinks’ main claim is that they improve athletic performance and recovery by replacing fluid, energy and electrolytes – sodium, potassium and chloride – lost during exercise. A review published in 2000 concluded that sports drinks probably do improve performance compared with drinking water. In 2006 the European Food Safety Authority agreed.

But most sports drinks also come with a stonking sugar content, and more recent studies have questioned earlier conclusions. An analysis published in the BMJ in 2012 found a “striking lack of evidence” for any claim related to sports drinks. They may help elite athletes, but are unlikely to do anything for ordinary people.

Sugar to go

In the meantime, there’s another competitor: low-fat chocolate milk. Its 4:1 mixture of carbohydrates and protein appears to be ideal for muscle recovery after a workout, and it is cheaper than most alternatives, too. “The research has been positive – most studies have found it to be just as effective or superior to an over-the-counter recovery beverage,” says nutrition and exercise scientist Kelly Pritchett of Central Washington University in Ellensburg.

Good hydrations: Does milk make healthy brains and bones?

It’s a richly nutritious mixture of sugars, proteins, vitamins, minerals and fat. Babies need it – but for the rest of us the evidence is semi-skimmed at best

milk

Plainpicture

Milk is a richly nutritious mixture of water, proteins, minerals, vitamins, sugars, saturated fat and cholesterol. All mammals make it, but humans are the only ones to drink it beyond their early years. Should we?

Breast milk – or synthetic versions of it – provides the “perfect balance of nutrients” for babies in their first year, says Andy Bernstein, a paediatrician at Northwestern University in Evanston, Illinois. After that, full-fat cow’s milk is recommended as a good source of fat for brain development, dropping to 1 or 2 per cent fat milk from age 2.

But although programmes in the US and UK that gave milk to children in schools were associated with huge health benefits, it is not clear why. “We don’t know if there is something specific or special about milk, or if it is just the fact that these children are getting more calories, protein, nutrients in general,” says Andrea Wiley of the University of Indiana at Bloomington. A recent study of children in Kenya found that supplemental milk helped those with stunted growth catch up in height, but provided no benefits over a non-milk nutritional supplement for children developing normally.

For adults, the benefits seem even more dubious. There is no conclusive evidence, for example, that getting extra calcium from milk is vital for maintaining healthy bones or avoiding fractures. Other foods besides milk – “beans and greens”, largely – are also rich in calcium, and most researchers now argue that a generally healthy diet and plenty of weight-bearing physical activity is what keeps bones healthy.

And we should perhaps be careful not to overdo the white stuff. A Swedish study published in 2014 found that drinking three glasses of milk a day over an average of 20 years increased overall mortality compared with drinking just one – while showing that consuming fermented milk products such as yogurt and cheese reduced both fracture risk and overall mortality.

The authors of that study recommend caution in interpreting the results, though, as there were a number of potentially confounding factors they couldn’t control for. The fermentation finding is not fully understood either, says Amy Lanou of the University of North Carolina at Asheville, although it might have something to do with a reduction in the milk sugar lactose during fermentation. “If some of these effects are mediated by milk sugar, that may be a reason,” says Lanou.

Soya milk

If cow’s milk isn’t necessarily all that healthy, what about its most common substitute? Soya milk has a bit less fat than cow’s milk, but often comes pre-sweetened, counting towards your intake of free sugar. Its reputation for reducing harmful LDL cholesterol is overblown, too – even if you drank about eight glasses per day that would only equate to a 3 per cent drop in LDL.

Other supposed health benefits – preventing breast and prostate cancer, reducing risk of osteoporosis and hot flushes associated with the menopause – are ascribed to soya milk’s high levels of compounds known as phytoestrogens. These can mimic the effect of the hormone oestrogen or, in some instances, block it. But none of these effects has been convincingly demonstrated in trials, while a few studies have suggested consumption of soya milk may actually increase breast cancer risk.

 

Organic or non-organic?

Organic milk contains higher levels of omega-3 fatty acids than non-organic milk: it comes from cows that eat more grass, which is high in these acids. But even with this boost, total levels of omega-3s are still low in organic milk. And neither kind is allowed to have any traces of antibiotics.

Another common reason to go organic is fear about hormone levels in non-organic milk. All milk naturally contains hormones, but in areas where cows are treated with growth hormones – as happens in some US states but not in the European Union, Canada, Australia and New Zealand – non-organic milk may have higher levels of insulin-like growth factor, a hormone linked to increased risk of some health problems. But the US Food and Drug Administration concluded that it poses no health risk at the levels present in mass-produced milk.

Good hydrations: Are health drinks healthy?

Coconut water, wheatgrass smoothies, vinegar, beetroot juice, even urine – the list of trendy cure-all potions is growing. These are the ones that work

beetroot

Clare Gainey / Alamy Stock Photo

Coconut water

Being potassium-rich, coconut water supposedly enhances your ability to absorb water during prolonged exercise. If that were true, though, it would also increase your risk of overhydration. In fact, studies show it is no better or worse at hydrating than a much cheaper beverage: water.

As yet there is no scientific verdict on more recently trending hyper-hydrating waters – including watermelon water, as endorsed by singer Beyoncé, and birch sap water, as endorsed by Nordic folklore.

Beetroot juice

Rich in nitrates that can relax blood vessels and improve blood circulation, there is some scientific support to the idea beetroot juice is good for you. But drink it in moderation: its sugar content is on a par with orange and other common fruit juices (see “Good hydrations: Juice and soda“). Too much nitrate has also been tentatively linked with an increased risk of stomach cancer.

Wheatgrass smoothies

Wheatgrass contains a smorgasbord of vitamins and minerals, as well as chlorophyll, claimed by some to boost the production of red blood cells. But studies show it is unlikely to benefit you much more than munching green veg such as broccoli and spinach.

Kefir

A fermented milk drink akin to yoghurt, kefir is prized for its supposed beneficial effects on microbes in our gut. Studies in mice suggest there might be a link – although it is too early to say whether there is an effect in humans, or how big it is.

Urine

Lost in the desert, you are far from any source of fresh water and your bottle is empty. What do you do? You know the drill: unzip your pants.

And not just there, if some have their way. From acne to anaemia via obesity and various cancers, many are the ills that urine has been said to alleviate – seeing as it contains vitamins, minerals, proteins, enzymes, hormones, antibodies and amino acids your body has discarded.

For Joel Topf, a nephrologist at Oakland University in Michigan, though, that’s a clue to how useful the active ingredients really are. “The chemicals are not necessarily toxic, but they aren’t something that the body wanted to hold on to the first time,” he says. Not only that, but they are at concentrations far too low to be useful.

So, urine is disgusting and unhelpful, but harmless, right? Well, maybe not. One component of urine rarely mentioned by those who promote drinking it is phosphorus, a possible cardiac toxin. The myth that urine is perfectly sterile is just that, too – a myth. Drinking it could bring you down with all sorts of nasties.

Let’s seek advice from the real survival experts. When it comes to preserving precious bodily fluids, the US army’s 1999 survival field manual puts urine firmly alongside blood, seawater and fish juices in its “DO NOT DRINK” category. It’s not a cultural thing that we don’t like drinking urine, says Topf – it’s evolutionary. “Urine is waste, not medicine. Stop drinking your urine.”

Vinegar

Cleopatra supposedly dissolved pearls in vinegar to make Mark Antony a love potion. Some 2000 years later, people are still banging on about vinegar’s power to cure erectile dysfunction – and lower your blood pressure, cholesterol and weight to boot.

On the cardiovascular front, they might be on to something. A small-scale study conducted in 2010 at Arizona State University showed that both diabetic and non-diabetic volunteers had more stable blood sugar and insulin after a meal of complex carbohydrates if they first had a drink of diluted vinegar. Other studies have shown similar, if small, effects.

Acetic acid – the source of vinegar’s characteristic mouth-puckering bite – is generally thought to be responsible, although no one can pinpoint how. Vinegar also contains a teeming collection of amino acids and polyphenolic compounds that might play a part. The jury is still out on whether all this actually makes you lose weight – although one South Korean study on the effects of drinking pomegranate vinegar did show that, regardless of whether participants lost weight, they did lose a particularly dangerous type ofbody fat.

Any benefits must be set against the deleterious effects of acetic acid on tooth enamel. And would-be Mark Antonys should note: for pearls to improve your sex life, they are best served whole.

 

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