Why drinking too much water can be risky

Why drinking too much water can be risky

You can’t go more than a few minutes at the moment without seeing a TV advert telling us to drink more.

With the Olympics in their sights, drink manufacturers are using team GB to endorse their so-called power and energy drinks, claiming we all “need” them.

Having hooked your attention, they then go on to claim these drinks hydrate you better than water, something that’s hard to believe given it’s water that hydrates you.

Take these ads with a pinch of salt. Hydration is about drinking water and that’s what the body really needs.

There is evidence that urging people to drink more â€" a minimum of three litres if the temperature is high, and to carry around a bottle of water at all times â€" can do more harm that good, because people have died of overhydration.

However, it is incredibly rare for someone to die of dehydration in a temperate climate, not even sportsmen who sweat a great deal.

But there are deaths reported from o verhydration. It goes by the name of exercise-associated hyponatraemia (EAH).

In simple terms, it means that you have drunk too much water and the excess has diluted your body fluids so that the levels of sodium (think sodium chloride, salt) have become life-threateningly low. And low sodium levels can kill because cells swell. That includes brain cells leading to coma and death. This can be a particular hazard for long-distance runners.

With half-marathons and marathons being staged all over the country, runners must resist the temptation to poison themselves with too much water. Water intoxication is always on the cards if you believe you have to “stay ahead of thirst” by drinking excessive quantities of water.

To do so is entirely unphysiological. Add to this the temptation to take on more fluid at every drink station and it’s possible to drink three to four litres during a run and that’s too much. The dangers of dehydration during endurance exer cise are greatly exaggerated and as a result EAH is on the rise.

The right way to drink water is on our TV screens all through the summer. When Roger Federer or Rafa Nadal play five hard sets of tennis in the baking sun, sweating profusely, how do they drink? They sip.

They may sip at every end change, but they certainly don’t gulp.

All runners should know that the overconsumption of fluids, whether it’s water or sports drinks, can be fatal, and I’m not exaggerating. EAH due to excessive drinking has caused at least 12 deaths worldwide and there have been more than 1,600 documented cases of it around the globe.

The International Marathon Medical Directors Association advocates “drinking to thirst” and no more. That means 0.03 litres per kilogram. So, for a 100kg person that’s three litres max. The average man is nearer 70kg. Work it out.

Five reasons to give up fizzy drinks

You will...

* Promote a prettier, healthier sm ile. The sugar and acid in soft drinks dissolves tooth enamel while the colouring in darker fizzy drinks leaves dark stains on teeth.

* Reduce your risk of heart disease. The high fructose corn syrup (HFCS) in many soft drinks increases the risk of developing heart disease and diabetes.

* Reduce your risk of osteoporosis. The phosphoric acid found in soft drinks can loosen a tight bolt, eat away metal, and leach calcium from the bones.

* Reduce your risk of diabetes. The connection between excess sugar consumption and type 2 diabetes is well-known.

* Stabilise blood sugar and energy levels. Simple sugars, the most harmful of which are HFCS, are carbohydrates that cause a rapid energy spike followed by a sudden plummet. Adding caffeine, also found in many soft drinks, intensifies this roller-coaster effect.

Dear Dr Miriam...

Eight months ago I found I had a cholesterol level of 6.6. I have changed my diet to include more fruit and veg, bo iled chicken, steamed fish, rice, etc. What is worrying me is that I have lost a stone in weight. How can I gain some weight without pushing my cholesterol up?

Dr Miriam says: I think you may be going about this the wrong way. There’s absolutely no need for you to exclude nutritious foods and lose so much weight.

You can only control 10% of your cholesterol through what you eat. The other 90% is genetically programmed and unchangeable other than by taking a drug that lowers chloesterol such as a statin. So if your cholesterol was 6.6, eating sensibly could only lower it to 6.0.

It’s wrong not to eat healthy fats. Your body needs them, especially the omega 3s, which actually help lower your cholesterol and keep your heart healthy.

Cholesterol-containing foods don’t, I repeat don’t, raise your cholesterol.

Animal fats are the culprit and it’s those that you should keep low. Regular exercise also helps keep your cholesterol normal.