Rethinking the science of hydration

True or False?

• Thirst is not a reliable gauge of a body's need for water
• Urine colour is a reliable gauge of hydration (dark=dehydrated; light = well hydrated)
• It is better to rehydrate with a sports drink after exercise than with water
• We should weigh ourselves before exercise, and after. We must then drink enough fluid to make up for that weight loss to ensure complete rehydration 
• Exercise-induced hyponatremia (low blood sodium) or electrolyte imbalances can be prevented (or avoided) by  drinking a sports drink during and/or after exercise rather than just water
• People get sick and/or collapse due to dehydration during sporting events where fluid is provided. 

 I would have answered 'true' to most, if not all, of these statements. In fact, I learned that many of these statements are true in school. However, last month, BMJ published The truth about sports drinks that shed some light on the science behind dehydration and sports beverages. 

The article describes clever marketing tactics on the part of the sports drink industry, including providing funding to scientists and science journals. For example, they reveal that Medicine and Science in Sport and Exercise, one of the leading sport medicine and exercise science journals,  is owned by the American College of Sports Medicine that has financial ties to Gatorade and Powerade. Many of the editors on the editorial board have (and have had) ties with sports drink companies. 

The article explains that this marketing, and hijacking of the science of hydration, has undermined our confidence in our own thirst mechanisms. 'They' have us believe that our bodies are unable to tell us when we're thirsty; that not drinking enough before, during or after exercise, can make us very sick ; that rehydrating only with water rather than a sports drink can cause the potentially fatal hyponatremia. 

However, according to this article, there is no evidence that anybody has ever gotten ill due to dehydration during a sporting event when fluid was available. That is because our bodies tell us when it's thirsty, and we drink to satisfy our thirst. 
Simple as that. 
The article also explains that overhydration can lead to electrolyte imbalances and is potentially very dangerous, but can occur by drinking sports drinks just as it can by drinking too much water. 

I highly suggest you read the article- it's definitely interesting. 

Here's a bit more from Professor Tim Noakes, Discovery health chair of exercise and sports science at Cape Town University:

Thank you, Umang!

Fact or Fiction?

Fact or Fiction?

Wine is the only alcohol that's beneficial to heart health, helping to increase the good or "healthy" HDL cholesterol and helping to reduce the formation of blood clots that can cause heart attacks or strokes.

Fiction!

All alcohol, not just the alcohol in wine, has these benefits. Red or white wine, beer, hard alcohol, cordials all have the same effect on cardiovascular disease. Drinking pattern is actually more important than type of alcohol.

Men who have 1-2 alcoholic drinks a day were found to have a 30-40% lower risk of heart attacks compared to men who didn't drink at all. Although more than 2 drinks a day has been associated with further heart and stroke protection, it has also been associated with increased mortality due to accidents, liver disease and other causes and it's not recommended.

For women, it's trickier. Women benefit from alcohol's ability to increase the good HDL cholesterol and reduce the risk of heart attacks and stroke but data from the Nurse's Health Study found that women who drank 2 alcoholic drinks a day had a higher risk of breast cancer- 20-25% higher (so the current average risk of developing breast cancer in the US is 12 out of 100 women but was 14-15 out of 100 for women that drank more alcohol).

The research shows that the link between breast cancer and alcohol intake was seen in women who didn't get enough folic acid and other B vitamins from their diet.

So, if you don't drink alcohol now, you don't have to start (the same benefits can be achieved by exercising!) but if you're a man with a history of heart disease, you may benefit from 1-2 standard alcoholic drinks* a day (of any type of alcoholic beverage). If you're a woman, the benefits of alcohol may be offset by an increased risk of breast cancer. Make sure you get enough folic acid in your diet (whole grains, dark leafy greens, beans and lentils).

Always talk to your doctor about your alcohol intake.

*What's a standard drink?

5oz wine (12% alcohol), 1 12-oz (360mL) beer (5% alcohol), 1.5oz spirits (40% alcohol).

Sources:

Willett, WC. Eat, Drink and Be Healthy. Free Press 2005.
European Cancer Conference. "Alcohol Amount, Not Type -- Wine, Beer, Liquor -- Triggers Breast Cancer." ScienceDaily 28 September 2007. 23 April 2008 /releases/2007/09/070927083251.htm>.

Fact or Fiction?

This will be another regular part of my blog!

Today’s Fact or Fiction?

Caffeine and Dehydration.

We all know we need to drink more fluids but we’ve all been told that caffeinated beverages don’t count in our total fluid intake because caffeine is a diuretic and therefore caffeinated beverages dehydrate us.
Fiction.

According to a literature review done by Lawrence Armstrong, hydration expert and professor at the University of Connecticut, caffeine is a very mild diuretic but does not lead to dehydration. In fact, its diuretic effect is the same as that of water.
Other studies and reviews of the literature have come to the same conclusion:

caffeinated beverages can contribute to total fluid intake.
However, at intakes above 575mg, caffeine does becomes a diuretic. That’s about 4 cups of generic brewed coffee.

http://www.ific.org/foodinsight/2002/ja/caffdehydnbfi402.cfm
Caffeine. Nutrition Action Health Letter. Centre for Science in the Public Interest. March 2008.
http://www.nytimes.com/2008/03/04/health/nutrition/04real.html