Thursday, June 19, 2014

The Electrolyte Myth

As the Old Man Winter finally settles into its long solstice slumber, and the temperature and humidity have begun to rise, I've already started to hear runners and cyclist talking about how many electrolytes they need to consume per hour in order to not only prevent cramping, but to continue exercising at a high level of performance.

However, as is so often the case, it appears the belief that endurance athletes need to replenish electrolytes is a bit exaggerated.

Electrolytes are sodium ions and they make up the bulk of the “salty” non-water part of your sweat. Potassium is also excreted in sweat, but electrolytes are lost 10 times faster than potassium.

While electrolytes are lost when you sweat, sweating actually increases the concentration of electrolytes in your body. This is because when you sweat, you are excreting more water than electrolytes. Just as you don’t loose potassium and electrolytes at the same rate, you don’t loose water and electrolytes at the same rate. The result is, as you become dehydrated – meaning you have less water in your blood – the sodium to water ratio also changes, causing a higher concentration of sodium.

In fact, some research shows that even after exhaustive exercise, the amount of sodium lost is quite small. This was supported by double blind placebo test, which demonstrated that people who consume sodium-free (electrolyte-free) sports drinks performed at the same levels as those who received sports drinks with added sodium.

Furthermore, there is evidence that even electrolyte-added sports drinks cannot prevent a drop in blood sodium levels, because the drinks hydrate you more than they replace electrolytes. Again changing the sodium - water ratio in your body.

However, that doesn’t mean that sports drinks are completely worthless. Drinks like Gatorade have the simple sugars needed to help replenish the carbohydrates burned by the body during long periods of exercise as well as the water needed to help stave off dehydration. In a study performed at the University of Texas in Austin, they found that male athletes experienced a 6 percent improvement in sprinting (on a bike) when they consumed enough water to remain properly hydrated when compared to a group which drank water, but didn’t consume enough water to stave off  dehydration. This shouldn't be all that surprising... dehydration hurts performance. 

The final word: adding electrolytes does not appear to be needed, especially for performances that are less than 2 hours in duration. However learning to properly fuel your body is still an important and necessary skill, particularly when exercising in the heat. Experiment and find out what works for you. Even if the research doesn't support it, placebos can have a strong performance enhancing ability. Now go get outside!  

Brazier, Brendan, Thrive Fitness; The Vegan-Based Training Program for Maximum Strength, Health, and Fitness. Da Capo Press, 2009.

Burke, L. M.; et al., “Carbohydrates for training and competition.” Journal of Sports Sciences 2011, 29 (sup1), S17-S27.

Coyle, E. F., “Fluid and fuel intake during exercise.” Journal of Sports Sciences 2004, 22 (1), 39-55.

Gisolfi, C.; et. al. “Intestinal fluid absorption during exercise: role of sport drink osmolality and [Na+].” Medicine & Science in Sports & Exercise 2001, 33 (6), 907-915.

Larson-Meyer, D. Enette, Vegetarian Sports Nutrition: Food Choices and Eating Plans for Fitness and Performance. Human Kinetics, 2007.

(Note Runner'sConnect also has an article on electrolyte consumption, and they were kind enough to point me to some of the articles they consulted.) 

As always the information presented in this blog is for educational purposes only. It should not be considered as specific medical, nutritional, lifestyle, or other health-related advice.

Sunday, June 1, 2014

Fish, our Oceans, and our Health Part I

Last summer I had a argument conversation with a family member who is the typical gun-totten, freedom-lovin’ ‘Merican that has come to personify the American Right. We don’t always see eye-to-eye, as we are essentially polar opposites, but he is family and has always been there for me when I needed him (typically arriving 20 minutes late, but still… eventually he’s there). Basically the conversation was about our diets impact on the environment - he categorically and instantly argued that fishermen are catching record levels of fish, as an indication that the world’s oceans are perfectly healthy.

While I will probably never convince him otherwise, the evidence is pretty stark in the opposite direction.  So today I’d like to talk about the choices you have: plant-based versus meat-based diets, and how they influence the marine environment. These choices we make have a dramatic effect, and it’s helpful to understand the impacts some of our choices have on the global environment. Because this is such a long post, I've decided to break it into three parts. This is Part I which will focus on our current fishing practices. Part II will focus on Farmed Fish, and finally Part III will talk about some of the health concerns involved in eating fish.

The oceans are currently stressed from the amount of fishing and unfortunately, farmed fish are no better of a choice, and come with their own host of problems (discussed in Part II). Today our global fish population is experiencing something of a crisis - and the idea that our oceans are inexhaustible can no longer go unnoticed.

Beginning in the mid-20th century, international efforts to increase the availability and affordability of protein-rich foods led to concerted government efforts to increase fishing capacity. Favorable policies and government subsides spawned a rapid rise of big industrial fishing operations.

If you look at this graph from a 2003 paper in Nature, they show, in stark terms, the decline of large predators in the ocean. These are the most popular fish to hunt and eat and as the chart demonstrates, there has been nearly a 90% decline in their overall populations. The graph can be read as an indicator of the concentration of fish remaining in the ocean. As Ivan Macfadyen recently wrote in his piece for the Herald, “The Ocean is broken.”

Another figure to help demonstrate this point is the total number of fish we bring in. According to international law, when fish are brought to port, fishermen are required to report their catches; and various organizations have kept track of these numbers since the 1960s. Since the ’90s, the total number of fish caught globally has leveled out. In 1989, 90 million metric tons of fish were taken from the ocean, representing a high-water mark. We have maxed out the ocean’s ability to produce since then.

According to the Food and Agriculture Organization of the United Nations (FAO), of the 600 marine fish stocks they monitor, 52% have been fully exploited and all of the 17 primary fishing stocks worldwide are either overexploited or on the verge of collapse. In 2003, a report announced that industrial fishing had reduced the number of large ocean fish to just 10% of their pre-industrial population. Examples of this collapse are the Grand Banks near Newfoundland and the Georges Banks of New England, both once considered the most productive fishing grounds on the planet, and both now nearly devoid of life.

While still hotly debated, many scientists are now supporting the theory that if current practices continue, all of the world’s fisheries could collapse by 2048.

Another indication of stress in the ocean is the average trophic level of fish caught throughout the globe. Harking back to high school biology class, a trophic level is the position in the food chain for a particular species. If a fish eats algae, it’s at the first tropic level. If it’s a carnivore that eats smaller fish, then it’s one level up and so it continues up to the largest predators in the oceans. Because the higher trophic-level fish, such as swordfish or tuna, bring in such large profits (some tuna sell for over $1 million dollars!) these are the preferred fish for fishermen. However, as their populations have declined, they’ve become more difficult to catch. The result is that fishermen have moved down the trophic-level. These fish have less value per pound but are currently more available than the higher trophic-level fish.

The impact of this is that we are now literally scraping the bottom of the ocean floors for whatever is left. Having to move down on the trophic-level is a dramatic indication that we have fished beyond sustainable levels.

Besides reducing the populations of the fish fisherman actually want to catch, we have also had a negative impact on less desirable species. Due to a process known as by-catch- fish unintentionally caught- many species have become endangered simply because we want to eat other fish. Sharks and more surprisingly seagulls have been large victims of this wasteful practice. Feel free to google image this. The images are too depressing for me to put up.

Finally, bottom trawling is, perhaps, the worst of all fishing practices. Basically, fisherman drag nets across the bottom of the ocean floor and gather everything in their wake. At the surface, they discard as much as 70% of what they pull up – all of it dead. It is a common practice used when shrimping. 

Unfortunately, the giant marlin that Santiago wrestled in Hemingway's "The Old Man and Sea" is becoming increasingly rare, and some day may only be found in the imagination of fiction. These issues about our environment and ecology need to be part of the public discourse. We need to face these hard truths if a true solution is to be found. 

Additional Reading:

“Overfishing: Plenty of Fish in the Sea? Not Always.” National Geographic.

Ivan Macfadyen, “The Ocean is Broken.”

Pauly, D., et all. “Towards sustainability in world fishers,” Nature 2002.

General Situation of World Fish Stocks, United Nations Food Agriculture Organization (FAO)
Harrington, J.R., et all., “Wasted Fishery Resources: Discarded By-Catch in the USA.” Fish and Fisheries 6.

Janicke Nordgreen, et all., “Thermonociception in fish: Effect of two different doses of morphine on thermal threshold and post-test behavior in goldfish.”Elsevier

Rosamond L. Naylor, et all., “Effect of Aquaculture on World Fish Supplies,” Nature Vol. 405, June, 2000.

Oppenlander, Richard. Food Choice and Sustainability: Why Buying Local, Eating Less Meat, and Taking Baby Steps Won’t Work. New York, Langdon Street Press, 2013. 

As always the information presented in this blog is for educational purposes only. It should not be considered as specific medical, nutritional, lifestyle, or other health-related advice.