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Science of the Run: Nutrition and Health

The issue of nutrition is a critical factor for world health. This applies to both malnutrition, which can be not getting enough calories or nutrients, as well as over nutrition which means getting too many calories. Health is closely related to nutrition, and people can become extremely ill at both extremes - for example people can develop type 2 diabetes with high sugar intakes and obesity as a result of consuming too many calories. Let's consider Type 2 diabetes as an example.

Science of the Run - Nutrition Energy & Health from GOi2P on Vimeo.

In Type II diabetes, insulin production is relatively normal, but the receptor cells become desensitized to insulin. As a result the target cells such as muscle or liver do not absorb glucose from the blood. This type of diabetes is associated with obesity, and closely related to lifestyle factors such as poor nutrition and lack of exercise. As for so many other chronic diseases exercise can be used as therapy for both types of diabetes, which can be done under the supervision of a physician. Because exercise mimics the effects of insulin on blood glucose levels, and facilitates glucose uptake into the cells, it can help reduce the amount of insulin needed by Type I diabetics. For type II diabetics, exercise can increase insulin sensitivity of the muscle tissue, thereby to some extent reversing the effects of the disease.

On one of our runs I tested blood lactate levels of the runners. Lactate is produced when our body burns sugars to provide muscles with energy very quickly. When the runners were moving at a comfortable pace - their heart rates were about 125-130 - their blood lactates were between 1.6 -3.0 mmol/L. That suggests that they were not working hard enough to burn any sugars, relying mostly on their fat stores and just a bit of sugar to fuel their muscles. Although the Youth Ambassadors were doing a long 30+ km run in the heat and sun I asked them to do a short sprint up a hill. Because the energy demands were so much higher on the short sprint and they had to also move uphill their muscles needed fuel more quickly. When the energy demands increase inside our bodies we burn sugars to temporarily meet those demands, and the byproduct of anaerobic sugar metabolism is lactic acid. The blood lactate levels at the end of the sprint were 4.9-12.2 mmol/L. Levels that high make your muscles feel like they are on fire and also makes you breathe very hard.

In addition to exercise, nutrition is a key factor in developing and maintaining health. However, there are tremendous challenges with regard to having people eat foods that are high in nutrients and lower in calories. For example, we visited a small town in northern India yesterday. In this town we found a few stores, and in one stall a vendor was selling vegetables - foods that are key to the prevention of chronic disease and for improving health. But in the next store highly processed foods were readily available. These included chips and candy bars - foods that are very high in calories and have minimal nutrients. Here are pictures of each store.


Before setting out on day 2, I posed a challenge to the Youth Ambassadors. I asked them to consider that given many people in developed countries such as Canada and the US are aware of what foods are healthier options, why so many individuals make poor decisions related to nutrition and health. We had a heated discussion over dinner, but we came to the conclusion that cost and convenience were major factors. If you have other ideas please send them to us on twitter @GOi2P or on the Q&A tab.

For the schools that are following, an interesting activity is to take a look at the number of calories in different foods like fruits such as bananas or oranges, vegetables such as carrots or broccoli, or more refined foods like a slice of bread or a soft drink. When we measured youth Ambassador Harshveer's caloric expenditure on the run recently we we found out that he burned over 2000 calories during the time we tested him. How many vegetables would he have to eat to replace those calories? How many chocolate bars would it take?

Ultimately the challenge for each of us around the world is to find the right balance between the foods that we eat to fuel our activities or that provide us with the nutrients we need to be healthy and staying physically active. Can you think of some barriers for you related to how well you eat on a daily basis? How can you increase your nutrient intake for example fruits and vegetables? What does it mean to have the right balance between exercise and nutrition for you?

Monday December 5 2011 :: posted by Dr. Greg Wells

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