Marathon Nutrition: Beyond Performance
By Dr. Kate-Rhéaume-Bleue, BSc., ND
When it comes to nutrition advice while preparing for a marathon, you’ll find a lot of information about macronutrients out there. The optimal ratio of carbs, fat and protein for endurance training has been studied extensively. Well-established, straightforward guidelines are easy to find if you want to know what your breakfast, lunch or dinner plate should look like on the days leading up to and following the big race.
Micronutrients
But what about micronutrients? The role of vitamins and minerals has received surprisingly little attention in sport nutrition research. The triage theory of nutrition posits that the body will direct resources – such as vitamins and minerals – to areas of the most urgent demand at the expense of less pressing, long term needs (McCann et al, 2009). For example, vitamin C that gets used up in the manufacture of cortisol in response to a long run won’t be available to bolster immunity later in the day. So, taking in extra nutrients during training isn’t necessarily about improving performance, but rather maintaining optimal short and long-term health in the face of greater-than-usual metabolic challenges.
Studies do suggest that runners have higher requirements for B vitamins. This is intuitive, as these nutrients are critical for carbohydrate metabolism and energy production. Folic acid, vitamin B12 and iron are essential to the genesis of red blood cells that carry oxygen throughout the body. Antioxidants, especially vitamins C, E and A, play a role in mitigating exercised-induced free radical damage to tissues.
Whole Earth & Sea Multivitamin and Mineral
The role of the long-overlooked vitamin K2 in sport nutrition is still upstream, although it’s established to help in the maintenance of bones, important for runners who are at high risk for bone density loss. Everyone’s multivitamin should contain vitamin K2, but this isn’t common yet. A notable exception is the Whole Earth and Sea Multivitamin and Mineral formula. All four formulas – one each for women and men, under and over the age of 50 – contain a respectable 80 micrograms of vitamin K2 per daily dose.
Increased Nutrient Demand & Supplements
Conventional thinking around micronutrients and sports nutrition seems to be that intense activity will stimulate appetite, so the problem of increased nutrient demand will take care of itself, as people who eat more automatically take in more vitamin and minerals. But I wonder if it is that simple. Eating more carbohydrates, for example, takes more B vitamins to convert those carbs into energy, leaving less than we might expect for muscle building. And food choices become so much more important during heavy training. Liver, for example, is the richest source of vitamin B12, vitamin A, iron, zinc and other nutrients, but who is eating that? If this isn’t on the weekly marathoner menu, it should be. If not, then a supplement is a good idea.
I think of a good multivitamin as inexpensive health insurance, and this applies doubly to long distance runners, whose metabolic demands are much higher than the general population of sedentary, or even moderately active people.
References
McCann JC, Ames BN. (2009). Vitamin K, an example of triage theory: is micronutrient
inadequacy linked to disease of aging? Am J Clin Nutr. 2009 Oct;90(4):889-907. doi:
10.3945/ajcn.2009.27930. Epub 2009 Aug 19.