Monday, June 30, 2014

6 important nutrients overlooked by athletes

Elite level athletes are always looking or an edge over their opponents.  Enhanced training or recovery modalities, better skill training, or better nutrition are all things an athlete can use to improve their performance.  When athletes look to nutrition, they are typically looking for something that they can take supra-physiological doses of in an effort to push their performance to the next level.  What they often neglect to do is look at nutrients found within a standard diet that are often deficient in those living a modern lifestyle.  In this blog I will go over 4 key nutrients that athletes should be paying attention to.

1)Vitamin D3 

Only 2 nutrients have receptors on every cell in the body: Thyroid hormone and Vitamin D3.  Research in to Vitamin D3 has uncovered quite a few physiological roles in the body, so many that the vitamin has been reclassified as a hormone.  Vitamin D3 is important for intestinal absorption of many minerals including magnesium, calcium, zinc, and iron.  Deficiency of any of these minerals can weaken the immune system, decrease muscular contractility, decrease insulin sensitivity and impact energy generation.  In addition to it's role in aiding absorption of these nutrients, Vitamin D3 also plays an important role in muscular contraction and a deficiency can lead to a decrease in performance(1).  Furthermore, sufficient Vitamin D3 levels also improve adaptations in Type II muscle fibers, the muscle fiber type associated with power sports such as tennis, football, and basketball(2).  The great thing about Vitamin D3 is that you don't need to focus on getting it from your diet.  The body makes Vitamin D3 when exposed to sunlight in the absence of sunscreen.  Most athletes should make a goal of getting their blood 25(OH)D above 50ng/mL.  This can be accomplished by getting between 20-30 minutes of sunlight in shorts and a T-shirt every day for a light skinned person.  Wearing more clothes or having darker skin tends to lower the amount of Vitamin D3 you absorb and many northern latitudes have time periods where you cannot get the necessary UV rays from the sun.  There is an app called D-finder that can help you optimize your sun exposure and Vitamin D3 levels based on many of the variables that affect Vitamin D3 status.


Magnesium is a mineral that is used as a cofactor for over 300 enzymatic reactions that go on within the body including energy generation, fuel storage, insulin sensitivity, and calcium regulation within muscle cells.  Despite being a nutrient critical to athletic performance, data on the performance benefits of magnesium is lacking with little to no effect found in some studies and a positive effect in others, with most of them suffering from several methodological failings(3, 4).  One of the biggest issues with these studies is that the predominant way that we measure a person's magnesium status is via serum magnesium even though 98% of the magnesium in the body is found within cells.  This would be like trying to measure the amount of gas in a car by looking at the amount in the fuel line, it doesn't work.  Cellular magnesium tests such as RBC magnesium are more valid because they measure magnesium where it is primarily found.  The reason magnesium is important for athletes is because strenuous exercise increases urinary magnesium excretion by up to 20% and sweating and stress also increase excretion(5).  Diuretics such as coffee also increase urinary magnesium losses.  For now, the key takeaway should be to ensure sufficient magnesium in the diet or through supplementation.  College athletes tend to get approximately 70% of the RDI(400mg for men, 310mg for women) of magnesium(4) and most Americans get around that level.  Foods that are high in magnesium are raw nuts, seafood, milk, seeds, bananas, potatoes, beets and leafy green vegetables.  If you supplement, magnesium citrate, glycinate or dimagnesium malate are preferred forms of magnesium since the oxide form found in most supplements is not very bioavailable to humans which could contribute to the lack of effect seen in studies.  While I mostly recommend getting nutrients from food, magnesium may be an exception as modern farming practices reduce the amount of magnesium in the soil and thus the amount that makes it in to crops.  At the very least you may want to overshoot on your daily magnesium intake if you choose not to supplement.


Pro- and prebiotics are fairly new on the scene but have the potential to have a profound effect on the way an athlete performs by improving digestive efficiency, nutrient absorption, and modulating the immune system.  I went over some of these effects in the blog found here.  Eating pro-and prebiotic foods and limiting the amount of processed food you consume should be the target intervention here.  Under certain situations, probiotics may be a useful therapeutic tool but we are still researching the effect of individual strains of probiotic bacteria.  Even if a strain is useful, it's important to provide food for that strain in the form of prebiotics if your goal is to colonize your digestive tract with beneficial bacteria, although colonization isn't necessary for a positive effect.


Sulforaphane is an interesting nutrient.  Found in most cruciferous vegetables, sulforaphane activates the NRF-2 antioxidant pathway.  As a result, the body produces more glutathione which helps clean up free radicals and reduce oxidative stress(6, 7, 8) which in turn reduces inflammation.  Since free radicals are generated as a natural byproduct of aerobic energy generation, intense training, particularly endurance training, increases oxidative stress dramatically.  For a good rundown of oxidative stress and training/exercise, take a look here.  The best way to get sulforaphane is from cruciferous vegetables such as broccoli, cauliflower, brussel sprouts, spinach, and cabbage.  Broccoli sprouts are loaded with sulfurophane, about 50x more than found in regular broccoli(9).  Since the effects of sulforaphane last for a few days and cruciferous vegetables, especially raw ones, contain goitrogens that can interfere with iodine uptake in the thyroid, having a serving of cruciferous vegetables every other day is adequate to keep glutathione levels high without a significant effect on thyroid function.


Thiamin is a B vitamin that is used heavily in energy metabolism.  I've gone over the ins and outs of thiamin here.  The takeaway is that anyone who relies heavily on the glycolytic energy pathways should make sure they get enough thiamin in their diet.  Many people who eat a low carbohydrate diet may feel that this doesn't pertain to them, the problem is that energy metabolism is activity specific, not specific to the diet.  So if you are in any sport that is explosive in nature, or that taps in to carbohydrate or lactic acid metabolism over the long-term, it's important to ensure adequate thiamin intake.  Thiamin also plays a crucial role in proper nervous system function and most of the diseases of thiamin deficiency lead to nervous system dysfunction.   Thiamin is also fairly important for the formation of myelin.  Thiamin can become depleted as a result of intense training and diuretics such as caffeine and alcohol can also deplete thiamin.  As mentioned in the blog, the most effective form of thiamin, allithiamine, is found in garlic and is fat soluble so it stands up better to cooking and is better absorbed from the digestive tract than the standard water soluble form of thiamin.  Eating garlic yields similar blood levels of thiamin as injecting the water soluble version.  If you aren't a fan of garlic, pork is also high in thiamin.


I've saved the best for last.  DHA, or Docosahexaeonic acid is an omega-3 polyunstaturated fat with many benefits.  In addition to its ability to activate the NRF-2 pathway that sulforaphane activates(10), it is a major component of myelin.  For those of you who have not read The Talent Code, myelin is the "insulation" that covers nerves that makes nerve conduction more efficient.  In the book, the author explains that neural circuits becomes hardwired through practice and this process is only possible through myelination of the nerves that help accomplish the task you are performing.  DHA is the most abundant fatty acid in the mammalian brain, likely through it's role in myelination, and improves speed of nerve conduction and neuroplasticity/neurogenesis(11).  DHA is an omega-3 fatty acid that can be found in fish, grass-fed beef, eggs, and organ meats.  As you would assume, brain tends to be very high in DHA.  For those of you not so daring, wild salmon has a very high DHA content.  While flaxseeds are considered to have a high level of omega-3 fatty acids due to their high alpha-linolenic acid content, humans do a terrible job of converting ALA in to DHA, a rate of less than 5%.  Since DHA is not an essential nutrient, there is no recommended daily intake.  I recommend shooting for at least 500mg per day.


Athletes should take special care to ensure that they are getting adequate amounts of nutrients in their diet.  The more typical approach to improving athletic performance via nutrient intake is in supplementation with supra-physiological doses of certain nutrients in the hope that it will improve performance.  A more logical approach is to look at nutrients that can become depleted by training or modern lifestyle factors and make sure that adequate levels are attained through the diet.