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Friday, 19 October 2012

Natural Sports Nutrition


Scientists are constantly discovering beneficial effects of various nutrients on both sports performance and health.  Consequently, sports nutrition has developed rapidly over the past few decades and there are now thousands of companies selling sports nutrition products ranging from vitamin pills to sport-specific ready meals. Ingesting dietary supplements or changing one's diet is a relatively easy way to enhance performance as it requires very little effort. Therefore, sports nutrition is alluring to athletes due to its performance benefits and it is equally attractive to sports nutrition companies as it is extremely profitable. Unfortunately, very few dietary supplements are either effective or evidence-based. Although a few have been shown to enhance performance, the majority of others lack scientific backing or have been found to be inconclusive. A further issue with certain supplements is the number of additives, preservatives and colourings that are added to make the product more palatable, increase shelf-life and make it look attractive to the consumer. For example, several commercially available sports drinks contain preservatives such as potassium sorbate and/or sodium benzoate, stabilisers such as acacia gum and sweeteners such aspartame and acesulfame K. If you consume these types of products infrequently then it may not necessarily be harmful, however, if you are training daily and consume these products on a regular basis, there could be some adverse effects such as the negative effects of artificial sweeteners that are well documented. It is exciting to see that several sport nutrition companies are aware that athletes are increasingly looking at ways to cut out additives in their diet and have therefore, started to manufacture natural sports nutrition products. The purpose of this article is to look at some natural nutrition ingredients that are ergogenic in their own right without the addition of additives and preservatives. More specifically, this article will summarise the science behind performance enhancing foods such as beetroot, milk, green tea, and fruit concentrates.


Beetroot


Relatively new exciting research seems to indicate that increasing the amount of nitrate in the diet by simply drinking a pint of beetroot juice can enhance exercise performance. Nitrate is composed of nitrogen and oxygen and most farmers add nitrate to soil as plants use nitrogen to produce amino acids which are the building blocks of protein. Therefore, nitrates are naturally present in root vegetables and in particular green leafy vegetables such as lettuce, spinach, celery and beetroot contain large amounts and drinking water can also contain considerable amounts of nitrate.  Depending on where the root vegetables are grown, the amount of nitrate can vary greatly due to the nitrate content present in the soil. Once ingested, nitrate is converted in the body to nitrite which subsequently gets converted to nitric oxide. Nitric oxide is considered an important signalling molecule because of its role in muscle function. More specifically, nitric oxide can increase blood flow to the muscle because of its vasodilatory effects. If more blood can reach the muscle, more oxygen can reach the muscle and for cyclists, that is very beneficial. The majority of the studies that have investigated the effects of beetroot on performance have used 500 mg of nitrate which is found in approximately one pint of beetroot juice. Several studies1-4 have found that drinking one pint of beetroot juice has the following positive benefits:

  • ·      Reduces the oxygen cost of exercise at a moderate intensity
  • ·      Increases time to exhaustion
  • ·      Reduces systolic blood pressure
  • ·      Enhances time trial performance


Early research on beetroot is promising and suggests that drinking one pint of beetroot juice 90 minutes before exercise can enhance performance. 


Milk


Milk is a very interesting natural food because it is the only food source that we consume during early infancy. Milk contains all the major macronutrients needed by the body such as carbohydrate, protein and fat and in addition, it also contains the majority of the vitamins and minerals required by the body. Table 1 provides a summary of the nutritional properties of milk.

Several scientific studies have investigated whether milk is a good sports drink for athletes and unsurprisingly, almost all of them have found positive effects. In 2008, Lee and colleagues5  conducted a study comparing the effects of an isotonic sports drink and milk to a placebo (water) on exercise capacity. Table 2 summarises the nutritional information of milk and a commercially available sports drink.  The researchers found that the isotonic sports drink increased exercise capacity by an average of 17.5% over the placebo and the milk trial increased exercise capacity by 10.4% over the placebo. With regards to recovery after exercise, Karp and co-workers6 designed a study to compare the effects of a chocolate milkshake to an isotonic sports drink in promoting recovery after an exhaustive bout of exercise. They found that when the milkshake was consumed after an exhaustive bout of exercise, participants were able to increase exercise capacity four hours later in comparison to the sports drink. These findings indicate that the chocolate milk was more effective in promoting recovery probably due to the carbohydrate and protein content of the milk. These findings have been consistently replicated in other studies showing that milk is an excellent drink to promote recovery after exercise.  As milk is naturally high in electrolytes, research has also been done on whether it is effective for rehydration. Milk has been found to be superior to water to replace fluid losses after exercise and just as effective as a commercially available sports drink.7 Due to milk's relatively high protein content, studies have examined whether it could be beneficial for increasing muscle mass. Predictably, several studies have found that milk and other natural dairy based products are effective in promoting protein synthesis, building muscle mass and reducing muscle soreness after exercise.8

As there is strong scientific evidence to show that natural dairy products are effective in promoting recovery after exercise, rehydration, and increasing muscle mass, it makes sense to incorporate them into a cyclist's diet.

Fruit Concentrates


The topic of antioxidants and recovery has been ongoing for a while. The theory is that as we increase the amount of exercise we do more free radicals are produced which can damage our cells. Antioxidants such as vitamin C and E can neutralise free radicals and can protect our cells from damage. This theory has led researchers to investigate the effect of several different antioxidant supplements such as vitamin C and vitamin E in much greater amounts than the daily recommended values. Some studies have even looked at supplementing antioxidants in doses 10 times greater than the daily recommendations! Unfortunately, the majority of these studies have been unsuccessful at finding any positive benefits of antioxidant supplements.9 Antioxidants are also naturally present in fruit and vegetables, and more recent research has attempted to look at the effect of polyphenol and phytochemical antioxidants present in natural fruit concentrates on recovery after exercise. Howatson and colleagues10 examined the effects of drinking concentrated cherry juice on recovery following the London marathon. The concentrated cherry juice was found to reduce inflammation and enhance recovery after the marathon. Several other studies have also found that concentrated cherry and pomegranate juice can reduce delayed onset muscle soreness that typically follows exhaustive exercise and improve other markers of recovery. 11 Although these findings are promising there is a disagreement amongst scientists on whether supplementing with antioxidants may be a wise thing to do. There is some evidence12 that consuming large doses of antioxidants either from single vitamins (such as C and/or E) or natural foods could impair training adaptations therefore, strategic use is recommended. For example, it may not be a good idea to take natural antioxidants on a daily basis but they could be beneficial if used during stage races where quick recovery is crucial for successful performance.        


Green Tea


Green tea originates from China and it is consumed by millions of people all over the world. Scientists are interested in green tea because of its high antioxidant content, in particular the high levels flavanoids and catechins. A compound called epigallocatechin-3-gallate (EGCG) is the main active ingredient found green tea and researchers have been investigating its effects on health, weight loss and sports performance. With regards to health, researchers have found that drinking several cups of green tea per day can reduce the damage to cell lipids and DNA, enhance cardiovascular health and could reduce the risk of hypertension.13 It is tricky to carry out research using cups of green tea because factors such as where the tea was grown, brewing time and water temperature all significantly effect the antioxidant content of the tea. Consequently, researchers have turned to using green tea extract because the dosage can be tightly controlled.  Studies using green tea extract have found that it can help with weight loss. A study14 recruited 132 obese adults and put them through a controlled diet and exercise program. One group consumed green tea extract and the other group consumed a placebo for 12 weeks. At the end of the study the group taking the green tea extract lost significantly more abdominal fat. A study conducted in Birmingham by Venables and collegues and colleagues found that green tea extract increased fat oxidation (burning). Participants were asked to cycle at 60% intensity and after ingesting green tea extract they were able to burn 17% more fat when compared to a placebo. These findings are remarkable because if more fat can be oxidized during cycling, carbohydrate stores can be preserved which can be beneficial during the latter parts of a race.

The research on green tea and green tea extract indicate that both could be useful for cyclists to help with fat loss and increase fat oxidation during cycling. Not all green tea's are the same and Japanese Matcha green tea has been found to have much higher amounts of EGCG.  

 

 

Conclusion


Nature has provided us with numerous natural foods that have been shown to be effective in promoting recovery and enhancing exercise performance. Natural foods don't contain any additives, preservatives and colourings that some sports supplements do which make them a healthy attractive alternative for athletes who can benefit from daily use. Whilst there are some dietary supplements and ergogenic aids that can significantly enhance performance, there are also natural alternatives that can have similar beneficial effects on both health and performance. Table 3 provides a summary of some natural alternatives to certain supplements.    















Table 1. Nutrition Properties of Milk

Macronutrients
Vitamins
Minerals
Carbohydrate
Protein
Fat
A
B Vitamins
C
D
E
K

Calcium
Phosphorus
Iodine
Magnesium
Zinc
Potassium


Table 2. Nutrition Information: Milk vs. Isotonic Sports Drink

Nutrition Information
Skimmed Milk
 500 mL
Isotonic Sports Drink
500 mL
Energy (kcal)
185
140
Carbohydrate (g)
25
32
Fat (g)
1.5
0
Protein (g)
18
0
Sodium (mmoL/L)
19
12
Potassium (mmoL/L)
23
2
Chloride (mmol/L)
17
1


Table 3. Natural Nutrition Alternatives

Supplement
Natural Version
Comments
Isotonic sports drink
Coconut Water
Coconut water contains carbohydrate and electrolytes making it a good drink to have after exercise to replace muscle glycogen, electrolytes lost in sweat and fluid.
L-Arginine
Beetroot Juice
Beetroot juice reduces blood pressure and reduces the oxygen cost of moderate intensity exercise
Vit E antioxidant tablets
Concentrated Cherry Juice
Concentrated cherry juice can be an effective drink to consume during stage races as it can help reduce inflammation and reduce muscle soreness
Caffeine tablets
Green Tea
Green tea has many positive health boosting properties. It can enhance fat oxidation, increase the metabolic rate and help with weight loss.
Powdered Recovery drink
Milkshake
Dairy products such as milk are effective in promoting recovery after exercise, rehydration, and increasing muscle mass


References


  1. Bailey SJ, Winyard P, Vanhatalo A,et al.(2009).Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol Oct;107(4):1144-55.
  2. Lansley KE, Winyard PG, Fulford J et al. (2011). Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled study. J Appl Physiol. Mar;110(3):591-600
  3. Lansley KE, Winyard PG, Bailey SJ, et al. (2011). Acute dietary nitrate supplementation improves cycling time trial performance. Med Sci Sports Exerc. Jun;43(6):1125
  4. Cermak NM, Gibala MJ, van Loon LJ (2012). Nitrate supplementation's improvement of 10-km time-trial performance in trained cyclists. Int J Sport Nutr Exerc Metab. Feb;22(1):64-71
  5. Lee JK, Maughan RJ, Shirreffs SM, Watson P. (2009). Effects of milk ingestion on prolonged exercise capacity in young, healthy men. Nutrition. Apr;24(4):340-7.
  6. Karp JR, Johnston JD, Tecklenburg S, Mickleborough TD, Fly AD, Stager JM. (2006). Chocolate milk as a post-exercise recovery aid. Int J Sport Nutr Exerc Metab. Feb;16(1):78-91.
  7. Watson P, Love TD, Maughan RJ, Shirreffs SM. (2008). A comparison of the effects of milk and a carbohydrate-electrolyte drink on the restoration of fluid balance and exercise capacity in a hot, humid environment. Eur J Appl Physiol. Nov;104(4):633-42. Epub 2008 Jul 10.
  8. Elliot TA, Cree MG, Sanford AP, Wolfe RR, Tipton KD. (2006). Milk ingestion stimulates net muscle protein synthesis following resistance exercise. Med Sci Sports Exerc. Apr;38(4):667-74.
  9. Howatson G, van Someren KA. (2008). The prevention and treatment of exercise-induced muscle damage. Sports Med.;38(6):483-503. Review
  10. Howatson G, McHugh MP, Hill JA, Brouner J, Jewell AP, van Someren KA, Shave RE, Howatson SA. (2010). Influence of tart cherry juice on indices of recovery following marathon running. Scand J Med Sci Sports. Dec;20(6):843-52.
  11. Trombold JR, Barnes JN, Critchley L, Coyle EF. (2010). Ellagitannin consumption improves strength recovery 2-3 d after eccentric exercise. Med Sci Sports Exerc. Mar;42(3):493-8.
  12. Gomez-Cabrera MC, Domenech E, Romagnoli M, Arduini A, Borras C, Pallardo FV, Sastre J, Viña J. (2008). Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance. Am J Clin Nutr. 2008 Jan;87(1):142-9
  13. Kanwar J, Taskeen M, Mohammad I, Huo C, Chan TH, Dou QP. (2012). Recent advances on tea polyphenols. Front Biosci (Elite Ed). 2012 Jan 1;4:111-31.
  14. Maki KC, Reeves MS, Farmer M, Yasunaga K, Matsuo N, Katsuragi Y, Komikado M, Tokimitsu I, Wilder D, Jones F, Blumberg JB, Cartwright Y. (2009). Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults. J Nutr. Feb;139(2):264-70.
  15. Venables MC, Hulston CJ, Cox HR, Jeukendrup AE. (2008). Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans. Am J Clin Nutr. Mar;87(3):778-84.

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