Antioxidants: supplements and pills may not be the answer to energising and recovery

Antioxidant nutrition is one of changing consensus among scientists and confusion among athletes and coaches.

Athletes and sportsmen and women burn more energy and therefore consume more oxygen than their sedentary counterparts, which is why many scientists now believe that they have a greater need for optimum antioxidant nutrition. But how best to achieve this? While many athletes have resorted to antioxidant supplements such as vitamin C and E, the unfolding story of antioxidant nutrition is one of changing consensus among scientists and confusion among athletes and coaches.

The link between increased antioxidant nutrient intake and improved athletic performance is not well understood. Although some studies on athletes taking supplements have shown benefits1-4, a significant number have produced inconclusive results5-8. This may be because many studies have focussed on single antioxidant nutrients such as vitamin C or E and as antioxidant nutrition has advanced, scientists have become aware of the synergistic function of nutrients working together. Moreover, there’s a growing realisation of the importance of naturally occurring plant chemicals (phytochemicals), which can function as powerful antioxidants in the body.

However, some very recent single nutrient studies have produced positive results in studies on post-exercise muscle soreness, which seems to support those founds in earlier studies9-11. For example, 3g per day of vitamin C before and after heavy resistance training in 18 healthy men resulted in less muscle soreness, less muscle breakdown and lower markers of oxidative muscle damage compared to placebo12. A study on cyclists pedalling to exhaustion on 2 consecutive days showed that an antioxidant fortified carbohydrate drink reduced muscle soreness compared to a carbohydrate-only drink13. But it’s not all positive news; a recent study on 50km-ultramarathoners showed that taking 1000mgs of vitamin C and 300mgs of E did not reduce post exercise damage or hamstring contractile ability.

Fruits and vegetables

While it’s true that the overall balance of evidence for taking antioxidant nutrients is more positive than negative, it’s still not totally convincing. This has led some scientists to speculate whether we’ve been barking up the wrong antioxidant tree! That’s because recent studies on phytochemicals found in foods such as fruits and vegetables have shown they have a massive antioxidant potential, which may be tens or even hundreds of times greater than that afforded by antioxidant nutrients like vitamin C and E.

For example a very recent study on oxidative stress generated during a 30-minute run at 80% VO2 max showed that a mixed fruit and vegetable powdered extract containing small amounts of vitamins C and E afforded as much protection as the pure vitamins supplemented at 4 times that found in the extract14. This indicates that it was the phytochemical content of the extract that was providing the protection.

Other recent studies on the use of fruit and vegetable extracts and juices for antioxidant protection during training look extremely encouraging. These include:

•    Cyclists taking grape, redcurrant and raspberry concentrates, which lowered measures of muscle damage compared to placebo15;
•    Rowers consuming chokeberry juice before strenuous workouts, which again lowered markers of muscle damage and oxidative stress16;
•    Resistance trainers who consumed cherry juice before and after eccentric exercise and who suffered less post-exercise muscle soreness and strength losses than those taking placebo17.

Applying these new findings

If you want to continue to take antioxidant nutrients such as vitamin C and E, then the balance of evidence suggests it’s still worthwhile doing so; however, it may be better to use synergistic combinations of these nutrients rather than large doses of a single nutrient. But how can athletes best harness the antioxidant power of phytochemical-rich fruits, vegetable and other high-antioxidant foods?

As a very rough approximation, the darker and more vivid the colour of the food, the higher the antioxidant capacity. Thus red cabbage is higher in antioxidant capacity than green cabbage, which in turn is higher in antioxidant capacity than white cabbage. However, there’s now a much more scientific method of estimating antioxidant capacity based on Oxygen Radical Absorbance Capacity or ORAC for short. These values are derived from laboratory experiments; foods with high ORAC values are demonstrably better at quenching and deactivating damaging oxygen free radicals than low ORAC foods. Low ORAC foods include lettuce, cucumber, celery and bananas with around 100 ORAC units per 100g. High ORAC foods include berries and currants at 1000 or more ORAC units per 100g (see table).

Although not yet in widespread use, the ORAC values of foods will almost certainly become a very topical issue in the coming years. Indeed, the US FDA already recommends a daily ORAC intake of around 7000 units per day to maintain optimum health. Athletes wishing to maximise their ORAC intake for maximum antioxidant protection therefore need to emphasise high ORAC foods in their diet. However, this should not be at the expense of variety, as we still don’t fully understand the individual roles of the hundreds of phytochemical compounds found in fruits and vegetables. The wise option is to consume a wide range of high ORAC foods each day. Finally, although there are some extremely high ORAC fruit/vegetable extracts on the market offering in excess of 20,000 ORAC units per 100g, it’s not known if the body can absorb or utilise such highly concentrated extracts. Until we do know, natural foods are still the best way to guarantee maximum antioxidant protection!

FOOD

ORAC UNITS PER 100g*

70% cocoa solid dark chocolate

13500

Pomegranate

10500

Dried prunes

5770

Red delicious apples

4270

Raisins

2830

Blueberries

2400

Garlic

2320

Blackberries

2040

Spinach

1700

Brussels sprouts

1580

Strawberries

1540

Broccoli flowers

1290

Raspberries

1220

Beets

1170

Plums

949

Red bell pepper

810

Oranges

750

Corn

720

Cherries

670

Onion

560

Cauliflower

510

Cabbage

480

Potato

460

Sweet potato

430

Leaf lettuce

410

String bean

390

Carrot

340

Iceberg lettuce

230

Tomatoes

195

Celery

130

Cucumber

110

 *Sources: US Dept. of Agriculture; Brunswick Laboratories; Journal of American Chemical Society

  REFERENCES


1.    Biol Trace Element Res 1995;47:279–85
2.    Int J Sport Nutr 1994;4:253–64
3.    J Appl Physiol 1978;45:927–32
4.    Acta Physiol Scand 1994;151:149–58
5.    J Sports Med Phys Fitness 1999, 38(4): 281-5
6.    Am J Clin Nutr 1997, 65(4): 1052-6
7.    Cancer Epidemiol Biomarkers Prev 2000, 9(7): 647-52
8.    J. Nutr. 2002, 132:1616S-1621S
9.    Int J Sport Nutr Exerc Metab 2001, 11(4): 466-81
10.    Free Radic Biol Med 2004, 36(8): 966-75
11.    Am J Physiol 1990;259:R1214–9
12.    Int J of Sport Nutr Exerc Metab 2006, 16;270-280
13.    Med Sci Sports Exerc. 2006 Sep;38(9):1608-16
14.    Med Sci Sports Exerc 2006, 38:6, pp1098-1105
15.    Eur J Appl Physiol. 2005 Dec;95(5-6):543-9
16.    Int J Sport Nutr Exerc Metab, 15(1): 48-58, 2005
17.    Br J Sports Med 2006;40:679-683
 
Original article and summary by Andrew Hamilton BSc Hons MRSC ACSM

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