The antioxidant capacity of foods


Currently, it is possible to measure the antioxidant activity of foods from the basic principles of: singlet electron transfer or hydrogen atom transfer.

This leads to two methods of evaluation:

  • The TEAC test (Trolox Equivalent Antioxidant Capacity) 
  • The ORAC test (Oxygen Radical Absorbance Capacity)

Trolox (3,4-dihydro-6-hydroxy-2,5,7,8-tetramethyl-2H-1-benzopyran-2-carboxylic acid) is a structural analogue of vitamin E that serves as a reference for the TEAC and ORAC tests.

The ORAC test is the most widely used in current research because this method is recognised for its biological effectiveness, taking into account the capacity of hydrophilic and lipophilic antioxidants in biological samples.

However, the ORAC value of a food can vary significantly depending on its growing conditions, its ripeness, its origin, how it is stored and, above all, how it is cooked.

The antioxidant content is higher on the skin of the fruit, as is the pesticide content.

These values allow us to have an indication of the choice of foods to be consumed in order to have an "antioxidant" diet.

However, it is important to take into account the various conditions mentioned above in order not to select a specific food.

The ORAC is expressed as μmol of Trolox equivalents per 100g of food (μmol TE/100g).

Recommendations

The recommended amount of ORAC provided by food would be between 3000 and 5000 units.

However, it is clear that these recommended intakes depend very much on our level of "oxidation" in relation to our lifestyle: tobacco, pollution, alcohol, stress, physical activity.

The ORAC value of a high-level competitive athlete can easily exceed these recommendations and reach 7,000 to 8,000 units.

It is easy to increase the ORAC score of athletes on days of intensive training, for example by adding:

  • Dried fruit (figs, dates, etc.)
  • Vegetables (kale, asparagus, etc.)
  • Oil seeds (almonds, walnuts, etc.)
  • Spices (thyme, saffron, etc.)

However, it must be taken into account that about 30% of the antioxidant content of foods is lost, depending on the variety, type of crop, ripeness, storage, cooking, etc.

It is therefore more objective to suggest a "near safety" ORAC contribution of 10,000 units/day.

ORAC value of a selection of foods

Orac (μmolTE/100g)

Fruits

  • Plums 8,059
  • Mulberries 5,905
  • Blueberries 4,669
  • Strawberries 4,302
  • Cherries 3.747
  • Golden apples 2,670
  • Dates 2,360
  • Red grapes 1,837
  • Peaches 1,922
  • Avocados 1,922
  • Oranges 1.819
  • Kiwi 1.210
  • Apricot 1,110
  • Banana 795
  • Tomato 423

Vegetables

  • Artichokes 6,652
  • Purple cabbage 2,496
  • Asparagus 2,252
  • Radishes 2.184
  • Spinach 1.513
  • Broccoli 1,510
  • Lettuce 1,017
  • Onion 913
  • Carrots 697
  • Cauliflower 529

Other

  • Pecan 17,940
  • Walnuts 13,057
  • Pinto peas (cooked) 904
  • Cooked lentils 7,282
  • Soybeans 5,409
  • Almonds 4,454
  • Green tea 1,128
  • Black tea 313
  • White tea 264

Spices

  • Cloves 290 283 
  • Thyme 157,380 
  • Cinnamon 131,420 
  • Oregano 175,295 
  • Cumin 50,372 
  • Curry 48,504
  • Paprika 21,932 

In practice

In order to correct oxidative stress, one must first of all rely on a specific diet.

The natural presence of antioxidants in the food we eat makes it possible to partially neutralise reactive oxygen species in complete safety (concept of hormesis).

To achieve this goal, it is important to choose fruit and vegetables with a "good ORAC", of high quality (optimal ripeness, limited storage, etc.) and from the organic sector if you want to consume the skin.

Nutrition Rules

Consume the following foods on a regular basis:

Sources of vitamin E and vitamin C

  • Oranges
  • Red fruits
  • Kiwi
  • Broccoli
  • Spinach
  • Peppers
  • Olive oil
  • Organic wheat germ
  • Oilseed Fruits
  • Avocados

Sources of beta-carotene

  • Pumpkins
  • Mango
  • Apricots
  • Carrots

Sources of taurine and zinc

  • Oysters (cooked or uncooked)
  • Mussels
  • Scallops
  • Golden bream

Omega-3 sources (EPA and DHA)

  • Herring
  • Sardines
  • Mackerel
  • Cod Liver

Sources of Magnesium and selenium

  • Seafood (whelks, mussels)
  • Pulses (lentils, white beans, chickpeas, etc.)
  • Oil seeds (walnuts, Brazil nuts, hazelnuts, pine nuts, etc.)
  • Sesame seeds
  • Yeast

Good ORAC value

  • Dried fruit (prunes, figs)

Hygiene rules

  • Reduce coffee consumption (maximum 2 cups per day) to avoid urinary magnesium losses and stimulation of the catecholaminergic pathway (adrenaline and noradrenaline).
  • Prefer steaming to boiling in order to preserve the mineral content of food.
  • Monitor the quality of the digestive tract (diarrhoea, constipation, flatulence, etc.), as this can lead to possible malabsorption and dysbiosis related to the psychic balance.
  • Limit physical activity after 8 pm to avoid problems with falling asleep due to exertional arousal (adrenaline release).