Vitamin Information Center

The ORAC, or Oxygen Radical Absorbance Capacity, is an index that shows the amount of antioxidants in a single food source. It has become an important indicator of a fruit or vegetable’s ability to eliminate free radicals that damage cells in the human body.

Free radicals
Imagine rust forming on metal. As rust eats away the surface, the metal erodes and eventually becomes unusable. This is how free radicals attack our body - they weaken our cells, organs, tissue and other important parts, leading to diseases such as cancer, heart ailments, osteoarthritis and dementia.

The ORAC scale
The ORAC test identifies and measures important antioxidants in a food source. Foods with a high ORAC score can raise the antioxidant levels in the blood by up to 25 percent. Doctors recommend that we consume fruits and vegetables with a total ORAC score of 1,750 per day.

Different plants have different levels of antioxidants. You may consume five kinds of fruits and get only 1,300 ORAC units. Yet a handful of blueberries can give you an ORAC score of 9,000 per 100 grams. The USDA’s recommended level of ORAC units is 3,000 to 5,000 daily.

Acai tops the ORAC list
Strawberries, raspberries, blackberries, cranberries and pomegranates score high on the ORAC index. But no single food source comes close to the ORAC score of the acai berry from Brazil.

A new research published in the Journal of Agricultural and Food Chemistry shows that the acai has the highest ORAC antioxidant value of any food.

Compared to blackberries (53), pomegranates (105), and blueberries (92), acai has an amazing ORAC score of 1,027 per gram. Some samples of freeze-dried acai even turned out ORAC results of up to 50,000.

While these figures are impressive, they do not apply to all acai. Acai berries that have been frozen, spray dried or air dried have a lower ORAC score because many of the phytochemicals, enzymes and nutrients of the acai fruit are lost in the procedure.

To achieve the highest ORAC values, buy only acai products that are properly freeze-dried.

The notion that antioxidant supplements such as vitamins C and E could slow ageing has been dealt a blow by a scientific study showing that the theory behind the advice is wrong.

Beloved of health food shops and glossy magazines alike, antioxidants have long been peddled as preventative pills that have the ability to slow ageing and protect against diseases such as cancer. But the research has shown that the molecular mechanism proposed to explain how they work is mistaken.

David Gems, at University College London, who led the study, said: “It really demonstrates finally that trying to boost your antioxidant levels is very unlikely to have any effect on ageing.”

The dominant theory for ageing has been around since the 1950s; it blames glitches in cells caused by the damaging byproducts of our metabolism. As cells break down sugars to release energy, they also unleash reactive forms of oxygen such as superoxide. These supposedly cause the damage which is the hallmark of ageing.

Gems’ team set about testing the theory that raising or lowering the body’s natural defences against superoxide could affect an individual’s lifespan: make the defences stronger, and lifespan should increase; make them weaker, and it should decrease.

As it would be unethical to experiment on humans, his team used the nematode worm, Caenorhabditis elegans. By tweaking its genes, the scientists were able to “tune” the worms’ natural defences - enzymes it produces to tackle superoxide. However, this made no difference to the worms’ lifespan.

“You can drastically change the natural defence levels and there’s just no effect on ageing,” said Gems, who published his results yesterday in the journal Genes and Development. He added that molecular damage was probably caused by numerous different chemicals within the cell.”With increasing lifespan comes greater exposure and vulnerability to the ageing process,” said Alan Schafer, head of molecular and physiological sciences at the Wellcome Trust. “Research such as this points to how much we have to learn about ageing, and the importance of understanding the mechanisms behind this process. This new study will encourage researchers to explore new avenues in ageing research.”

Gems’s findings coincide with a recent US study on the effectiveness of antioxidants against cancer. The clinical trial on nearly 15,000 men tested whether vitamin C and E supplements were effective against the disease. After following the subjects for several years, researchers found no statistical difference in the number of cancers between the groups taking the vitamins and those on a placebo.