An estimated 19 million people are affected by diabetes in the EU, equal to four per cent of the total population. This figure is projected to increase to 26 million by 2030.
The rhizome of the ginger plant (Zingiber officinale) is a rich source of antioxidants, including gingerols, shogaols, zingerones and other ketone derivatives. It has long been used as a remedy for nausea, especially associated with morning sickness.
The new study, published on-line in Food Chemistry (doi: 10.1016/j.foodchem.2006.01.013), assessed the effects of ginger on the blood antioxidant levels and kidney health of diabetic rat models.
Twenty-four male rats were divided into three groups of eight. The first group (control 1) were healthy rats, the second group (control 2) were diabetic and non-supplemented, and the third group (test) was diabetic and had the diet supplemented with ginger powder as five per cent of the daily food intake.
After eight weeks of supplementation the researchers, led by Dr Ali Taghizadeh Afshari from the Emam Khomeini Hospital, reported: "Antioxidant capacity in the ginger supplemented rats was higher when compared to the other groups."
The blood antioxidant levels, measured by using the ferric reducing-antioxidant power (FRAP) assay, were 582, 586, and 763 millimoles per litre for the control 1, control 2 and test groups, respectively.
"At the same time, ginger supplemented diabetic rats had significantly reduce nephropathy," said Afshari.
"Impaired glucose metabolism leads to oxidative stress, proteins glycation and formation of free radicals," explained the researcher.
"Thus, an augmentation of plasma antioxidant capacity decreases plasma free radicals, as shown by this and other studies when consuming herbals extracts containing antioxidants."
The researchers proposed that the ginger might work by regulating the vasoconstrictor thromboxane and the vasodilator prostacyclin to preserve the natural blood vessel balance.
"In diabetes, levels of thromboxane are increased while prostacyclin levels are decreased and this imbalance leads to a decrease of blood flow which in the kidney will cause nephropathy [kidney damage]," said Afshari.
This is the first such report that links ginger with diabetic kidney damage, and as such a leading diabetic expert could not to offer comment on the findings. Much more study is needed before any firm conclusions can be drawn.
Questions are also raised about the size of the dose, and whether smaller doses would be equally effective.
The researcher stressed that normal diabetic treatment with insulin was not in question, but offered that increased ginger intake may be a "useful addition" to the diet.
Ginger has been given a class one safety rating by the American Herbal Products Association (AHPA), indicating that a wide dosage range is safe.