Scientists at Penn State University in the USA have shown that garlic can inhibit cancer causing toxins generated from nitrate compounds in the diet. It is a well known fact that nitrates in our food can be converted to carcinogenic compounds in the digestive tract. We also know that nitrates derived from plant foods are not generally considered to be as dangerous as those derived from meat products.
The reason for this apparent discrepancy is that nitrate containing plants generally provide significant amounts of vitamin C - and vitamin C is a well known inhibitor of the mechanism whereby these compounds are converted into carcinogenic nitrosamines.
The process is whereby nitrates and nitrites are changed to nitrosamines is called NITROSATION - this conversion process is usually associated with certain nitrates derived from certain foods and contaminated water. Nitrosamines are also be produced when nitrate containing foods are prepared at very high temperatures.
Writing in the journal of Analytical Chemistry, Prof. Earl Harrison and his colleagues show how they found that garlic can actually inhibit the nitrosation of nitrites and so reduce the quantity of toxic nitrosamines that are produced during the breakdown of dietary nitrates and nitrites.
The researchers set out to prove this in a clinical trial where they gave four different groups of volunteers either 1,3 or 5 grams of fresh garlic or 3 grams of aged garlic extract. A fifth group was given 500mg of vitamin C.
The volunteers were all given the same daily amount of sodium nitrate asked to take it along with their specific dosages of garlic or vitamin C for a period of seven days.
To assess the efficacy of the garlic in countering nitrosation the researchers measured the levels of NITROSOPROLINE in the volunteers' urine - nitrosoproline being an indicator of nitrosation activity.
When the urine samples were analyzed the researchers found that the quantity of nitrosoproline in the urine of the different groups of volunteers was inversely proportional to the dosage of garlic that they had taken each day. In other words the higher the dose of garlic the lower the levels of nitrosamines. The group taking vitamin C also had low levels of nitrosoproline.
Previous studies have shown how spices can prevent the formation of other cancer causing compounds - such as the heterocyclic amines that are produced when meat is cooked at high temperatures. This study is yet another reminder of the health benefits that even a single spice can confer on those who are prepared to eat it in sufficient quantities on a regular basis.
It also strengthens the case for the inclusion of a wide variety of culinary herbs and spices in our diet as compounds in these foods have synergistic relationships that can boost one another's beneficial effects.