In USA, 18,000 individuals are on the national waiting list for a liver transplant. However the annual cadaveric donor liver number has reached a plateau at around 4500. Thus, there is a need to find an alternative source of donor livers to bridge the shortfall.

A normal liver possesses an enormous ability to regenerate when injured. Half a century ago, it was shown that when 70% of a rat’s liver was surgically removed, the remaining 30% of the liver grew to almost the original size in 10 to 14 days! It is this amazing regenerative capability which has allowed surgeons to use living donors to perform liver transplantation. The first living donor liver transplant (LDLT) from an adult to a child was performed more than 10 years ago. Subsequently, the first adult to adult LDLT with the right lobe of the liver was reported in 1998. Since then, increasing numbers of adult to adult LDLT have been performed worldwide.

Before an individual can be accepted as a potential living liver donor, he or she has to undergo extensive evaluation by a hepatologist, a transplant surgeon and a psychiatrist. In addition, he or she has to undergo a whole barrage of blood tests and X-ray studies of the liver with helical computed tomography (CT) or magnetic resonance imaging (MRI). The imaging is to ensure that the volume of the liver to be transplanted is adequate, to make sure that the liver looks normal and to check the anatomy of the liver before surgery. Despite this extensive evaluation process, surprise findings within the donor liver at the time of surgery do occur and have led to the cancellation of the liver transplant operation. The only way to be sure that the donor’s liver is normal is to perform a liver biopsy. This involves the insertion of a needle into the liver under X-ray guidance and a small piece of liver is removed for examination under the microscope by a liver pathologist. However, routine liver biopsy as an integral part of the evaluation process of a potential living liver donor is still controversial.

A recent study by the UCLA School of Medicine (J Gastroenterol Hepatol 2006; 21: 381-383) looked at the accuracy of the living donor evaluation process and the corresponding liver biopsy. Seventy potential living liver donors underwent the evaluation process and were found to have no contraindications for donating part of their liver. All 70 patients then underwent liver biopsy. Of these, 2/3 of the liver samples showed unexpected abnormality! Only one third of the patients (23 patients) had a normal liver biopsy. The most common abnormality in the supposedly normal looking liver was steatosis (fatty infiltration of the liver). This was found in 38.5% of the potential donors. Normally steatosis is associated with being overweight or obese. However, one quarter of those with steatosis were definitely not overweight or obese as determined by the average body mass index (BMI). MRI did not show fat in the liver in one third of the potential donors with proven steatosis.

Fatty infiltration of the liver is known to affect the eventual function of the transplanted liver in the recipient. For example, when more than 30% of the liver is infiltrated with fat, the risk of the transplanted liver not working after transplantation is 5 times more than a donor liver which has no fat infiltration.

This study highlighted the fact that individuals with normal BMI can have steatosis, MRI of the liver can miss the presence of fat within what seems like a normal liver and liver function tests can be normal despite the presence of fat within the liver.

Nothing is absolute in medicine.

‘Drink that glass of milk.’ “Why?” ‘It will help you grow!’
No doubt this sounds familiar to all parents! Well, it might just be the kind of advice that we, as parents (or at least the dads), may well be wise to follow if we want a lowered risk of developing colorectal cancer.

In a Swedish study involving 45,306 men, without a history of cancer, aged between 45 and 79 years, volunteers completed a food-frequency questionnaire in 1997 and were followed up for 7 years. The study (Am J Clin Nutr 2006; 83: 667-673) showed that total dairy intake and calcium intake is inversely related to colon cancer risk. High dairy consumption was associated with a lower risk of colorectal cancer. The risk for developing colorectal cancer in men taking at least 7 servings per day of dairy foods was half that of men taking less than 2 servings per day. Milk was the dairy food that had the most influence on colon cancer risk. The more milk you drink, the lower the risk of colon cancer. Men who consumed more than one and a half glasses of milk per day were found to have a 33% lower risk for colorectal cancer than those who drank less than 2 glasses of milk per week. The benefit of drinking milk is not related to the milk fat content.

Darn, there goes my excuse for not buying low fat milk.

“Sausages, hot dogs and bacon” is music to the ears for both young and old. However, too much of these processed meat products in your diet over a prolonged period of time may well give you an increased risk of stomach cancer! A recent Swedish population based study involving 61,433 women (Larsson SC et al, Int J Cancer 2006; March 20 Epub) investigated the associations between ingestion of processed meat, other meats and N-nitrosodimethylamine and the risk of stomach cancer. These women were followed up for 18 years. The study showed that high consumption of processed meat but not other meats, such as red meat, fish and poultry, was associated with increased risk of developing stomach cancer. The risk of stomach cancer is doubled in those women who consumed the highest amount of processed meat when compared to those who ate the least processed meat.

N-nitrosodiethylamine is the most frequently occurring nitrosamine in foods. Sodium nitrite reacts with amines in the meat to produce nitrosoamines. Nitrosamines are also present in beer, tobacco products, gastric juice, rubber manufacturing and pesticide production. Interestingly, N-nitrosodiethylamine, a yellow liquid at room temperature, was previously used to make rocket fuel. Its use was stopped after very high levels of N-nitrosodiethylamine were found in the air, water and soil samples around the rocket fuel manufacturing plant.

Sodium nitrite is added to processed or cured meat as a preservative. It prevents toxin production by Clostridium Botulinum, the bacteria responsible for botulism, a severe form of food poisoning. For example, the nitrite in bacon is converted to nitrosamines by the high heat used to cook the bacon. Bacteria in the mouth convert nitrate in vegetable into nitrite. In the acidic stomach, the nitrite reacts with amines in the food stuff to form nitrosamines.

Nitrosamines have been shown to cause cancer in animals. Although there is no direct evidence to show that nitrosamines cause human cancers, there is substantial indirect evidence that nitrosamines do cause cancers in man. The most obvious and visible one is tobacco-specific nitrosamines as one of the many agents which can cause lung cancer. While the risk of nitrosamine formation from sodium nitrite additive in processed meat has been kept to a minimum by the food manufacturing industries and regulatory bodies, the potential risk of excessive amount of nitrosamine exposure for those who eat large amounts of processed meat in their life time is still there. Although there might be other factors working together with nitrosamines to cause cancer in humans, we can at least help by reducing our exposure to nitrosamines by watching what we eat and what we inhale as second hand smoke.