Chemical contained red meat may cause heart damage

A study carried out by researchers from Cleveland Clinic in Ohio, US, has found that the chemical L-carnitine can increase the risk of suffering from heart problems. Saturated fat and the manufacturing process involved with how meat is preserved are widely believed to be related to heart problems, but many health experts think there is more to it. 

Lead researcher of the new study, Dr Stanley Hazen, commented: “The cholesterol and saturated fat content of lean red meat is not that high, there’s something else contributing to increases in cardiovascular risk.”

L-carnitine is a nutrient which is contained in red meat, dairy products and some dietary supplements.  The study, published in the journal Nature Medicine, showed that the carnitine contained red meat was broken down by naturally occurring bacteria in the gut. 

However, this later resulted in higher levels of cholesterol and an increased risk of heart disease as the resulting broken down product - trimethylamine-N-oxide (TMAO), is known to speed up the build-up of plaque in arteries and cause them to harden (atherosclerosis) – a main cause of heart disease.

Part of the researchers’ investigations was conducted in humans, whilst other testing was carried out with mice. Studies involving animals can be sometimes difficult to interpret, and some degree of caution should be shown when generalising the findings to humans.

For the study, 77 healthy volunteers were administered a supplement of L-carnitine. Of this total, 26 were classified as vegans or vegetarians. Some of the meat-eaters in the group were told to eat an eight-ounce sirloin steak - this works out at around 180mg of L-carnitine.

Researchers then gave antibiotics to the participants for a one week period. These prevented bacteria in their gut from converting L-carnitine into TMAO. After this, the 77 people again were given L-carnitine. Tests were conducted on blood and urine at the beginning of the study and up to three weeks following L-carnitine being given. Some of the people also had their faeces analysed.

In addition, L-carnitine levels were checked in the blood of 2,595 other people, all of whom had attended a heart check-up. The researchers thought this would be an effective measure of assessing a potential link with L-carnitine levels and known cardiovascular disease, or risk of a cardiovascular event (i.e. a heart attack or stroke).

Finally, plaque levels were studied in the arteries of mice and this was done by comparing mice fed normally against a group of mice fed L-carnitine, for a 10 week period. Some of these mice were given antibiotics beforehand. 

The main findings were:

. Meat-eaters produced more TMAO compared to vegans or vegetarians following L-carnitine ingestion.

. A ‘significant’ link was found between L-carnitine concentrations and risk of cardiovascular event in those having heart check-ups. However this was only for those with a high TMAO concentration. Researchers state they believe this shows that TMAO, rather than L-carnitine, is the main factor of this link.

. A study of the faeces showed L-carnitine affected how much TMAO was in the blood.

. Mice given L-carnitine, were at a double risk of developing a plaque build-up in their arterial walls, - but only when they had their normal gut bacteria. When the animals were given antibiotics to clear the gut, L-carnitine did not cause the same arterial wall build-up.

Dr Hazen says that TMAO can be underestimated, and said: “It may be a waste product but it is significantly influencing cholesterol metabolism and the net effect leads to an accumulation of cholesterol. The findings support the idea that less red meat is better. I used to have red meat five days out of seven, now I have cut it way back to less than once every two weeks or so.”

Breaking news! Eggs are comparable to smoking for heart disease risk

In news that may break the heart of many people across Britain who love nothing more than a good old fashioned fry-up to kick-off their day, it is unfortunately our duty to report that scientists are claiming that the egg yolks are ‘almost as bad as smoking’ in regards to the negative effects they can have on health. The debate about how good eggs are for you has been active for a number of years and no doubt this new study to emerge will add fuel to the fire.

The egg is a staple of many Brits’ morning breakfast, with fry-ups or ‘egg and soldiers’ being most common dishes. The bearer of bad news is Dr David Spence from the University of Western Ontario, London, Canada. Dr Spence claims that eating egg yolks for a sustained time period can speed up the onset of atherosclerosis. This is where cholesterol and fat begin to build up in the artery walls and then result in the gradual creation hard structures called plaques. The damaged narrow arteries can then restrict blood flow causing organs to stop functioning correctly, or there is a risk of blood clot. When the blood supply to the heart is restricted this could lead to a possible heart attack, or a stroke may be triggered when the brain’s blood supply has been affected.

Dr Spence conducted an analysis of 1,231 participants in total from London Health Sciences Centre’s University Hospital clinics in Ontario. For a fair result, he looked at a mixture of both men and women. The patients had an overall average age of 61.5 and each patient completed a questionnaire that quizzed them about their lifestyle and medicines taken. Dr Spence wanted to know each patient’s pack-years of smoking (number of packs per day of cigarettes times the number of years), and the number of egg yolks roughly eaten per week times the number of years consumed (egg yolk-years).

An ultrasound machine was utilised to assess the total plaque area levels of each person. After thorough analysis it was discovered that carotid plaque area rose linearly with age after 40, but increased exponentially after several years of frequent smoking and egg yolk consumption. It was also observed that the people who typically ate at least three egg yolks per week had notably more plaque area than those who restricted themselves to consuming just two a week.

Dr Spence warned, “The mantra ‘eggs can be part of a healthy diet for healthy people’ has confused the issue. It has been known for a long time that a high cholesterol intake increases the risk of cardiovascular events, and egg yolks have very high cholesterol content. In diabetics, an egg a day increases coronary risk by two to five-fold.”

He continued to stress that regular egg consumption can actually be two-thirds as dangerous as smoking in terms of plaque build-up. In addition, Dr Spence revealed that a typical jumbo sized egg can contain a whopping 237 milligrams of cholesterol, adding, “It’s more than the cholesterol in a Hardee’s monster thick burger which is two-thirds of a pound of beef, three slices of cheese and four slices of bacon.”