Monday, November 30, 2009

Butter vs margarine email


For many years there has been an email hoax doing its best to frighten you from using margarine. Reader Alyson brought it to my attention again. The email claims that margarine is high in trans fats, the kind of fats that act like those evil saturated fats. This is a dead give-away that the email came from the US where many margarines are high in trans fats. In Australia, table margarine has been virtually free of trans fats since 1998.

The email also states that margarine is “one molecule away from being plastic”, which might startle anyone who hasn’t done chemistry at school. For those that have done chemistry, the statement doesn’t make sense on any level.

Water is H2O. Everyone knows that. It is essential for life. Add an oxygen atom and you have H2O2, hydrogen peroxide, a cleaning agent and disinfectant which, if you swallow it can corrode the lining of your throat and make you sick. That makes water just one atom away from a powerful bleaching agent. Just one atom! Should you stop drinking water? OK, it’s a silly game, but lots of people play the “If I don’t understand chemistry, then neither should you” game.

Butter? Marg? Your choice. If your blood cholesterol is high then choose a poly- or mono-unsaturated margarine. Remember, scary emails about food are usually a hoax.

Eat like a cave man


What is the perfect diet? If you go by what you read in the media, you might toss up between the Mediterranean diet, the low-carb diet, or the Japanese diet. Now and again you will hear of the hunter-gatherer diet, or cave man diet, touted as the ideal choice as it was the diet for most of human ancestry.

The hunter-gatherer diet should probably be termed the gatherer-hunter diet as our forebears did more gathering than hunting. Either way, from here on I shall call it the Paleolithic diet. This is the diet we enjoyed before humans started to cultivate plants, domesticate animals and consume dairy foods about 10,000 years ago.

No bread, milk or baked beans for most of evolution

So, for two million years humans and their ancestors dined on wild animals, fruits, vegetables, nuts and seeds (but not legumes). There were no oils, dairy or grain-based foods in this time. This may be the ideal diet as our physiology evolved to make best use of these foods. Ten thousand years is a relatively short time to adapt to the dramatic changes we have experienced in our diet. Certainly, no-one would suggest that the body was designed to eat Krispy Kreme donuts.

Paleolithic diet improves metabolism

A University of California study was designed to see the effect the Paleolithic Diet on human physiology when compared to the modern diet. Due to the time and commitment required only nine healthy people completed the 17 day trial in which the last 10 days was exclusively the Paleolithic diet. During that time their blood cholesterol dropped by 16%, triglycerides by 35% and a significant drop in blood pressure even though none had high blood pressure in the first place. Blood glucose and insulin levels also improved. There was no weight loss or change in exercise patterns in the group, so any metabolic effects observed were due to the change in diet.

As Professor Loren Cordain, a big fan of the Paleolithic Diet said: "Our genome is very well adapted to wild plant and animal foods, and these giant come-latelys (grains, dairy, legumes) have potential effects of being discordant with our genome”. This small study suggests at least a short-term benefit to trying the diet.

“So what are the recommendations? Reduce processed foods, and increase fresh fruits, vegetables, nuts, lean meats and seafood” Cordain concluded. Makes sense all round. There are many adherents to the diet. For more information on the Paleolithic Diet go to http://www.paleodiet.com.

What does it all mean?

I think the debate on the ideal diet is all a bit theoretical. Even if the Paleolithic Diet is the best diet for humans, I don’t think I could live the rest of my life without camembert cheese, red wine and chocolate. I prefer the Comidas del Mundo Diet, which is one I just made up. It doesn’t have a web page yet, but should it become fashionable, then you will know where it began. Basically, you choose good quality food and dishes that originated from around the world and enjoy them, such as tomatoes (origin South America), tea (China), yogurt (Persia), chocolate (Switzerland via South America), macadamias (Australia), and combine that with activities that exercise the brain and body. I might call the combination La Vida Ecl├ęctica Health and Anti-Aging Program. But, then again, I probably won’t. I don’t really like to be programmed.

Reference: European Journal of Clinical Nutrition 2009; 90: 269-275

Sunday, November 22, 2009

Biting less than you can chew


“Don’t put so much in your mouth” is the advice parents give at the dinner table, especially to teenagers just arrived home after sports training. I used to eat at the same table as a motorbike fanatic at boarding college in Adelaide. We used to call him “hoovermouth” as he would fill his mouth until he had cheeks like a trumpet player. He would also eat with oily hands because his theory was that bacteria couldn’t live in oil.

It appears that how much you stick in your mouth could influence how much you keep sticking in your mouth. One weight loss tip has always been to take small bites, chew your food and put your knife and fork down between mouthfuls (assuming you haven’t got your mitts around a burger or dipping your fingers into a bucket of popcorn).

Custard experiment

Now Dutch researchers have added a touch of credibility to that advice. Twenty two healthy, young people, without eating disorders or strange boarding house table habits were selected for the experiment. And they had to like chocolate custard too.

The custard was provided in controlled amounts – small bite size, large bite size and bite size of choice – while also being in the mouth for set amounts of time – three seconds, nine seconds or a time they preferred. The time in the mouth was termed the Oral Processing Time, or OPT, as scientists love acronyms. Every thing was automated. Little beeps would signal when to bite and when to swallow. They were told to stop eating when they felt comfortably full.

Less food, more time

The least total amount of custard was eaten when the bite size was the smallest and the OPT was the longest. Compared to eating the custard ad libitum, they ate 32% less food before feeling full. Once either the bite size was increased or the OPT was shortened, more total food was consumed.

Although the eating situation was highly controlled and therefore not natural, the results were supportive of previous similar research. One earlier study even had people wear a dental prosthetic to reduce the oral cavity in the mouth and found they ate 25% less food. Why hasn’t someone put those on the market yet?

What does it all mean?

It makes sense that if we take longer to eat our meal, the hormones that trigger the appetite centre are going to kick in before we overeat. It also makes sense that we should take a little longer to enjoy the flavour and texture of food (aka chewing).

The advice to bite off smaller amounts and enjoy them over a longer time has always been good advice it seems. There lies one of the problems we have with many take-away foods – their flavour hits the palate quickly in the form of fat, sugar and salt and they are usually soft and quick to eat, chewing hardly required.

Reference: American Journal of Clinical Nutrition 2009; 90: 269-275

Monday, November 9, 2009

Does chocolate give you zits?


Well, your Mum always reckoned it did when you were a teenager. That’s only because she loved you and thought it was helpful advice, not because she had read all the science on the topic. But, then again, there wasn’t much science on the link between food and acne anyway.

A lot of the research conducted last century wasn’t really high quality and led to the scientific view that what you ate probably didn’t make any difference to pimple production. A 1997 review article in the New England Journal of Medicine on the treatment of acne states: “Physicians should dispel the myth that diet or failure to cleanse the skin is responsible for acne.”

Case closed. And then reopened

When subscriber Mel asked if there was a link between chocolate and pimples, the answer would have been easy last century: No, Mel, there isn’t. The research on chocolate and other foods had shown no link between it and pimples. The case was closed. Then the case had to be re-opened again as a new theory emerged. Before I tell you about that, first what is acne?

What is acne?

Acne is an abnormality within the sebaceous glands associated with hair follicles on the face, back and chest. The whole process of acne begins at the age of 7-10 years, when hormonal surges cause the sebaceous glands to enlarge. Acne usually becomes visible in puberty, initiated by an increase in androgen hormones, especially dehydroepiandrosterone sulphate (DHEAS). The sebaceous glands secrete sebum that naturally flows to the surface of the skin. Should this flow be blocked by a plug (called a comedo), the oily sebum accumulates, and bacteria (Propionibacterium acnes) feed on the fats in the sebum and accumulate to eventually reach levels that form a pimple. (OK, close your eyes and repeat that back to me).

Not one food, but the diet as a whole

In 2002, a theory was proposed that, as non-westernised societies have almost no acne, a diet of high Glycaemic Index (GI) foods might influence the formation of pimples. Those carbohydrate foods that are quickly digested (ie high GI foods) may trigger high levels of insulin in the blood, elevating Insulin-like Growth Factor 1 (IGF-1), which in turn stimulates sebum production.

Subsequent published research tends to give this theory some credibility. A pilot study at the Royal Melbourne Institute of Technology, Australia on a small group of male teenagers confirmed that a high GI diet influenced hormones to promote acne development. This is still only a theory and more research needs to be done before any conclusions on GI and acne can be made.

As chocolate has a low to moderate GI (and has a moderate insulin response), this theory may not be relevant to chocolate consumption anyway. So, the answer to the original question remains: No, Mel, there isn’t.

What does it all mean?

Although we have a lot more to learn about pimples and diet, it seems safe to say that no single food causes acne; it is more likely to be the effect of the overall diet. As a general rule of thumb, the better the quality of the diet, the lower the GI and the less likelihood of getting a zit. Choosing highly processed foods tends to lead to higher blood glucose levels, higher insulin, changes in hormonal levels and a greater chance of waking up with a huge zit in the middle of your forehead.

Reference: Mol Nutr & Food Research 2008; 52 (6): 718-726

Chocolate after a heart attack

Chocolate is a much studied food. Now there is yet another research paper suggesting that it is never too late for chocolate. It has been long known that the cocoa in chocolate has antioxidants that seem to promote healthy arteries, lower blood pressure, reduce blood clots (eg deep vein thrombosis) and stop LDL-cholesterol from being oxidized into a dangerous form. All good news if you are otherwise healthy and eat only sensible amounts of choc.

But what if you have already had a heart attack and been lucky enough to survive it? A study of 1169 people who had a heart attack in the 1990s found that chocolate eaters had a 27% reduced chance of another attack when compared to those never eating chocolate. Although an occasional nibble conferred some protection, those that ate chocolate at least twice a week had the best outcome. The patients were not asked if the chocolate was milk or dark.

This was an observational study and we must be careful not to conclude that chocolate was the answer. On the other hand, sometimes it is nice to jump to conclusions on certain food experiences.

Reference: Journal of Internal Medicine 2009; 266: 248-257