Tuesday, August 30, 2011

Carbohydrate blockers

Hi Glenn,

Thank you for your newsletters. I always find your information up to date and interesting, and so relevant to everyday life.

I work in a gym and have a patron whose latest questions are all about products that inhibit the uptake of carbohydrates.

He has asked about white kidney bean extract – “I’m going to use it in my next cutting phase, so I’m wondering what is the best way to use it? Eat white kidney beans? Or buy a supplement/pill?”

He has also asked about the product C-plex 60 which claims to reduce carbohydrate absorption by over 80%.

I am sceptical about these products but the individual seems hell bent on trying to convince me that they are legitimate.

Many thanks,

Georgie Feakes

Thanks for your note Georgie.

Be aware that if someone has a deep belief then nothing you or I will say will make a difference.

Also be aware that anything that causes significant carbohydrate malabsorption will also cause severe gut pain, gas and diarrhea. The gut was designed to digest and absorb food. Stopping that function is unnatural and the body will react in a very uncomfortable fashion. There is no way a product will reduce carbohydrate absorption by 80%. If it did, then you would be in hospital.

Some products may cause a very small amount of carbohydrate malabsorption. There is evidence that the white kidney bean extract you mention does encourage weight loss], in the region of 1kg per month, through inhibiting some carbohydrate digestion. I would argue "Why not eat a little less instead. Cheaper, easier and probably more effective".

Get educated (Perth, Western Australia)

Once again, for those of you living Perth, Western Australia, I shall be running two different nutrition courses for the University of Western Australia Extension Program. The first is an honest, sometimes quirky, seminar on living for long life. The link for this course is here.

For the first time at the university I shall also be running a very practical course on nutrition for sports performance. There is more here. Whether you are building up to your first 10 km run or if you are a long-course triathlete there will be something here to improve your sports performance.

Love to see your face.

When the gavel falls

There you are, waiting the decision. You’ve done the crime and you’ve done the time. Now you reckon you should be released from prison so you can start life afresh. The judge reads the report, listens to your arguments for release and makes the decision: you are to remain in prison. Not what you wanted to hear. The judge then calls for a recess and heads off to morning tea.

It is all about timing
What you experienced was probably more a case of bad timing than a poor argument on your part. There is a saying that a decision often “depends upon what the judge had for breakfast.” Research on over a thousand parole decisions agrees. Judges make decisions more likely to favour a prisoner if the judge has just returned from a meal or a break. And the difference is significant.

No chance just before lunch
At the start of the morning or just after a food break, around two thirds of prisoners got a favourable parole decision. By the end of the session, with the judge due for a meal or a break, virtually no prisoners heard the words they wanted to hear. The researchers state: “the percentage of favourable rulings drops gradually from 65% to nearly zero within each decision session and returns abruptly to 65% after a break.”

Food and a rest is the key
Naturally, the researchers looked at other factors that could be playing a role. Did the better class of prisoner come in near the start of a session? No. Did the judges know each case before they appeared and scheduled a break after a couple of tough prisoners? No. The truth is that it was an entirely random process. It all came down to how well fed and refreshed the judge was. How’s that for justice?

What does it all mean?
This research has much broader implications. I used to mark university student assignments. The best I could do was 15 at a time. By the time I got to #12 my brain was beginning to disintegrate. I’m sure the last 3-4 in a marking session got lower marks because my brain was fried. What if you are the last person to be interviewed for a job? Have you got the same chance as the first two?

And then think about what you do during the day. Would you and your thinking benefit from more breaks? Did you eat breakfast? If you did, we know from other research that you will likely be thinking better and making wiser decisions.

And if you ever have to front up to court make sure you take some fruit to offer the judge because if it is coming up to his/her lunch break it could save you a lot of grief.

Proceedings of the National Academy of Sciences 2011; 108 (17): 6889-6892

Thursday, August 11, 2011

When wine meets your teeth

You may remember that a couple of issues ago Warwick Boardman asked about the pH of wine. I though I would give you a brief update. You see, Warwick had asked a question I didn’t know the answer to, and that upsets the equilibrium of my brain, so it was off the Medical Library for me.
pH of wine
First, a real quick reminder. It is the low pH levels (high acidity) of soft drinks, fruit juice and sports drinks that is the most likely to cause tooth enamel erosion, not the sugar content. For more, see my  blog here.

What about the pH of a social and relaxing glass of wine? I like the commitment of the German researchers who analysed the pH of 50 white wines and 50 red wines (ref 1). They found that they range from 3.0 - 3.9 for white wine and 3.4 – 4.1 for red wine, which makes acidic, although less acidic than soft drinks and fruit juices which have a pH commonly around 2.3 – 3.2.

Just based on those figures you could guess that white wine, generally, had the greater potential to cause tooth enamel erosion. You would be correct. Exposing extracted human teeth to wine found that white wine caused more calcium release from teeth than red wine. Note that this study was done with extracted teeth dropped into a beaker of wine. It did not take into account the buffering effect of saliva or food that might be present in the mouth of a consumer.

An Australian study looked at the buffering effect of saliva after drinking wine (ref 2). They found that saliva was “relatively ineffective” at neutralising the acid because the pH in the mouth remained low enough, for long enough, after drinking wine for enamel to start to dissolve. Pity, because I always thought that saliva would be helpful.

Quick tip. Don’t clean your teeth straight after consuming acidic drinks. You might think that helps avoid erosion. It doesn’t. Any micro-damage from the acid will occur quickly. Allow time for your saliva to remineralise your teeth. That’s a critical function of saliva. It’s not just for licking the occasional envelope. Wait, say, for an hour between drinking and brushing your fangs.

Wine tasters
Already you have been thinking: “What about wine tasters?” An enviable occupation, that’s for sure. Some of these folk will be tasting 20 – 100 wines a day, maybe more, and the wine can stay in the mouth for some time. Yes, there have been reported cases of the teeth of wine tasters being affected by wine. One wine taster had tasted at least 20 wines a day for 10 years and had a five year history of tooth sensitivity to hot and cold food (ref 3). A 56 year young lady who drank a bottle of wine a day for 34 years also presented to her dentist with tingly teeth (ref 4). Yep, the acidity of wine can be a problem for frequent wine consumers.

What does it all mean?
Like any drink with a low pH, don’t let wine wash around your teeth for too long. A glass each day is unlikely to be a problem, but if you enjoy half a bottle or more at dinner every day then your teeth (and liver) might complain down the track. The same goes for juice, soft drinks and sports drinks – some OK, but if you drink them in the litres each day, make sure you see your dentist regularly. Or try drinks closer to neutral pH, like water or milk. Old fashioned, I know, but we have been consuming them for centuries with good results.

Right now I’m looking for research funds to determine the pH of reds bottled in the 1960s and 1970s. If you could help out with either funds or the bottles I would be gratefully smashed.

1. Nutrition Research 2009; 29: 558-567
2. Australian Dental Journal 2009; 54: 228-232
3. Australian Dental Journal 1998; 43: 32-34
4. Journal of the American Dental Association 2005; 136: 71-75

The never-ending salt saga

I am an avid reader of your newsletter, thank you for all your efforts, they are much appreciated I’m sure by all who read it.

I am 28 years old, very fit and active, and someone who pays much attention to things I eat (apart from the usual chocolate and cakes now and then). I limit my saturated fat intake, and although I’m vegetarian, I eat more than enough protein from dairy, soy and legumes. The only thing that I don't concern myself with is sodium. But then again my blood pressure has never been a problem - always 110-120 / 70-80. Is this a mistake on my part?

So I guess my central question is this - does the research suggest that high levels of sodium cause high blood pressure or is it the case that reducing your sodium intake when you already have high blood pressure helps on reducing it? Or as logicians would ask: Does A cause B or does notA cause notB?

As far as I was aware, salt and hypertension were intimately connected, but in recent weeks I have been hearing contrary study results. Then today I was reading this interview, and this one, both from Scientific American, and things confused me even more.

Would love to hear your take on things. Thanks for this,


No simple matter Farid. In one of your articles, Marion Nestle's comments have been echoed by many. If you get people to reduce their salt by 10-20% you may not see any effect on blood pressure. Some people may need to reduce their salt intake by 50-80% to have an effect on blood pressure. That is difficult because most salt is added by food manufacturers and salty food doesn't often taste salty, such as bread & cornflakes. Hunter-gatherers ate about 200 mg of salt each day; westerners eat 3000-6000 mg a day, that is, about 15x - 30x as much as we were designed to consume.

Also remember that a high salt diet increases calcium losses via urine, so even if you cut back on salt and there is no effect on blood pressure, it is still good for your bones.

Anyway, there will always be debate. Why are there no clear-cut answers? 

1. Because, in nutrition, you can't increase/decrease a nutrient/component in food/diet without changing many other things in a free-living human. Eating less salt is likely to mean eating more fresh foods, such as fruit and vegetables. Is any response due to less salt or more vegetables?

2. We all have differing genetic backgrounds.

3. We all respond differently to our environment, including the food we eat.

I wish I could provide a simple answer. I can't. Just reading the articles you have found will give you some insight as to lack of agreement, one key reason is because we can't find westerners on a truly low salt diet to compare with those on a high salt diet, so we may just be comparing those with a very high salt intake to those with a high salt intake.

The August 2011 edition of GI News also discusses the influence of food and lifestyle on our blood pressure. Scroll down about two-thirds for the article by Alan Barclay.

My view? Keep doing what you are doing. Eat well. Don't add salt to food. Choose lower salt varieties of commercial foods. No harm. It may be better for you, who knows?