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.

Saliva

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.

References: 

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,

Farid

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?

Onion myth

I’ve been attached to the internet for 16 years. Still fondly remember the first desktop modem and its dial up sound. Since that first modem I have never received an unsolicited nutrition/food based email that made any sense. I’ve been told that Diet Coke rots the stomach, that I should never eat bread with fruit because it confuses the digestive enzymes and that margarine is a molecule away from plastic, which makes as much sense as wine being a molecule away from that nice steak you are having with it. And now one about onions and the flu.

  

The onion email hoax

Apparently when the flu epidemic hit the world after the WW1 a doctor asked a farmer why his family didn’t get the flu when many around did. He believed the solution had been an onion placed in a dish in every room. The doctor supposedly placed the onion under a microscope and discovered it had “absorbed the bacteria, therefore, keeping the family healthy.”

Hold up there! The flu is a virus, so what’s this about absorbing bacteria? Virus. Bacteria. Very, very different. And did I read the onion went under a microscope? Well you are only likely to see a virus under a scanning electron microscope and you couldn’t get hold of one of those until 1965. Sadly, many can’t sense a hoax when it smacks them in the face. If you have time to burn then you can read the email on the snopes.com site http://www.snopes.com/medical/swineflu/onion.asp.

Onion and food poisoning

Some of the onion email hoaxes go on to claim that the onion is one of the highest risk food-poisoning foods around. Why? Because the onion is a bacteria magnet, remember, stopping you getting the flu caused by a virus! They say the onion is not safe even in a zip-lock bag in the fridge. Apparently, cookbook author Zola Gorgon wrote the original story about onions being a common cause of food poisoning. Now, don’t bother looking for cookbooks by Zola Gorgon, just think about her name for a moment. Zola Gorgon.

Raw onions safe

Food safety expert Dr Ben Chapman from North Carolina State University says there haven’t been any recorded food poisoning outbreaks due to raw onions. Not one. He says that onions are not a food that supports pathogenic growth, well, not raw ones.

What does it all mean?

Remember, scary food/nutrient/nutrition emails have a 100% record of being wrong. Just look for the “forward this to everyone you love” at the bottom of the email. It is code for “hoax”.

It is exasperating to educate the public if there are huge sections who lap up a good story, and not for a second ask themselves if the story is plausible. Why don’t we get government programs urging us to leave an onion in a dish as we come into winter? Why isn’t there a Ministry of Onion if it is the best thing for flu avoidance?

What’s the best evidence that someone just made this stuff up for a joke? You probably got it. The cookbook author, Zola Gorgon. Well done. If she existed and was an author she would be listed as Gorgon, Zola. Now you must get it. All a bit cheesey and on the nose. Why don’t you make up a ridiculous food story and send it around and see how quick you get onto snopes.com? And don’t forget to give yourself a silly name.

Zinc and the common cold

We have previously discussed that vitamin C is not a useful supplement for lowering the risk of the [http://glenn-glenncardwell.blogspot.com/2011/01/vitamin-c.html common cold]. Our good friends at the Cochrane Database has crunched the science behind what might be a useful adjunct to scare away the common cold virus far better than an onion. The answer is zinc, but you have to get in early.

Zinc taken as a lozenge or syrup within 24 hours of cold symptoms being detected reduced both the severity and duration of the cold in otherwise healthy people. The zinc supplement will need to be taken for at least five days. For some, taking zinc can create side-effects of nausea, especially with the lozenges.

The problem is that no-one is really sure what is the effective dose of zinc. We need between 8mg (women) and 14mg (men) of zinc each day. The Nutrient Reference Values recommend that we don’t consume more than 40mg of zinc a day. There is also evidence that vitamin D, often low in winter, also helps keep the common cold at bay. Maybe, just maybe, D + Zinc could help you sail through your next cold.

Reference: 

Singh M, Das RR. Zinc for the common cold. Cochrane Database of Systemic Reviews 2011, Issue 2 (just put this info into your search engine and you will easily find this free downloadable pdf).

Sugar - evil for 40 years

It is nearly forty years since John Yudkin wrote the book Pure, White and Deadly. He thought there was a direct link between sugar consumption and heart disease, since disproven. Are we now eating more sugar than ever or are we eating the same amount as in 1980? Is there a link between our sugar consumption and obesity? Wise people at the University of Sydney have given this some thought.

Sugar consumption, up or down?

Surprising to many who had made assumptions about our sugar consumption, we are eating less than 30 years ago. Yep, less. Hang on, before we go any further, what are we talking about? Sugar is not singular, it is plural. Common sugars include fructose, glucose (also called dextrose), galactose, lactose (glucose joined to galactose), sucrose (fructose joined to glucose), and maltose (two glucose molecules joined together).

Add sugar to your coffee and you are adding sucrose; eat a bowl of yogurt and you are eating lactose, and possibly some added sucrose if it was flavoured yogurt; eat a banana and you get a flavoursome mix of glucose, fructose and sucrose.

What sugar?

So what sugar are we talking about? The Uni of Sydney found that we are eating less sucrose, also known as table sugar or cane sugar, in the last 30 years. More specifically, Australia, the UK and the US are eating less sucrose (23%, 10% and 20% less respectively). If you included all sugars used for sweetening then Australia is eating 16% less sugars (note: plural), the UK 5% less, but the US are chugging down an extra 23% sugars. That is, the US are eating less sugar (sucrose) but more sugars, mainly as high fructose corn syrups.

One thing that contributed to the drop in sugar in Australia was a big switch from regular soft drink (soda) to diet versions. We are drinking less sugar-sweetened drinks, with the decline starting at the beginning of the century, such that one third of soft drinks now are diet drinks. Even the kids have got the message. Fewer children are consuming sugar-sweetened drinks and those that do are drinking a bit less.

Is sugar making us fatter?

Will getting people to consume less sugar make a dent in the number of overweight? The answer seems to be “No” on a population basis. Australians and the British eat less sugar and gain more fat. The answer might be “Yes” on an individual basis. It is not just soft drink that can add sugar and calories/kJs to the diet, it is the biscuits (cookies), cakes and sweet pastries that add their fair share too. Cutting back on those will reduce sugar, along with fat and sodium.

What does it all mean?

I dare say that most readers don’t have a sugar problem. The occasional sweet food (eg chocolate) and the occasional sweet drink (eg fruit juice, soft drink) is not going to bring you unstuck. As we consume less sugar, we still become plumper as a nation, so getting Australians and the Brits to cut back further on sugar may not make a big difference to obesity levels. The US, on the other hand, mmmm, maybe Michelle Obama has it on her list.

What you are more likely to have is a sodium problem. Most of you will eat more than you need and possibly venture into the unhealthy levels (especially if you enjoy cheese, olives, sauces, bread, spreads, breakfast cereals). We still have a population stuck in the 1970s worrying about a bit of sugar and not having a clue where their sodium comes from.

Enough on that. I’m off for a lovely Tasmanian camembert on wholegrain toast. Hey, I’ve told you before, I ain’t perfect!

Reference:

Nutrients 2011; 3: 491-504 (you can download it free from here if you fancy )

pH of wine & beer

Hi, Glenn.

It's a bummer about fizzy drinks being acidic. I always drink through a straw when available. However, I don't drink beer through a straw – yet. It is possibly more acidic given it probably has higher carbon dioxide content than soft drinks. Perhaps these drinks should not just have nutrition labeling but also an acid rating! Should we wait for these drinks to go flat?

Regards,

Warwick Boardman

A good thought Warwick. Maybe we should put the pH level on drinks. As we have discussed before, the acid content of soft drinks, sports drinks and fruit juices is high and can cause tooth enamel erosion.

As far as I can gather wine has a pH around 3.0-3.5 and beer has a pH of about 4, both in the acid range, although not as acidic as fruit juice, soft drinks and sports drinks, which tend to have a pH of 2-3. There have been reported cases of wine tasters, wine makers and even wine lovers suffering marked dental erosion due to the low pH of wine. To reduce wine contact with the teeth, and to stimulate saliva flow (saliva buffers the acid), drink wine with a meal.

Oh, and Warwick, never let your beer go flat! That is plain unnatural.

To Snack or Meal?

They say there was a time last century when we used to eat three meals a day and we should have been thankful for that many because kids were starving in Africa. I suspect they were talking about working adults between 1901 – 1970. I doubt whether kids, teenagers or housewives would have existed on three meals only. If they could sneak a biscuit, leftovers or some bread and dripping they would have gone for it.

Snacking & weight & diabetes

Today, for most readers, food is abundant and affordable and available 24 hours a day. That has led to the question from reader Ken Lynn regarding whether it is better for our weight and health to snack through the day or go back to the three meals a day like grandpa did.

A review by nutrition experts in Australia has looked at the research on snacking and health. There was no clear indication whether snacking had any long-term influence on body weight.

It has been theorised that snacking helps control the appetite and reduce hunger. Nice theory, no evidence. Others have suggested that snacking may cause over-eating, but most studies suggest we compensate to balance the kilojoules in the long-term whether we meal or snack. In other words, we tend to over-eat but snacking doesn’t seem to be the cause.

Snacking doesn’t appear to increase your chances of getting diabetes, nor did it seem to help control blood glucose if you had diabetes.

Snacking & the heart

On the other hand, people who snack and maintain their weight seem to have lower blood lipids (eg blood cholesterol and triglycerides). This link has been known for two decades or more, but we are reminded that these studies haven’t gone for longer than two months, so we don’t know the long-term effects. That’s the consistent problem with human studies of this nature is that they don’t go for long because they are so expensive to run.

Also remember that these types of studies don’t generate profits for a company. For example, if snacking was proven to reduce the chance of a heart attack, it won’t change the nutrition message – if you snack, snack smart on fruit, healthy sandwiches, low-fat, low-salt food bars etc. You see, no quick profit for anyone there because the message is the same.

So what is a snack?

Inherent in many eating research studies is that there is no definition of a snack. That cheese and salad sandwich may be a snack to you, a nibble to an elite athlete, but it might be a meal for grandma. You may recall that I discussed the confusion of snacks vs meals in an earlier blog.

What does it all mean?

I think it is still fair to say that, no matter when or how frequently you eat, your health and weight depends on what you choose to eat. Whether you __meal it__ or __snack it__ will be dictated by how you feel and what suits you. I breakfast, then snack, then finish the day with a meal. Perfect for me, but maybe not for you. In the US they say that snacking will become the norm.

Ken says he is 65 years and wants to crack 85 years. Well Ken, I reckon with a few smart food choices you can make 99 years. It is wise not to make it to 100 because dopey journos have nothing more original than to ask your secret to longevity.

If I ever make it that far my answer would be: “Secret to longevity? Air. Keep alternating an inhalation with an exhalation. Now get lost while I eat my cake.”

Reference: Nutrition & Dietetics 2011; 68: 60-64