Monday, May 24, 2010

Meal vs snack

What’s the difference between a meal and a snack? Don’t look at me; I don’t know the answer. You probably have your own definition, like, a meal is eaten at a table, while a snack is eaten next to the computer. Or, for a meal you use a knife and fork, and a snack is eaten from the hands.

Snack, meal, feast?

One of our favourite researchers, Brian Wansink of Cornell University, interviewed 122 students and staff at his university, because they were handy, to try and determine the difference between a snack and a meal. Of course, you know instinctively that a definition is going to be difficult to fathom.

I’ve worked with world class rugby players and seen what they eat as a snack – some would call it a meal for a family of five. I once measured the kilojoules consumed by elite footballers and some of them were bowling over 20,000-25,000 kJs (about 5000-6000 Cals) in a day. So, volume of food can’t be a broad guide.

Vegetables maketh the meal

The researchers found that the inclusion of meat or vegetables was more likely to be thought of as a meal, especially if the meal was seen as “expensive”. Thinking that food was “healthy” linked it to being a meal, while less healthy food more often fell into the snack category. Even a person’s mood changed the perception of the food. A happy mood was associated with a meal, while boredom was associated with a snack.

If you ate with the family at a table, that was a meal; eat alone and it is likely to be seen as a snack. They even tested for aspects I hadn’t considered. If you were given a cloth napkin then the food was seen as a meal, but if you were given a paper serviette then it became a snack.

What does it all mean?

Whether you are eating a meal or snack will depend on your personal definition that suits your lifestyle. You can probably think of other examples in addition to those given above. When I look at my situation, a snack usually involves bread or fruit, while a meal involves cooking.

The researchers felt that how you classified an eating occasion could even influence how much you ate. If, in your mind, the food you ate was defined as a meal then you would eat more than if you saw it as a snack. So, if you have people around for dinner and you are hoping for some leftovers, give the guests paper serviettes. If you want them to leave early, try paper plates as well.

Reference: Appetite. 2010; 54: 214- 216

How many holes in your salt shaker?

Martina alerted me to a story about salt shakers. I remember back as a student in the nineteenth century learning that you can reduce the amount of salt people use by putting less holes in the top of the salt shaker because people shook based on time not on the amount of salt that came out of the shaker.

A recent project by Gateshead Council in England compared standard shakers with 17 holes to a new version with only 5 holes and found that this strategy cut salt used by around 60%. This could be a useful public health program if you can get the big fast food franchises to come on board and modify their salt shakers. You can find the story here:

More detail on the actual study can found here:

Now if they could just design salt shakers so teenagers couldn’t open them, we would have a lot less salt being adding to sugar dispensers in restaurants. Well, I stopped doing that when I turned 20 anyway.

Different salts

Alice in Canada asked about the difference between sea salt and other salts on the market, like garlic salt, rock salt and the regular salt. There are two main differences – flavour and price. You are still getting sodium chloride, which is 40% sodium and 60% chloride, with the sodium part being the concern when we get too much.

Now, I know there is plenty of hype around different versions of salt, and some may have a sprinkle of other minerals (eg magnesium); just ignore the claims and have a small amount of whatever type you choose.

Caffeine & Calcium

David asked if caffeine reduced calcium absorption from food. Well, if it does it is only a small effect. One review paper suggests that just a teaspoon (5 mL) of milk would offset any reduced absorption of calcium, so if you have milk in your tea and coffee (average 30 mL) then you are ahead in the calcium stakes. Sometimes you will hear that caffeine is associated with osteoporosis (brittle bones). This is not the case in those getting enough calcium each day, according the latest review papers.

As we have hinted in the past, caffeine is pretty innocuous and is certainly not the demon you heard about in the 1980s and 1990s.

Tuesday, May 11, 2010

Salt shaken

Think of salt and health and the first, and possibly only, association you can make is to link salt and high blood pressure. That’s understandable as anyone with hypertension is told cut out salt and choose salt-reduced foods. Having high blood pressure also increases the chances of having a stroke.

Salt, sodium?

It can get confusing when the words salt and sodium get interchanged. The easy thing to remember is that salt is sodium chloride, and it is the sodium part that seems to be the problem. About 10% of the sodium in our diet is found naturally in food; another 10% or so is added at the table or in the kitchen. Guess where the other 80% comes from? More on that later.

Salt effects more than blood pressure

Salt may be causing more problems than high blood pressure. A high salt diet is also known to be associated with osteoporosis because the extra sodium causes calcium to leach from the bones.

Collaborative work between researchers from Australia, New Zealand and the US found that high salt could be having an effect at the level of the artery wall too. Previous research on salt reduction in high salt consumers had shown an improvement in artery function. This was a small study of 34 adults designed to see if the opposite could happen, that is, did adding extra salt to the diet for four weeks cause artery damage?

The answer was “Yes”. The extra sodium in the diet caused artery walls to stiffen as well as causing an increase in blood pressure. What was interesting about this study was that the effect of the extra salt was independent of blood pressure. So, if you eat plenty of salt-laden foods, but your blood pressure is fine, you are likely to still be causing artery damage. Put another way, don’t wait for the doc to tell you that your blood pressure is high before you eat healthy and cut the salt.

What does it all mean?

We fret so much about fat, saturated fat, trans fatty acids and anything that hints of grease, yet not give even a sideways glance at the salt content of foods. I have met only two people who know the definition of a low salt food (one that has less than 120 mg sodium per 100g) and very few people know that “non-salty tasting” foods like bread, cheese and breakfast cereal can pack a fair sodium punch. I don’t want to unduly worry you, but I do think it is time to take note of the one food additive that can definitely affect your health.

Just don’t expect me to be perfect. I love olives and cheese.

Reference: American Journal of Clinical Nutrition. 2010; 91: 557- 564

Salt on the wane

When I tell people that the most dangerous food additive they are likely to eat is salt they get really disappointed because they expect me to say an artificial sweetener or flavour, neither of which probably has any effect on their health. Salt is off the radar; no-one cares about salt.

It’s easy to tell people to stop sprinkling salt on their meals, but in reality this does little to reduce overall salt intake as 80% of the salt in the diet has been put there by food manufacturers.

At the Public Health Association of Australia annual conference recently in Canberra, we were told that the Heart Foundation’s tick program has reduced salt levels by 12% on average in foods with the tick. Kelloggs’ 12 most popular cereals have dropped their sodium by 40% on average. For example, the Cornflakes people ate in the 1980s had one and a half times more salt than the Cornflakes today. Yikes!

By 2013 all the major bread manufacturers will reduce their salt content to a maximum of 400mg/100g. This is a significant step because bread is the main salt source in many people’s diet.

Even Smiths crisps have dropped their salt by 17% and Vegemite has gradually got less and less salt over the last two decades. I’m not suggesting that bread, crisps and Vegemite are, or will become, “low salt”, just that they have a lot less salt than before. Good to see the food industry taking a step in the right direction.

Pasteurisation and calcium

Hannah asked whether pasteurisation (a process that kills bugs) or homogenisation (evenly distributes the fat) of milk affects the calcium content.

Dietitian Helen Mair from Dairy Australia tells us that neither process has any effect, which does make sense because pasteurisation is a very rapid heating and cooling process and minerals like calcium are very stable compounds in food. Even UHT (Ultra High Temperature) milk has retained its calcium.

As mentioned in earlier blogs, low fat milks generally have a higher calcium content.