DON'T BELIEVE THE 

NUTRITIONAL HYPE

 

As a fan of old school hip hop I thought it only apt that Public Enemy should lead you into this latest blog. The hype that I am referring to is the way that many of our foods are demonised 👹 and thought of as being "bad" or conversely described as "superfoods" when in truth the picture is far more nuanced and as a result more interesting.

Sadly what makes headlines are statements like "all carbs are bad for you" and "Danger I ate some gluten and died" - the latter is a figment of my imagination, but I think you get where I am coming from 😉. The actual reality is that what we eat and how we eat it is a far more complex picture than that painted by the headlines/tweets/posts - food and the whole process of nutrition just ain't that simple.

Now, I want you to stop for a minute and imagine you are in a restaurant and have ordered a 3 course meal.

Now I bet you haven't ordered the following:

For your starter Sir/Madam a lovely glass of olive oil

And now for your main course some protein powder - Chef's recommendation

And to finish off might I suggest some carbohydrate in the form of sugar?

I would be very surprised if anyone did eat like that (though I am prepared to be proved wrong), however this is the way food is often presented to us - as if we really do eat components of food in isolation. There is a reason why I chose fats, protein and carbohydrate - they are what are termed macronutrients and tend to make up the bulk (in terms of their size) of food (water aside). The other term you might be familiar with is micronutrients and they consist of vitamins and minerals and tend to make a much smaller contribution in terms of their size (hence micro) but their nutritional value is just as valid.

All of the macro and micronutrients have different functions within our bodies, for example protein in growth, vitamin A in night time vision and iron for transporting oxygen. Each food doesn't contain just one single nutrient, but is in fact a rich mixture, even something like a potato

BUT HERE'S THE THING... the humble spud that you might consider to "just" be a carbohydrate has far more hidden under its skin (fibre to help keep your gut happy and healthy, vitamin C and B vitamins to name just a few). So the danger of viewing potatoes purely as a source of carbohydrate (and in some people's eyes "bad"), is that the sum is more than the parts (plus carbs are your body's preferred source of fuel - but that's for another blog)…

To get a better picture of what I am talking about, how about I take you on a whirlwind tour of your digestive system?

As you can see we start digesting/breaking down our food as soon as it enters our mouth as the saliva contains an enzyme* that starts the breakdown of cooked starch.

* JARGON ALERT* Enzymes are really cool molecules that are responsible for all kinds of chemical reactions in our bodies. They are very specific in terms of what they will react with, so for instance in terms of the digestive enzymes some only break down protein, others fats and others carbohydrates. This is often described as a "lock and key" - no matter how hard you try to force a key in if it's the wrong one, the lock won't open!

Once the food reaches the stomach  the process of protein digestion starts, after the stomach comes the small intestine where the vast majority of digestion takes place. Enzymes don’t work in isolation i.e. just one kind being released at a time, but are found in our digestive juices, as we eat a mixture of foods. Our bodies are perfectly adapted to digest all different kinds of foods if eaten at the same time, the only thing that might be affected is how fast the components travel down the gut, get broken down and ultimately enter the bloodstream.

So far, so great. We have this amazing piece of machinery (i.e. our gut) whirling away with lots of different enzymes all doing their jobs. 

Here’s another curve ball though- not only are foods complex in terms of their composition, but also they interact with each other when we start digesting them! Again this is often overlooked when trying to place foods on a theoretical hierarchy and reinforces the importance of not over-simplifying food and what we eat. The different components within the food interact with each other and can influence the speed at which they travel down the gut, for example fat delays the gastric emptying of carbohydrates i.e the carbs stay longer in the stomach before they enter the small intestine . 

So what does all of this mean in reality?

Well the glycaemic index* (GI) is a case in point. 

* This is basically a measure of how quickly the carbohydrate contained in a  specific food is broken down to glucose and enters the bloodstream. High GI quickly released into the bloodstream, low GI slowly released.

When people refer to the  glycaemic index, this tends to refer to the food in isolation (for example white bread) and as I said earlier, we don’t tend to eat just one kind of food by itself. Adding butter to the high GI white bread slows down how quickly the carbohydrate in the bread leaves the stomach and ultimately delays when it enters the bloodstream as glucose. 

Ah you might be thinking - this all sounds very interesting, but what relevance does it have to me and my fitness?

If we want to look at all of this from an exercise perspective then some research findings by Prof Louise Burke exemplifies what I am describing perfectly. Prof Burke has been a leading light in sports nutrition for the past 40 years, (she was Head of Sports Nutrition at the Australian Institute of Sport from 1990-2018) and has spent the best part of a decade investigating the roles of fats and carbohydrates in terms of endurance athletes. I will discuss this in further blogs, but for now I want to concentrate on some other findings of physiological importance. Endurance athletes’ performance was compared when they followed either a ketogenic diet (extremely high fat, minimal carbohydrate), or a more traditional carbohydrate rich diet. By adopting a holistic approach her team investigated  other biological markers when the athletes followed the 2 diets; they found that both the oral and gut microbiome was compromised in the subjects following the ketogenic diet. What this translates to is they had less "healthy" or "good" bacteria in their gut  and the number of nitrate-reducing bacteria were reduced in the oral cavity. I have already discussed the potential benefits of dietary nitrates (https://canbeetrootimprovesportingperformance.blogspot.com/2021/11/running-along-trails-during-autumn-is.html) - this finding means less of the nitrates (beetroot juice for example) get converted to nitric oxide and so hence you get less of a performance boost. The interplay between all these nutrients following dietary manipulation can have more far-reaching consequences that predicted - in this case to the detriment of nitric oxide production and hence reduced improvement in exercise performance.

So to wrap up here are my take home messages:

1. Food(s) are not just carbohydrates, fats and proteins in isolation and we certainly don't eat them like that!

2. Try not to think of certain foods as "carbs" and avoid them as they will contain several other really valuable and important components such as fibre and minerals 👍

3. When we eat them and digest them, the macronutrients (fat and protein in particular) can influence the rate at which the food is digested, but NOT how as we have enzymes to take care of proteins, fats and carbohydrates. 👏