ice cream

Personalising dietary advice – Banana vs Cookies

Have less ice cream or chocolates, and more fruits and vegetables – that’s great dietary advice for good health right? Wrong!  Well, at least for some people.

Let me pose you a simple question : Which do you think will lead to higher blood glucose levels after consumption – a banana or several cookies? (let’s say they were Famous Amos)


Cookies of course!  (you say?)

This group of Isreali researchers attached a continuous glucose monitor to 800 participants and measured their responses to over 40,000 meals. They found that there was high variability in post-meal blood glucose responses.

Let me illustrate what this means:

cookies and bananas
Personalised Nutrition by prediction of glycemic responses, Cell, 19 Nov 2015

Let’s have a look at what happened here. The graphs above plots the blood glucose levels of 2 different participants after consuming a banana, and several cookies, on separate occasions. Fascinatingly, for Mr Participant No. 445, he had a big spike after the banana and a muted response to the cookies. While Mr Participant No. 644’s blood glucose level went bonkers on the cookies and didn’t get much change on the banana.

(oh I’d love to be participant No. 445 : I can binge on cookies all day!)

This is probably one of the more extreme examples in the study, which the authors have handpicked to prove their point. But it still belies the point that there is still so much about our bodies that we do not understand yet.

Outwardly, we look the same, homo sapiens : 2 eyes, a nose, a mouth, 2 arms, 2 legs. But there is a significant amount of genetic variation in all of us. Simplistically, it’s plausible and not difficult to believe that the difference in response to foods among individuals could be related to expression of enzymes and other molecular pathways. Mr 644 could have higher amounts of a specific enzyme that metabolise the carbohydrates in bananas fast, leading to the large spike.

Does this matter? To most of us, it doesn’t. Our bodies have self-regulating mechanisms (involving the hormones insulin and glucagon) that keep the glucose levels in our blood at a relatively stable level over long periods of time.

However, for someone living with diabetes, this is crucial. In diabetes mellitus, the body has lost a good amount (or even most) of the glucose self-regulating function.

It’s like turning on the manual-mode in your automatic car : now you need to do the gear changes on your own, when before it changed automatically once you reached a certain speed.

tesla automatic
Whoa…automatic! (

Understanding which foods cause your blood glucose level to rise high into the mountains and avoiding them is essential to reduce glucose load and variability. Lowering glucose load and variability leads to reduced symptoms and reduced long-term risks.

This study shows that general recommendations and intuition doesn’t always work. The only way to know is to test and monitor your own blood glucose levels regularly (using a glucometer), before and after each meal, so that over time you know which foods work for you.  Dietary advice should not be ‘one-size-fits-all’, but rather personalised based on individual characteristics.

As continuous glucose monitors become smaller, cheaper and more consumer-friendly, leading to widespread use, we’ll be able to better understand the relationship between our diet and diabetes, and manage it better. There has already been baby-steps in predicting a person’s glucose profile, based on behavioural data, blood tests and and microbiome analysis. I say baby-steps because it’s a still a long way before we can generalised this to the wider population, given our genetic diversity and enormous variety of food available.

Until we unlock the answers to the genomes and microbiomes in our bodies – that would be the holy grail.

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