In this blog, we unpack a report published by the British Medical Journal in February this year, spotlighting the relationship between cereal grain intake and cardiovascular disease.
This one is a particularly interesting piece of research as it dissects specific food groups, rather than just adding fuel to the fire of the debate around whether carbohydrates are ‘good’ or ‘bad’.
A bit of background info before we begin:
The study analysed data from 137,130 participants.
These participants were from 21 different countries.
All participants were aged between 35-70.
Participants were both male and female.
The participants were followed up every 3 years, from 2003-2019.
During this time period, the study recorded any incidents of cardiovascular disease, disease occurrences or any registered deaths.
The participants also each kept a food diary, which was analysed to assess dietary intake and portion sizes.
Researchers scrutinised the intake of 3 main food groups:
- Refined grains (cereals, white bread, white pasta, etc.)
- Whole grains (wholemeal pasta, wholemeal flour, brown rice, oats, etc.)
- White rice (white rice was examined separately, as many of the countries participating in the research were from Asia, where rice is a diet staple.)
So, what did the findings reveal?
The relationship between geography and grains:
The highest consumption of refined grains was found to be in China.
The highest intake of rice was amongst Southeast Asians.
The highest intake of whole grains was reported in African countries.
Getting granular: grain by grain
Now, let’s break more of the findings down…
When looking at low intake of refined grains (less than 50g per day) vs. a high intake (more than 350g per day), high intake carried:
- 28% higher risk of mortality.
- 33% higher risk of cardiovascular disease.
- 47% higher risk of stroke.
For every 50g daily increase in refined grain intake, risk of mortality and cardiovascular disease increased by 2%, regardless of whether an individual took medication for cardiovascular-related health issues or not.
Not great news for refined grains!
There was an increased risk of health issues for individuals who had little to no whole grains in their diet, but not a significant reduction in those who had lots.
It’s the phytochemicals and vitamins found in whole grains that mean many believe them to be heroes of cardiovascular and metabolic health. However, this study suggests that any major health benefits come from the exclusion of refined grains, rather than the inclusion of whole grains.
Plus, when overcooked or consumed alongside sugary foods, the benefits of whole grains are cancelled out.
The reason the study may not have seen a distinct positive impact of whole grains on health is due to the wide variety of whole grain types, volume and cooking methods across the 21 different countries.
However, there are several studies out there that do show a positive effect of whole grain intake on cardiovascular health, so it’s certainly a topic that should be researched further.
What was the verdict on white rice?
Interestingly, there was no difference in health risk regardless of white rice intake.
However, eating three slices of white bread per day was associated with a 5% higher risk of mortality, with no significant difference if this was whole wheat bread or rice equivalent (1 cup).
Why are refined grains so bad for us?
As with most things, moderation is key. A slice of white bread or a bowl of your favourite cereal every now and again isn’t going to harm you. That said, refined grains are best in small doses.
The main reason for refined grains being bad for our health is due to the process by which they are made. This process strips the fibre, vitamin and mineral content down to a minimal level, leading to higher spikes in blood sugar post-consumption.
This, in turn, increases insulin concentration, making you feel more hungry throughout the day, causing you to consume more calories and develop more excess body fat.
It’s a domino effect.
Words of wisdom:
“Cereal is a medium through which we learn to confuse hunger with marketing.” – Bee Wilson, First Bite: How We Learn to Eat.