Whole grains all equal?

[Article updated on 19/09/2023]

For several years, we have only been talking about “whole grains”, but what additional benefits can they provide for health and are they all equal?

What is a whole grain?

A so-called complete cereal includes all the fragments of the cereal:

• The husk: composed of the bark and bran (15% of the grain): source of fiber, group B vitamins, trace elements (minerals) and antioxidants;
• Almond (80% of the grain): source of energy in the form of carbohydrates (starch);
• The germ (5% of the grain): vitamin fraction (B, E) and antioxidants.

Is white flour whole grain?

Traditionally in France, white flour is refined. This technological manipulation consists of separating the almond from the rest of the cereal grain (husk and germ) then grinding it to reduce it to flour. This step is often carried out because the germ and the husk contain nutrients likely to deteriorate the flour more quickly. But removing these fragments from the rest of the grain removes the vitamins, minerals, fiber and antioxidants, leaving only the carbohydrates in the form of starch.

As industrial technologies evolve, it is now possible to preserve the envelope and the germ in order to benefit from the most interesting fractions. Depending on the degree of refinement, we will go from a T 110 flour (brown or wholemeal), to a T 80 flour (semi wholemeal), to a T55 flour (white).

A whole grain will be richer in minerals, fiber, vitamins and anti-oxidants, with a slightly lower amount of carbohydrates.

A quick summary of the main nutrients:

For 100g (source: https://ciqual.anses.fr/)

		T110			T80		T55
Energy (Kcal)		343			355		346
Protein (g)		10.3			10.9		9.9
Carbohydrates (g)		68.6			73.2		73.7
Lipids (g)		1.5			1.18		1
Fiber (g)		6.8			4.2		3.2

Starch, the complex carbohydrate

L’starch is the majority source of carbohydrates present in flour (96%). This starch has a complex biochemical structure. Our body can digest it thanks to enzymes present in our body: amylases.

These enzymes, like a mechanic working in a car scrapyard will break down the vehicle, will gradually degrade the starch. This work takes a long time, which is why we call starch “a slow sugar ” or “complex carbohydrates » like the “fast sugars” Or “simple carbohydrates » contained for example in sodas or white sugar.

Concept of glycemic index

This biochemical degradation work is the same for refined cereals as for whole cereals. However, the presence of dietary fiber complicates the work of enzymes.

Let’s take the example of our mechanic, who this time recovers a car that was the victim of a storm and covered in branches: he has more difficulty accessing the vehicle and his work will take even longer.

This is the case with so-called wholemeal flour, the fibers prevent the action of enzymes for the degradation of starch. Concept ofglycemic index : the carbohydrates contained in the food are broken down then enter the blood circulation and cause an increase in blood sugar levels (glycemia).

The less blood sugar is increased, the lower the glycemic index. So-called wholemeal flour will therefore have a lower glycemic index than refined flour.

The benchmark often used in France is that of glucose, we compare the glycemic indexes (GI) of foods with glucose equal to 100 as a reference point. In this benchmark refined white flour has a glycemic index of 85 while wholemeal flour a glycemic index of 60. These glycemic indexes are still in the category of high glycemic indexes (GI > 60), while dried fruit flours (almonds, hazelnuts) have a low glycemic index (GI < 21).

To go further, it is necessary to take into account not only the glycemic index but also the quantity consumed, we will then speak of glycemic load.

Faced with all these observations, it should be said that a whole grain is richer in nutrients and trace elements and that its glycemic index is lower.

Are all whole grain products equal?

We have just seen that the properties of cereals can be modified depending on their composition (whole cereals with a lower glycemic index). However, other properties can be modified depending on the technological treatments applied to them.

What is extrusion?

Extrusion is a technological process aimed at applying pressure to a cereal, it can be completed with cooking or not. This process leads to significant modifications at the structural level of the transformed material, such as the gelatinization of starch or the denaturation of proteins. Concretely, the starch will be more accessible to the enzymes. Let’s take the example of our mechanic again, this time: the car to be dismantled arrives partially dismantled, the owners of the vehicle had recovered the valuable parts, so his work will be even faster. It is the same with this type of technological process, whether for extruding cereals, or even blowing them. The glycemic index will therefore be increased, the denaturation of proteins will also reduce the phenomenon of satiety.

The consumption of cereals of an extruded nature generates a more rapid increase in blood sugar (leading to a more brutal hormonal response), and reduces the phenomenon of satiety. However, manufacturers of breakfast cereal products are careful not to mention this information in their “pro-whole grain” campaign. Indeed, it is not very salesy to promote a food product causing low satiety.

The wave of “healthy eating” also interferes in our food choices; currently the simple fact of consuming whole grains is satisfactory, without taking into account the technological treatments applied to the grains. To date, there are no scientific studies relating to the analysis of the glycemic indexes of extruded cereals, whether whole puffed or not.

Don’t panic, however, for consumers of breakfast cereals!

The glycemic index of white bread is also high, and is equivalent to breakfast cereals. However, be sure to prefer them in the whole version, and to combine them with a fruit for fiber (see above: reduction in the GI of the meal). It is still preferable not to consume these products outside of meals (like our teenagers).