What's the difference between wholegrain and wholemeal?by Jennifer Bowden
QUESTION: Are wholegrain and wholemeal essentially the same? If they’re not the same, is one just a crushed form of the other, or what is the difference?
ANSWER: It’s an intriguing question – how does a change in a food’s physical structure affect our health? For example, what happens when whole grain is turned into flour?
The topic has intrigued Jim Mann, professor of human nutrition and medicine at the University of Otago, for many years. Mann points to a 1999 Swedish study in the journal Diabetes Care in which adults with type 2 diabetes were given two identical, but structurally different, diets. One group was given foods such as whole red lentils and wholegrain bread whereas the second group had ground lentils and wholemeal bread.
Although “wholegrain” and “wholemeal” have no universally agreed definitions, whole grain typically refers to an intact grain that has all its key parts: bran, endosperm and germ.
Bran is the fibre-filled outer shell that protects the seed and contains B vitamins and minerals; endosperm provides energy for the seed and contains carbohydrates, protein and B vitamins; and the germ nourishes the seed, providing B vitamins, vitamin E, healthy fats, phytochemicals and minerals such as magnesium, calcium, iron, zinc and selenium.
The term wholemeal, however, has traditionally been used to refer to milled or ground whole grains, such as wholemeal flour. The same three components are present – bran, endosperm and germ – but they have a different physical structure.
Just to confuse us, New Zealand’s Food Standards Code defines wholegrain as “milled, dehulled, cracked, flaked or ground grains that contain the bran, endosperm and germ in the same proportions as the intact grain”. Hence, wholemeal is technically grouped under the umbrella term of wholegrain.
In the Swedish study, participants ate randomly assigned diets for 24 days. Intriguingly, although they ingested identical amounts of energy, protein, fat, carbohydrate, starch and dietary fibre, those eating the ground foods had higher glucose and insulin responses and higher LDL cholesterol levels – undesirable changes from a health perspective.
A healthy, lean adult would show less-pronounced effects, says Mann, but the same tendency would be apparent. What’s more, a processed whole-grain diet will also have other health consequences.
Beneficial gut bacteria are fuelled by the carbohydrates in whole grains. So, what happens if we substitute ground grains for the whole variety, resulting in more nutrient absorption in the upper intestine rather than the lower gut?
Mann’s research team are intent on finding out. “Is some of the benefit of dietary fibre a result of it not being too ground up or too refined or too processed?” he says. “It’s been intriguing me for years – if we can solve this one, I’ll retire.”
I’d put my money on foods that are as close to their natural state as possible providing the greatest nutritional benefits. That means eating bread with intact whole grains rather than the wholemeal variety made from finely ground flours. And while we’re on the topic, whole fruits and vegetables are a better bet than a smoothie made from the same ingredients.
In the end, the best whole grain or piece of fruit is the one we eat. So find ones you like and enjoy their health benefits.
This article was first published in the December 2, 2017 issue of the New Zealand Listener.
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