Online exclusive
As well as Jennifer Bowden’s columns in the NZ Listener and here at listener.co.nz, subscribers can access her fortnightly “Myth busters” column, in which she explores myths around food and nutrition. This week, she looks at whether a low-carb lifestyle is as good as it’s made out to be.
Carbohydrates have earned a rather dark reputation in recent years, thanks largely to the proliferation of high-carb ultra-processed foods, confusing health headlines and a culture of online influencers peddling miraculous low-carb life stories.
From trendy low-carb plans to widespread fear of weight gain, the idea that carbs are inherently bad has led to confusion about their role in nutrition. In reality, not all carbohydrates are created equal. Far from being the moral downfall of our lives, the right carbohydrates are essential for providing energy, supporting brain function, and promoting overall wellbeing. So, it’s time to reclaim carbs as a vital player in a balanced, healthy diet.
Carbohydrates are one of three macronutrients in food that fuel our bodies. The others are protein and fat. Carbohydrates contain building blocks called saccharides, or sugars, joined in short or long chains.
The simplest forms are single saccharide units, such as the fructose found naturally in fruit, or two saccharide units bonded together, such as the sucrose found in sugar cane, which consists of a glucose molecule and fructose molecule bonded together. Sucrose is refined from sugar cane or sugar beet to produce the white refined sugar added to many processed foods, coffees and baking.
When many saccharide units are bonded together in chains, they’re called polysaccharides. These carbohydrates are found in ultra-processed foods like instant noodles and fries (which scientists advise us to avoid), and everyday foods such as pasta, bread and potatoes.
But polysaccharides, which include many forms of dietary fibre, are also found in fruit, vegetables, nuts, seeds, grains and legumes – nutritious foods we’re encouraged to enjoy for good health. So how can polysaccharides be harmful in one food and good in another?
“People don’t eat nutrients; they eat food,” was the sage advice of my nutrition lecturer decades ago. None of us head to the supermarket to buy a loaf of carbohydrates or a bottle of calcium for our breakfast.
Instead, we buy a loaf of bread or a bottle of milk, then we top our white toast with jam or pour milk on our oat-based muesli. Both breakfasts contain carbs, but one is more nutritious than the other.
“Ditch the black-and-white idea about carbs being bad, and while you’re at it, ditch the food guilt, too.”
Contrary to popular belief, the mere presence of carbs is not the primary deciding factor in determining how nutritious a meal is. Instead, “carbohydrate quality rather than quantity determines major health outcomes,” according to a substantial 2019 review in the Lancet journal.
University of Otago researchers combed through nearly 135 million person-years of data from 185 prospective studies and 58 clinical trials with 4635 adult participants. They found a 15-30% decrease in all-cause and cardiovascular-related mortality, and incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer when comparing the highest dietary fibre consumers with the lowest consumers (fibre is typically a form of carbohydrate).
Clinical trials showed significantly lower systolic blood pressure and total cholesterol when comparing higher with lower intakes of dietary fibre. Indeed, those eating between 25g and 29g of dietary fibre each day had the lowest risk of critical outcomes. Higher intakes of dietary fibre may even protect against cardiovascular diseases, type 2 diabetes, and colorectal and breast cancer.
The research team concluded that higher intakes of dietary fibre and whole grains have a “striking dose-response” type relationship to several non-communicable diseases; in other words, the more fibre and whole grains one consumes, the lower the risk of those diseases.
It means good health is less about avoiding carbs and more about choosing your carb-containing foods wisely.
Ditch the black-and-white idea about carbs being bad, and while you’re at it, ditch the food guilt, too. Instead, look for ways to include nutritious whole foods such as whole grains, fruits, vegetables, nuts, and legumes to boost your intake of fibre and complex carbs, which will enhance your health and wellbeing.
