The scoop on redefining wholegrains with Prof Jennie Brand-Miller.
‘Consume more wholegrains is enshrined in dietary guidelines around the globe and has become something of a mantra by doctors, dietitians and nutritionists’ says Prof Jennie Brand-Miller. ‘But does the science stack up to scrutiny? When you see wholegrains on a pack, do you assume it’s the real McCoy? Has it got everything that the original had – all the micronutrients and characteristics that make wholegrains into health foods? Well, I think we are being hoodwinked. Wholegrain products might have started with the germ, the endosperm and the bran of the grain, but often the finished product has been cooked, flaked, toasted, puffed and popped beyond recognition. It’s a long, long way from the grain that came in nature’s packaging.
It’s true that many scientific studies have found that consuming more wholegrains (brown bread, brown rice, brown pasta) is associated with lower risk of cardiovascular disease. For example, the Nurses’ Health Study reported that women who ate wholegrains every day – generally wholegrain breakfast cereals, brown rice and wholewheat bread – were 30% less likely to develop heart disease than women eating merely one serving a week. Unfortunately, studies like this don’t prove that wholegrains are responsible for the good health outcomes. It’s highly likely that people who choose to eat wholegrain foods are unique human beings and health conscious in all sorts of ways. They don’t smoke, they try to be physically active, they eat less red meat and more fruit and vegetables. Of course, good studies will statistically “adjust” for these confounders, as they are called. But I have a niggling feeling that not all the confounders may have been accounted for. Perhaps the person who chooses brown rice over white rice looks after their health in ways that are not yet recorded by researchers eg they eat more slowly, they breathe deeply and they get less stressed.
There are clinical trials in which wholegrains were consumed as one component of a healthy eating pattern (less saturated fat and salt, more fruit, vegies and fibre) but we can’t conclude that the presence of wholegrains were essential for the good outcome. I mention this because there are very few clinical trials that have directly compared a “brown” diet with a “white” diet that was otherwise identical. In the largest clinical trial of its sort to date, UK researchers found that when they provided 316 overweight men and women with a range of wholegrain foods and asked them to substitute them “like for like” for refined grain foods in their typical diet over a 16 week period, there was not even a hint of difference in heart risk (cholesterol, triglycerides, insulin sensitivity and a range of common inflammatory markers) between those who substituted wholegrain foods into their diet, and those who didn’t (the control group). Rather than substitute wholegrains for refined grains, the people actually ate the wholegrains as well as the refined grains, and the authors postulated that this may be the way that the average person interprets dietary guidelines that simply advise people to eat more wholegrains (and not cut back on refined grains). This study should have sounded a note of caution about health claims for wholegrain-rich foods and cardiovascular health … but it still hasn’t.
More recently, an editorial in a scientific journal extolled the virtues of wholegrains and the dangers of refined grains. Yet the editorial was actually prompted by a new study that found that replacing saturated fat with carbohydrates with high-glycemic index (GI) values was associated with increased future risk of myocardial infarction in a cohort of Danish men and women. In contrast, replacing saturated fat with carbohydrates with low GI values appeared to be protective. The editorialist, however, equated high GI carbohydrates with refined carbohydrates and sugar. Unfortunately, this is unscientific, wishful thinking. The reality is that for most cereal products today, both the “white” version and the “brown” version have a high GI. Nor is it correct to imply that low GI carbohydrates are less processed and refined. Nearly all kinds of white pasta have a low GI, as do some varieties of white rice, canned legumes, fruit juices, dairy products (sweetened or otherwise), and many confectionery items containing refined sugars. Thus many low GI foods are “processed” products. Nonetheless, low GI and low glycemic load diets have been associated with good health outcomes in scores of observational studies and clinical trials. What’s more, the “health bias” that accompanies diet rich in wholegrain foods is absent because the GI is still a term that means little to many.
For all these reasons, I’d like to suggest that we re-define wholegrains as “foods that not only contain the germ, the endosperm and the bran, but also the GI characteristics of the original grain.” At least then, we might see some real benefits of eating wholegrains. In the meantime, here are some of my favourite low GI wholegrain foods that are easy to find in your supermarket:
- Pearl barley
- Low GI brown rice – there are even speedy 2-minute microwave options including brown basmati
- Wholemeal/wholewheat spaghetti and pasta shapes.’