VIEWPOINTS FROM THE CHARLES PERKINS CENTRE, SYDNEY UNIVERSITY

PROF JENNIE BRAND-MILLER ON NUTRITION FOLLIES: #3 – WHOLEGRAIN FOLLIES

• Wholegrain or wholewheat products have everything that’s in the original grain.
• Substituting refined grains with unrefined grains improves your health.
• Consuming wholegrain products reduces your risk of heart disease.

Wholegrain or wholewheat products have everything that’s in the original grain
Most consumers seeing “wholegrain” or “wholewheat” on a packaged food assume it has everything that’s in the original grain – all the vitamins, minerals and dietary fibre that make traditional grains such a healthy choice. That assumption is wrong. Products labelled “wholegrain” are rarely the whole grain that came in nature’s packaging (Why ‘whole grain’ is not always healthy). In many cases, the finished product has been soaked, ground, milled, cooked, flaked, toasted, puffed and/or popped beyond recognition. Indeed, this is why most breakfast cereals whether highly refined or not are fortified with certain vitamins and minerals.

Substituting refined grains with unrefined grains improves your health
Advice to consume “wholegrain foods” is enshrined in dietary guidelines around the globe. To put it simply, that means they are telling us we should consume most of our cereal products as wholegrains aka eat a “brown” diet (no white bread, not even sourdough, no white rice and no golden yellow durum wheat pasta). In my book, that’s quite a sacrifice. And there’s a question: does brown diet science convincingly show that substituting refined grains (a white diet) with less refined (brown) grains improve our health? Not yet.

It’s true that many observational studies report that consuming wholegrain products is associated with lower risk of cardiovascular disease. The Nurses’ Health Study showed women who ate the most wholegrains (an average of 2.5 servings per day), generally as wholegrain breakfast cereals, brown rice and wholewheat bread – were 30% less likely to develop heart disease than women eating next to none.

But such observational studies don’t actually prove wholegrains are responsible for the good health outcomes. It’s just an association. It’s probable people who choose to eat wholegrain foods are health conscious in all sorts of ways. They don’t smoke, they try to be active, they eat less red meat and more oily fish, fruit, vegetables and legumes. Of course, good studies statistically adjust for known confounders. But residual confounding may still be present. For example, to my knowledge, they never adjust for salt intake. And perhaps the person who chooses brown rice over white looks after their health in ways that having nothing to do with food at all, e.g. they breathe deeply, they sleep better, and they get less stressed.

The best test of the wholegrain hypothesis is whether wholegrain products produce improved outcomes when we switch from refined to wholegrain cereals as part of a randomized, controlled trial. You’ll find surprisingly few 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 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. Over a period of 2–4 months, there was not even a hint of difference in cardiovascular risk. In other words, there was no difference in blood 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).

More recently, a very small American study in 33 participants found that wholegrain foods improved diastolic blood pressure but it had absolutely no effect on body weight, fat loss, systolic blood pressure, total cholesterol, or LDL cholesterol compared to the control diet.

Consuming wholegrain products reduces your risk of heart disease
So where does that leave the consumer wanting to make better food choices and reduce intake of saturated fat? What should replace those saturated fat calories? Foods with more carbs, or more good fats, or more protein, or a combination of all three? First of all, the nutritional attributes of the replacement foods are critical.

• The carbs should be good carbs: slowly digested and absorbed foods such as beans, peas, lentils, pasta, cracked wheat, couscous, minimally processed grains and the traditional foods made from them. Have at least 5 serves of fruit and vegetables every day.
• The fats should be good fats: avocado, nuts, olive oil, canola oil and rice bran oil.
• The proteins should come from a combination of sources: fish and seafood, lean red meat, pork, poultry, eggs and legumes.

Secondly, don’t make the mistake of thinking any wholegrain product will be a good replacement for saturated fat. I say this because several studies have reported that replacing saturated fat with high GI carbohydrates (wholegrain or otherwise) was likely to increase future risk of heart attack. In contrast, replacing saturated fat with low GI carbs or polyunsaturated fats (e.g. safflower oil) appears to be protective. Low GI diets and low glycemic load diets have been associated with good health outcomes in scores of observational studies and clinical trials. Here are three useful studies to look at.

• Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index
• Glycemic index, glycemic load, and chronic disease risk—a meta-analysis of observational studies
• Glycemic response and health—a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes

Source: Low GI Vegetarian Cookbook (Hachette Australia).

FAQ: Are all wholegrains low GI?
No. People assume wholegrains are low GI because they have more fibre. But this is wishful thinking. The reality is most processed cereal products today, white or brown, have a high GI. Nor is it correct to imply that all low GI carbs are less processed and refined. White pasta (cooked al dente) has a low GI, as do some varieties of white rice. Where does that leave the consumer? Choose those proven to be low GI, preferably whole grains, which contain more micronutrients. Here are some less processed staples we happily call wholegrain:

 
Professor Jennie Brand-Miller (AM, PhD, FAIFST, FNSA, MAICD) is an internationally recognised authority on carbohydrates and the glycemic index. She holds a Personal Chair in Human Nutrition in the Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders and Charles Perkins Centre at the University of Sydney. She is the co-author of many books for the consumer on the glycemic index and health. Her latest book (with Professor Arne Astrup and Dietitian Christian Bitz) is The Nordic Way (Pam Krauss Books).