Amy Vong and Wong Hui Xin, dietitians at Mount Elizabeth Novena Hospital, tells us exactly how whole grains are beneficial for our health.
How exactly do whole grains benefit a person?
Amy Vong: Current scientific evidence shows that consuming whole grains is linked to better health in many ways.
It lowers the risks of chronic diseases like coronary heart disease, diabetes, and cancer, and helps control your body weight. This is due to various reasons:
Firstly, whole grains help us feel fuller for a longer time. This increased sense of satiety helps us avoid overeating.
Secondly, the higher fibre content in whole grains slows down the absorption of carbohydrates, keeping your blood sugar level steady – which is especially important for warding off potential diabetes complications such as heart disease, kidney disease, nerve damage and stroke.
Thirdly, whole grains have antioxidant and anti-inflammatory properties, promoting the growth of healthy bacteria in the gut, which helps digestion and metabolism, as well as reduces allergies.
Taken as a whole, the research points us towards including whole grains in a balanced diet and healthy lifestyle.
How significantly do whole grains lower health risks?
Amy Vong: When tracking groups of people over time or conducting surveys on people's diets, researchers have found that people who eat a diet based on whole grains generally tend to have a lower body mass index (BMI) and better overall health.
If you are in the habit of eating whole grains, you have a significantly lower risk of contracting coronary heart disease – a risk lowered by 20 – 40%. The lowered risk of diabetes is similar at a 20 – 30% reduction.
People who consume the greatest amounts of whole grains, beyond experiencing the benefits above, also have a lower risk of developing some cancers.
What does the latest research on whole grains say?
Amy Vong: In general, we have been seeing an increase of evidence that bolsters older findings, and we understand better how a diet high in whole grains helps in general health.
Most of the evidence for whole grains comes from observational studies, where we have limited control over the participants' other lifestyle aspects (which also impact their health) besides their diet.
However, there has been an increase of evidence for the benefits of whole grains from intervention studies (where tests resemble drug tests), which are generally more stringent than observational studies.
We are therefore now even more confident that whole grains are good for health.
Do some whole grains provide more benefits than others?
Wong Hui Xin: There are differences between types of whole grains, and each person will need differing amounts.
Grains, such as wheat, rice, oat, barley and rye, vary markedly in the types and amounts of phytochemicals they contain depending on their genetics and a variety of agro-climatic factors.
Whole grains are generally higher in the 'good stuff' – dietary fibre, vitamins, minerals, and phytochemicals. They have similar macronutrient compositions, ie. energy, carbohydrate, protein and fat content.
However, different whole grains have different nutritional profiles.
Certain grains such as wheat, oat, barley and rye have higher fibre content (more than 10g of fibre per 100g). If your diet is low in fibre, you will want to eat more of these.
Research has also shown that beta glucan, found in oat and barley, is more effective in lowering blood lipids (fat) as compared to other grains. If you need to lose weight, replacing refined grains with oat and barley may help with the process.
On the other hand, corn has the highest phenolic acid content, followed by wheat, oat, and rice. The phenolic acid concentration of whole grains corresponds to their antioxidant capacity.
How much more beneficial is eating unprocessed whole grains (eg. oats) instead of processed whole grains (eg. wholemeal bread)?
Amy Vong: Whether it makes a big difference depends on each individual. As a rule, we should all be making healthier choices, but an underweight 17-year-old and an overweight 70-year-old will definitely have different priorities.
To make sense of how you should be adjusting your diet, we first need to understand the difference between unprocessed whole grains and processed whole grain foods.
On one end we have unprocessed whole grains which have the bran, endosperm, and germ intact.
On another end, we have refined grains, which have been stripped of the bran and germ.
Processed whole grain foods fall somewhere in the middle.
The United States Food and Drug Administration (FDA) in 2006 defined 'whole grain' as any mixture of bran, endosperm and germ in the proportions as in an intact grain – but the grains can be, and usually are, processed so that the 3 parts are separated and ground before being incorporated into foods.
Moreover, for a food product to be considered 'whole grain', the FDA says it must contain at least 51% of whole grains by weight. Processed whole grain foods may therefore have lower fibre and nutrient and antioxidant levels compared to intact grains.
In practice, when you buy whole grain bread from the supermarket, that bread will have a whole other list of ingredients that are not whole grains. A whole grain bread made with plenty of sugar or sweetened dried fruit is going to have different effect on your body from, say, brown rice or oats.
At the supermarket, we should be choosing whole grain products that are higher in fibre. Also, remember that including a variety of whole grain foods in the diet is the best way to reap the different health benefits.
The following are examples of unprocessed whole grain, and whole grain food products:
- Unprocessed whole grain: wheat, oat, barley, maize (corn), rye, sorghum, teff, millet, triticale, amaranth, buckwheat, quinoa
- Whole grain food products: whole wheat flour, whole wheat bread, rolled oats / oatmeal, popcorn, rye bread, whole grain pasta, whole grain tortilla, whole grain breakfast cereals, whole grain snacks and baked goods (eg. crackers, bars, muffins, etc).
Are there certain groups of people who should pay more attention to eating whole grains?
Wong Hui Xin: Everyone should consume whole grains over refined grains to help reduce risk of developing heart disease, diabetes, and cancer, as well as for weight control and digestive health.
Besides eating a diet based on whole foods, we should also adopt a healthy lifestyle by engaging in physical activities for 150 minutes each week.
Whole grain foods may particularly benefit people with diabetes and overweight individuals.
For people with diabetes, eating whole grain foods helps to control blood sugar levels better due to the higher fibre content which slows down the absorption of carbohydrates.
For overweight individuals, eating whole grains helps to promote satiety, which helps reduce food consumption and overeating.
