Nutrition Research > Whole Grains

Whole Grains

Quick Facts

Most North Americans do not consume the recommended amounts of whole grains and are missing out on the many benefits.

Research shows that consuming whole grains is associated with a number of positive outcomes, from reduced risk of heart disease, stroke, cancer, diabetes, dementia and obesity to improved blood pressure, cholesterol levels, blood glucose control, and a healthier weight.

Including whole grains in your daily routine is easy. Choose whole grain whole wheat breads or swap out regular pasta for a whole grain version.

What about whole grains?

Whole grains are the seeds of cereal grasses. Examples include wheat, barley, oats and brown rice. Seeds can be used in their whole form, cracked, or ground into a flour that contains the entire grain or kernel.

Whole grains contain the entire grain kernel, which is made up of three parts – the bran, germ, and endosperm. You can learn more about the parts of the wheat grain here.

Foods that are made with whole grains are high in dietary fibre. They also contain important vitamins and minerals, especially zinc, magnesium, potassium, and phosphorous.

Dietary recommendations

Countries around the world agree, grains are an important part of a healthy dietary pattern.

  • Canada’s Food Guide emphasizes including grains with every meal by focusing on filling one-quarter of your plate with whole grain foods.
  • In the USA, the ‘My Plate’ dietary guidelines suggest about one-quarter of the meal be grains and to focus on making at least half of these whole grains.
  • In the United Kingdom, the ‘Eatwell Guide’ indicates one-third of the meal be made of starchy carbohydrates with an emphasis on whole grain options.

Most North Americans do not consume adequate amounts of whole grains in their diet based on government and public health recommendations and are missing out on the many benefits.

It’s important to note, most nutritional research has focused on grains (including wheat) for human health, but not always wheat on its own.

You can read more about whole grain recommendations here:

Nutrient shortfalls

Canadians are not meeting the recommendations for many nutrients, vitamins, and minerals, which can be found in whole grains like wheat.

  • The majority of Canadian adults have inadequate intakes of vitamin A, vitamin D, vitamin C, magnesium, calcium, potassium and fibre.
  • Most Canadian children and adolescents lack sufficient potassium, vitamin D, calcium, magnesium and fibre.
  • Some of these nutrients have been identified as nutrients of concern by the Institute of Medicine (IOM) due to the underconsumption by the population and their importance for human health.
  • Dietary fibre has been classified as a nutrient of public health concern because under-consumption has been linked in scientific literature to adverse health outcomes like constipation, digestive issues, higher body weight and an increased risk of intestinal cancers. You can learn more about fibre here.

Grain foods, including whole and refined grains, are important sources of nutrients for Canadians.

  • Grains contribute approximately 45% of our daily intake for folate, 41% of our daily intake for iron, and 35% of our daily intake for dietary fibre.
  • Canadian children and adults consuming grain foods have higher intakes of fibre, folate, iron, niacin, thiamin and riboflavin, compared to those who consume the lowest amount of grain foods.
  • Removal of grain-based foods can lead to deficiencies of several key nutrients. For example, an analysis of 2009-2016 American diets showed that removal of grain foods from the diets of adults and children could result in deficiencies of thiamin, iron, magnesium, calcium, zinc, and dietary fibre in 30 to 50% of the population not meeting recommendations for thiamin, iron, magnesium, calcium, zinc, and dietary fibre1

Whole grains are a great way to increase dietary fibre

The recommended intake of dietary fibre for Canadian women and men is between 25 to 38 grams of dietary fibre per day, however, most adults are not reaching this amount.

In fact, most Canadians are only reaching about 50% of the recommended amount of fibre intake per day. Inadequate fibre intake has been linked to constipation, digestive issues, higher body weight, and even an increased risk of some diseases such as intestinal cancers.

Considering this lack of dietary fibre in the diets of Canadians of all ages, it is important to focus on whole grains as a great source of both soluble and Insoluble fibre.

You can read more about dietary fibre here, or read these source studies below.

Whole grains contribute to risk reduction of disease and improve human health

Research shows that consuming whole grains as part of a healthy, balanced diet is associated with improvements in many health outcomes including a reduced risk of heart disease, stroke, cancer, diabetes, dementia, and obesity as well as improved blood pressure, cholesterol levels, and blood glucose control, and a healthier weight.

Gut health, digestion, and colorectal cancer

Healthy beneficial bacteria in our intestine are important for the successful digestion of food and the absorption of nutrients. They are also important due to the role our gut bacteria play in modulating the risk of many diseases.

The majority of the research on grains and wheat, in particular, show beneficial effects from the consumption of these foods on our gut health and gut microbiota. Many of these studies used whole grain breakfast cereals and saw improvements in the number and diversity of beneficial gut bacteria. These results are likely due to the dietary fibre content of these foods.

Colorectal or bowel cancer is common worldwide but is especially prevalent in industrialized countries like Canada. Areas with lower rates of colorectal cancer have fibre-rich diets. The consumption of whole grains and fibre has been linked to a reduced risk of colorectal cancer.

You can read more about gut health and wheat here, or read these source studies below.

Whole grains and body weight management

The evidence is overwhelmingly positive that the consumption of dietary fibre, particularly from whole grains, contributes to lower measures of body weight and a decreased tendency to gain weight over time.

There are a few proposed mechanisms at work here:

  • Whole grains promote satiety (feeling of fullness) and decrease appetite after their consumption.
  • Whole grains are high in fibre which support healthy gut bacteria and colonic fermentation.
  • Diets with adequate dietary fibre intake also tend to include nutrient-rich fruits and vegetables and whole grains – these diets are generally more nutrient dense and less energy dense (high nutrients, but lower calories).

In a survey of children and adolescents, those who ate breakfast that included a variety of grains such as wheat, had a lower prevalence of obesity than those who did not eat cereal at breakfast or who skipped the meal altogether. Children and adolescents who skipped breakfast also showed higher body weight.

Maintaining a healthy body weight is also beneficial for lowering the risk of diseases such as diabetes and cardiovascular disease (CVD).

Whole grains and diabetes

Research supports an association between higher dietary fibre intake and lower diabetes incidence. This is mainly due to the combined beneficial effects that whole grains and fibre consumption have on enhancing insulin response and reducing blood glucose levels in the blood after a meal.

Studies are also supportive of the benefits whole grain intake may have on glucose metabolism.

You can read more about wheat and diabetes here, or in the studies below.

Whole grains and heart health

Reviews of the science support the role of whole grains and cereal fibre in the reduction of risk of cardiovascular disease (CVD) based mostly on observational studies.

There are a few mechanisms of action that help to explain the beneficial effects of whole grains on heart health.

  1. Whole grains are high in fibre which decreases the absorption of cholesterol from our food and into our blood. High cholesterol levels in our blood can create blockages in our blood vessels and heart.
  2. Whole grains also decrease blood pressure, which prevents our heart from working harder than it needs to in order to pump blood around our bodies.
  3. Whole grains improve glucose and insulin responses in our blood which, if not managed properly, increase your risk of heart disease.
  4. Whole grains help with the management of a healthy body weight, which also reduces the risk factors for heart disease.

There are great resources online for incorporating whole grains, like wheat, into your daily routine, so you can enjoy the many benefits.

You can read more here about whole grains and heart health below:

Types of nutritional research studies

Observational studies – the habits or behaviour of individuals are observed and recorded, without any intervention or direction. For example, a study looking at the eating patterns of individuals, without making any recommendations of which foods they should eat.

Experimental studies or trials – individuals are divided into groups and researchers introduce a specific intervention or change and measure the results. For example, a drug trial where one group is given the medication and the other is given a placebo. The researchers then measure the outcome on both groups.

Whole grains and brain health

While it only makes up 2% of your body mass, your brain uses 20% of your daily energy.
Glucose, which is a carbohydrate sugar, is required by all body tissues, especially the brain. Parts of the brain such as the frontal cortex are particularly sensitive to falling glucose levels – this explains why a drop in blood sugar can impair thoughts and create confusion.

Additionally, carbohydrate-rich foods, such as whole grains and whole wheat, contain a variety of antioxidant and bioactive compounds that may counter oxidative stress and inflammation in the brain, helping to prevent damage to brain tissue and support the preservation of optimal cognitive functioning.

Whole grain consumption has been associated with reduced blood pressure, vascular disease, obesity, cholesterol, and type 2 diabetes, which may indirectly promote healthy brain function.

Research supports the role of whole grains as part of a healthy diet which can promote brain health.

The myth of ‘grain brain fog’

There is no evidence to suggest whole grains or wheat in particular, creates any drowsiness or ‘afternoon slump’ after consuming. This feeling of sluggishness is often due to a rapid fall in blood sugar. Whole grain whole wheat is a source of complex carbohydrates, which can help slow this rapid drop in blood sugar and help maintain more consistent glucose levels in our blood.

To learn more about wheat and brain health you can visit these resources:

Consumer Confusion About Whole Grains: Research Spotlight