Eating three serves of whole grains every day may help keep your waist trim and blood pressure and sugar levels under control in middle age and beyond, according to a new study.
The US study of the effects of whole-and refined-grain intake on five risk factors of heart disease found people who ate at least three daily servings of whole grains had lower than average increases in waist size, blood sugar levels and blood pressure compared with participants who had a low intake of whole grains.
Additionally, the researchers found participants who ate fewer refined grains (less than two servings a day) also had lower average waist size increases and a greater decline in triglyceride (fat found in the bloodstream) levels.
Risk factors for cardiovascular disease
High levels of triglycerides in your blood, large waist circumference, high blood pressure and sugar, and high LDL (‘bad’) but low HDL (‘good’) cholesterol, are all risk factors for heart disease, which is the leading cause of death worldwide.
Managing these risk factors as we age may help protect against heart disease, according to senior author Nicola McKeown.
“Our findings suggest that eating whole-grain foods as part of a healthy diet delivers health benefits beyond just helping us lose or maintain weight as we age. In fact, these data suggest that people who eat more whole grains are better able to maintain their blood sugar and blood pressure over time,” Dr McKeown says.
How whole grains may help
Co-researcher Caleigh Sawicki says there are multiple ways whole grains may work to mitigate these risk factors as we age.
“The presence of dietary fibre in whole grains can have a satiating effect, and the magnesium, potassium and antioxidants may contribute to lowering blood pressure. Soluble fibre, in particular, may have a beneficial effect on post-meal blood sugar spikes,” Dr Sawicki says.
Whole grains vs refined grains
Whole grains have a fibre-rich outer layer and an inner germ layer packed with B vitamins, antioxidants, and small amounts of healthy fats.
Whereas refined grains have these nutrient-dense components removed and won’t satisfy you for as long.
How to get your daily wholegrain serves
Previous research has recommended the optimal daily intake of whole grains to be 100g-150g a day.
Examples of a serving are one slice of whole-grain bread, a half cup of rolled oats cereal, or a half cup of brown rice.
Other whole grains to try include:
- bulgur (cracked wheat)
- wholegrain bread
- wholegrain rye
- wholegrain couscous
In Australasia the average daily intake of whole grains is around 30g, in the UK it’s around 20g, and in the US only eight per cent of the population consumes three or more serves.
Study method and limitations
The subjects of the research were from a famous long-term cohort study called the Framingham Heart Study, which started in 1948. There were 3100, mostly white, participants in the 18-year-long study and the average age was mid-50s, when it began.
The researchers relied on self-reporting of food consumption, which can under or over-estimate intakes. And the study was observational, so can’t prove cause and effect.
Article sources and references
- Caleigh M Sawicki, Paul F Jacques, Alice H Lichtenstein, Gail T Rogers, Jiantao Ma, Edward Saltzman, Nicola M McKeown, Whole- and Refined-Grain Consumption and Longitudinal Changes in Cardiometabolic Risk Factors in the Framingham Offspring Cohort, The Journal of Nutrition, 2021;, nxab177, https://doi.org/10.1093/jn/nxab177https://academic.oup.com/jn/advance-article/doi/10.1093/jn/nxab177/6311830
- Science Daily 13 July 2021. Eating whole grains linked to smaller increases in waist size, blood pressure, blood sugar. Accessed July 2021https://www.sciencedaily.com/releases/2021/07/210713165308.htm
- Mayo Clinic Triglycerides: Why do they matter? Accessed July 2021https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/triglycerides/art-20048186
- HDL cholesterol: How to boost your 'good' cholesterol. Accessed July 2021https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/hdl-cholesterol/art-20046388
- Cleveland LE, Moshfegh AJ, Albertson AM, Goldman JD. Dietary intake of whole grains. J Am Coll Nutr. 2000 Jun;19(3 Suppl):331S-338S. doi: 10.1080/07315724.2000.10718969. PMID: 10875606.https://pubmed.ncbi.nlm.nih.gov/10875606/
- orld Health Organization. Cardiovascular diseases. Accessed July 2021https://www.who.int/health-topics/cardiovascular-diseases
- Framington Heart Study. About the Framingham Heart Study. Accessed July 2021https://framinghamheartstudy.org/fhs-about/