The two of us have mainly been doing clinical treatment studies in relation to Nutrition and Mental Health. For example, Julia has studied broad-spectrum nutrient treatment of the symptoms of inattention, impulsivity, and mood regulation in adults, including insomnia. However, we have also studied nutrient treatment in groups of people without psychiatric diagnoses who were exposed to the extreme stresses of earthquakes and floods. Those studies have consistently shown general population health benefits from nutrient supplementation.
As a consequence, we have been interested in the broad public health implications of nutrition, such as the findings from national health population surveys. This blog will describe a few recent findings based on data from the Canadian Community Health Survey (CCHS), a large cross-sectional survey that collects information related to health status, health care and health determinants for the Canadian population. The CCHS collects data from participants 12 years of age or older in the ten provinces and three territories of Canada.
In a CCHS study on the economic burden of poor eating habits, Ekwaru and colleagues obtained the responses of 63,964 Canadians to validated questions on the frequency of consuming vegetables and fruit. They summarized the data as a single variable representing the total number of servings of vegetables and fruit consumed daily. First, they found that about 80% of the women and 89% of the men were eating fewer fruit and veggies than recommended by Health Canada (5-9 half-cup servings per day). Then they estimated the proportional reduction in chronic disease that would occur if all Canadians consumed the recommended number of servings of vegetables and fruit. The estimates obtained in the Ekwaru study for inadequate consumption of fruits and vegetables were $3.3 B per year.
It is interesting to compare the Ekwaru results with other findings on economic burden caused by lifestyle variables. In Canada, Krueger et al. compared fruit and vegetable burden to previously estimated annual economic burdens attributable to physical inactivity ($10.8 B), excess body weight ($23.3 B), and tobacco smoking ($18.7 B). So the estimates are that the cost to our societies of physical inactivity, excess body weight and tobacco smoking are greater than inadequate fruit and veggie consumption, but none of these are trivial costs.
And there is another interesting way to examine these data: over the next 20 years an increase of just one serving of vegetables and fruit per day would avoid approximately $9.2 B in health care costs. In a country like Canada, with 1/10th the population of the USA, that is an amazing number.
So far, these findings have related to physical health. But what about mental health? Those figures are not available yet in exactly the same form, but Bonnie and one of her former students Karen Davison published some relevant findings in 2017, again using data from the CCHS.
They examined relationships among three variables: food insecurity, diet quality, and perceived mental health. Data were available from 15,546 adults aged 19-70 years. The measures of food insecurity and diet quality were conventional ones (e.g., the Healthy Eating Index), but the only measure of perceived mental health that was available for analysis was fairly general (good versus poor).
After adjustment for covariates, they found a fairly consistent association with mental health for the two primary variables: both food insecurity and poor diet quality were associated with 60% increased probability of reporting poor mental health. In addition, suboptimal intake of two micronutrients (folate and iron) were associated with about a 50% increased probability of mental health being perceived as poor. Several other nutrients were associated with milder effects (e.g., B1 and zinc).
What conclusion can be drawn from these studies, all of which used the CCHS data in Canada? Improving people’s diets may protect them from experiencing poor mental health. And we already know from much other research that food insecurity caused by low income is a strong predictor of diet quality. All the more reason to ensure everyone earns not the minimum wage, but a living wage.
A study published two years ago emphasizes the importance of all of these findings. Noble et al. reported on brain scans from 1,099 typically developing individuals aged 3-20 years. The research was based in part on the scientific knowledge that income is related to success on a variety of cognitive tests. What the scans showed was that income was logarithmically associated with brain surface area. In other words, higher income was associated with larger amounts of brain development at the cortical level. And as the authors mention, there are multiple variables that might explain their cross-sectional study results, and nutritious food is one of them (others of course are more cognitively stimulating environments which have been shown in lab animals to increase brain development — so this would include both home environments as well as higher-quality child care settings; also the provision of more opportunities for physical activity; and also perhaps less exposure to environmental pollutants and stress).
As always in our blogs, we are not saying that nutrition is the ONLY variable of interest. We are simply trying to raise awareness of the scientific data showing that nutrition is a very important variable with respect to brain and mental health.
