National statistics indicate that several nutrient shortfalls are common in the United States, including potassium, dietary fibre, choline, magnesium, calcium, and vitamins A, D, E, and C. The high cost of healthy diets, coupled with persistent high levels of income inequality, put healthy diets out of reach for around three billion people globally in every region of the world in 2019, especially the poor. Risk of selenium, zinc, folate, and B12 deficiency may also be found among select populations.
Multiple factors may play a role in nutrient deficiency, including the prevalence of highly processed Western-style diets with low vegetable, fruit, and whole grain intake, topsoil erosion and a decline of nutrient levels in the soil, and food insecurity or limited access to healthy foods and variety. Micronutrient malnutrition, or deficiencies in one or more crucial vitamins or minerals, may negatively impact both physical and mental health and potentially lead to chronic illness
To compound the issue, chronic psychological and environmental stress may negatively impact micronutrient concentrations in the body, leading to micronutrient depletion. After the World Health Organization declared the rapid spread of coronavirus disease to be a pandemic, there has been a dramatic rise in the prevalence of mental health problems both nationally and globally. A nutrient-dense diet made up of foods full of vitamins, minerals, and phytonutrients can be a powerful tool in promoting mental wellness and combating chronic disease.
From Magnesium to B Vitamins: Impacts on Anxiety and Depression
Magnesium is one micronutrient commonly under-consumed in the US, yet it is present in a variety of foods, from greens to whole grains. Although there is some conflicting evidence, low levels of magnesium intake have been associated with depression. Most recently, a 2019 cross-sectional analysis of medical records from 3,604 adults found a positive correlation between lower serum magnesium levels and depressive symptoms.
Beneficial effects of magnesium supplementation on anxiety and stress-related symptoms have been suggested, though further trials may be required to confirm efficacy in all populations. For example, a 2017 randomized controlled trial (RCT) found that magnesium and zinc supplementation (320 mg magnesium sulphate and 27 mg zinc sulphate/day) did not reduce depression and anxiety symptoms in postpartum women after an eight-week intervention. However, a 2018 RCT found that magnesium intake (300 mg/day) alleviated stress symptoms in men and women with low magnesemia. Further, for participants who reported severe stress, a combination of magnesium (300 mg/day) and vitamin B6 (30 mg/day) demonstrated greater improvements.
Some B vitamin deficiencies have been linked to an increased risk of depression, and consistent and sufficient intake of those nutrients, specifically folate and vitamin B12, may potentially decrease the risk of depression relapse and the onset of symptoms in an at-risk population. A 2019 systematic review and meta-analysis of 18 research articles suggested that B vitamin supplementation benefited both at-risk (poor nutrient and mood status) and healthy populations specific to improving their reported stress symptoms and overall mood.
Phytonutrients & Antioxidants
A diet that incorporates a varied and colourful rainbow of fruits, vegetables, whole grains, spices, and herbs provides essential minerals and vitamins, including antioxidants. In addition, the bountiful phytochemicals that contribute to the colour, taste, and smell of plants provide both physical and mental health benefits. A 12-week RCT in 2018 specifically studied curcumin and found that an increasing dose (from 500 to 1,500 mg/day) as an adjunctive treatment for major depressive disorder had significant antidepressant effects. Another 12-week RCT in 2017 with similar curcumin doses also indicated similar effects, benefiting depressive symptoms as well as reducing anxiety in depressed adults.
Research suggests that acute and chronic psychological stress is associated with increased inflammatory activity in the body, contributing to the adverse mental health symptoms and furthering inflammatory processes. The anti-inflammatory properties of dietary phytonutrients and antioxidants may provide direct benefit. A 2018 RCT evaluated the effects of carotenoids (13 mg or 27 mg/day) on 59 young, healthy participants and found that carotenoid intake reduced psychological stress and improved emotional and physical health compared to placebo. Other antioxidants such as vitamins A, C, D, and E may also play a role in the development and alleviation of anxiety and depressive symptoms. An observational study of 80 patients found that those with generalized anxiety disorder had lower initial levels of those vitamins in their blood serum compared to healthy controls. After a six-week treatment of vitamins A, C, and E, a significant increase in blood levels of antioxidants and a significant reduction in anxiety and depression were reported.
Research also suggests that omega-3 polyunsaturated fatty acids are protective against depression and reduce depressive symptoms. A 2018 RCT evaluated omega-3 supplementation as an adjuvant therapy to standard antidepressant medication for patients with major depressive disorders. After a 12-week treatment, compared to placebo, those participants in the omega-3 treatment group reported less symptoms of depression, anxiety sensitivity, and sleep disturbances and improved regulation of their emotions.
Nutrition is a cornerstone of functional medicine care. Diet quality is a crucial consideration when evaluating chronic physical and mental health conditions and when implementing personalized interventions that address imbalances in order to optimize a patient’s overall wellness. Dietary patterns that include adequate and varied consumption of foods that are rich in essential micronutrients, including antioxidants and phytonutrients, positively impact mental health. In addition, helping patients manage chronic psychological stress may not only decrease the risk of micronutrient depletion but also promote mental and physical wellness