When any food is served, we examine it by its esthetics, color, smell and taste, and the end evaluation is summarized by a simple question that echoes in our mind: did we like it? So food is not just nourishment. It may have psychic effects of all sorts. We enjoy food, we speak about food, eating together may be a social event.
The relationships between dietary glycemic index, glycemic load, and other carbohydrate measures (added sugars, total sugars, glucose, sucrose, lactose, fructose, starch, carbohydrate) and depression in the women who participated in the Women’s Health Initiative Observational Study at baseline (n = 87,618) and at the 3-year follow-up (n = 69,954) were investigated . The results suggested that high glycemic index diets could be a risk factor for depression in postmenopausal women. What we eat is usually categorized as healthy or unhealthy, depending on its contents. Studies are still being published to demonstrate the advantage of raw, plant-based foods over processed foods. As an example, a recent study in young adults showed that raw fruit and vegetable intake predicted reduced depressive symptoms and higher positive mood, life satisfaction, and flourishing . A cross-sectional study in China among 906 postmenopausal participants identified three dietary patterns: processed foods (refined grains, preserved foods, fat meat, fried foods, and sweets), whole plant foods (whole grains, vegetables, and fruits), and animal foods (fish, lean meat, and milk products) . The conclusion was that dietary patterns featuring a low intake of processed foods and/or a high intake of whole plant foods were associated with a reduced risk of depression and perceived stress. Contrarily, the highest tertile score for processed foods was associated with a 79% increased risk of depression. It appears that various electrolytes and minerals may also play an important role in regard to mood and cognition. Adequate physiologic status of iron and zinc may enhance cognitive and emotional functioning . Several studies found improvements in aspects of mood and cognition after iron supplementation, regardless of whether the participant was initially iron-insufficient or iron-deficient.
The Dietary Inflammatory Index (DII) was developed in 2009 to measure the role of inflammation induced by diet. It was found that DII is associated with C-reactive protein, interleukin-6 and homocysteine, glucose intolerance and dyslipidemia components of the metabolic syndrome. The Iowa Women’s Health study showed that a pro-inflammatory diet, as evidenced by higher DII scores, may be associated with total mortality as well as mortality from digestive cancer, cardiovascular disease, coronary heart disease and chronic obstructive pulmonary disease . A study from Australia (6438 women with a mean age of 52 years at baseline were followed-up at five surveys over 12 years) pointed at an association between the DII score and depression (defined as a score of ≥ 10 on the Center for Epidemiologic Studies Depression-10 scale) . Women with the most anti-inflammatory diet had an approximately 20% lower risk of developing depression compared with women with the most pro-inflammatory diet.
A relatively new, rapidly developing field in medicine investigates the symbiosis between the human body and the intestinal microbiome. Food may determine the composition and characteristics of the microbiome, which in turn secretes a large number of metabolites which are absorbed and influence brain development, function, behavior and mood in humans . Adding probiotics to food may alter the gut flora as well and create a more health-friendly environment, but as of today this mode of therapy is limited to other specific diseases, not related to mental health.
So could we say that our feelings and emotional state reflect what we eat? It might be true just in the sense of one piece in a whole puzzle of mechanisms involved in the physiology of our brain. Nevertheless, based on growing knowledge of the interaction between nutrition and mental health, it seems necessary to counsel our patients and recommend on healthy diets, enriched with specific constituents as part of therapeutic strategies in medical and psychiatric care . As an example, a study from France looked for the influence of diet on prevention of new-onset depression . Higher adherence to the Mediterranean diet at midlife was associated with a lower risk of incident depressive symptoms, particularly in men. Perhaps the best way to end this report is by saying ‘bon appetite’.
Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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