The secret to happiness may be in your next meal. According to findings from studies that have examined the connection between food and mood, what you eat plays a role in how content you feel. As fitness professionals, you can pass along some of the research results on mood and emotional state and give your clients one more reason to eat correctly, feel great and live well.

What the Research Shows

While research studies on the link between food and mood are ongoing, scientists already know some things about how diet affects our emotions. For example, the literature shows that protein-rich foods affect alertness and that carbohydrate-rich foods help with relaxation.

How certain types of diet affect mood has also been investigated. For example, studies have shown that eating a Mediterranean diet results in a lower risk of developing depression, according to a large population-based study (Sánchez-Villegas et al. 2009). Even after results were adjusted for other healthy lifestyle behaviors, those who more closely followed the Mediterranean diet pattern were up to 58% less likely to develop depression (Sánchez-Villegas et al. 2009). The reason for this beneficial effect was because this diet pattern is high in monounsaturated fats and includes plenty of fruits, vegetables, fish, legumes, cereals and nuts. Perhaps just as important is what the Mediterranean diet doesn’t include: a lot of red meat, alcohol or dairy.

The specific foods that had the most mood-lifting benefits were fruits, nuts, legumes and olive oil, according to one of the study’s authors, Miguel A. Martínez-González, MD, PhD, MPH, chair of the department of preventive medicine and public health at the University of Navarra in Pamplona, Spain. “However, the overall pattern is more important than [any one particular food],” cautions Martínez-González.

In other population-based studies, “traditional” diets rich in plant foods were consistently more protective against depression than “Western” diets (Jacka et al. 2010). In observing more than 1,000 women (aged 20–93), researchers found that a diet full of processed and fried foods, refined grains, sugary products and beer was associated with more symptoms of depression (Jacka et al. 2010). A similar study found that participants in their 50s who ate a diet full of sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products had a 11/2 times greater risk for depression than those whose diet was heavily loaded with vegetables, fruit and fish (Akbaraly et al. 2009).

Researchers have found that even modest increases in fruit and vegetable intake improve rates of frequent mental distress (FMD) in adults. In one study, subjects who ate two to four daily servings of fruits and vegetables had a 41% lower incidence of FMD than those who ate one or no serving a day; getting more than five daily servings conferred even more benefits (a 52% lower rate of FMD) (Rohrer & Stroebel 2009). Interestingly, these results were independent of exercise. Overall, the “traditional” diets that provide the most protective benefits for mood are based on vegetables, fruits, whole grains and fish.

Studies have shown that adolescents are also affected by the foods they eat. A large study of teenagers found that a diet high in added sugar and red meat was linked to poor mental health and higher rates of both depression and aggression, whereas teens who ate more leafy greens and fresh fruit had better behavioral scores (Oddy et al. 2009).

Best Foods for Improving Mood

Your clients are likely getting enough carbs, fat and protein to meet their basic needs. However, optimizing their mental and overall health is about getting high-quality versions of these macronutrients in the form of complex carbohydrates, omega-3 fatty acids and lean protein. Here is a look at some high-quality macronutrients that may help improve mood.

Healthy Carbs

There’s no denying that low-carb weight loss diets have lost favor with many consumers. And most nutrition experts would agree that clients should reduce their intake of any carbohydrates that are processed and contain added sugars.

However, it would be a mistake to cut out good carbs, such as those found in healthy whole grains. In fact, a recent study found that a high-carb, low-fat approach to weight loss resulted in happier dieters in the long run (Brinkworth et al. 2009). This randomized clinical trial involved 106 overweight and obese participants in their 50s; all participants received the same amount of calories per day, but one group ate a diet very low in carbs and high in fat, whereas the other group ate a diet high in carbs and low in fat. While both groups experienced improvements in mood after 2 months, only the high-carb dieters still had improved scores on mood, hostility, confusion and depression after 1 year (Brinkworth et al. 2009).

Fatty Fish & Omega-3s

Let’s start off by saying that there are a lot of reasons to include more omega-3 fatty acids in the diet, not least of which is to improve cardiovascular health. However, the research to date on the link between omega-3s and mood has shown mixed results.

In fact, one recent study failed to find any evidence of omega-3s improving mood among cardiac patients with diagnosed depression who were taking antidepressants (Carney et al. 2009).

On the other hand, another study suggested that higher intakes of the omega-3 fatty acids found in fish might be associated with a more optimistic outlook in adults over 60 years old (van de Rest et al. 2009). Subjects in this study who had the highest dietary intakes of omega-3s also had the fewest symptoms of depression, though this finding was not considered statistically significant (van de Rest et al. 2009).

In another population-based study of approximately 1,200 older adults, those without signs of depression had higher fish intakes than the nearly 70% of test subjects who did show signs of depression (Bountziouka et al. 2009).


Protein foods contain an amino acid called tryptophan, which is a precursor to serotonin, a neurotransmitter related to mood and appetite. In general, adequate protein derived from lean poultry and meat, fatty fish and legumes is known to improve “vigilance attention,” the long-term attention span responsible for accuracy during a long-term repetitive task.

Serotonin relays messages in the brain that relate to mood, appetite, sexual desire, memory, learning and more. In fact, the role of serotonin in mood regulation is so strong that some antidepressants work by blocking the reabsorption of serotonin so that more is left in the synapses to keep working.

B Vitamins

Folate and vitamin B6, two B vitamins that are abundant in plant foods, also help maintain beneficial levels of serotonin. These two B vitamins help convert tryptophan into serotonin. Low levels of folate, in particular, have been associated with depression.

The mood-boosting benefits of folate may be stronger in men than in women—provided that the overall diet is healthy. In a recent study, both men and women experienced a mood lift with higher intakes of fruits, vegetables, whole grains, all grains and milk, along with fewer discretionary calories (i.e., added fats and sugars); folate had an added mental health benefit for the men (Baydoun et al. 2010).


Tea, especially green tea, may also play a role in mood. One study found that drinking 4 or more cups of green tea a day lowered the risk of developing symptoms of depression among elderly Japanese (Niu et al. 2009). The control group drank 0–1 cup of tea per day and were 66% more likely to be mildly or severely depressed (Niu et al. 2009). “We think theanine may play a role. It’s one of the major amino acid components in green tea and can pass through the blood-brain barrier,” says lead researcher Kaijun Niu, MD, PhD, an associate professor at Tohoku University Graduate School of Biomedical Engineering in Sendai, Japan.

Water, a somewhat overlooked component in tea, may also play a role. After water, tea is one of the most hydrating fluids. Simply staying well-hydrated may improve mood and attention, according to a small study of 54 male and female college athletes (D’anci et al. 2009). The athletes were either adequately or inadequately hydrated for team practices, then surveyed and tested. The researchers found that athletes who were dehydrated had more negative mood ratings and worse long-term attention than those who were adequately hydrated.


When it comes to helping clients make healthy changes, a good mood can go a long way in laying the foundation for lasting healthy habits. Remember that the strongest evidence supports an overall healthy eating pattern packed with plant foods and unsaturated fats. If a food-mood chat works to get your clients excited about eating right, go for it, and feel good about recommending the same solid nutrition advice that will benefit overall health.