Datum objave: 14. 01. 2005.

Most people know how food can influence our weight, our waistline and our nutritional status but very few are aware that it can also influence our emotions. Did you know that what you eat can make you sad, glad or even mad?
In fact, certain nutrients behave as psychoactive agents and are essential for our well-being. This observation is not new. The relationship between food and mood has intrigued people for ages..Three thousand years ago the Aryuvedic sages of India described how the body’s natural rhythms were affected by the time of the day, seasonal changes, and diet. They observed that morning is the time of clearest thinking, whereas mid-afternoon is the time of irritability and fatigue. Hippocrates, the father of Medicine, continuously insisted: “let food be your medicine and medicine be your food”.
For the majority of people, the concept of “mood food” is limited to eating a chocolate bar or indulging some sort of sweet to feel happier; drink coffee to kill sleep and increase concentration or eat oysters as aphrodisiac, but the current concept of mood food goes farther beyond that as we will see…
Depression is a very significant contributor to human illness. Over the last 100 years, the age of onset of major depression has decreased, and its overall incidence has increased in Western countries. It has been predicted that by 2020, depression will rank second as a contributor to the global burden of disease, measured in terms of “disability-adjusted life years”. The increase in depression, up to 20-fold higher in the last half of the XX century, cannot be fully explained by changes in attitudes of health professionals or society. There must be something else…explanation for this lies elsewhere (food enriched with brain-toxic additives perhaps ?) Therefore, to clarify if certain foods can prevent depression and modify our emotions is a very important task for nutrition professionals nowadays.

Theories about how food affects behaviour revolve around chemicals called neurotransmitters, biochemical messengers of the brain that pass information from cell to cell. They exert control over many of the body's functions, including the regulation of mood and appetite, thoughts, feelings and of course, behaviour.
Our brain synthesizes neurotransmitters from amino acids, the “building blocks” of protein. There are two amino acids that play a part in the food/mood response: tryptophan and tyrosine. Tryptophan is converted into serotonin, whereas tyrosine is the principal ingredient in dopamine and norepinephrine, both major performance enhancers.

Dopamine and norepinephrine are responsible for feelings of alertness, excitement, action and mental acuity. Low levels of these neurotransmitters result in depressed mood, fatigue, and poor concentration, whereas high levels can create agitation and anxiety.
The undisputed leader of the “Mood Food” movement is Dr. Judith Wurtman, a PhD in Cell Biology from the Massachusetts Institute of Technology (MIT) in the US. She is the founder and director of the TRIAD Weight Management Center at Harvard University. Twenty-five years ago Wurtman's husband Richard, a neuroscientist also from MIT, was the first scientist to catch on the idea that carbohydrates affect brain chemistry. After feeding rats meal composed mostly of starch and sugar, he found their levels of serotonin elevated, the brain chemical most associated with good mood. Carbohydrates, the Wurtman´s discovered, increase serotonin levels by starting a chain of events that results in more tryptophan entering the brain, as I will explain in a moment.
Since Wurtman´s early observations almost three decades ago, a lot of recent research has focused on serotonin, the “feel-good hormone”, which is naturally produced by foods containing tryptophan, as just mentioned. One clever experiment found out that just seven hours after starting a tryptophan-free diet, almost 70% of people began to show signs of depression. When tryptophan was reintroduced, their mood improved.
Serotonin is the neurotransmitter responsible for feelings of optimism, relaxation, general sense of well being, and the ability to focus and concentrate. However, depending on the time of day, high levels of serotonin can make you feel tired and sluggish. Low levels of serotonin result in depressed mood, difficulty sleeping, poor concentration, and increased food cravings.

Keep in mind that a couple of handfuls of cashew nuts delivers the same dose of serotonin in a natural way as antidepressant drugs do artificially. It is pure and simple chemistry!
So, does this mean we need to eat a lot of protein-rich foods in order to feel great ?
No. It doesn´t. Because there is a catch (as everything else in life): Despite the fact that serotonin is manufactured in the brain from tryptophan, found in protein-rich foods, a meal rich in protein actually lowers the blood level of tryptophan.
And how is this possible? Well, protein-rich foods contain a variety of amino acids, including tryptophan and tyrosine among others, all of them competing with each other to get through the "Blood Brain Barrier", which is sort of “the gateway keeper” of the brain.

When you eat protein, you literally flood the system with these competing amino acids and they start fighting for entry. Tryptophan is a large amino acid; only a small amount actually makes it through since it has to fight against another five smaller amino acids. Therefore, the serotonin level does not increase very much. As a result, your brain gives you the order to eat more carbohydrates.
Carbohydrates will help tryptophan to get into the brain in a roundabout way. A carbohydrate meal will result in fewer competing amino acids, because carbohydrates trigger the pancreas to release insulin. Insulin directs most amino acids in the blood stream to be absorbed into the cells of the body. For some reason we still don´t understand very well, insulin leaves tryptophan behind, free to flood the brain. Tryptophan, which remains in the blood stream, then has an easy entry into the brain. When that happens, mood improves: Serotonin levels will increase resulting in a more relaxed, focused mood.
But if you fail to eat carbohydrates during or after a protein-rich meal, your mood does not improve or even worst, you may not sleep well that night. If you don´t believe me, give it a try.
There is also one important thing to remember: Not all carbohydrates are created equal. There are big differences between the ability of carbohydrates to offer mood-altering results. The best way to consume carbohydrates is in the form of whole grains and complex carbohydrates. Whole grains are broken down over long period of time, keeping a constant flow of serotonin in our body. It is important to remember this: to experience the maximum effect of carbohydrates on your mood, it is important to eat them alone. Eating any of the following grains will help you feel more focused and relaxed: bread, pasta, potatoes, rice, corn, barley and oatmeal. So, in order to boost the production of serotonin, go for carbohydrate-rich foods (with balanced moderation of course) and to increase the level of tyrosine in your brain, simply eat foods high in protein such as meat, yogurth, cheese, fish, beans, nuts, and soy products.
But tryptophan and tyrosine are not the only nutrients necessary for a healthy brain. Another one is vitamin B3 (niacin). Dr. Abram Hoffer, a Canadian psychiatrist, described great improvements in psychotics and schizophrenics after administration of a large dose of niacin during the 1950’s. More recently, another study has shown that a high niacin diet lowers the risk of Alzheimer´s disease by 70%.

Perhaps the most popular nutrients in the XXI century regarding this “mood food” trend are omega-3 fatty acids.

Omega- fatty acids are long chain polyunsaturated fatty acids (PUFAs) of plant and marine origin. Because these essential fatty acids cannot be synthesized by the human body, they must be obtained from dietary sources. Flaxseed, hemp, canola and walnut oils are all generally rich sources of the “parent” omega-3: alpha linoleic acid (ALA). Dietary ALA can be metabolized in the liver to the longer chain omega-3 eicosapentanoic (EPA) and docosahexanoic (DHA) acids.
Approximately 20% of the dry weight of the brain is made up of PUFAs and one out of every three fatty acids in the central nervous system are PUFAs. So their importance cannot be argued. Our brain is basically made up of fat!
There is a lot of epidemiological studies supporting a connection between dietary fish and sea food consumption and a lower prevalence of depression. Significant correlations have been reported worldwide between fish oils and protection against post partum depression, bipolar disorder, seasonal affective disorder and so on.
But how do they work ? Omega-3 fatty acids can alter cell membrane fluidity by displacing cholesterol from the membrane. An optimal fluidity is required for neurotransmitter binding and the signaling within the cell. So what this means, is that they improve the “neuronal talking”. They also exert significant influence through cytokine modulation. Researchers have found that elevations of pro-inflammatory cytokines such as interleukin-1 beta, and tumor necrosis factor alpha are associated with the severity of depression. Even stress can cause an elevation of these “bad guys”. Omega-3 fatty acids and EPA in particular are well documented inhibitors of these pro-inflammatory cytokines and may influence the production of a “good-guy” called Brain Derived Neurotrophic Factor (BDNF) which is a polypeptide that supports the survival and growth of neurons through development and adulthood. Serum BDNF is low in depression but antidepressants, voluntary exercise and certain nutrients such as omega-3 fatty acids can enhance BDNF, while diets high in saturated fat and sucrose as well as psychological stress inhibit BNDF production.
Epidemiologic studies show that low fish intake is a risk factor for suicide. Depression is accompanied by a depletion of omega-3 PUFAs. A very interesting research was conducted recently in China. They studied 100 suicide-attempt cases and another 100 control patients injured by accidents who were admitted to three hospitals.

EPA levels in red blood cells in the case subjects were significantly lower than those of the control subjects (.74 +/-.52% vs. 1.06 +/-.62%, p .0001). Their findings suggest that low omega-3 fatty acid levels in tissues were a risk factor of suicide attempt.
Both depression and suicide show a seasonal variation and are related to disorders in the serotonergic system. Results of another recent study show that there is a true seasonality in long-chain PUFAs, such as arachidonic acid (AA), EPA and DHA. The results suggest that the seasonality in PUFAs may be related to the incidence of violent suicide and the expression of the serotonin transporter complex.
Lack of enough omega-3 PUFAs may also explain the depression commonly seen in elderly people. One Dutch study screened 3884 adults (aged or = 60 years) for depressive symptoms. They compared percentages of omega-3 and omega-6 PUFAs and their ratios between 264 subjects with depressive symptoms, including 106 subjects with depressive disorders, and 461 randomly selected reference subjects. Authors concluded that in elderly people, fatty acid composition is related to depression.

It is also to consider that some other nutrients can ultimately influence omega-3 status. The “Fantastic Four” are: zinc, selenium, folic acid and dietary antioxidants. So future research will focus on what is the ideal nutrient profile to enhance omega-3 supplementation. In the mean time, the best advice I can offer you is to cut down the bad fat, eat more fish and start exercising if you want to avoid depression…
So much for depression, but what about behaviour ? Do we behave the same when we don´t eat the right stuff ? Apparently not. There is a growing body of evidence suggesting links between food and violence. A British study performed in 2002 conducted in young offenders found that nutrient supplements caused a 37% drop in violence offences.
In conclusion, food scientists are beginning to explore the relationship between diet and mental disorders such as depression. Current research is again examining the connection between the mind and the body, attempting to explain what the ancients observed: that what and when we eat can alter brain chemistry.
The fact is, whether we like it or not, that WE ARE WHAT WE EAT.
Main problem with modern diet is that it contains a lot of additives which are often toxic to the brain besides being nutritionally poor. Eating habits have changed a lot in the last decades. Nowadays, people tend to eat while on the move, out of home.

And what people wants is everything to be fast, easy and tasty. But fast, easy and tasty means no compromise with nutritional content and does very little for our health. Truth is: very few are actually concerned with what they eat. Most people don´t care about food content nor food safety. Shame on them.
And I´ll better go get something to eat, I am starting to feel violent…

Dr. Daniel Fuentes
Schiphol Airport, Amsterdam
December 24, 2004
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Table 1. Percentage of Omega-6 and Omega-3 in dietary oils


Total EPA/DHA (mg/100g)





Canadian Salmon




Norwegian Salmon


Rainbow Trout


Pacific Halibut










Table 2. Selected Sources of EPA and DHA
1.- Logan A. Omega-3 fatty acids and major depression: a primer for the mental health professional. Lipids in Health and Disease 2004; Nov 3(25):1-8
2.- Huan M et al. Suicide attempt and n-3 fatty acid levels in red blood cells: a case control study in China. Biol Psychiatry. 2004; Oct 1 56(7):490-6.
3.- De Vriese SR et al. In humans, the seasonal variation in polyunsaturated fatty acids is related to the seasonal variation in violent suicide and serotonergic markers of violent suicide. Prostaglandins Leukot Essent Fatty Acids. 2004; Jul 71(1):13-8.
4.- Naliwaiko K et al. Effects of fish oil on the central nervous system. A new potential antidepressant ? Nutr Neurosci. 2004; Apr;7(2):91-9
5.- Tiemeier H et al. Plasma fatty acid composition and depression are associated in the elderly: the Rotterdam Study. Am J Clin Nutr. 2003; Jul 78(1):40-6

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