Depression:
What Dietitians Should Know
Today’s Dietitan
By Carol Brannon, MS, RD, LD
Vol. 6, No. 8, p. 18
“I feel overwhelmed.”
As a consulting dietitian, I frequently offer clients
emotional support in addition to nutrition information. It is a
sign of trust when a client reveals his or her innermost thoughts
and emotions. But this client had no motivation to exercise, keep
food records, or monitor her own weight-loss progress, and her thoughts
and emotions were exclusively and morbidly negative. Did she suffer
from clinical depression?
Since health and appearance are associated with
self-esteem, change can cause great emotional upheaval and sometimes
reveal underlying conditions such as depression. Dietitians must
be alert for signs of depression and know what to do when it appears.
This article should help you answer the following questions:
• What is depression?
• How is depression diagnosed?
• What are the causes of and risk factors associated with
depression?
• How is depression treated or managed?
• Are diets and supplements beneficial?
• What are the best counseling and support tactics?
Definition and Symptoms
Everyone experiences discouragement and sadness, but for most people
these feelings pass and a sense of hope returns. A person suffering
from clinical depression, however, stays in a state of intense sadness
and despair for more than two weeks. Feelings of loneliness, irritability,
worthlessness, hopelessness, agitation, and guilt abound. Caused
by an imbalance in brain chemicals, its onset can be gradual or
sudden. A person is considered depressed if he or she experiences
five or more of the symptoms or signs listed in Chart 1 almost every
day for at least two weeks.1
Forms of Depression
Sometimes referred to as “mood disorders,” depressive
illnesses are associated with genetic and biochemical factors of
the brain, not functions of the mind. The forms of depressive illnesses
include major depression, dysthymia or minor depression, postpartum
depression (PPD), and manic depression.2
• Major depression (“clinical”
or “unipolar” depression) is characterized by the signs
listed in the chart. It lasts at least two weeks but can linger
much longer. Episodes of major depression may reoccur during a person’s
lifetime. The average age of onset is the mid-20s. Major depression
is the leading cause of disability in the United States and is potentially
life-threatening.2,3 In the United States, nearly 30,000 people
committed suicide in 2000. The suicide death rate is four times
higher for men, but women are two to three times more likely to
attempt suicide. The accurate diagnosis and timely treatment of
depression can be a matter of life or death.3
• In dysthymia (“mild” or “minor”
depression), the symptoms are similar but less severe. Dysthymia
persists for at least two years in adults and one year in children,
but it often goes undiagnosed. In general, dysthymia affects young
people, with onset during childhood, adolescence, or early adulthood.
People with dysthymia are often mistaken as having a “personality
disorder” or “going through a phase” because they
are consistently gloomy, anxious, sensitive, and/or irritable. They
live a life devoid of joy and enthusiasm and can experience episodes
of major depression.2
• PPD usually disappears a few weeks after
the birth of a child, but for approximately 10% of women, it persists
and develops into dysthymia or major depression.3
• Manic depression (“bipolar”
depression) is characterized by episodes of depression followed
by episodes of intense, euphoric activity. Manic depression is much
less common than other types.3 A discussion of manic depression
is beyond the scope of this article.
Causes
Genetic, physiological, psychological, and environmental factors
can trigger depression. Some people may inherit a biological predisposition
for depression. Low self-esteem, intense stress, grieving over the
death of a loved one, and/or a major life change such as divorce
can contribute to depression. Exposure to environmental pollutants,
toxic chemicals, pesticides, and heavy metals may also contribute.
Some people react to shortened periods of daylight or seasonal time
adjustments. Anniversaries and holidays can trigger episodes.2,3,4
Clinical depression, regardless of its etiology,
occurs when there is an imbalance of the mood-regulating brain chemicals,
or neurotransmitters. Neurotransmitters are released by neurons,
specialized nerve cells. Neurons have axons and dendrites. Axons
are long fibrous projections that branch into nerve terminals, while
dendrites are shorter branchlike projections with receptor molecules.
Neurotransmitters are released from the nerve terminal of one neuron
and bind to receptors on the dendrites of the target neuron. Each
receptor is specialized to receive only a particular neurotransmitter,
similar to a key fitting into a lock. Neurotransmitters allow “communication”
between neurons, as well as between neurons and gland and muscle
cells.4
The primary neurotransmitters implicated in depression
are the catecholamines (dopamine and norepinephrine) and serotonin.
Dopamine has a variety of functions, including control of movement
and emotional and hormonal responses. Norepinephrine plays a role
in arousal, sleep and mood regulation, and blood pressure. The amino
acids tyrosine and L-phenylalanine are the precursors to dopamine
and norepinephrine. Generally speaking, high-protein foods can boost
the levels of catecholamines within minutes of consumption. An increase
in these neurotransmitters can raise alertness and speed of thought.4,5
Serotonin appears to play an important role in regulating
mood, appetite, sleep, pain sensation, and arousal. Insufficient
levels of serotonin in the brain result in depression. The amino
acid tryptophan is converted to 5-hydroxytryptophan (5-HTP), then
to serotonin. Complex carbohydrates can contribute tryptophan, increase
serotonin levels, and promote a positive mood.4,5
Stress can alter the balance of neurotransmitters
and various hormones. Stress is difficult to define because it is
shaped by individual perceptions of life events, which influence
a person’s internal physiological responses.2,4
Prevalence
Clinical depression affects people of all ages from all cultural
and ethnic backgrounds. The rate of depression has increased over
the past decade in western countries. In the United States, the
National Mental Health Association estimates that 19 million people
suffer from depressive illnesses; of these, more than 12 million
are women. One out of four people suffer from some type of depression.3,6
Depression rarely affects children under the age
of 6. Only approximately 2% of children in elementary school experience
depression. The incidence increases to approximately 8% of adolescents
in the United States. Children and teenagers who have experienced
neglect, abuse, trauma, or chronic illness have an increased risk.3,6
In adults over the age of 65, depression is estimated to affect
7% to 36% of medical outpatients and 40% of hospitalized patients.6,7,8
Seven percent to 12% of adult men and 20% to 25%
of adult women experience major depression during their lifetime.
Women are almost two times more likely than men to become depressed
and are especially susceptible during and after pregnancy. Approximately
10% to 15% of pregnant and postpartum women are affected by debilitating
depression.3,6
Female hormones, particularly fluctuations in estrogen
levels, are suspected of contributing to depression due to their
effect on neurotransmitters. Women respond differently to severe
stress and major life-changing events such as the death of a spouse
or child, divorce, illness, relocation, and job loss and tend to
engage in ruminative thinking—thinking distressing thoughts
and/or mentally replaying possible adverse consequences of situations.
Genetics may contribute to a woman’s increased sensitivity
to stress and propensity for depression.3
People with chronic illness are twice as likely
to experience depression as people with no chronic illness. The
relationship between chronic illness and depression is complex and
not fully understood, but healthcare professionals should be mindful
of the connection. A depressed person is four times more likely
to suffer a heart attack and die after cardiac bypass surgery than
a nondepressed person. Depressed patients are less likely to comply
with the management and treatment of their chronic conditions, resulting
in medical complications and/or new illnesses.9,10
In summary, the risk factors for depression are
the following9:
• female gender;
• personal history of depression;
• family history: first-degree relative with depression;
• chronic illness;
• poor social or family support;
• pregnancy and postpartum stress/hormonal changes;
• major life-changing events;
• domestic violence/childhood abuse;
• alcohol or substance abuse; and
• risk-taking behavior in teenagers.
Recognizing Depression
Depression often masquerades as fatigue; its symptoms are attributed
to stress, or sufferers may feel ashamed of behaviors or thoughts.
It is no surprise that depression, particularly dysthymia, often
goes undiagnosed. Unfortunately, a stigma has long been attached
to mental illnesses.3 Dietitians can reassure their clients and
patients that seeking help is not a sign of weakness.
Depressed people may seek help and counseling outside
the medical community—a pastor, priest, rabbi, or spiritual
counselor can provide valuable support and encouragement, but they
are not qualified to prescribe medications, make dietary recommendations,
or diagnose possible physical causes, such as hypothyroidism.3
People usually seek help from their family doctor rather than a
psychiatrist. Although people seek help from their PCPs [primary
care providers], not all PCPs are trained to identify and treat
depression. Patients are best served by seeing a psychiatrist for
an evaluation, possible medication, and concurrent therapy with
a mental health professional. Research has proven that talk therapy
and medication together is the most effective course of treatment
for depression.2,4 Depression is the second most common chronic
condition seen by PCPs. However, the symptoms of depression are
vague and frequently overlooked by family practitioners whose time
is limited.6 One prospective study reported that only 29% of patients
with chronic or comorbid conditions were accurately diagnosed for
depression compared with 67% accuracy in diagnosis of depression
without comorbid conditions.9,11
Screening and Diagnosis
There are various screening tools available for use in assessing
the presence and severity of depression. The U.S. Preventive Services
Task Force (USPSTF) has proposed that affirmative answers to the
following two questions indicate the need for more in-depth screening
or diagnostic verification:
• “Over the past two weeks, have you ever felt down,
depressed, or hopeless?”
• “Have you felt little interest or pleasure in doing
things?”
The USPSTF recommends that adults be routinely screened
for depression in a primary care setting, where in-depth measures
can be used to assess severity: Beck Depression Inventory, Center
for Epidemiological Studies Depression Scale, Edinburgh Postnatal
Depression Scale, and the Zung Depression Rating Scale. These measures
or questionnaires can also be used to monitor progress once treatment
for depression has been initiated.6
After initial screening, the diagnosis of major
depression is verified using the Diagnostic and Statistical Manual
of Mental Disorders (4th edition) by ruling out any physical causes,
allergies, or confounding disorders such as anxiety disorder or
attention deficit disorder and by evaluating a person’s psychiatric
and social history.6
Once a diagnosis is verified, a treatment plan can
be developed and implemented. It is best if both the physician and
patient collaborate in treatment planning, which usually includes
medication and some type of psychotherapy. Diet modification (discussed
below) should be an important part of managing depression.12
Antidepressant Medication
There are three classifications of antidepressants: monoamine oxidase
inhibitors, tricyclic antidepressants, and selective serotonin reuptake
inhibitors (SSRIs), which have come to predominate due to fewer
side effects and drug interactions.2 SSRIs include citalopram (Celexa),
fluoxetine (Prozac), paroxetine (Paxil), sertraline (Zoloft), and
escitalopram oxalate (Lexapro). SSRIs are effective in elevating
the brain levels of serotonin by inhibiting the reuptake of serotonin
by the presynaptic neuron.
It takes approximately four to six weeks for antidepressants
to take effect. The initial dosage is low—approximately 10
milligrams—and may be increased to 20 milligrams if needed.
SSRIs should be taken for four to 10 months to prevent a recurrence
of depression. The side effects of SSRIs may include nausea, diarrhea,
constipation, loss of appetite, stomach pain, dizziness, drowsiness,
sleep problems, fatigue, increased sweating, and/or dry mouth.2,13
Nutrition and Depression
“Food and mood” is a hot topic. A search using the key
words “depression” and “food” yielded almost
57,000 books. The effect of foods on mood is not completely understood;
however, an abundance of information on this subject exists in bookstores
and on the Internet. Countless books are available that advocate
“natural” or nutritional therapy for depression.
There are two schools of thought on the relationship
of diet and depression. The first is that a diet deficient in calories
and essential nutrients contributes to depression. The second is
that mood is adversely affected by a diet consisting primarily of
processed foods, which are high in saturated fats, refined sugars,
preservatives, and artificial sweeteners. Of course, a diet high
in processed foods can also be deficient in essential nutrients.14,15,16,17,18,19
Nutrient Deficiencies
A depressed person often finds little enjoyment in eating or has
little energy to prepare meals. The nutritional quality of their
diet is likely to be poor. Weight loss is common, resulting in deprivation
of essential nutrients, including amino acids, vitamins, and minerals.1,2
• Amino acids: Low levels of tryptophan cause
a depressed mood. A study involving 42 women (19 with a history
of depression, 23 with none) on a 1,000-kilocalorie diet found that
tryptophan was the first nutrient to be depleted. The women with
a history of depression responded to the tryptophan depletion with
an acute lowering of mood. Although this was a small study, it suggests
that low-calorie dieting may trigger a recurrence of depression.
Depression and obesity are prevalent among women and often coexist.
This study supports the rationale that sensible eating, exercise,
and gradual weight loss is the optimal approach to weight loss and
possibly protects against depression.20
• B-complex vitamins: The B-complex vitamins—thiamin,
niacin, riboflavin, folic acid, biotin, B6, and B12—appear
to play a role in normal maintenance of mood, and deficiencies are
linked to depression. Deficiencies of certain B vitamins, particularly
niacin, can result in disturbed thinking. Studies indicate that
depressed individuals have low levels of B vitamins, especially
folic acid. Consumption of foods rich in B-complex vitamins should
be encouraged. Taking vitamin B-complex supplements helps manage
depression, but megadoses of B vitamins can be harmful.14,15,16,17
Omega-3 Fatty Acids
Omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and
docosahexaenoic (DHA), are important in the treatment and management
of depression and other psychiatric disorders. EPA and DHA, found
in cold-water fish and fish oil, are essential components of the
central nervous system and play important roles in its functioning.
Several studies indicate a deficiency of omega-3 fatty acids, particularly
DHA in plasma and red blood cells, is linked to the etiology of
major depression.18
Over the past decade, the dietary intake of omega-3
fatty acids has decreased in the United States while the rate of
depression has increased. Although causation cannot be assumed,
observational and epidemiological studies have found lower rates
of depression in Japan, Taiwan, and Hong Kong where people consume
a higher dietary intake of fish. Hibbeln21 found a negative correlation
between total seafood intake and the incidence of PPD in 22 countries.
In addition, higher concentrations of DHA in mother’s milk
are associated with a lower incidence of PPD.21,22
One hypothesis suggests that depression adversely
alters omega-3 fatty acid metabolism in the same way inflammation
alters fatty acid metabolism. Therefore, omega-3 fatty acid supplementation
may be beneficial in treating depression because it is for inflammatory
conditions. Several clinical studies indicate supplemental intake
of omega-3 fatty acids or fish oil, as adjuvant to antidepressant
therapy, reduces the severity of depressive symptoms.
Impressive results were found in a 12-week, randomized,
double-blind, placebo-controlled trial where depressed patients
were divided into three dosage groups. Patients who received 1 gram
of EPA had the best outcome, with 53% reporting a 50% reduction
on Hamilton depression scores.23 Clinical findings indicate omega-3
fatty acids act either by alleviating depression by a different
pathway than antidepressants, enhancing the effectiveness of antidepressants,
or by both of these ways.18
Currently, there is no established therapeutic dose
of omega-3 fatty acids (fish oil supplements) for depression. Fish
oil supplements are generally well-tolerated and have proven safe
for long-term use at doses of 1 gram daily. The major side effect
is a fishy aftertaste and belching, but this can be minimized if
taken after a meal. More research is needed to clarify the role
of EPA and DHA. It is still unclear whether EPA, DHA, or both are
responsible for the beneficial effects in managing depression.18
Dietary Supplements
There are many dietary supplements that claim to be effective in
treating depression. These include amino acids (tyrosine, L-phenylalanine,
5-HTP, and L-tryptophan), omega-3 fatty acids (fish oil), vitamins
(niacin, thiamin, riboflavin, folic acid, B6, B12), minerals (selenium,
chromium), S-adenosylmethionine, melatonin, and St. John’s
wort (SJW). The effectiveness of “antidepressant supplements,”
which combine amino acids, vitamins, minerals, and herbs packaged
in one pill, is unclear and controversial.2,24
SJW, or Hypericum perforatum, has been used for
more than 2,000 years to treat a variety of conditions. SJW contains
a variety of phytochemicals, including hypericin and pseudohypericin,
flavonoids, hyperforin and adhyperforin, and oligomeric procyanidins,
which may be responsible for its antidepressant properties. The
mode of action is unknown.
In general, there is strong clinical evidence supporting
the effectiveness of SJW in treating mild to moderate depression.25
However, one study, which has been criticized for excluding an antidepressant
treatment group,26 found that SJW was not significantly better than
a placebo in treating major depression in 200 adults.27
The most common daily adult dosage is 600 to 900
milligrams daily of a whole plant extract. SJW is safe but should
be avoided by pregnant and lactating women, persons taking antidepressants,
and dietary supplements like kava-kava and tryptophan.26
Tactics and Goals
Aside from making sure your client is not malnourished, the most
effective course a dietitian can take is to encourage him or her
to seek a physician’s help or the help of a qualified therapist
or psychiatrist. It is important to be a patient and sympathetic
listener—despite clients’ negative thoughts and resistance
to suggestions, they can often talk themselves far enough out of
a bad mood to seek medical or psychiatric help and become interested
in diets and supplements. Reflective listening is generally effective
in working with depressed people because they want to be heard and
understood, not told how they should or should not feel.28
A good tactic to improve diet is to give the client
an “assignment”—buy and eat whole grain breads
and cereals instead of refined ones, for example. Encourage clients
to focus on “proactive eating”—what to eat instead
of what not to eat. Eating a diet rich in whole grains, fruits,
dark green, leafy vegetables, and foods high in omega-3 fatty acids
can help in attaining and maintaining positive mental health.
Encourage depressed clients to focus on only one
dietary or lifestyle change per week. Change and improvement is
cumulative—positive events bring positive changes, which bring
positive attitudes, which are the antithesis of depression.
— Carol Brannon, MS, RD, LD, is a consulting
dietitian at Fowler YMCA and in private practice in Georgia.
References for this article are available upon request
by e-mailing TDeditor@gvpub.com.
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