Research on the dietary connection
While depression is not new, the numbers affected have risen and the age group affected has dropped dramatically in the past few decades. The National Institutes of Mental Health notes that prior to World War II, depression typically affected people in their 50s. Today it occurs most among 24- to 44-year-olds.
In the 1980s, statistics began to show a startling increase in depression among young children and a dramatic increase in teenage suicides.
Research on the brains of suicide victims has indicated that they tend to have an abnormality in the production and use of serotonin, one of the many chemical messengers that brain cells use to communicate. Other research indicates that while the tendency to suffer from depression may be inherited, it is also impacted by biochemical and environmental influences, such as the reduced light during the winter months which results in seasonal affective disorder (SAD) in some people.
The studies listed below are organized by date, with the most recent date first. Some of the full texts will need a password because they are kept in a locked file to protect their copyright. For educational purposes only, we are allowed to share the password with you if you write to us.
If you are trying to find a particular author, see the Index below which lists all the primary authors alphabetically with their publication dates.
- Corvaglia 1999
- Edwards 1998
- Horrocks 1999
- Klaassen 1999
- Novembre 1992
- Zeisel 1986
Klaassen 1999: Study on tryptophan & depression
Mood effects of 24-hour tryptophan depletion in healthy first-degree relatives of patients with affective disorders. Klaassen T, Riedel WJ, van Someren A, Deutz NE, Honig A, van Praag HM, Biological Psychiatry 1999 Aug 15;46(4):489-97
“…Overall, after 6 hours, TRP depletion lead to a lowering of mood … Mood changes and gastrointestinal side effects were significantly more evident in FH+ subjects than in FH- subjects. CONCLUSIONS: Our data support the hypothesis that subjects with a positive family history for depression are predisposed to increased vulnerability to the adverse consequences of serotonergic imbalance.” Note: FH = Family history of depression
Horrocks 1999: Review of DHA benefits on behavior & health
Health benefits of docosahexaenoic acid. Horrocks LA, Yeo YK, Pharmacological Research 1999 Sep;40(3):211-25
[DHA is one of the omega-3 essential fatty acids] “… The inclusion of plentiful DHA in the diet improves learning ability, whereas deficiencies of DHA are associated with deficits in learning…The visual acuity of healthy, full-term, formula-fed infants is increased when their formula includes DHA … DHA deficiencies are associated with foetal alcohol syndrome, attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression, aggressive hostility, and adrenoleukodystrophy….DHA is present in fatty fish (salmon, tuna, mackerel) and mother’s milk. DHA is present at low levels in meat and eggs, but is not usually present in infant formulas…. DHA has a positive effect on diseases such as hypertension, arthritis, atherosclerosis, depression, adult-onset diabetes mellitus, myocardial infarction, thrombosis, and some cancers.”
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Corvaglia 1999: Case studies on celiac disease causing depression
Depression in adult untreated celiac subjects: diagnosis by the pediatrician, Corvaglia L, Catamo R, Pepe G, Lazzari R, Corvaglia E, American Journal of Gastroenterology 1999 Mar;94(3):839-43
“Untreated celiac disease can lead to serious behavioral disorders. We describe three adult patients with undiagnosed or untreated celiac disease without particular intestinal signs, causing persistent depressive symptoms in three of the parents of our pediatric patients… In all three patients, the depressive symptoms improved quickly with a gluten-free diet. In conclusion, celiac disease should be taken into consideration in the presence of behavioral and depressive disorders, particularly if they are not responsive to the usual antidepressive therapy. ”
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Edwards 1998: Omega-3 fish oil help depression
Omega-3 polyunsaturated fatty acid levels in the diet and in red blood cell membranes of depressed patients. Edwards R, Peet M, Shay J, Horrobin D, Journal of Affective Disorders 1998 Mar;48(2-3):149-55
Novembre 1992: Case studies on Yellow 5 and benzoate sensitivity
Unusual reactions to food additives, Novembre E, Dini L, Bernardini R, Resti M, Vierucci A, Pediatria Medica e Chirurgica 1992 Jan-Feb;14(1):39-42
“…In this study, we report two cases of unusual reactions to food additives (tartrazine and benzoates) involving mainly the central nervous system (headache, migraine, overactivity, concentration and learning difficulties, depression) and joints (arthralgias), confirmed with diet and double blind challenge. The possible pathogenetic mechanisms are also discussed.”
MedLine (article in Italian)
Zeisel 1986: Diet affects neurotransmission
Dietary influences on neurotransmission. Zeisel SH, Advances in Pediatrics 1986;33:23-47
“Diet clearly influences neurotransmission. … Components of foods can also be used as drugs. … Tryptophan, tyrosine, and choline may be useful in treatment of humans with sleep disorders, pain depression, mania, hypertension, shock, or dyskinesias. Other components of the diet that may affect behavior include food additives … “
The Diet Connection
We can’t tell you that the Feingold diet will help depression, because there has not been enough research on such a connection; we can, however, tell you that hundreds of parents have reported that their own or their child’s depression has been lifted by simply removing the additives.
Omega-3 fatty acids, available in fish oil supplements, appear to have had a profound effect on helping people who suffer from a variety of mental disorders. During a clinical trial of fish oil and depression at Harvard University, the improvements were so favorable for those taking the fish oil that the study was stopped before completion, and omega-3 fatty acids were given to all of the 44 participants.
Fish oil is rich in the fatty acids which are believed to be vital for proper functioning of the brain, the eyes, the arteries, and virtually all parts of the body. They are essential in building and repairing cells.
Side effect of medication
Depression or irritability are often listed as side effects of medications. If you or your child are taking any medications – orally, by injection, or even eye drops – ask your pharmacist for a listing of all (not just the most common) side effects. Although we usually assume that if there is going to be a side effect it will happen with the first dose of medication, this is not always true. A side effect of the hair loss drug propecia, for example, involves depression that may not start until after the person has been on the drug for 9 months! If you believe that you (or your child) may be suffering depression as a side effect of a medication, discuss alternatives with your doctor. Remember to never stop medication on your own, because that may be dangerous.
For many years the public has been urged to reduce their intake of fat in order to lower cholesterol and reduce the risk of a heart attack. Cholesterol-reducing drugs are among the most-prescribed drugs in the United States, and suggestions have been made to begin prescribing them for children as well.
However, newer studies have raised questions about the assumption that less is better – it appears that when cholesterol is reduced, the risk of a heart attack may be reduced, but the risk of depression and violent behavior increases. One theory is that low cholesterol is associated with a decrease in serum free tryptophan, the primary building block of the brain chemical serotonin. Low levels of serotonin are strongly linked to depression, suicide, and impulsive aggression. Steegmans (1996) found that plasma serotonin concentrations are lower in men with naturally low serum cholesterol concentrations than in men with average cholesterol concentrations, supporting the hypothesis that “serotonin metabolism may be implicated in the observed association between low cholesterol concentrations, behavioral changes, and violent death.”