U. WERNEKE
treatment effect of omega-3 fatty acids was non-significant
(Hannestad & Bloch, 2012), only to be countered by a re-anal-
ysis finding the opposite (Martin et al., 2012). Some supple-
ments, such as folic acid, may work best if used complementa-
rily, i.e. in addition to, rather than alternatively, i.e. instead of
conventional treatments (Taylor et al., 2004). Vitamin D sup-
plements may only be worth considering in people who clearly
have a vitamin D deficit or who live in geographical regions
where sun exposure is low during winter time (Parker & Brot-
chie, 2011). They may work less well in those without an ob-
vious vitamin D deficiency. This suggests that nutritional defi-
cits identified in mental disorders do not automatically pave the
way to treatment strategies. It is much easier to show that the
lack of substance may lead to a deterioration of mood than the
replacement of the substance lead to an improvement. Because
once a depressive episode is set into motion, it may maintain
itself, even if a precipitating factor such as a nutritional deficit
is corrected.
The Tip of the Iceberg
Possibly, the failure to deliver robust evidence for food or
supplement based interventions also stems from the fact that
major depression is a multi-factorial condition. Genetic, social
and psychological factors may play an equally important role as
food deficiencies and all these factors may conspire together to
bring on a major depressive episode. But if many factors cause
or contribute to a mental health problem, it is unlikely that fix-
ing just one factor will solve the whole problem. However, if a
factor such as a clearly identified nutritional deficiency, could
be rectified it should. Thus, correcting underlying nutritional
deficit s may be necessary to treat depression, but in most cases
this is not sufficient and nor will it ever be.
Lifestyle Instead of Diet
As multifactorial problems require multifactorial solutions, it
follows that lifestyle interventions covering various aspects of
wellbeing may be superior to dietary interventions for most suf-
ferers of major depression. We know for instance that physical
activity is beneficial for mood (as long as we do not overdo it).
Alcohol, smoking and substance abuse are other worthwhile as-
pects to consider (Berks et al., 2013). And finally, supportive
psychotherapy and motivational interviewing are integral con-
stituents of many life-style interventions. Sometimes, it is even
possible to get the best of both worlds through one single in-
tervention. After all, the bes t way to stock up on vi ta mi n D is to
go out and take a walk in the sun.
Conflict of Interest
Ursula Werneke is writing a book in a related area to be pub-
lished by Kiener Verlag, Munich, Germany
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