Last week, I
discussed food as an addiction. On my homepage, I provided a continuation of
how food can be medicine and food can poison. In it, I highlighted the power of eating fish for brain health. Recently, a study caught my eye relating salmon
consumption to reducing anxiety in ninety-five male forensic inpatients.
Specifically,
the study investigated how consumption of Atlantic salmon could modulate
biology and self-reported anxiety. The researchers measured heart rate variability
(HRV) and heart rate (HR) as indicators of the nervous system response to
dietary components. Furthermore, they investigated the outcome measures in
relation to specific nutrients such as Vitamin D status and two omega-3 fatty
acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).The participants were randomly assigned
to the fish group (portion size 150-300g) or
a meat group. The meals were consumed three times a weak. HRV (using root mean square deviation, rMSSD),
HR, and state-and trait-anxiety (STAI) were analyzed pre-intervention and after
23 weeks of the dietary intervention. The study reported:
The Fish group showed significant
improvements in both rMSSD and HR. The Fish group also showed significant
decreases in state-anxiety. Finally, there was a positive relationship between
rMSSD and vitamin D status. The findings suggest that Atlantic salmon
consumption may have an impact on mental health related variables such as
underlying mechanisms playing a key role in emotion-regulation and
state-anxiety.
The authors
also analyzed for levels of mercury, dioxins, and dioxin-like PCBs found in the
fish. They concluded even with 31% of tolerable weekly limit (TWI) in a person
weighing 100 kg, there were no adverse effects:
The content of several undesirable
substances was also determined in the Atlantic salmon. The level of mercury was
22 µg/kg, and the level of dioxins and dioxin-like PCBs was 0.48 ng TEQ/kg;
both are far below the EUs upper limits of 500 µg/kg and 6.5 ng TEQ/kg in fish,
respectively. Taking into account the amount of salmon consumed per week during
the weeks with the highest salmon intake, the intake of dioxin and dioxin-like
PCBs per week represents 31% of the tolerable weekly intake (TWI) in a person
weighing 100 kg [27]. Persons with higher body weight will have a correspondingly lower
percentage of TWI. Importantly, no adverse side effects were reported during
the intervention trial [12].
A recent
E-blast by Trudy Scott, CN, commented on the study findings and made similar observations
as me. She stated:
- The salmon was farmed and mercury and dioxin
levels were measured. Despite this, mental health benefits and reduced
anxiety was observed. I suspect even more favorable results would have
been observed had wild salmon been used - The authors mention that a longer intervention
as in this study i.e. 23 weeks/6 months is likely to lead to better
results than a shorter intervention - The Fish group had a significant increase in
both omega-3 fatty acids: EPA and DHA - The authors speculate about how improved
vitamin D status in the Fish group may help regulate serotonin production
and thereby help regulate heart rate variability and reduce anxiety - The study highlights nutritional benefits of
fatty fish other than marine omega-3 fatty acids and vitamin D: selenium,
iodine, vitamin B12 and high quality proteins. I’d like to add that it is
a source of zinc and iron too, both of which are co-factors for making
brain chemicals. - Although the study found a significant decrease
in state-anxiety, it did not find any changes in trait-anxiety (here are
the differences in state-anxiety and trait-anxiety). The authors suggest that
trait-anxiety may be more difficult to change during a 6-month
intervention study. I’d like to add that other concurrent nutritional and
biochemical interventions would likely have provided additional mental
health benefits. This could include: a gluten-free diet, targeted individual amino acids, addressing dysbiois, addressing high or low histamine, pyroluria, and zinc-copper imbalances and son on.
In another study, supporting brain benefits for fish consumption, those on a fishy diet had lowered risk of
depression:
Fish contains high concentrations of
omega-3 polyunsaturated fatty acids. Several studies have reported depletions
of omega-3 fats among depressed patients, and a cross-national comparison has
revealed a significant inverse correlation between annual prevalence of major
depression and fish consumption. In a sample of 3,204 Finnish adults,
depressive symptoms were estimated with the Beck Depression Inventory. A
frequency question was used to measure fish consumption. Multiple logistic
regression analysis was conducted to assess the association between depression
and fish consumption. After the analysis adjusted for potential confounders,
the likelihood of having depressive symptoms was significantly higher among
infrequent fish consumers than among frequent consumers.
Last year, I
wrote about how fish oil was shown in several studies to reduce hostility in
troubled youth. You can read about
that here and learn more about the importance of a fishy diet for brain
health.
References:
Hansen AL,
Olson G, Dahl L, et al. Reduced Anxiety in Forensic Inpatients after a
Long-Term Intervention with Atlantic Salmon. Nutrients. 2014;6(12):5405-5418.
doi:10.3390/nu6125405.
Scott, Trudy. Reduced anxiety in forensic inpatients – long-term
intervention with Atlantic salmon. E-Blast. August 8, 2016.
Tanskanen A, Hibbeln JR, Tuomilehto J, Uutela A, Haukkala A, Viinamäki H,
Lehtonen J, Vartiainen E. Fish consumption and depressive symptoms in the
general population in Finland. Psychiatr Serv. 2001 Apr;52(4):529-31.
Freeman, MP,
et al 2006. Omega-3 fatty acids: evidence basis for treatment and future
research in psychiatry. Journal of Clinical Psychiatry 67 (12): 1954-1976.
Review.