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The Best Foods for the Brain: An
Update
It has been nearly a year since Medscape
published Brain Food, a look at how what we eat influences our mental
and neurologic health. Since then, our understanding of how diet affects the
brain has grown significantly. The current slideshow, based primarily on
Medscape news coverage, reviews the previous year's studies on nutrition and
brain health.
Diet for Depression
Research
from the past several years suggests that consumption of monounsaturated fatty
acids (found in olive oil, avocados, and nuts), polyunsaturated fatty acids
(PUFAs; found in nuts, seeds, fish, and leafy green vegetables), and
supplements containing eicosapentaenoic acid decreases depression risk over
time.[1-3] To that end, adhering to Mediterranean
dietary patterns specifically -- that is, a diet rich in fruits,
vegetables, nuts, whole grains, and fish and high in unsaturated fat -- is
associated with a 30% reduction in depression risk, compared with meat- and
dairy-heavy diets and diets high in trans-fatty acids; intake of the latter is
associated with an increased depression risk over time.[4] Conversely,
low levels of PUFAs may increase the risk of developing postpartum depression,
according to a 2012 literature review published in the Canadian
Journal of Psychiatry.[5] Keep in mind, however, that
although there is strong evidence of an association between diet and
depression, most
studies to date have not proven causality, supporting the need for large,
randomized primary prevention trials.[6]
Rethinking Fat
Beyond reducing depression risk, the
unsaturated fatty acids common in the Mediterranean diet have other benefits
for the brain. A 2012 review published in Pediatrics reported on
the evidence linking PUFA deficiency to attention-deficit/hyperactivity
disorder, as well as findings from trials where these fats were used
successfully to address ADHD symptoms.[7] Another small study
showed that increasing omega-3 fatty acid consumption enhances working memory
in young adults.[8] Previous work has linked Mediterranean
diets high in olive oil consumption with a lower risk for ischemic
stroke,[9,10] mild cognitive impairment, and Alzheimer
disease, and particularly the latter two when associated with high levels
of physical activity.[11,12]
Fruit to Fend Off Stroke
2012 was a good year for fruit. An analysis
from the Nurses' Health Study found that high consumption of flavanones, a
flavanoid subclass found in high concentrations in grapefruits and oranges, is
associated with a 19% lower risk for ischemic stroke in women.[18]
A Finnish
study[19] published in Neurology reported that
a diet high in lycopene, a potent antioxidant found in tomatoes, may cut stroke
risk in men. Previous work has shown that polyphenols, namely anthocyanins,
found in berries and other darkly pigmented fruits and vegetables may slow
cognitive decline by inducing autophagy (a process by which cells clear
proteinaceous debris linked to memory loss) and reduce cardiovascular disease
risk by reducing oxidative stress and attenuating inflammatory gene expression.[20-22] Each of these studies points to the importance of a
healthy diet high in plant foods and low in processed foods for a range of
health outcomes, both physical and mental.
Cut the Soda, Keep Up the Coffee
2012 saw more evidence that coffee might be
the original
wonder drug. A new observational study[23] to be presented
at the American Academy of Neurology meeting in March shows that people who
drink 4 cups of coffee a day are 10% less likely to develop depression. Those
who opted for 4 or more servings a day of diet soda or fruit punch were 30% and
38% more likely, respectively, to develop depression. Past work also
suggests that the world's most widely used stimulant cuts depression risk,
possibly by altering serotonin and dopamine activity and through its
antioxidant and anti-inflammatory properties.[24-27]
Alcohol: Always in Moderation
The Greeks touted "nothing in
excess," a refrain that still rings true: Low to moderate* alcohol
consumption has been associated with numerous potential physiologic benefits
with neurologic implications, including improved cholesterol profiles,
beneficial effects on platelet and clotting function, and improved insulin sensitivity.[28] Last year we reported
that limited alcohol use is associated with a lower risk for dementia[28,29] and that moderate alcohol -- especially antioxidant-rich
red wine -- intake may protect against cerebrovascular disease.[30-32]
A new study published in Circulation Research found that dealcoholized
Merlot reduced blood pressure by approximately 6/3 mm Hg in a sample of 67 men
at high cardiovascular risk, suggesting that the beneficial effects of wine
consumption may not strictly be due to its alcohol content.[33]
However, the health costs to the brain of alcohol consumption can quickly
outweigh the benefits, as heavy and long-term alcohol use can lead to alcohol
abuse and dependence, impair memory function, contribute to neurodegenerative
disease, and hinder psychosocial functioning.
*The US Food and Drug Administration
defines "moderate alcohol consumption" as up to 1 drink per day for
women and up to 2 drinks per day for men. One drink is equivalent to 12 fluid
ounces of regular beer, 5 fluid ounces of 12% alcohol wine, or 1.5 fluid ounces
of distilled spirits.
Chocolate -- and Still More
Antioxidants
Many recent studies have added to the already
robust body of evidence suggesting that dark, flavonol-rich chocolate may have
cardiovascular benefits. A meta-analysis published in Cochrane Database of
Systematic Reviews reported that individuals who consumed 100 g of dark
chocolate every day -- a standard Hershey bar weighs 43 g -- saw an average
blood pressure drop of 2.77/2.20 mm Hg compared with control participants.[34] A study out of Finland[35] published in Neurology
reported that individuals who eat at least 52 g of chocolate per week have a
17% lower risk for stroke, compared with those who eat less than 12 g a week.
The flavonols in dark chocolate likely contribute to the reported benefits by
scavenging free radicals and improving endothelial and platelet function. But
always check the label, as some processed chocolate contains trans-fats, which
should be avoided.
What Not to Eat: Cut the Carbs
Various 2012 studies further clarified how
overly sweet, unhealthy foods affect the brain. An animal study[36] out of UCLA found that diets high in fructose can impair
cognitive function, which is reversible with omega-3 fatty acid
supplementation. Coauthor Fernando Gomez-Pinilla, PhD, told Medscape
Medical News, "High fructose consumption can induce some signs of
metabolic syndrome in the brain and can disrupt the signalling of the insulin
receptors and reduce the action of insulin in the brain." Other work[37] published in JAMA suggests that fructose
consumption modulates the neurophysiologic pathways involved in appetite
regulation and encourages overeating. An October 2012 study[38] published in the Journal of Alzheimer's Disease reported
that a diet high in carbohydrates and sugar raises the risk for mild cognitive
impairment in the elderly, while a diet high in fat and protein may reduce this
risk. Lead author Rosebud O. Roberts, MD, an epidemiologist at Mayo
Clinic in Rochester, Minnesota, commented to Medscape Medical News
that an "optimal balance" of carbohydrates, fat, and protein may help
"maintain neuronal integrity and optimal cognitive function in the
elderly."
What Not to Eat (cont)
Mounting evidence in 2012 reinforces that
high consumption of red meat increases stroke risk. The largest
meta-analysis to date[39] looking at the atherogenic
effects of red meat found that the risk for total stroke increased by up to 13%
for each increase in a single serving of fresh, processed, and total amount of
red meat consumed per day. Earlier in the year another study[40]
found that processed and unprocessed red meat is associated with a higher risk
for stroke, while poultry was associated with a reduced risk. A study by
Sánchez-Villegas and colleagues[4] found that a diet high
in fruits, vegetables, grains, and fish led to a 30% lower depression risk
compared with a meaty diet. But, as we pointed out last year, meat quality
might be a factor: Moderate consumption of unprocessed, free-range red meat may
actually protect against depression and anxiety.[41] Mental
health nutrition expert Dr. Felice Jacka, a research fellow at Deakin
University in Geelong, Australia, comments in this report that despite the
growing locavore movement, much of the livestock in the United States is raised
on industrial feedlots, which "...increases saturated fat and decreases
very important good fatty acids...pasture-raised animals have a much healthier
fatty acid profile."
References
- Sánchez-Villegas
A, Verberne L, De Irala J, et al. Dietary fat intake and the risk of
depression: the SUN project. PLoS One. 2011;6:e16268. - Sánchez-Villegas
A, Toledo E, de Irala J, Ruiz-Canela M, Pla-Vidal J, Martínez-González MA.
Fast-food and commercial baked goods consumption and the risk of
depression. Public Health Nutr. 2012;15:424-432. - Sublette
ME, Ellis S, Geant AL, Mann JJ. Meta-analysis of the effects of
eicosapentaenoic acid (EPA) in clinical trials in depression. J Clin
Psychiatry. 2011;72:1577-1584. - Sánchez-Villegas
A, Delgado-Rodríguez M, Alonso A, et al. Association of the Mediterranean
dietary pattern with the incidence of depression: the Seguimiento
Universidad de Navarra/University of Navarra follow-up (SUN) cohort. Arch
Gen Psychiatry. 2009;66:1090-1098. - Pierre
JM. Mental illness and mental health: is the glass half empty or half
full? Can J Psychiatry. 2012;57:704-712. - Sanchez-Villegas
A, Martinez-Gonzalez MA. Diet, a new target to prevent depression? BMC
Med. 2013;11:3. [Epub ahead of print] - Millichap
JG, Yee MM. The diet factor in attention-deficit/hyperactivity disorder. Pediatrics.
2012;129:330-337. - Narendran
R, Frankle WG, Mason NS, Muldoon MF, Moghaddam B. Improved working memory
but no effect on striatal vesicular monoamine transporter type 2 after
omega-3 polyunsaturated fatty acid supplementation. PLoS One. 2012;7:e46832.
- Fung
TT, Rexrode KM, Mantzoros CS, Manson JE, Willett WC, Hu FB. Mediterranean
diet and incidence of and mortality from coronary heart disease and stroke
in women. Circulation. 2009;119:1093-1100. - Kastorini
CM, Milionis HJ, Ioannidi A, et al. Adherence to the Mediterranean diet in
relation to acute coronary syndrome or stroke nonfatal events: a
comparative analysis of a case/case-control study. Am Heart J.
2011;162:717-724. - Scarmeas
N, Stern Y, Mayeux R, Manly JJ, Schupf N, Luchsinger JA. Mediterranean
diet and mild cognitive impairment. Arch Neurol. 2009;66:216-225. - Scarmeas
N, Luchsinger JA, Schupf N, et al. Physical activity, diet, and risk of
Alzheimer disease. JAMA. 2009;302:627-637. - Chowdhury
R, Stevens S, Gorman D, et al. Association between fish consumption, long
chain omega 3 fatty acids, and risk of cerebrovascular disease: systematic
review and meta-analysis. BMJ. 2012 Oct 30;345:e6698. - Hedelin
M, Löf M, Olsson M, et al. Dietary intake of fish, omega-3, omega-6
polyunsaturated fatty acids and vitamin D and the prevalence of
psychotic-like symptoms in a cohort of 33000 women from the general
population. BMC Psychiatry. 2010;10:38. - Sanchez-Villegas
A, Henriquez P, Figueiras A, et al. Long chain omega-3 fatty acids intake,
fish consumption and mental disorders in the SUN cohort study. Eur J Nutr.
2007;46:337-346. - Jacka
FN, Pasco JA, Williams LJ, Meyer BJ, Digger R, Berk M. Dietary intake of
fish and PUFA, and clinical depressive and anxiety disorders in women. Br J Nutr. 2012 Oct 10:1-8.
[Epub ahead of print] - Amminger
GP, Schäfer MR, Papageorgiou K, et al. Long-chain omega-3 fatty acids for
indicated prevention of psychotic disorders: a randomized,
placebo-controlled trial. Arch Gen Psychiatry. 2010;67:146-154. - Cassidy
A, Rimm EB, O'Reilly EJ, et al. Dietary flavonoids and risk of stroke in
women. Stroke. 2012;43:946-951. - Karppi
J, Laukkanen JA, Sivenius J. Serum lycopene decreases the risk of stroke
in men. Neurology. 2012;79:1540-1547. - Brooks
M. New mechanism for berries' potential brain benefits uncovered. Medscape
Medical News. August 31, 2010. http://www.medscape.com/viewarticle/727764
Accessed January 10, 2013. - Polouse
S. Berry extracts and brain aging: clearance of toxic protein accumulation
in brain via induction of autophagy. Program and abstracts of the 240th
National Meeting of the American Chemical Society; August 22-26, 2012;
Boston, Massachusetts. Abstract 60. - Basu
A, Rhone M, Lyons TJ. Berries: emerging impact on cardiovascular health.
Nutr Rev. 2010;68:168-177. - Chen
H. Sweetened beverages, coffee and tea in relation to depression among
older US adults. American Academy of Neurology 65th Annual Meeting; March
16-23, 2013; San Diego, California. Abstract 2257. - Lucas
M, Mirzaei F, Pan A, et al. Coffee, caffeine, and risk of depression among
women. Arch Intern Med. 2011;171:1571-1578. - Pasco
JA, Nicholson GC, Williams LJ, et al. Association of high-sensitivity
C-reactive protein with de novo major depression. Br J Psychiatry.
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F, Berk M, Dean O, Bush AI. Oxidative stress in psychiatric disorders:
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A. Coffee drinking linked to less depression in women. New York Times.
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S, Schäufele M, Wiese B, et al; German AgeCoDe Study group (German Study
on Ageing, Cognition and Dementia in Primary Care Patients). Current
alcohol consumption and its relationship to incident dementia: results
from a 3-year follow-up study among primary care attenders aged 75 years
and older. Age Ageing. 2011;40:456-463. - Peters
R, Peters J, Warner J, Beckett N, Bulpitt C. Alcohol, dementia and
cognitive decline in the elderly: a systematic review. Age Ageing.
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Gaetano G, Di Castelnuovo A, Rotondo S, Iacoviello L, Donati MB. A meta-analysis
of studies on wine and beer and cardiovascular disease. Pathophysiol
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RS, Baroncini LA, Précoma LB, et al. Resveratrol causes antiatherogenic
effects in an animal model of atherosclerosis. Arq Bras Cardiol.
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AA, Das DK. Grapes, wines, resveratrol, and hearth health. J Cardiovasc
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G, Urpi-Sarda M, Ros E, et al. Dealcoholized red wine decreases systolic
and diastolic blood pressure and increases plasma nitric oxide: short
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K, Sullivan TR, Fakler P, et al. Effect of cocoa on blood pressure.
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SC, Virtamo J, Wolk A. Chocolate consumption and risk of stroke: a
prospective cohort of men and meta-analysis. Neurology. 2012;79:1223-1229.
- Agrawal
R, Gomez-Pinilla F. 'Metabolic syndrome' in the brain: deficiency in
omega-3 fatty acid exacerbates dysfunctions in insulin receptor signalling
and cognition. J Physiol. 2012;590:2485-2499. - Page
KA, Chan O, Arora J, et al. Effects of fructose vs glucose on regional
cerebral blood flow in brain regions involved with appetite and reward
pathways. JAMA. 2013;309:63-70, 85-86. - Roberts
RO, Roberts LA, Geda YE, et al. Relative intake of macronutrients impacts
risk of mild cognitive impairment or dementia. J Alzheimes Dis.
2012;32:329-339. - Kaluza
J, Wolk A, Larsson S. Red meat consumption and risk of stroke. Stroke.
2012;43:2556-2560. - Bernstein
AM, Pan A, Rexrode KM, et al. Dietary protein sources and the risk of
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FN, Pasco JA, Williams LJ, et al. Red meat consumption and mood and
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Which
Foods Are Best for the Brain?
Diet is
inextricably linked to conditions such as heart disease, obesity, and diabetes.
However, what we consume also seems to have significant implications for the
brain: Unhealthy diets may increase risk for psychiatric and neurologic
conditions, such as depression and dementia, whereas healthy diets may be
protective. Based primarily on recent Medscape News coverage, the following
slideshow collects some of the more prominent investigations on nutrition and
the brain into a single resource to aid in counseling your patients.
Make
for Malta in Depression, Stroke, and Dementia
A 2009 study
published in Archives of General Psychiatry found that people who follow
Mediterranean dietary patterns -- that is, a diet high in fruits, vegetables,
nuts, whole grains, fish, and unsaturated fat (common in olive and other plant
oils) -- are up to 30% less likely to develop depression than those who
typically consume meatier, dairy-heavy fare.[1] The olive oil-inclined also show a lower risk for ischemic stroke[2,3] and are less likely
to develop mild cognitive impairment and Alzheimer disease, particularly when
they engage in higher levels of physical activity.[4,5]
Fat:
The Good and the Bad
A study conducted in
Spain[6,7] reported that consumption of both polyunsaturated fatty acids
(found in nuts, seeds, fish, and leafy green vegetables) and monounsaturated
fatty acids (found in olive oil, avocados, and nuts) decreases the risk for
depression over time. However, there were clear dose-response relationships
between dietary intake of trans fats and depression risk, whereas other data
support an association between trans fats and ischemic stroke risk.[8] Trans fats are found extensively
in processed foods, including many commercial chocolates (hence, check that
label when considering the chocolate slide below). A deficiency in
polyunsaturated fatty acids has been linked
to attention deficit/hyperactivity disorder in children.[9]
Fish
Oil to Fend Off Psychosis?
Thanks to their
high levels of polyunsaturated fatty acids, namely omega-3 fatty acids, fish
can help fend off numerous diseases of the brain. A 2010 study
correlated fish consumption with a lower risk for psychotic symptoms,[10] and concurrent work suggested that
fish oil may help prevent psychosis in high-risk individuals.[11] Although data are conflicting,
new research shows that the omega-3 fatty acids eicosapentaenoic acid and
docosahexaenoic acid are beneficial in depression and postpartum
depression, respectively, and other research suggests that omega-3
deficiency may be a risk factor for suicide.[12-16]
Oily, cold-water fish, such as
salmon, herring, and mackerel, have the highest omega-3 levels.
Berries
for Oxidative Stress
Polyphenols,
namely anthocyanins, found in berries and other darkly pigmented fruits and
vegetables may slow cognitive decline through antioxidant and anti-inflammatory
properties. A study in rats from 2010 showed that a diet high in strawberry,
blueberry, or blackberry extract leads to a "reversal of age-related
deficits in nerve function and behavior involving learning and memory."[17] In vitro work by the same group
found that strawberry, blueberry, and acai berry extracts -- albeit in very
high concentrations -- can induce autophagy, a means by which cells clear
debris, such as proteins linked to mental decline and memory loss.[18] Berry anthocyanins may also reduce
cardiovascular disease risk by reducing oxidative stress and attenuating
inflammatory gene expression.[19]
A
"Whole" Diet: Make Room for Red Meat?
A so-called
"whole" diet high in fruits, vegetables, whole grains, and
high-quality meats and fish results in a 30% risk reduction for depression and
anxiety disorders, compared with consumption of a "Western diet" high
in processed foods and saturated fats, according to a 2010 study.[20] Even unprocessed red meat seems to
be protective against depressive and anxiety disorders,[21] in contrast to many studies in
which red meat often falls into the category of "unhealthy" food. In
speaking with Medscape News, principal investigator Dr. Felice Jacka
specifically addressed the importance of farming practices: Despite the growing
locavore movement, much of the livestock in the United States is still raised
on industrial feedlots, which "...increases saturated fat and decreases
very important good fatty acids...pasture-raised animals have a much healthier
fatty acid profile." A "whole" dietary pattern may also reduce
depression risk, as assessed at 5-year follow-up.[22]
