Planning a picnic during the long weekend, but not sure what to put in picnic basket? Here is a list of healthy foods with lots of benefits for your brain.
A: Amino acids:
Your
body cannot synthesise all of the 20 amino acids. Nine of them can only
be obtained through food, including tryptophan and phenylalanine. These
two amino acids, along with tyrosine, are the biosynthetic precursors
for the neurotransmitters serotonin, dopamine, and norepinephrine. The
amino acids glutamate and aspartate are themselves neurotransmitters as
well. However, they are not taken up into the brain from the diet.
Regular meals containing aspartate and glutamate have no effect on the
levels of these neurotransmitters in the brain. The brain is only
affected when glutamate is administered alone in extremely large doses
[1]. Meat, fish, eggs, dairy products and legumes are rich in protein
and thus, amino acids.
B: B complex vitamins
A
typical component of dietary supplements for the brain are vitamin B
complexes, which include Vitamin B6, B12 and folic acid. Vitamin B6 is a
cofactor in the production of cysteine and vitamin B12 is a cofactor
needed in folic acid metabolism. Folate promotes the regeneration of
methionine from homocysteine. They all work by reducing levels of
homocysteine and their deficiency leads to hyperhomocysteinemia. This
can lead to DNA damage, increase the generation of reactive oxygen
species, contribute to excitotoxicity and cause mitochondrial
dysfunction which may lead to apoptosis [2]. Further, vitamin B12
deficiency and high levels of homocysteine double your risk for brain
atrophy and cognitive decline [3, 4]. Taking vitamin B6, B12, and folic
acid can reduce brain atrophy and improve brain function [5]. Vitamin B6
can be found in dairy products, meat and fish, but also in cabbage,
beans, whole meal products, nuts, yeast, avocados and bananas. Foods
with high folate content are dark green leafy vegetables like spinach,
avocado, liver, asparagus, brussel sprouts, nuts, beans, dairy products
and eggs. Animal products are the best source of vitamin B12; you find
it especially in liver, but also in eggs and dairy products. For vegans
it is difficult to get enough B12. A recent study suggests that dried
purple laver (Nori) could be a good source of B12 for vegans and
vegetarians [6].
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| Brainfoods by Claudia Willmes |
C: Calcium
This is one of the most important messengers in neurons
. Indeed,
only a few neuronal functions are immune to the influence of calcium! A
transient rise in cytoplasmic calcium concentration allows activation
of a large number of Ca
2+-binding proteins that start
signalling cascades. As calcium participates in the transmission of the
depolarizing signal and contributes to synaptic activity, calcium
deficiency impairs many neurological functions. Milk and dairy products
as well as green vegetables, sesame seeds and nuts are an excellent
source of calcium.
C: Chromium
Chromium is
a trace mineral found in many nutritional supplements, especially in
weight-loss and muscle-building pills. The use of chromium-containing
dietary supplements is controversial, owing to the absence of any
verified biological beneficial effect on healthy people [7]. However,
eating some chromium should not hurt. Food sources of chromium are
broccoli, grapes, whole-wheat products and potatoes.
F: Fat
Many
people avoid eating fat because they are afraid of gaining weight, but
never underestimate their necessity for a functioning brain! Fatty acids
are structural components of myelin. Both prenatal and postnatal fatty
acid deficiency in rodents reduces the amount and alters the composition
of myelin [8]. Avocado, olives and coconut oil are an excellent source
of essential fatty acids. Very often, omega 3 fatty acids are found in
dietary supplements. There are two main omega-3 fatty acids,
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The latter
shields against age-related mental decline and improves both learning
and memory in older adults [9]. People with low DHA levels actually have
smaller brains and exhibit more cognitive impairment than those with
adequate levels [10]! The best sources of omega-3 are animal products:
cold-water fish such as salmon, as well as dairy products from animals
on a grass-fed diet. Plants only contain the fatty acid precursor
alpha-linolenic acid
(ALA), of which a tiny amount eventually
gets converted to EPA and DHA in the body. If you are vegan, eat pumpkin
seeds, walnuts, soy beans and seaweed.
G: Glucose
This
is the second important addition in neuro-drinks and the brain's
primary energy source. Blood glucose levels influence mood and attention
span. Glucose administration also improves performance in cognitively
demanding tasks [11]. The brain cannot store glucose and needs a steady
supply, but this does not mean you should constantly be sipping soda! To
ensure a constant glucose supply to your brain, eat food with high
fiber carbohydrates such as carrots, beets, potatoes or dark fiber-rich
whole wheat bread.
I: Iodine
The body
cannot produce iodine, so it is an essential part of your diet. This
trace element is required for producing thyroid hormones [12] which, in
turn are required for brain development. Iodine deficiency in utero or
during early postnatal development results in impaired cognitive and
motor development [12]. Pregnancy, smoking and increased alcohol intake
are risk factors for iodine deficiency. Great sources for iodine are
saltwater fish and seafood, milk and dairy products, and, of course,
iodized salt.
I: Iron
Iron is an
important mineral for neurodevelopment and neuronal function. It plays a
fundamental role in neurotransmitter synthesis, myelination and ensures
oxygenation and energy production in the brain. Iron deficiency appears
to alter the metabolism of the monoamines dopamine and norepinephrine
[13] and decreased iron intake is associated with reduced myelination
[14]. Iron deficiency is linked to attention-deficit/hyperactivity
disorder and abnormal development of cognitive functions. Iron
deficiency is particularly common in women and is associated with
depression [15]. Rich sources of dietary iron include red meat, fish,
legumes such as lentils and chickpeas, leafy vegetables and whole-grain
products.
M: Magnesium
Magnesium is often
listed as a supplement in brain-boosting drugs or drinks. It is involved
in all the major metabolic pathways such as oxidation-reduction and
ionic regulation. It also blocks the NMDA receptor, thereby preventing
glutamate excitotoxicity. In magnesium deficiency, NMDA receptors become
hyperexcitable, leading to excessive intracellular calcium. This can
cause production of toxic reactive oxygen species and eventually lead to
neuronal cell death. People with low magnesium are more susceptible to
migraine attacks [16]. Parkinson's patients have low magnesium levels in
the brain and rats with chronic low magnesium rapidly lose dopaminergic
neurons [16]. Supplementary magnesium may thus be beneficial to prevent
Parkinson's disease. Increased magnesium intake can also lead to
improvement in patients with mania and depression [16]. The exact
benefit of magnesium supplementation however is not yet definitive.
Although whole grains contain magnesium, phytic acid in grains can
inhibit its absorption. Therefore, the best sources of magnesium are
dairy products, beans, leafy green veggies, and nuts.
V: Vitamin C:
This
is an important antioxidant, serving as an electron donor in biological
reactions. The brain has higher concentrations of Vitamin C compared to
other organs [17]. It participates in neuronal maturation and myelin
formation and supplies electrons for dopamine-β-hydroxylase, catalyzes
the formation of norepinephrine from dopamine and is involved in
presynaptic re-uptake of glutamate. Thus, it modulates the cholinergic,
catecholinergic, and glutamergic systems [17]. Studies show that vitamin
C levels are low in patients with dementia while research with animal
models show that vitamin C supplementation can reduce cognitive decline
[18]. Foods rich in vitamin C are citrus fruits, berries, bell peppers
and sea buckthorn
.
V: Vitamin D:
Although it's difficult to obtain from food, one thing you should definitely not get too little of is vitamin D
. The
best food source by far is cod liver oil (yuck!). Luckily, vitamin D is
created when our skin is exposed to sunlight. Vitamin D has profound
effects on the brain during all stages of life. Continuing to get
adequate vitamin D throughout adult life can ward off cognitive decline,
dementia, and Alzheimer’s disease [19, 20].
W: Water:
Obviously
the most important thing for your brain is water. It helps the blood
flow and consequently the oxygen supply of the brain. Thus, our advice:
Try to drink 2 liters of water per day.
Z: Zinc:
The
organ containing the highest amount of zinc is the brain, especially
the hippocampus and cerebral cortex. Zinc acts as an antagonist of the
NMDA receptor, induces BDNF gene expression and is a cofactor in the
conversion of homocysteine to cysteine. Early postnatal zinc deficiency
impairs neurogenesis, leading to learning and memory deficits persisting
into adulthood [21]. Studies with rodent depression models and clinical
studies have demonstrated the benefit of zinc supplementation in
antidepressant therapy [22]. In animal models of depression, zinc
treatment has antidepressant-like effects and dietary zinc insufficiency
induces depressive behaviors [23]. Even though zinc has been
associated with many psychological disorders, the nature of this
relationship remains unclear. Seafood, beef, lamb, "variety meats" such
as liver or brain, and some cheeses such as Emmental, Edam and Gouda are
excellent sources of zinc. Plants provide us with zinc as well, but
with lower bioavailability. Vegetarians and vegans should consume seeds,
nuts, spinach, cocoa and beans to get enough zinc.
Our advice: Add these smart foods to your shopping list and go out for a picnic in the sun!
[1] Fernstrom, J Am Diet Assoc, 1994
[2] Kronenberg, Curr Mol Med, 2009
[3] de Jager, Neurobiol Aging, 2014
[4] Tangney et al, Neurology, 2011
[5] Douaud et al, PNAS, 2013
[6] Watanabe et al, Nutrients, 2014
[7] EFSA Panel, EFSA Journal, 2014
[8] Salvati et al, Dev Neurosci, 2000
[9] Yurko-Mauro et al, Alzheimers, 2010
[10] Tan et al, Neurology, 2012
[11] Brandt et al, Behav Neurosci, 2013
[12] Delange, Proc Nutr Soc, 2000
[13] Burhans et al, Nutr Neurosci, 2005
[14] Todorich et al, Glia, 2009
[15] Lozoff et al, Semin Pediatr Neurol, 2006
[16] de Baaij et al, Physiol rev, 2015
[17] Normann Hansen et al, Nutrients, 2014
[18] Harrison et al, Nutrients, 2014
[19] Lee et al, J Neurol Neurosurg Psychiatry, 2009
[20] Anastasiou et al, J Alzheimers Dis, 2014
[21] Chowanadisai, J Neurochem, 2005
[22] Nowak et al, Pharmacol Rep, 2005
[23] Swardfager et al, Neurosci Biobehav Rev, 2013
by Claudia Willmes, PhD Student AG Eickholt / AG Schmitz
This article originally appeared 2015 in CNS Volume 8, Issue 3, Food for Thought.
