Answer by Anuj Agarwal:
A brain-healthy diet is one that encourages good blood flow to the brain, is rich in anti-oxidants, omega-3 fatty acids, have enough minerals like Vitamin C, E, B12 and folate and is low in fat and cholesterol. Like the heart, the brain needs the right balance of nutrients, including protein and sugar, to function well. A brain-healthy diet is most effective when combined with physical and mental activity and social interaction.
Here is a list of food, in order of importance, you might want to include in your daily diet for maintaining a healthy brain.
1. Dark skinned Vegetables rich in Antioxidants
- Spinach – Spinach is rich in the antioxidant lutein, which is thought to help protect against cognitive decline, according to researchers from Tufts University.
- Brussels sprouts – Has Tryptophan which converts to Serotonin in the brain
- Alfalfa sprouts
- Cauliflower – Assists in cleansing white matter in brain
- Beets – good source of naturally-occurring nitrates, which help improve blood flow to the brain
- Lettuce – Helps increase blood flow to the brain and cleanse blood plague.
- Red bell pepper
2. Fruits rich in Antioxidants
- Blueberries – Improve learning and motor skills
- Prunes, raisins, blackberries, strawberries, raspberries, plums, oranges, red grapes and cherries
3. Food rich in Omega-3 fatty acids
- Cold water fish like Halibut, Mackerel, Salmon, Trout and Tuna Oily fish like Sardines, Herring
- Fatty fish have been linked to lower risk of dementia, improved focus and memory.
4. Nuts & Seeds rich in Vitamin-E/Antioxidants
Walnuts, hazelnuts, Brazil nuts, Pine nuts, Pecans, Filberts, Almonds, Cashews, Peanuts, Sunflower seeds, Sesame seeds, Flax seed, and unhydrogenated nut butters such as Peanut butter, Almond butter, Tahini
5. Get enough Vitamin C and Zinc
Diets low in vitamin C and zinc may affect children's mental and physical development. Good sources of zinc include oysters, beef, crab, fortified breakfast cereals, beans, yogurt, cashews, chickpeas, oatmeal, almonds and peas. Foods rich in vitamin C include red peppers, oranges, grapefruit, kiwi, green peppers, broccoli, strawberries, Brussels sprouts, cantaloupe, cabbage, cauliflower, potato, tomatoes, spinach and green peas.
6. Memory-Boosting Foods
Choline is a precursor to acetylcholine, a substance that helps stimulate the brain; a more stimulated brain is better able to make new connections, which is an important part of memory. Foods high in choline include eggs, liver, soybeans, peanuts, butter, potatoes, cauliflower, lentils, oats, Swiss chard, collard greens, sesame seeds and flax seeds. The substances anthocyanin and querecetin may help boos memory, according to a Harvard study; good sources include berries, cherries, black currants, eggplant, red, purple and black grapes, red onion, red apples, beets, onions, kale, leeks, cherry tomatoes, broccoli, blueberries and apricots.
Be sure to get enough to keep your body and brain hydrated. Dehydration can cause a headache now, and can lead to long-term neuronal damage sustained from elevated stress hormones. When a person becomes dehydrated, their brain tissue actually shrinks. And several studies have shown that dehydration can affect cognitive function.
8. Whole grains – Oatmeal, whole-grain breads, and brown rice promote good blood flow to the organ system, which includes brain.
9. Tea or Coffee – Modest amount of caffeine Boosts brain power by enhancing memory, focus, and mood. Green tea is beneficial as they are rich in Antioxidants. Aside from caffeine's brain boosting effects, coffee's antioxidant richness helps maintain brain health. And some research suggests that drinking coffee can actually stave off depression in women.
10. Beans – It Stabilize glucose (blood sugar) levels. The brain is dependent on glucose for fuel and since it can't store the glucose, it relies on a steady stream of energy — which beans can provide.
Eg Lentils, Black beans.
11. Pomegranate juice – Offers potent antioxidant benefits which protect the brain from the damage of free radicals.
12. Dark Chocolate – It has powerful antioxidant properties, contains several natural stimulants, including caffeine, which enhance focus and concentration, and stimulates the production of endorphins, which helps improve mood.
13. Wheat Germ – It is a rich vegetarian source of choline — a nutrient that is involved in the body's production of acetylcholine, a neurotransmitter that boosts memory.
14. Moderate alcohol consumption raises levels of healthy high-density lipoprotein (HDL) cholesterol. Alcohol also lowers our cells' resistance to insulin, allowing it to lower blood sugar more effectively. Insulin resistance has been linked to dementia.
15. Avocados – contributes to healthy blood flow and And healthy blood flow means a healthy brain. Avocados also lower blood pressure and as hypertension is a risk factor for the decline in cognitive abilities, a lower blood pressure should promote brain health
16. Garlic – Garlic may help stave off some forms of brain cancer, according to research published in Cancer, the medical journal of the American Cancer Society. Investigators found that the organo-sulfur compounds in garlic actually worked to kill glioblastoma cells — a type of malignant tumor cell.
17. Vegetables rich in Betacarotene – such as carrots, sweet potatoes and spinach, have also been shown to improve the health of the brain.
Foods that affect Brain Activity
- High blood sugar levels may take a toll on the brain 
- Obesity-inducing junk food could also give you dementia through high blood pressure and cholesterol, which interrupt blood supply to the brain
- Low-carb diets could also be draining your brain 
- Even small amounts of glucose or fructose can slow down brain and memory functions
Some other useful tips
- Research indicates that "Eating Breakfast" is beneficial for children's cognitive performance. 
- A study by researchers from the Centre for Research in Environmental Epidemiology suggested that vitamin D consumption by mothers during pregnancy could lead to better brain health for their babies.
 Diet for Healthy Brain Function in Children http://www.medicaldaily.com/articles/11992/20120907/diet-healthy-brain-function-children.htm
 Adopt a Brain-Healthy Diet http://www.alz.org/we_can_help_adopt_a_brain_healthy_diet.asp
 Eat Smart for a Healthier Brain http://www.webmd.com/diet/features/eat-smart-healthier-brain
 Seven ways to a healthy brain http://www.independent.co.uk/life-style/health-and-families/healthy-living/seven-ways-to-a-healthy-brain-834556.html
 Baby's brain health may be linked to mother's vitamin D consumption, according to a new study http://www.nydailynews.com/life-style/health/baby-brain-health-linked-mother-vitamin-consumption-a-new-study-article-1.1167248
 Dehydration affects brain structure and function in healthy adolescents. http://www.ncbi.nlm.nih.gov/pubmed/20336685
 Emerging Science: The Role of Lutein in Neural Health – From the Retina to the Brain http://www.nutraconference.com/networknow/public/SessionDetails.aspx?SessionID=1004689&FromPage=nz_ALSessionSearch.aspx
 Coffee Cuts Depression Risk In Women, New Study Shows http://www.huffingtonpost.com/2011/09/27/coffee-cuts-depression-women_n_982122.html
 Ask the Expert: Omega-3 Fatty Acids http://www.hsph.harvard.edu/nutritionsource/questions/omega-3/index.html
 Boost your memory by eating right http://www.health.harvard.edu/newsletters/Harvard_Womens_Health_Watch/2012/August/boost-your-memory-by-eating-right
 Certain foods may hurt, help the brain http://articles.ky3.com/2012-09-24/silent-strokes_34067314
 High Blood Sugar Levels Linked to Brain Shrinkage http://abcnews.go.com/blogs/health/2012/09/04/high-blood-sugar-levels-linked-to-brain-shrinkage/
 Sugar and high fructose diet slows brain and memory functions http://www.naturalnews.com/037130_fructose_memory_loss_sugar_consumption.html
 Junk food could also damage brain, says study http://indiatoday.intoday.in/story/junk-food-could-also-damage-brain-says-study/1/215443.html