Something people might not even count as nutrition: water! The brain is very sensitive to the optimum amount of water in the body. Whenever you are thirsty, the body tries to assure your brain's water supply stays constant, in other words: it deprives other parts of your body of water in order to keep the water level in your brain within the required range. However, when your body yearns for water, then eventually your brain gets distracted much as you won't be able to think clearly if you are starving – your conscious mind will try and concentrate on where to find food first before solving mathematical equations. The same goes for water only that often the feeling for thirst is not as distinct as hunger is.

So make sure you (or your children) drink enough water. And by water we mean water – unadulterated water. Your body needs water to get rid of the surplus nutrients your body consumes. If a beverage already contains a lot of ingredients apart from water then in effect you might even increase your water requirements by "drinking". This goes for alcoholic beverages as much as for those that contain a lot of sugar. (This does not mean we advocate using lemonade that contains non-caloric sugar substitutes – these may cause you to become hungry and thus are probably counter-productive if you want to watch your waistline; but that I s another discussion).

So: make sure your body has enough water. Many people think they need a cup of coffee first thing in the morning to really "wake up" – studies have shown that most people seem to feel the same invigorating effect if they drink the same amount of pure water. There are various ways (and philosophies) to calculate the right amount of water intake. Some suggest to drink about one litre of water for every three of four kilos (six or eight pounds approximately) of body weight. Since you are taking in water with your food and with any drink you consume you are probably safe with less pure water altogether.

However, if you do a lot of sports and thus perspire, you might need to drink more and you might also want to replenish your mineral reserves that have been depleted by losing a lot of salts through your sweat.

So, water is the first prerequisite for a functioning brain. If you sit an important exam or are being tested, you should make sure you drank enough water beforehand (i.e. over several days. Then you need to make sure you have enough minerals, esp. magnesium, which your nerves need to function properly.

All that won't directly increase your intelligence, however, they are prerequisites for your brain to function at its optimum. Only then can you hope to increase your already existing intelligence level by some points through a sensible diet.

If you want to check whether your food intake is optimised for your brain to function, you might want to check out 7 Nutrition Tips for Increasing Brain Power where Daniel G. Amen lists the foods that contain unsaturated fats and other brain-friendly nutrients.

One concern is the attack of oxidising substances on the brain cells which can be offset by substances that absorb these so-called radicals. A list of foods ordered by their "oxygen radical absorbance capacity (ORAC)" can be found in "Nutrition and Brain Function" by Rosalie Marion Bliss, based on studies by James A. Joseph, Ph.D.

Many people feel they cannot eat as well and as healthy as they wished because they have to eat in places where they feel the food isn't as nourishing as they wish, be it at their workplace or while travelling or because they feel they cannot spend enough time preparing food at home that would qualify.

For those there are nutritional supplements. However, their dosage and necessity are highly controversial and we do not wish to be drawn into the debate.

Certainly, when there is a gross undersupply of one's body with e.g. an essential vitamin, science has found that supplying the missing nutrient heals the disease, cf. the treatment of scurvy with vitamin C or fresh fruit. We do not quite see why what works in sick people should not work with otherwise healthy people. Also, when you consume a certain amount of foodstuff then you can never be sure if you overdose some of its ingredients if the right dosage were all that matters. Everyone's experience seems to clearly show that if you eat much fruit you do not feel negative effects although you might inadvertently have taken an "overdose" of some vitamins hen compared to the "Recommended Daily Amount" (RDA) or other guidelines.

Likewise, at least provided the nutritional supplements are of natural origin, we therefore fail to see why these supplements should prove harmful. So, if, to be on the safe side, someone who is unsure if he or she takes enough of certain essential nutritional components with their normal diet wants to supplement these we feel they might err on the safe side rather than do harm to themselves.

At least that seems to go for natural ingredients that have not been synthesised chemically. The reason seems to be that some nutrients have a different structure when synthesised but more so that they often are accompanied by phytofactors that greatly influence the way these essential nutrients are metabolised.

Your brain (or your nervous system in general) needs certain substances that control the transmission of information (nerve impulses). These are synthesised from certain basic substances that you need to supply with your daily diet. Here is a list (from "Nutrition and the Brain" from Washington University:

• Aspartic Acid: Used to make aspartate; found in peanuts, potatoes, eggs and grains.
• Choline: Used to make acetylcholine; found in eggs, liver and soybeans.
• Glutamic Acid: Used to make glutamate; found in flour and potatoes.
• Phenylalanine: Used to make dopamine; found in beets, soybeans, almonds, eggs, meat and grains.
• Tryptophan: Used to make serotonin; found in eggs, meat, skim milk, bananas, yogurt, milk, and cheese.
• Tyrosine: Used to make norepinephrine; found in milk, meat, fish and legumes.

Some tips on what to eat to assure optimal levels of neurotransmitters can be found in "BRAIN FOOD".

Another very good collection of articles can be found at the Franklin Institute "The human Brain – Diet and Menu" by Nutrition Counsellor Debra Burke, giving an overview of the effects of certain fatty acids, glucose and essential brain micronutrients.

While optimal levels of these do not of itself ensure that your intelligence increases they are necessary to forestall any intelligence decrease. Studies show that there are three factors that can make your mental capacities decrease:

• lack of exercise (probably directly linked to lack of blood and oxygen supply for your brain)

• lack of challenge (people who didn't challenge their brains e.g. during a long vacation tend to see a significant drop in some areas of their IQ tests!)

• lack of essential nutrients.

So, to keep your level of intelligence you need to eat well, exercise and use your brain.

There are strong indications that esp. the optimal supply of n-3 polyunsaturated fatty acids during pregnancy and during later life affect mental capacity positively. Studies showed that "use of food supplements in late adulthood is associated with cognitive performance" (cf. "Intelligence increase: Childhood intelligence and food supplements") and that the same holds true for the supply of omega-3-fatty acids during pregnancy where children tested with lower IQs if their mothers lacked optimal fatty acid levels during pregnancy. Again, this does not mean you necessarily should take supplements as, like most findings when it comes to nutrition, are disputed (cf. "ω-3 fatty acid supplementation during pregnancy" by the College of Family Physicians of Canada). We believe that the facts bear out the basic findings and that means that at least you should check whether as a pregnant mother your or later your children's diet contains enough Omega-3 fatty acids (cf. "Essential Fatty Acids Improve Infant IQ" by Richard N. Podell, M.D.: "infants given a DHA-enriched formula had superior problem-solving ability at 10 months compared with infants who drank the standard, low-DHA commercial product.", but remember: mother's milk provides enough of these nutrients provided your own diet is balanced enough!).

Eating oily fish during pregnancy may reduce risk of later attention disorders in children, and eating any kind of fish may increase IQ levels significantly over children born to mothers who didn't (cf. "Oily Fish Intake during Pregnancy--Association with Lower Hyperactivity but Not with Higher Full-Scale IQ in Offspring" by Catharine R. Gale et al.). More proof: "Maternal intake of very-long-chain n-3 PUFAs [very-long-chain n-3 polyunsaturated fatty acids] during pregnancy and lactation may be favorable for later mental development of children." (cf. "Maternal Supplementation With Very-Long-Chain n-3 Fatty Acids During Pregnancy and Lactation Augments Children’s IQ at 4 Years of Age"

So from conception through lactation and later life human beings seem better off and tend to be more intelligent if their diet contains enough omega-3 polyunsaturated fatty acids. To make sure your brain has enough arachidonic acid, another of its main components, you might consider eating butter regularly – it supplies the necessary amounts of cholesterol and foods with arachidonic acid are eggs, liver, and butter and even staves off depression ("Healthy Fats? Yes, Fats Play a Big Role in our Emotional Health"). Counter to common belief your body is in dire need of healthy cholesterol (cf. http://www.cholesterol-and-health.com/: "The War on Your Brain - one of cholesterol's most important functions is to support learning and memory — that is why the brain is so rich in cholesterol", see also "The 20 Health Benefits of Real Butter").