Diet & your brain: appetite
Recently, at a Symposium on “Changing Paradigms in Clinical Nutrition”., a booklet which was called “Nutrition and Brain”, published by Nestle, was made available to delegates. One of the most fascinating articles in this booklet describes how dietary factors and so-called monoamine neurotransmitters control our appetite.
A complex process
The control of appetite in humans is a highly complex process. The human nervous system transmits messages in the form of electric signals through the brain and nerves. Although this system is similar to electric wiring, nerve ends are not connected to each other. To transmit the message from one nerve ending to another, a so-called neurotransmitter chemical has to be released.
Some of the best known neurotransmitter chemicals are serotonin (5HT), dopamine and norepinephrine. Researchers have been studying these neurotransmitters for years to discover how message transmission can be selectively changed to produce specific results, for example to control appetite.
Appetite-suppressing drugs
Drugs have been developed to influence the three abovementioned neurotransmitters in an attempt to control appetite and combat overeating which leads to obesity.
* Selective enhancement of serotonin release or activity of 5HT will suppress appetite
(Example: sibutramine which is a selective serotonin or 5HT reuptake inhibitor)
* Selective enhancement of dopamine release will suppress appetite (Example: amphetamine)
* Selective enhancement of norepinephrine will suppress appetite (Example: phentermine)
Pharmaceutical appetite suppressants, which include these 3 monoamines, can all have a wide variety of side-effects. To be safe you should only take these appetite suppressants under medical supervision and stop immediately if you develop any negative side effects.
Manufacturing our own monoamine chemicals
Research has also shown that the so-called monoamines are manufactured in the human body from amino acids:
* the amino acid tyrosine is used by our bodies to synthesize dopamine and norepinephrine,
which can suppress appetite
* the amino acid tryptophan is used to synthesize serotonin or 5HT, which can suppress appetite
An important factor in the manufacture of monoamines is availability of substrate or basic material from which these chemicals are produced in our bodies. It is, therefore, theoretically possible to boost the concentrations of these appetite-suppressing monoamines in our bodies by dietary manipulation.
Dietary factors that boost monoamine synthesis
If we need the amino acids tyrosine and tryptophan to produce dopamine, norepinephrine and serotonin or 5HT, then it is logical that increasing the amount of tyrosine and tryptophan in the body will boost their production and possibly cause appetite suppression.
To increase the availability of these two amino acids, research has indicated that we need to do the following:
Boosting tryptophan
Contrary to expectation, levels of the amino acid tryptophan are not by eating very high-protein diets. To boost your brain levels of tryptophan and thereby increase the manufacture of serotonin or 5HT you need to eat a carbohydrate-rich diet.
Because serotonin is the brain chemical that makes us feel more positive and happy, this also explains why people get carbohydrate cravings. Readers often ask what they can do to control their irresistible urges to eat sugar, sweets and processed starches. One of the reasons why they have these urges is probably that their brain levels of serotonin are low. By eating sugar, sweets and starches they boost their brain tryptophan levels, which in turn boost serotonin or 5HT production and makes them feel more positive.
The urge to eat carbohydrates is a signal from your body that you either have a problem with serotonin production, or that your basic intake of carbohydrate is too low (for example slimmers who eat low-carbohydrate diets often get depressed and crave carbohydrates). To remedy this situation you need to ensure that you are eating sufficient unprocessed or minimally processed carbohydrates (e.g. unsifted maize meal, high-bran cereals, brown rice, potatoes, samp, crushed wheat, wholewheat bread). The high-carbohydrate diet must also contain moderate amounts of low-fat protein such as lean meat, fish, eggs, and low-fat milk and dairy products to provide tryptophan to the body.
Boosting dopamine and norepinephrine
To boost the production of these 2 monoamines humans require a high-protein diet. This is also the reason why high-protein diets give slimmers a “high”. The use of high-protein diets is associated with many risks. The risks include too high an intake of saturated fat and cholesterol which can have a negative effect on blood fat levels, development of acidosis and ketosis with damage to the kidneys, coma and death, constipation and a variety of other negative effects.
If you want to boost your intake of tyrosine, it may be safer to use an amino acid supplement which is low in fat together with a normal diet, rather than a diet overloaded with fatty proteins. Once again, it is not a good idea to overdo this supplementation. Use the amino acid supplements as described on the container and don’t think that if the prescribed dose may suppress your appetite, then taking double and treble the dose will give better results. If you find that you start getting depressed, then increase your intake of unprocessed carbohydrates to boost tryptophan and serotonin levels in the brain.
It is evident that the control of appetite is a very complex process and that interfering with the brain chemicals that control appetite can be potentially dangerous. So be careful what you take to suppress your appetite and never overdo the intake of one category of food.
Diet & your brain: aggression
Nutrients and aggression
In this series on “The Influence of Diet on the Brain & Nervous System”, we have already discussed dietary factors that can influence appetite, and the role of inositol in bulimia and psychiatric conditions, such as panic disorders, depression and obsessive compulsion. This article will consider how diet can potentially influence aggression.
The Aggressive Age
We live in an aggressive world if the War in Iraq and clashes in other parts of the globe are anything to go by.
Aggression has many causes, including psychological stresses, political pressures and hormonal factors, such as testosterone. In individual human beings aggression can manifest as antisocial behaviour, road rage, physical assault, including murder, and many other actions that cause harm to fellow humans. Recent research has indicated that dietary factors may well play a role in calming aggression.
Teenage offenders
Aggression is not necessarily age-related, but it is a fact that the teenage years are often fraught with aggressive behaviour, particularly in young men. A sad consequence of this teenage rage and lack of control, is the fact that many young offenders land up in jail or in correctional facilities. While such youngsters are incarcerated, they often vent their rage and frustration on fellow inmates. Such behaviour is usually punished by strict discipline and loss of privileges.
Researchers in the UK recently conducted a study with 231 young adult prisoners who were randomly chosen to either receive placebo (inactive substance), or a vitamin and mineral supplement together with omega-3 fatty acids. The vitamin and mineral supplement also contained trace elements such as selenium, chromium and manganese. All the nutrients in the supplement were included at levels of more or less the Recommended Daily Dietary Allowance (RDA).
At the start of the trial, the young participants were given psychological tests to measure aggression and their usual dietary intake was determined. The disciplinary offence records of each prisoner before and during the trial were compared.
Promising results
The results of this British study showed that young offenders who received vitamin, mineral, trace element and omega-3 supplementation, had 35% fewer disciplinary offences than those subjects who were receiving placebo. Interestingly the greatest improvement in antisocial behaviour was found for really serious offences such as physical violence.
Aggression in schoolchildren
Not all young offenders are put in jail. Many schoolchildren, particularly in economically deprived populations, also exhibit rage, antisocial behaviour, aggression and general ‘bad behaviour’. In a second study conducted in the USA, researchers gave 80 schoolchildren aged six to 12 years, vitamin and mineral supplements, or placebo, in an attempt to decrease delinquency.
These supplements provided approximately 50% of the RDA of the different nutrients for a study period of four months.
Once again, the results of the American study indicated that vitamin and mineral supplements can reduce aggressive behaviour. The study group receiving supplements were 47% less likely to exhibit delinquent behaviour than those receiving placebo.
Diet and Aggression
Although there have been indications in the past that a poor or inadequate diet lacking essential nutrients can cause aggressive behaviour, research in this field has to date been rather limited. The results of these two studies which produced dramatic decreases of 35% in aggression in teenage offenders, and of 47% in delinquent schoolchildren, are therefore most encouraging.
Because the subjects in both studies took supplements, which contained a wide variety of vitamins, minerals, trace elements, and omega-3 (in the UK study), we still don’t know at this stage which of the nutrients had this positive effect. Experts theorise that low tryptophan levels may influence serotonin levels in the brain, or that an imbalance in the copper-zinc ratio, or a deficiency in omega-3 fatty acids, may contribute to violence and aggression. There are also some indications that hypoglycaemia or low blood sugar levels can trigger outbursts. A great deal of additional research remains to be done in this important field to try and pinpoint more accurately those nutrients that can calm rage and prevent antisocial behaviour.
At the present moment, the best approach to controlling aggression in children and teenagers, is to make quite sure that they are eating a balanced diet and do not suffer from hypoglycaemia. To achieve this, they need to eat regular meals and healthy snacks, avoid junk food and get plenty of exercise. If you are struggling with a really rebellious teenager or an impossible family member who flares up at the slightest provocation and tends to violence, it may be a good idea to give them a complete vitamin and mineral supplements, as well as Salmon oil capsules for omega-3.
Inositol and Bulimia
Bulimia nervosa is a debilitating condition, which is classified as an eating disorder. Patients suffering from bulimia and binge eating, alternate between gorging themselves with food and then get rid of this food by inducing vomiting or using harsh purgatives to induce diarrhoea. The patient is driven to overeat and then ‘punish’ her-/himself by regurgitating the food.
Such behavior has drastic effects on both the psychological and physical well-being of bulimics. The feelings of guilt engendered by constantly overeating and purging tend to destroy the patient’s self-esteem and interfere with normal functioning. From a dietary point of view, these patients do not manage to absorb sufficient nutrients because the food they eat does not remain in the digestive tract long enough to allow proper digestion and absorption to take place. Consequently, bulimics are often undernourished and deficient in macronutrients, vitamins, minerals, trace elements and omega fatty acids.
Research conducted in Israel with a small group of patients suffering from bulimia and binge eating has shown that inositol may help these individuals to get control of their lives again. In the Israeli study, patients with bulimia and binge eating disorder were either treated with 18 g of inositol or 18g of placebo (inactive substance) per day for a period of 6 weeks. Statistically significant improvements in psychological test results were obtained when the patients received inositol.
Inositol and Panic Disorder
Panic disorder is another psychiatric condition that appears to respond to treatment with inositol. Individuals who suffer from panic disorder develop acute, debilitating attacks of anxiety that literally ‘paralyse’ them when faced with a given trigger or situation. For example someone suffering from panic disorder may not be able to leave home because of an intense fear of open spaces. Panic disorders, therefore, interfere significantly with everyday life and any new approach that could assist these patients is to be welcomed.
A recently published study originating in the same Israeli research centre as the bulimia trial mentioned above, compared the effect of inositol (up to 18g/day) and fluvoxamine (a psychiatric drug at a dose of 150g/day). Each treatment was given for a period of one month. The researchers found that the subjects receiving inositol had considerably fewer panic attacks than those taking fluvoxamine.
Inositol and bipolar depression
Another study indicated that patients with bipolar depression also reacted favourably to inositol doses of 12g per day. The results of this third study were not as positive as the effects found for bulimia and panic disorders, but the patients did show improvements in their clinical status.
What is inositol?
Inositol is a so-called sugar alcohol which is found in many foods, especially cereals with a high bran content. Although nutritionists have been aware of inositol for many years, this is the first research that indicates that inositol may help to alleviate certain psychiatric conditions.
Inositol supplementation is known to help premature infants survive respiratory distress syndrome. Inositol plays an essential role in the physiology of phospholipids, which are important for the proper functioning of all membranes, including the membranes lining the lungs of premature infants. In addition, inositol has been identified as a compound that acts as a ‘second messenger’ helping with the release of calcium during the transmission of nerve signals that control muscle movements.
It seems likely that these three recent research studies have identified new roles for inositol. Although these investigations are of a preliminary nature and more research is required to obtain more conclusive evidence, the results do indicate that inositol may help patients suffering from psychiatric conditions such as bulimia nervosa, panic disorder and bipolar depression. It has been suggested that inositol supplementation could be used as an alternative for certain psychiatric drugs and/or as an adjunct to conventional therapy.
From a dietetic point of view, the potential of inositol supplementation in treating bulimics, is welcome news. Such patients may also benefit from eating a diet rich in unprocessed grains and cereals, which are known to contain inositol.
B vitamins against Alzheimer's
Progress through research and expansion of our understanding of diseases and conditions that plague the modern world, is always exciting. I received a Clinical Nutrition Update published by Arbor Communications on progress that has been made in the quest to discover what factors affect Alzheimer’s Disease. There are indications that certain B vitamins may be implicated in the development and progression of Alzheimer’s
This sly illness which creeps up on so many people, not only in old age, but while they are still in their forties and fifties, is particularly distressing for all who are associated with it.
Patients progressively lose their cognitive functions, their memory and their dignity. Anyone who has seen “Iris”, the film that so movingly chronicles the frightening descent into dementia that Iris Murdoch suffered before her untimely death, will be aware of the destruction this disease causes. Iris was one of Britain’s foremost modern authors, with a sharp and scintillating brain. The portrayal by Dame Judy Dench, of Iris’ loss of her mind, is one of the most shattering performances I have ever seen.
Alzheimer’s Disease not only affects the patient, but also all who love and care for the person whose mind disintegrates. Caregivers and family members are helpless to do anything and at present there is no cure for this dreaded disease.
Many theories
Scientists have been trying to establish what causes Alzheimer’s Disease and are looking for potential cures and treatments. Many theories have been proposed - there is the virus theory which contends that the sticky plaques that develop in the brain are triggered by viruses. In another theory, the use of aluminum cooking utensils has also been considered as a causative factor, but our knowledge is still frustratingly limited.
Latest research
In the latest Arbor Clinical Nutrition Update, the editors review three studies that have come up with exciting new facts.
In the first study, homocysteine levels were tested in more than a 1000 people who participated in the Framingham Study, a long-term study conducted in the UK to identify the influence of nutrition on many different conditions over very long periods. Homocysteine is a chemical compound that has previously been linked to risk of heart attacks. In the Alzheimer’s Disease study, researchers analysed the homocysteine levels in the blood of participants over a period of 16 years. They found that subjects with high homocysteine levels had a much higher incidence of dementia and Alzheimer’s Disease. In fact, the risk of developing Alzheimer’s disease was doubled in those individuals who had abnormal homocysteine levels exceeding 14 micromol per litre of blood.
In the second study, two groups of participants who had participated in a Scottish mental health survey when they were 11 years old, were tested for homocysteine levels and mental function at the ages of 63 and 78 years. The researchers found that in older participants, raised homocysteine levels in the blood were linked to decreased mental function, such as is seen in Alzheimer’s Disease.
The third study compared homocysteine levels with the results of MRI scans in more than 1000 Dutch subjects, aged 60 to 90 years. Once again the scientists discovered that raised homocysteine levels were associated with an increased risk of finding so-called “silent brain infarcts” and severe white matter lesions, both of which indicate brain damage.
What does this mean?
Although research into the link between raised homocysteine levels and Alzheimer’s Disease is still in its early stages, these three studies indicate that there may well be an association between raised homocysteine levels in the blood and the risk of developing progressive brain damage.
Research on the link between raised homocysteine levels and heart disease which has progressed much further, has found that raised homocysteine levels can be reduced to normal by ensuring that patients have adequate folic acid, vitamin B12 and B6 intakes.
In relation to Alzheimer’s Disease, it may, therefore, also be important to ensure that patients, and in fact all older individuals, get sufficient folic acid, vitamin B12 and vitamin B6 from their diets and/or by means of supplements.
Imagine what benefits would ensue if Alzheimer’s Disease could either be prevented and/or treated by something as simple as 3 of the B vitamins! The Editors of the Arbor Clinical Nutrition Updates state that there is now sufficient evidence to encourage doctors to take homocysteine levels into account when treating elderly patients at risk of developing dementia or Alzheimer’s Disease. They also believe that such patients should be monitored to determine if they suffer from folic acid, B12 and to a lesser extent, B6 deficiencies, and if this should be the case, that they should be treated with these 3 B vitamins.
Next week we will take another look at folic acid, vitamin B12 and vitamin B6, which could just hold the answer to one of the most tragic diseases of modern times.
Think of fish as a good thing - particularly if you're a woman looking to reduce your risk of stroke. The more fish women eat, the greater the benefit, says a new study.
"We found that women who ate fish just one to three times a month had a seven percent lower risk of stroke than those who ate it only once a month," says study author Dr Kathryn M. Rexrode, an internist at Brigham and Women's Hospital in Boston.
"Increase your fish intake to once a week, and stroke risk could go down by 22 percent," she says. "Two to four times a week reduces risk to 27 percent, and eating fish five times a week or more brings down the risk of stroke by up to 52 percent." Findings will appear in this week's Journal of the American Medical Association.
Experts say the likely reason fish protects women is the concentration of omega-3 fatty acids, nutrients that prevent the formation of clots, mostly by making blood less "sticky." This, in turn, reduces the risk of ischemic stroke, which is caused by blood clots that form either in the brain (leading to a thrombotic stroke) or elsewhere in the body and then travel to the brain (causing an embolic stroke).
Epidemiologist Gail Frank, a spokeswoman for the American Dietetic Association, says the new findings enforce what dietary experts long have believed.
"We have known for several decades that fish, by the nature of the fatty acid composition, when eaten more often, can alter lipids and, potentially, the clotting mechanism as well as plaque formation. Over time, it can change a little bit of the chemistry of the body," Frank says.
"This study is important because there has been a deficit of research to look at women," she says. "It's an important message for women to now know something positive they can do to reduce their risk of stroke."
In addition to reinforcing the preventive link between omega-3 acids and ischemic stroke, the new study finds fish acids do not contribute to hemorrhagic stroke, which occurs when a blood vessel inside the brain ruptures or "leaks."
Normally, factors that decrease the risk of blood clotting, including omega-3, are thought to increase the risk of a "leaky" hemorrhagic stroke, but the latest study shows that's not the case for consumption of fish, the researchers say.
"Our research showed that eating fish does not have an adverse effect on hemorrhagic stroke," Rexrode says. "It doesn't increase the risk, which is something we did not know for certain before."
The researchers also found that fish is not likely to further reduce the risk of clot formation for people already taking aspirin to reduce their risk of stroke.
"Platelet aggregation, or the formation of blood clots, is a kind of all-or-nothing mechanism. You either turn it on or you turn it off," Rexrode says. In other words, once the biological switch is thrown to turn off platelet aggregation, which is something aspirin does, then additional attempts to do the same thing, such as eating fish, do not increase the effects, she says.
"If they work on the same mechanism, you're not going to see any added benefits to eating fish among aspirin users, because it's already being taken care of by aspirin, and aspirin is more potent in blocking this effect," Rexrode says.
But this does not mean that taking aspirin precludes the need to eat fish - or the other way around, she says.
"Studies have shown fish may have other important health benefits, so adding two to four servings per week to your diet is still important, even if you are already taking aspirin," she says.
Likewise, she says, aspirin still may be an important and necessary treatment, even if you're eating fish.
What to do
While adding more fish to your diet appears healthful, it's important to note that not all fish are alike. Light-meat fish, like flounder or whiting, have only about 0.5 grams of omega-3 fatty acid per 4-ounce serving, while dark-meat fish, such as salmon, sardines, mackerel or bluefish, have roughly 1.5 grams of the protective fatty acid in the same amount of fish. - (HealthDayNews)
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