Richard G. Petty, MD

Violence and Diet

We have talked before about the link between nutrition and violence.

The evidence has continued to mount and I was pleased to see that the Wellcome Trust is funding trials in three British prisons to investigate the link between nutrition and behavior. This is a placebo study that will examine which nutrients are most important and at what dosage.

Volunteers from three young offenders institutions housing male prisoners aged 16 to 21 will take nutritional supplements in addition to their normal choice of food to ensure they receive the necessary vitamins, minerals and essential fatty acids to meet daily guidelines. The investigators will monitor how levels of nutrients affect a range of behaviors including violence, drug-related offences and incidents of self-harm.

The new trials build on previous research published in the British Journal of Psychiatry that was conducted at the then maximum security Young Offenders Institution in Aylesbury, Buckinghamshire. That study was funded by Natural Justice, a research charity that investigates the social and physical causes of offending behavior. Nutritional supplements – 2 grams per day of the omega-3 fatty acids EPA and DHA for three months – were given to ensure that inmates’ diets reached recommended UK dietary standards. The researchers found that the prisoners who consumed the active nutrient capsule committed on average 26% fewer disciplinary offenses overall than those taking the placebo and 37% fewer violent offenses.

The most likely reason why supplements can have such a large effect is because the proper functioning of nerve cell membranes and signaling molecules depends upon adequate amounts of minerals, vitamins and essential fatty acids in the diet.

This is extremely important work. Clearly nutrition is not the only driver of violence but it has been wondered for a long time whether the industrialization of our diets has contributed to the enormous rise in violent crime between the 1950s and 1970s.

“Violence is the last resort of the incompetent.”
Isaac Asimov (Russian-born American Biochemist and Writer, 1920-1992)

“Blessings crown the head of the righteous, but violence overwhelms the mouth of the wicked.”
–The Bible (Proverbs 10:6)

“Peace cannot be achieved through violence, it can only be attained through understanding.”

–Ralph Waldo Emerson (American Poet and Essayist, 1803-1882)

Antioxidants May Raise Cancer Risk?

Regular readers will know that I have for some years now been raising a red flag the wholesale promotion of antioxidants.

The trouble is this: antioxidants are supposed to help rid us of some of the free radicals that have been implicated in a small number of diseases, and may also play a role in some of the physical aspects of aging. However, free radicals are also some of the major cancer killers in the body, so eradicating them – even if it were possible – hardly seems like a good idea.

According to an analysis of a dozen studies including more than 100,000 patients in the Mayo Clinic Proceedings taking antioxidant supplements do not reduce cancer risk.

In fact smokers who take beta carotene supplements could be increasing their risk of smoking-related cancer and death.

Different antioxidants have different effects, and their effects may also vary depending on the part of the body involved.

The researchers looked at 12 trials that compared antioxidant supplements with placebo on cancer incidence and mortality. Antioxidant supplements did not reduce the risk of cancer. When they looked separately at beta carotene, they found the nutrient actually increased cancer risk by 10 percent among smokers. There was also a trend toward a greater risk of dying from cancer with beta carotene supplementation.

Selenium supplements reduced cancer risk by 23 percent among men, the researchers found, but had no effect on women. While vitamin E had no anti-cancer effect overall, supplementation with the nutrient was tied to a 13 percent lower prostate cancer risk.

A large study looking at vitamin E supplementation for prostate cancer is currently underway. While future studies of beta carotene and vitamin E for cancer prevention are very unlikely to show effectiveness, it would be worth doing further studies on selenium.

The moral of the story: we should be going for a balanced diet and a balanced life in general rather than putting our hopes in an over-simplified nutritional message.

Nutrigenetics: A Peak Into the Future

At any given time only about ten percent of you genes are thought to be active. They are switched on and off in response to all kinds of internal and environmental changes. This is particularly true in the metabolic pathways, where gene activation is an essential part of the normal response to dietary changes. We also know that many of us have genetic reasons for varying in our nutritional requirements.

Anybody who has looked into diet and nutrition knows that there is no one approach that works for everyone, and the Holy Grail of weight management is to be able to identify which diet will work for whom.

This goal has just come a little closer with the publication of a report from researchers in Greece, London and Colorado that has been published in the Nutrition Journal.

The paper, “Improved weight management using genetic information to personalize a calorie controlled diet” is available for free download.” The study population consisted of 50 patients who had failed to lose weight. They were offered a nutrigenetic test screening 24 variants in 19 genes involved in metabolism. 43 patients attending the same clinic were selected for comparison using algorithms to match age, sex, frequency of clinical visits and BMI at initial clinic visit. The second group of 43 patients did not receive a nutrigenetic test. BMI reduction at 100 and over 300 days and blood fasting glucose were measured.

The results are very promising. After 300 days of follow-up individuals in the nutrigenetic group were more likely to have maintained some weight loss (73%) than those in the comparison group (32%). Average BMI reduction in the nutrigenetic group was 1.93 kg/m2 (5.6% loss) vs. an average BMI gain of 0.51 kg/m2 (2.2% gain). Among patients with a starting blood fasting glucose of >100 mg/dL, 57% (17/30) of the nutrigenetic group but only 25% (4/16) of the non-tested group had levels reduced to <100 mg/dL after >90 days of weight management therapy.

The paper concludes by saying that the addition of nutrigenetically tailored diets resulted in better compliance, longer-term BMI reduction and improvements in blood glucose levels.

This is a small “proof of concept” study, and the effects are not enormous, but there is easily enough here already to vigorously pursue this genetic approach.

Genes, Breastfeeding and IQ

Studies on intelligence and breastfeeding have come up with conflicting results. The major question has been whether the results have been skewed because more educated or more affluent mothers were more likely to breastfeed.

A new study by colleagues in London, New Zealand and here in the United States has just been published in the Proceedings of the National Academies of Sciences and indicates that a single gene influences whether breastfeeding improves a child’s intelligence.

The gene in which the researchers were interested is a fatty acid delta desaturase – FADS2 – that is involved in the genetic control of fatty acid pathways. Children with one version of the FADS2 gene scored seven points higher in IQ tests if they were breastfed, but breastfeeding had no effect on the IQ of children with a different version of the gene.

Researchers at the Institute of Psychiatry, Kings College London, used data from two previous studies of breast-fed infants in Britain and New Zealand that had involved more than 3,000 children. IQ was measured at various points between the ages of five and 13 years in the studies. The only thing that we do not know is exactly how long the children were breastfed.

This is yet another study to show us why the nature/nurture debate needs a radical re-think. Nutrition and genetics act together. People have been arguing about the roots of intelligence for at least a hundred years, and this research shows nature working via nurture to create better outcomes.

Around 90% of people carry the version of the gene that was associated with better IQ scores in breastfed children. We do not know if there are any ethnic differences in those numbers, but there may be.

And that seven point difference in IQ? It s not going to determine how well someone is going to do in life, but in school it might be enough to put the child in the top third of the class.

Fat and Cancer

It is not every day that a medical story hits the front page of USA Today, but today one has, and for a very good reason.

The World Cancer Research Fund (WCRF) has just published a report that we have been eagerly awaiting for several years. It is the most comprehensive analysis ever published on the link between cancer and diet, weight and physical activity. Researches at nine academic institutions across the world looked for every relevant study published since records began in the 1960s. They initially found half a million, and in the end 7,000 of them were judged to be the most relevant and robust for inclusion in the report.

It includes 10 recommendations from a panel of 21 world-renowned scientists that represent the most definitive and authoritative advice that has ever been available on how the general public can prevent cancer. UNICEF and the World Health Organization were among the official observers of the report’s process.

A key finding is that maintaining a healthy weight (a BMI of 20-25) is one of the most important things you can do to prevent cancer. The number of types of cancer where there is “convincing” evidence that body fat is a cause has risen from one to six since the last WCRF report was published in 1997, including colorectal cancer and post-menopausal breast cancer.

Prof Sir Michael Marmot, who was Chair of the Panel, said that,

“We are recommending that people aim to be as lean as possible within the healthy range, and that they avoid weight gain throughout adulthood.

“This might sound difficult, but this is what the science is telling us more clearly than ever before. The fact is that putting on weight can increase your cancer risk, even if you are still within the healthy range.

“So the best advice for cancer prevention is to avoid weight gain, and if you are already overweight then you should aim to lose weight.”

Other findings in the report include:

There is “convincing” evidence that processed meats, including ham and bacon, increase the risk of colorectal cancer. People who consume them are advised to do so sparingly.

The evidence that red meat is a cause of colorectal cancer is stronger than ever before. People should not eat any more than 18 ounces (500g) of red meat a week.

This figure is for cooked meat, and is the equivalent of between 15-30 ounces (700-750g) of non-cooked meat.

Here is something that is almost a first, at least for a cancer report. It has made a breastfeeding recommendation: mothers are advised to breastfeed exclusively for six months and to continue with complementary breastfeeding after that. This is because of “convincing” evidence that breastfeeding protects the mother against breast cancer and “probable” evidence that it protects the child against obesity later in life.

Dietary supplements are not recommended for cancer prevention. The evidence that alcohol is a cause of cancer is stronger now than ever before.

Professor Martin Wiseman, Project Director of the Report, said:

“This report is a real milestone in the fight against cancer, because its recommendations represent the most definitive advice on preventing cancer that has ever been available anywhere in the world.

“When individual studies are published, it is impossible for the public to put them into context and know how seriously they should be taking the findings. But the great thing about this report is that it does this job for them.

“If people follow our recommendations, they can be confident they are following the best advice possible based on all the scientific research done up to this point. These recommendations are not based on one study but are based on 7,000.”

In the United Kingdom, plans are afoot to establish a Cancer Reform Strategy. Professor Mike Richards, the British Government’s Clinical Director for Cancer, had this to say:

“The WCRF report is the most authoritative and exhaustive review done thus far on the prevention of cancer through food, nutrition and physical activity.

“For those of us wanting to lower our risk of developing cancer, the Report provides practical lifestyle recommendations. The Report also provides public health goals. Both will form an important element for the forthcoming Cancer Reform Strategy.”

These are the main recommendations:

  • Limit red meat
  • Limit alcohol
  • Avoid bacon, ham, and other processed meats
  • No sugary drinks
  • No weight gain after 21
  • Exercise every day
  • Breastfeed children

Have you seen those infomercials where someone tells you that there is some conspiracy by shadowy people who don’t want you to know the truth about diet, exercise and cancer? Next time remember this research. If some expensive supplement or the juice of an exotic berry from the Himalayas could really reduce the risk of cancer, these studies should have noticed something by now.

Folic Acid: Too Much of a Good Thing?

If you believe everything that your read in the media or hear on those infomercials, you would think that you should spend all day munching pounds of fruits and vegetables while taking megadoses supplements chasers.

While that may sound good in theory, in practice things are not so simple and this approach may actually do you harm.

A good example has just come to light in a report from the Institute of Food Research in the United Kingdom that has just been published in the British Journal of Nutrition.

We have talked before about the potential value of fortifying food with folic acid. Apart from reducing the risk of neural tube defects in babies, it may also reduce the risk of depression.

The new report suggests that fortifying flour with folic acid may lead to a range of health problems.

Folic acid is a synthetic form of folate, a B vitamin found in a wide variety of foods including liver and leafy green vegetables. Folates are metabolized in the intestine, whereas folic acid is metabolized in the liver. The liver is an easily saturated system, and at doses of half the amount being proposed for fortification that could lead to significant unmetabolized folic acid entering the blood stream.

This excess folic acid could cause a number of problems:
It may interfere with some treatments for leukemia and arthritis
Women being treated for ectopic pregnancies
Men with a family history of colon cancer
People with blocked arteries being treated with a stent
In women undergoing in-vitro fertilization, it may increase the likelihood of conceiving multiple embryos
Unmetabolized folic acid accelerates cognitive decline in the elderly with low levels of vitamin B12 (If they have normal levels of B12, folic acid may slow brain aging)
While dietary folates have a protective effect against some cancers, folic acid supplementation may increase the incidence of colon cancer
Folic acid may increase the incidence of breast cancer in postmenopausal women, though other studies have shown the opposite

The trouble is that it could take 10-20 years for any potential harmful effects of unmetabolized folic acid to become apparent.

The latest study follows a letter to the Food Standards Agency from Sir Liam Donaldson, the Chief Medical Officer of England, requesting further expert consideration of two recent studies linking folic acid to bowel cancer before the government gives the final go-ahead for mandatory fortification of food with folic acid. However the Food Standards Agency has stuck to its position that fortification is safe. Mandatory fortification has already been introduced in the US, where it has been required since 1998, Canada and Chile, where it has cut neural tube defect rates by up to half.

Professor Nicholas Wald, director of the Wolfson Institute of Preventive Medicine, said:

“Fortification would prevent many cases of spina bifida and would also benefit the health of the country as a whole. Further delay in this public health measure will result in hundreds more babies being disabled by this serious disorder, or pregnancies being needlessly terminated due to a neural tube defect.”

When it comes to analyzing risks and benefits, one of the most important things is to realize that more is not necessarily better, and that folate and folic acid are not the same thing at all.

Second is the point that we discussed before: some people have the right genes to be able to metabolize folic acid with impunity, while others may get a range of problems from taking it.

Chocolate, Comfort Foods and Depression

Most people have done a bit of comfort eating from time to time: candies and chocolates are usually the favorites. That’s not a coincidence. Not only do they taste good, but chocolate also contains chemicals that may improve mood, and sugar can have an indirect impact on the uptake of specific amino acids into the brain, where they go on to form the chemical neurotransmitters involved in inter-cellular communication and learning.

On the more serious side, some types of mood disorders, particularly seasonal affective disorder, premenstrual syndrome and the so-called “atypical depression” are often associated with quite sever cravings for chocolate.

So I was very interested to see a paper from colleagues in Australia in this month’s issue of the British Journal of Psychiatry.

Gordon Parker and Joanna Crawford examined links between chocolate craving in people who are depressed and both personality style and atypical depressive symptoms, with a web-based questionnaire completed by nearly 3000 individuals reporting clinical depression.

People accessing a mood disorder consumer information website ( were invited to participate in an online survey of lifetime treatments for a depressive episode, together with some interesting evaluation tools.

Half of the respondents said that they craved chocolate, and the number was slightly higher in women. They said that they felt that chocolate helped with depression, anxiety and irritability. The ones who said that chocolate helped were more likely to score higher on a “neuroticism” scale, particularly irritability and rejection sensitivity.

Five years ago the same team found that atypical depression was associated with a personality that was especially sensitive to rejection, and also tended to be linked with several symptoms – including food cravings – that tie in with behaviors aimed to try and make us feel better and to maintain internal balance.

The results suggest that people with certain personality styles derive personal benefit from comfort eating. Some research has linked carbohydrate craving to the opioid system in the brain, and it is possible that munching on chocolate may be an example of genuine self-medication. People eat to chocolate to calm down their ability to feel emotional distress.

The trouble is, of course, that although chocolate is yummy and may even be therapeutic, too much can be a bad thing. Weight problems are common in people with chronic depression, especially the “atypical” type.

“Chocolate causes certain endocrine glands to secrete hormones that affect your feelings and behavior by making you happy. Therefore, it counteracts depression, in turn reducing the stress of depression. Your stress-free life helps you maintain a youthful disposition, both physically and mentally. So, eat lots of chocolate!”
–Elaine Sherman (American Culinary Expert, Teacher and Writer, 1938-2001)

“Look, there’s no metaphysics on earth like chocolates.”
–Fernando Pessoa (Portuguese Poet, 1888-1935)

Nutrition, Learning and Memory

We have talked about the burgeoning data linking food with mood, behavior and cognition.

I have just seen a new study that really adds to our knowledge and contributes information that we can all use.

Scientists in Europe, Australia and Indonesia have published data in the American Journal of Clinical Nutrition suggesting that nutrition can improve verbal learning and memory in schoolchildren.

This study was undertaken by the NEMO study group (Nutrition Enhancement for Mental Optimization) that consists of the Unilever Food and Health Research Institute (Vlaardingen, The Netherlands); CSIRO, Human Nutrition (Adelaide, Australia) and the SEAMEO-TROPMED Regional Center for Community Nutrition, University of Indonesia (Jakarta Pusat, Indonesia).

It was a 12-month study of 780 children in Australia and Indonesia in which the researchers evaluated the effects of adding a specific vitamin and mineral mixture to a daily drink.

The study population consisted of 396 well-nourished children in Australia and 384 poorly nourished children in Indonesia. In each country, the children were randomly allocated to one of four groups, receiving a drink with either:

  1. A mixture of micronutrients (iron, zinc, folate and vitamins A, B-6, B-12 and C)
  2. Fish oil (DHA and EPA)
  3. Both the micronutrient mixture and the fish oil
  4. Nothing added, i.e. placebo

In Australia, children who received the daily drink with the added vitamin and mineral mixture performed significantly better on tests of mental performance tests than children in a control group who received the drink but without added nutrients. In Indonesia a similar trend was observed, but this time only in the girls.

After twelve months, children in Australia who received the drink with the nutrient mix showed higher blood levels of these micronutrients, which means that their bodies were taking up the nutrients. In addition, they performed significantly better on tests measuring their learning and memory capabilities compared to children in the other groups. A similar trend was observed in Indonesia, but only in the girls. The addition of fish oil to the fortified drink did not conclusively show any additional effects on cognition.

This study adds to the mounting evidence that nutrition plays an important role in cognitive development in children, even in children who are enjoying a “normal” diet. Deficiencies in iron and iodine have been linked to impaired cognitive development in young children for over a century and there is now emerging evidence that deficiencies in zinc, folate and vitamin B12 may each compromise mental development in children. More recently, fish oils (EPA, DHA) have also been linked to child cognitive development.

Most previous studies have focused on deficiencies in single nutrients in young age groups, despite the well-known observation that the brain continues to grow and develop during childhood, adolescence and early adulthood. Little is known about the role of nutrition on mental development after the age of 2. In addition very other few studies have looked at the effect of offering a mix of nutrients. Until this study, there were very few randomized controlled intervention studies assessing the impact of a multiple-micronutrient intervention on cognitive function in schoolchildren.

The investigators recommend further research to investigate the exact role of DHA and EPA in healthy school-aged children. Another research focus is the further optimization of cognitive development tests with respect to their validity and sensitivity across cultures. The scientists suggest that the smaller effects of the vitamins and minerals in Indonesia could be a result of a lower sensitivity of the cognitive tests in that country.

This research raises many interesting points:

  • Is it possible that the healthy Australian diet is actually nothing of the sort?
  • Is it possible that if the diet is adequate, that “super-nutrition” can help a child to exceed his or her potential?
  • Are there key ages when nutrition can help, or is the effect maintained across the age range?
  • Does nutritional supplementation have a long-term impact on a child?
  • Have we even found the optimal mixture for child cognitive development? Might higher amounts of any nutrients – particularly fish oils – produce better effects, or might they be toxic, as we saw in the case of vitamin A supplementation?
  • Are we using the correct cognitive development tests to pick up changes in different cultures? As an example, could the smaller effects of the vitamins and minerals in Indonesia be a result of a lower sensitivity of the cognitive tests in that country? Or is it that the children are also missing out on some other trace nutrients?

Many questions, but the take home message is this: careful nutritional supplementation may have considerable benefits to a child, even one growing up in an affluent culture.

“Learning is a weightless treasure you always carry easily.”
–Chinese Proverb

Food Additives, Food Colorings and Hyperactivity

Regular readers will know that I am very interested in the impact of food and food additives on cognition and behavior. Unfortunately it is a field that has generated more heat than light, with some patients associations and commercial organizations providing rather unbalanced assessments about the whole issue and how best to deal with it.

What we do on this website is to provide you with information that has a solid foundation. A good example is a new study published this week in the Lancet by a team of researchers from Southampton University in the United Kingdom. (The full article is available here).

An alarming number of foods contain artificial food color and additives (AFCAs), and there has been a great deal of concern about their potential impact not only on behavior, but also on the developing brain.

A study published three years ago examined the impact of specific mixtures of additives on hyperactivity in three-year-old children. It was an important piece of work, but the worry was that the study focused on parental rather than objective ratings of hyperactivity. Though parents are usually very good at observing their own children, most of us also have our own ideas about the things that may cause problems.

In this new study was sponsored by the British Food Standards Agency and the researchers looked at the effects of additives on changes in children’s behavior in a community-based, double-blinded, placebo-controlled, crossover trial.

The study involved 153 children aged 3, plus 144 children aged 8-9. They were given either a drink containing sodium benzoate plus one of two AFCA mixes, or a placebo drink. The two AFCA mixes contained:

  • Mix A – included 20 mg of artificial food colorings (5 mg sunset yellow [E110], 2⋅5 mg carmoisinetartrazine [E102], and 5 mg ponceau 4R [E124, and 45 mg of sodium benzoate [E211]. (These were the same ingredients used in the previous study). [E122], 7⋅5 mg
  • Mix B was designed to be what the average 3 year-old and 8-9 year old may be consuming today, and included 30 mg of artificial food colorings (7⋅5 mg sunset yellow, 7⋅5 mg carmoisine, 7⋅5 mg quinoline yellow [E110], and 7⋅5 mg allura red AC [E129]) and 45 mg of sodium benzoate.

The children’s behaviors were measured by a “global hyperactivity aggregate” (GHA) that is based on teachers’ and parents’ ratings. The older children also received a computerized test for attention.

The main findings were that:

  • Mix A had a significant adverse effect on children in GHA for all the 3 year-olds, compared to the placebo.
  • Mix B produced mixed results for 3 year-olds
  • Both Mix A and Mix B had significant adverse effects on the 8-9 year olds, compared to the 8-9 year-olds on the placebo
  • Children vary greatly in their levels of adverse effects from consuming AFCA

So this new research indicates that foods containing AFCAs may fuel hyperactive behaviors in children from early to middle childhood. An important point is that AFCAs may impact any child: the effect is not restricted to children who are already hyperactive or have attention-deficit/hyperactivity disorder (ADHD). The problem with hyperactivity is not so much the challenge of living with an overly energetic child, but rather the impact of hyperactivity on development and education, particularly on reading skills. The hyperactive child may not get the full benefit of a conventional education.

The researchers do not yet know whether their findings apply to older children. But they raise the question whether complete withdrawal of AFCAs from the food supply might decreases the overall rate of hyperactivity in the population.

However, they ask whether the general levels of hyperactivity in children in the general population might not go down significantly if AFCAs were withdrawn completely.

Depression, Folic Acid and Bread

A remarkable study was published in the July edition of the Journal of Epidemiology and Community Health, by researchers at the University of York and Hull York Medical School.

They reviewed 11 studies involving 15,315 individuals and confirmed that there is a link between depression and low levels of folate, a vitamin that comes primarily from leaf vegetables such as spinachturnip greens, dried beans and peas, fortified cereal products, sunflower seeds and certain other fruits and vegetables are rich sources of folate, as is liver. and

Last month, the British Food Standards Agency recommended to Health Ministers that they should introduce mandatory fortification of either bread or flour with folic acid to prevent neural tube defects, which can result in miscarriage, neonatal death or lifelong disability. This new study suggests that the measure may also help to reduce the frequency and severity of depression.

Lead author Simon Gilbody said:

“Our study is unique in that for the first time all the relevant evidence in this controversial area has been brought together. Although the research does not prove that low folate causes depression, we can now be sure that the two are linked. Interestingly, there is also some trial evidence that suggests folic acid supplements can benefit people with depression. We recommend that large trials should be carried out to further test this suggestion.”

Recent research from the same team published in the American Journal of Epidemiology has also shown that people with depression, bipolar disorder and schizophrenia commonly have a genetic mutation named MTHFR C677T in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene on chromosome 1. The enzyme that the gene codes for is involved in folate metabolism, and the mutation (polymorphism) means that they process folate less efficiently. Folate is linked to the production of some of the chemicals in the brain, including serotonin, that in some part some the brain elevate mood. The identification of this gene provides a plausible explanation as to why folic acid supplements may help people with depression.

There is also another implication of the finding: it is well known that some diseases are more common in people who have depression, bipolar disorder and schizophrenia, including coronary artery disease ad some forms of cancer.

This same genetic polymorphism has been linked to cancers of the breast and lung, as well as coronary artery disease. It may be that folate is one of the factors involved in both.

Yet another research project!

logo logo logo logo logo logo