High Vitamin D Levels Linked to Lower Risk of Colon Cancer

High blood levels of vitamin D are associated with a lower risk of colon cancer, finds a large European study published online in the British Medical Journal. The risk was cut by as much as 40% in people with the highest levels compared with those in the lowest.

Several previous studies have already suggested a link between vitamin D and colorectal cancer, but the evidence has been inconclusive with limited information from European populations.

So, researchers from across Europe set out to examine the association between circulating vitamin D concentration as well as dietary intakes of vitamin D and calcium with colorectal cancer risk in Western European populations. Colorectal cancer is the combination of colon and rectal cancer cases.

Their findings are based on the European Prospective Investigation into Cancer Study (EPIC), a study of over 520,000 subjects from 10 Western European countries.

Between 1992 and 1998, participants completed detailed dietary and lifestyle questionnaires and blood samples were collected. The subjects were then tracked for several years, during which time 1,248 cases of colorectal cancer were diagnosed and these were matched to 1,248 healthy controls.

Participants with the highest levels of blood vitamin D concentration had a nearly 40% decrease in colorectal cancer risk when compared to those with the lowest levels.

However, some recent publications have suggested maintenance of blood vitamin D levels at 50 nmol/l or higher for colorectal cancer prevention. Thus, the authors also compared low and high levels of blood vitamin D concentration to a mid-level of 50-75 nmol/l. This comparison showed that while levels below the mid-level were associated with increased risk, those above 75 nmol/l were not associated with any additional reduction in colon cancer risk compared to the mid-level.

Although the results support a role for vitamin D in the etiology of colorectal cancer, the authors caution that very little is known about the association of vitamin D with other cancers and that the long term health effects of very high circulating vitamin D concentrations, potentially obtained by taking supplements and/or widespread fortification of some food products, have not been well studied.

With respect to colorectal cancer protection, it is still unclear whether inducing higher blood vitamin D concentration by supplementation is better than average levels that can be achieved with a balanced diet combined with regular and moderate exposure to outdoor sunlight, they say.

The findings of previous randomised trials have been inconsistent. As such, new trials should be carried out to evaluate whether increases in circulating vitamin D concentration can effectively reduce colorectal cancer risk without inducing serious adverse events, they conclude. Currently, the best recommendation to reduce ones risk of colorectal cancer is to stop smoking, increase physical activity, reduce obesity and abdominal fatness, and limit intakes of alcohol and red and processed meats.



Obesity Ups Cancer Risk, and Here's How

Obesity comes with plenty of health risks, but there’s one that’s perhaps not so well known: an increased risk of developing cancer, and especially certain types of cancer like liver cancer. Now, a group of researchers reporting in the January 22nd issue of the journal Cell, a Cell Press publication, have confirmed in mice that obesity does indeed act as a “bona fide tumor promoter.” They also have good evidence to explain how that happens.

“Doctors always worry about our weight, but the focus is often on cardiovascular disease and type 2 diabetes, both of which can be managed pretty well with existing drugs,” said Michael Karin of the University of California, San Diego. “However, we should also worry about elevated cancer risk. If we can reduce cancer deaths by as many as 90,000 per year, that’s a lot of people — a lot of lives.”

Karin’s team shows that liver cancer is fostered by the chronic inflammatory state that goes with obesity, and two well known inflammatory factors in particular. The findings suggest that anti-inflammatory drugs that have already been taken by millions of people for diseases including rheumatoid arthritis and Crohn’s disease may also reduce the risk of cancer in those at high risk due to obesity and perhaps other factors as well, Karin said.

The epidemiological studies reported earlier showed that obese people have about a 1.5-fold increase in their risk of cancer overall. That may not necessarily sound like a lot, Karin said, but it equates to about 90,000 extra cancer deaths per year in the United States alone. When it comes to liver cancer, the study showed obese people have a 4.5-fold greater risk.

Given the apparent connection between obesity and liver cancer in particular, Karin’s team decided to investigate in mice prone to develop hepatocellular carcinoma (HCC). The mice are typically given HCC either by exposure to a chemical carcinogen, known as DEN, when they are two weeks old, or by exposure to that same carcinogen at three months of age followed by the tumor-promoting chemical phenobarbitol.

In the new study, the researchers gave two-week-old mice DEN and then divided them into two groups — one fed a normal, relatively low-fat food and the other fed on high-fat chow. “It was clear that the mice on the high fat diet developed more liver cancer,” Karin said.

To further confirm the link, they gave DEN to two-week-old mice that were fed a normal diet but carried a gene that made them obesity-prone. Those mice, too, developed more liver cancers, evidence that it wasn’t the high-fat diet that led to cancer, but rather something about the animals obese state.

But Karin said perhaps the biggest surprise came in studies of mice on a high-fat diet who were given DEN a little later in life, when they were three-months-old. Normally, mice on the standard diet given the chemical at that age really don’t develop liver cancer unless DEN exposure is followed up with phenobarbitol, Karin explained. But the obese mice developed the disease without that extra push.

“We expected to see more cancer in our first experiments, but I was stunned to see here that only the mice who were obese developed the cancer,” Karin said. “Obesity appears to be as strong as phenobarbitol; we can conclude, at least in mice, that obesity is a real tumor promoter.”

His team was able to trace the source of obesity’s tumor-promoting effect to a rise in two inflammatory factors known as IL-6 and TNF. Obese mice lacking either the TNF receptor or IL-6 don’t show the same rise in liver cancer.

Those treatments also led the mice to accumulate less fat in their livers, he said. “They still get fat, but the distribution of the fat is different,” he said. “The fat goes to other places, but not to the liver.”

Karin suggests that clinical studies of people who are already taking anti-TNF drugs should be done, to find out if their livers are less fatty and cancer-free.

The researchers include Eek Joong Park, Jun Hee Lee, Guann-Yi Yu, Guobin He, Syed Raza Ali, Ryan G. Holzer, Christoph H.Osterreicher, Hiroyuki Takahashi, and Michael Karin, of University of California, San Diego, La Jolla, CA.


Magnesium Supplement Helps Boost Brainpower

New research finds that an increase in brain magnesium improves learning and memory in young and old rats. The study, published in the January 28th issue of the journal Neuron, suggests that increasing magnesium intake may be a valid strategy to enhance cognitive abilities and supports speculation that inadequate levels of magnesium impair cognitive function, leading to faster deterioration of memory in aging humans.

Diet can have a significant impact on cognitive capacity. Identification of dietary factors which have a positive influence on synapses, the sites of communication between neurons, might help to enhance learning and memory and prevent their decline with age and disease. Professor Guosong Liu, Director of the Center for Learning and Memory at Tsinghua University in Beijing, China, led a study examining whether increased levels of one such dietary supplement, magnesium, boosts brain power.

“Magnesium is essential for the proper functioning of many tissues in the body, including the brain and, in an earlier study, we demonstrated that magnesium promoted synaptic plasticity in cultured brain cells,” explains Dr. Liu. “Therefore it was tempting to take our studies a step further and investigate whether an increase in brain magnesium levels enhanced cognitive function in animals.”

Because it is difficult to boost brain magnesium levels with traditional oral supplements, Dr. Liu and colleagues developed a new magnesium compound, magnesium-L-threonate (MgT) that could significantly increase magnesium in the brain via dietary supplementation. They used MgT to increase magnesium in rats of different ages and then looked for behavioral and cellular changes associated with memory.

“We found that increased brain magnesium enhanced many different forms of learning and memory in both young and aged rats,” says Dr. Liu. A close examination of cellular changes associated with memory revealed an increase in the number of functional synapses, activation of key signaling molecules and an enhancement of short- and long-term synaptic processes that are crucial for learning and memory.

The authors note that the control rats in this study had a normal diet which is widely accepted to contain a sufficient amount of magnesium, and that the observed effects were due to elevation of magnesium to levels higher than provided by a normal diet.

“Our findings suggest that elevating brain magnesium content via increasing magnesium intake might be a useful new strategy to enhance cognitive abilities,” explains Dr. Liu. “Moreover, half the population of industrialized countries has a magnesium deficit, which increases with aging. This may very well contribute to age-dependent memory decline; increasing magnesium intake might prevent or reduce such decline.”



Vitamin D Supplements Could Fight Crohn's Disease

A new study has found that Vitamin D, readily available in supplements or cod liver oil, can counter the effects of Crohn’s disease. John White, an endocrinologist at the Research Institute of the McGill University Health Centre, led a team of scientists from McGill University and the University de Montreal who present their findings about the inflammatory bowel disease in the Journal of Biological Chemistry.

“Our data suggests, for the first time, that Vitamin D deficiency can contribute to Crohn’s disease,” says Dr. White, a professor in McGill’s Department of Physiology, noting that people from northern countries, which receive less sunlight that is necessary for the fabrication of Vitamin D by the human body, are particularly vulnerable to Crohn’s disease.

Vitamin D, in its active form (1,25-dihydroxyvitamin D), is a hormone that binds to receptors in the body’s cells. Dr. White’s interest in Vitamin D was originally in its effects in mitigating cancer. Because his results kept pointing to Vitamin D’s effects on the immune system, specifically the innate immune system that acts as the body’s first defense against microbial invaders, he investigated Crohn’s disease. “It’s a defect in innate immune handling of intestinal bacteria that leads to an inflammatory response that may lead to an autoimmune condition,” stresses Dr. White.

What Vitamin D does

Dr. White and his team found that Vitamin D acts directly on the beta defensin 2 gene, which encodes an antimicrobial peptide, and the NOD2 gene that alerts cells to the presence of invading microbes. Both Beta-defensin and NOD2 have been linked to Crohn’s disease. If NOD2 is deficient or defective, it cannot combat invaders in the intestinal tract.

What’s most promising about this genetic discovery, says Dr. White, is how it can be quickly put to the test. “Siblings of patients with Crohn’s disease that haven’t yet developed the disease might be well advised to make sure they’re vitamin D sufficient. It’s something that’s easy to do, because they can simply go to a pharmacy and buy Vitamin D supplements. The vast majority of people would be candidates for Vitamin D treatment.”

“This discovery is exciting, since it shows how an over-the-counter supplement such as Vitamin D could help people defend themselves against Crohn’s disease,” says Marc J. Servant, a professor at the University de Montral’s Faculty of Pharmacy and study collaborator. “We have identified a new treatment avenue for people with Crohn’s disease or other inflammatory bowel diseases.”

This study was funded by a grant from McGill University.



How fish oils add years to your life (and take years off your face!)

There seems to be no end to the benefits of fish oils. Not only are they said to boost heart, brain and joint health, but they also prevent cancer, eye disease and bone problems.

Last week, a new study suggests they could assist the body against premature aging. But how do you separate the facts from the hype? Peta Bee asked the experts…


Fish oils are a type of polyunsaturated fat – a ‘healthy’ fat. Unlike saturated animal fats, they don’t raise your cholesterol levels, but are known to have a positive effect on health.

Polyunsaturated fats are divided into two groups of what are called Essential Fatty Acids (or EFAs) – omega-3 and omega-6.

Both omegas are essential in helping to regulate blood clotting, body temperature, blood pressure and the immune system; they are also needed to make prostaglandins, important hormone-like chemicals in the body. The only way we can get them is through our diet.

Omega-3 has particular benefits, producing vital substances such as DHA (docosahexaenoic acid), thought to play a key role in the development of brain and cognitive function, and EPA ( eicosapentaenoic acid), vital for brain health.

The richest source of omega-3s are fish oils – salmon, mackerel, fresh tuna and herring.

While most Britons consume more than enough omega-6 oils (found in most edible oils, but particularly sunflower and corn, as well as meat), they are deficient in omega-3.


There have been a number of studies suggesting fish oils boost heart health, but the most compelling evidence was a study last year published in the Journal Of The American College Of Cardiology.

Led by Dr Carl Lavie, of the Ochsner Cardiology Clinic in Louisiana, the study showed omega-3 oils help to prevent blood clotting and regulate or lower blood pressure.

The strongest heart-protective effect is for patients with established cardiovascular disease, the study found.

This isn’t just hype – we now have tremendous and compelling evidence from very large studies, some dating back 20 and 30 years,’ Dr Lavie said.

Under guidelines issued by the National Institute for Health and Clinical Excellence (NICE), doctors are encouraged to prescribe supplements to patients after they have had a heart attack to prevent repeat attacks.


There has been great interest in the fish oil effect on the brain – both in preventing disease and boosting brain power.

Studies have shown, for instance, that DHA can reduce the formation of plaques in the brain; these have been linked to Alzheimer’s disease and dementia. Too little omega-3 has been linked to mild depression, and there is some evidence that fish oils may help here.

DHA has been shown to boost foetal brain development.

However, parents who feed their children fish oil supplements before exams might be wasting their money, as the evidence for fish oils boosting intelligence and exam performance is tenuous.


Eating oily fish once a week has been shown to protect against age-related macular degeneration, the most common cause of blindness in the older generation.

They might also be helpful in the fight against some forms of cancer.

Last year, Professor John Witte, from the University of California, suggested a high intake of omega-3s reduced men’s risk of prostate cancer by about 60 per cent. There is some evidence, too, that a regular consumption of omega-3s can help prevent bowel cancer.


Last week researchers from the University of California suggested omega-3s – whether from supplements or fish – helped cells

in the body live longer. When they studied heart disease patients, they found the more omega-3 the subjects ate, the slower the damage to the DNA in their cells.

That, in turn, meant better protection against inflammation and the aging process.

So will fish oils help you live longer – and look younger?

Heather Yuregir, a researcher at the British Nutrition Foundation, says it’s possible, although more evidence is needed to confirm the anti-aging effect.

‘The study found fish oils may protect against aging, which does indicate another possible benefit of consuming such oils in the diet.

‘But it must be remembered that it is only one study; the claims need to be strengthened.’


The best food supply of omega-3s is oily fish such as salmon, tuna, mackerel and herring.

Other sources include rapeseed, evening primrose and walnut oils, fresh seeds such as pumpkin and sunflower, wholemeal bread and wholegrain cereals. However, they provide omega-3s in a different chemical form which is more difficult for the body to convert into DHA and EPA, so it would be difficult to consume enough.

In Britain, there are no recommended daily levels for fish oils, although the Food Standards Agency (FSA) and the British Nutrition Foundation (BNF) say eating two portions (140g each) a week of fish, including one of oily fish, will meet most people’s needs – providing around 250mg of omega-3s. (Note, canned tuna does not count, as the processing reduces its omega-3 levels to those similar to white fish).

However, a team of doctors reporting in the Journal Of The American College Of Cardiology last year suggested there is now ‘compelling evidence’ for the benefits of fish oils and recommended people try to consume 500mg of omega-3 fish oil a day, while those with heart disease or heart failure take at least 800 to 1000mg in their diet.

Many experts think it is better to eat fish to provide the oil, as this ensures you also get other important nutrients and protein, and the suggestion by some researchers to take supplements instead remains controversial.

‘UK guidelines suggest adults get their omega-3 intake from fish and there is no recommendation to take supplements as well,’ says Bridget Benelam, of the BNF.

Indeed, although NICE now recommends those who’ve had a heart attack take a supplement, eating more oily fish is preferable, explains June Davison, a senior cardiac nurse at the British Heart Foundation.

The charity recommends anyone who has suffered a heart attack eats two to three portions of oily fish a week over taking a capsule.

‘For most people with or without heart disease, supplements are not generally suggested as a daily requirement,’ says Davison.

However, last week a survey of more than 3,000 British consumers by NutraSea found 40 % of people never cook fish. Getting your omega-3 from other sources is preferable to getting none, says Dr Rafe Bundy, nutrition lecturer at Glasgow University.


Cod liver oil does contain some DHA and EPA, but not as much as the oily fish – but there are other reasons to consider it.

It’s a good source of vitamin D, and experts are increasingly concerned that in Britain our levels of this vitamin are low (the main source is the sun).

Vitamin D deficiency is now being linked to a range of conditions, including diabetes. The vitamin is also important to prevent the bone disease rickets, which has made a comeback.

Last week, the British Medical Journal revealed that spending too much time indoors, combined with poor diets, has led to a drop in vitamin D levels among children – and a rise in rickets.

The fact that children are no longer being given a daily slug of cod liver oil is also thought to be contributing to the problem.