An international research team that includes University of Otago scientists has found that excessive salt intake “reprogrammes” the brain, interfering with a natural safety mechanism that normally prevents the body’s arterial blood pressure from rising.

While the link between salt and hypertension is well known, scientists until now haven’t understood how high salt intake increased blood pressure. By studying the brains of rats, a team led by Professor Charles Bourque of McGill’s Faculty of Medicine discovered that ingesting large amounts of dietary salt causes changes in key brain circuits.

Associate Professor Colin Brown of Otago’s Centre for Neuroendocrinology and Department of Physiology and Dr Su Young Han, a former PhD student in his laboratory, were members of the team.

Professor Bourque says the team found that a period of high dietary salt intake in rats causes a biochemical change in the neurons that release vasopressin into the systemic circulation. Vasopressin is a hormone that increases vasoconstriction which causes an increase in arterial blood pressure.

“This change, which involves a neurotrophic molecule called BDNF (brain-derived neurotrophic factor), prevents the inhibition of these particular neurons by other cells.”

The team’s findings, newly published the journal Neuron, found that high salt intake prevents the inhibition of vasopressin neurons by the body’s arterial pressure detection circuit. The disabling of this natural safety mechanism allows blood pressure to rise when a high amount of salt is ingested over a long period of time.

While the team’s discovery advances the understanding of the link between salt intake and blood pressure, more work is needed to define new targets that could potentially be explored for therapeutic intervention. Among the questions for further research: Does the same reprogramming effect hold true for humans? If so, how might it be reversed?

In the meantime, Bourque says, the message remains: limit dietary salt.

Scientists from the University of North Texas Health Sciences Centre, Neurocentre Magendie, France and Centre for Neuroendocrinology, University of Otago, New Zealand contributed to this study.

"High Salt Intake Increases Blood Pressure via BDNF Mediated Downregulation ofKCC2 and Impaired Baroreflex Inhibition of Vasopressin Neurons" Katrina Y. Choe, Su Y. Han, Perrine Gaub, Brent Shell, Daniel L. Voisin, Blayne A. Knapp, Philip A. Barker, Colin H. Brown, J. Thomas Cunningham, and Charles W. Bourque. Neuron, Jan. 22, 2015.

Men who are overweight or obese are at greater risk of developing advanced prostate cancers, including aggressive cancers that are fatal, a leading cancer prevention charity has found.

The finding was made after an analysis of the global scientific research into lifestyle factors and prostate cancer in the World Cancer Research Fund’s Continuous Update Project (CUP). The report, the most in-depth review to date, analysed 104 studies involving more than 9.8 million men and over 191,000 cases of prostate cancer.

A clearer picture has emerged, showing there is now strong evidence of a link between being overweight or obese and advanced prostate cancer. Annually we estimate that around 10% of advanced prostate cancer cases in the UK could be prevented, if men kept a healthy weight.

However, a less consistent picture has emerged of the links between prostate cancer risk and certain foods. The evidence linking diets high in calcium to an increased risk of prostate cancer has been downgraded from “strong” to “limited”. And evidence that foods containing lycopene (such as tomatoes) decrease the risk of prostate cancer, has been downgraded from “strong” to no conclusion possible. The evidence that a diet higher in dairy products increases risk, remains limited.

Our conclusions have changed as a result of studies into different prostate cancer types that have emerged since our previous detailed review of prostate cancer research in 2007. Today’s CUP report, the result of a partnership with Imperial College London, is the most in-depth review to date of research linking diet, physical activity, and weight to the risk of developing prostate cancer.

The evidence paints a complex picture in which not all prostate cancers are alike. More studies are separating out fatal, advanced or aggressive and non-advanced cancers. While this has clarified what we know about prostate cancer and body fatness, it has clouded our understanding of the relationship between prostate cancer and certain foods. We are not saying there is no link. What we are saying is, if there is a link, it is more difficult to see.

Kate Allen, Executive Director Science and Public Affairs at World Cancer Research Fund International, said: “The report’s finding in relation to being overweight or obese is important. It is the first time we have been able to show any kind of link between advanced prostate cancer and weight. It adds to our general understanding of the impact of being overweight or obese on cancer risk and helps inform our cancer prevention efforts.

“But the CUP also points to a more complicated picture than first thought. More research has emerged into lifestyle, diet and prostate cancer since our last review. The result is that some of the evidence linking certain foods to prostate cancer risk has become less clear.”

The emergence of a link between body fatness and advanced prostate cancer could have important implications. It may raise questions in relation to prostate cancer screening, in particular, whether excess weight ought to be included alongside factors like family history in discussions between GPs and men at risk of advanced prostate cancer.

Dr Jonathan Rees, GP and Chair of the Primary Care Urology Society, said: “With so much controversy over the merits of screening for prostate cancer, it is vital in primary care for us to understand which patients are most at risk of developing this disease and are therefore most likely to benefit from PSA testing. The findings of this review have significant implications: they add strength to the rationale for encouragement of a healthy lifestyle and control of weight, in terms of cancer prevention; they point us towards recognising overweight or obesity as a risk factor to take into account when discussing screening with patients; and they point us towards avenues of research that may help us to reduce the impact of this disease which kills over 10,000 men a year in the UK alone.”

We recommend men maintain a healthy weight and check their BMI and waist measurement regularly. We also recommend following our Cancer Prevention Recommendations to reduce the risk of prostate cancer as well as other cancers and chronic diseases.

Learn more about the Continuous Update Project.

To read the free research paper in full, go to: http://www.parliament.nz/en-nz/parl-support/research-papers/00PLLawRP2014041/obesity-and-diabetes-in-new-zealand

It is based on the Heart Foundation's Dietary Patterns and Heart Health Background Paper 2013 and the USDA's Series of Systematic Reviews on the Relationship Between Dietary Patterns and Health Outcomes 2014.

To read the full text of this position statement, go to: http://www.heartfoundation.org.nz/uploads/Dietary_patterns_position_statement_2014.pdf

For the first time, a report from an ongoing, systematic review of global cancer research has identified potential links between diet, weight and physical activity and longer survival for women diagnosed with breast cancer.

In partnership with the American Institute for Cancer Research (AICR), World Cancer Research Fund (WCRF) International’s Continuous Update Project (CUP) today released a report that found indications of links between survival and:

• A healthy body weight
• Being physically active
• Eating foods containing fiber and soy
• A lower intake of fat, particularly saturated fat

To read the full media release and to view the report, go to: http://www.aicr.org/press/press-releases/2014/aicr-wcrf_breast_cancer_survivorship_report.html

The paper provides an overview of obesity and type 2 diabetes among adults, describing the epidemiology of each disorder, how the two conditions are linked and why they present a major public health challenge. Latest available data and evidence from England illustrates prevalence trends in both obesity and diabetes at a national and local level as well as the potential implications in terms of health consequences, inequalities and cost. The paper also signposts latest relevant policy and guidance documents.

Access to the full text of the paper is free online at: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/338934/Adult_obesity_and_type_2_diabetes_.pdf

This 2013 background guide, produced specifically for the use of health professionals, gives some background information on the main messages in the 'Healthy Heart' initiative.

Access to the full text of this guide is free online at: http://www.heartfoundation.org.nz/uploads/HF_HealthyHeart_Guide_Final.pdf

This 'Healthy Heart' guide is accessible from the Heart Foundation website.

The visual food guide shows the balance of foods to eat, foods that can be substituted for each other within food groups, and the types of food to eat for good health.

This 'Healthy Heart' guide is accessible from the Heart Foundation website.

The briefing focuses on policy issues linked to food environments and diet, with learnings from other areas such as tobacco and alcohol control.

International Obesity Taskforce. (2014). The prevention of obesity and NCDs: Challenges and opportunities for governments. London: International Association for the Study of Obesity.

To read the full text of the briefing, go to: http://www.iaso.org/site_media/uploads/iaso_preventingobesitybriefing.pdf

The guidance includes a range of approaches for people aged 16 and over, from single interventions delivered as the opportunity arises to planned, high intensity interventions that may take place over a number of sessions.

The guidance aims to help tackle a range of behaviours including alcohol misuse, poor eating patterns, lack of physical activity, unsafe sexual behaviour and smoking. These behaviours are linked to health problems and chronic diseases (such as cardiovascular disease, type 2 diabetes and cancer). This means interventions that help people change have considerable potential for improving health and wellbeing.

Access to the full text of this guidance is available at: https://www.nice.org.uk/guidance/ph49

N.B. This guidance was developed for use in England.

University of Otago researchers say that helping people with pre-diabetes and diabetes to follow a healthier diet will significantly improve their blood sugar levels, and they are calling on smaller portion sizes to be offered at cafés and eateries to support this cause.

Thursday this week is World Diabetes Day and to reinforce their point, the researchers are specifically visiting a café in Port Chalmers, Coffee Dot, which specialises in smaller portion sizes such as for slices.

Dr Kirsten Coppell, Professor Jim Mann and colleagues from the University’s Edgar National Centre for Diabetes and Obesity Research have found that following a better diet, people with pre-diabetes are much less likely to go on to develop diabetes, and people who already have diabetes will have better control of their disease, preventing the onset and progression of complications.

“Diabetes is a common chronic disease with significant morbidity, mortality and cost. Seven per cent of New Zealand’s adult population aged 15 years and over has diabetes,” says Dr Coppell.

“Over one-quarter have pre-diabetes and are at high risk of developing type 2 diabetes. The numbers with pre-diabetes, on top of an already-high national diabetes rate, should be of major concern to New Zealanders.” Diabetes education and prevention is the focus of World Diabetes Day.

“Better diabetes control and prevention of diabetes is possible through sustained sensible dietary habits. Rather than focusing on a strict diet, smaller meals and reducing the amount of unhealthy components in the diet is effective,” she adds.

The effect of reducing portion sizes and dietary changes (on top of medication) as an important and effective strategy has recently been the focus of research at the Edgar Centre, in the Lifestyle Over and Above Drugs in Diabetes (LOADD) study.

Rather than focusing on a strict diet, advice in the study was tailored to match each individual’s socio-economic and cultural circumstances. It involved elements such as encouraging smaller meals, reducing unhealthy components in their diets while eating more fruit and vegetables.

“However, making and sustaining such lifestyle changes can be difficult for many people. Having specialist health professionals who can assess individual circumstances and provide regular advice and encouragement, as well as supportive family members, appears to be a key factor to succeeding in this.”

Accordingly, the research’s ultimate goal is to develop an appropriate programme, involving such experts, which could be put in place to improve the health of the hundreds of thousands of people in New Zealand living with type 2 diabetes, as well as those with pre-diabetes, she says.

The study was supported by the Health Research Council of New Zealand, the Southern Trust, Diabetes New Zealand Inc. and the National Heart Foundation.

Research at the Australian National University has found increased body mass index significantly increases the risk of heart disease – regardless of exercise level, smoking status and whether or not someone has diabetes.

Over 158,000 Australian participants of the Sax Institute’s 45 and Up Study with no history of cardiovascular disease were tracked over four years to see how incremental increases in body mass index (BMI) increased their risk of going to hospital for a range of cardiovascular diseases.

The study found even relatively minor increases in BMI come with increased cardiovascular risk.

“The risk of heart attack and angina increased by 23 per cent with each 5 unit increase in BMI,” said lead author of the paper outlining the study, Dr Grace Joshy of the National Centre for Epidemiology and Population Health (NCEPH) at ANU.

“The lowest risk is for a BMI from 20 – 22.5 and then it increases gradually from there. For moderately overweight people, the risk is 43% higher. For a BMI of above 32.5, the risk of heart attack and angina is more than doubled.”

“We used to think that it was only people with very serious weight problems that were at an elevated risk of heart disease,” said senior author Professor Emily Banks of NCEPH and the Sax Institute.

“These are the first large-scale Australia data to show us that there is no ‘safe’ level of overweight, when it comes to heart disease. The increase in risk was found in people who did and did not exercise, those with and without diabetes and in urban, rural and remote areas.”

“If you want to minimise your risk you need to pay attention to your weight. It’s a serious matter and it does impact your risk of cardiovascular disease,” said Professor Banks.

“Improving your odds is alright in a horse race but the race to a heart attack is certainly not one you would want to win,” said Dr Rob Grenfell, Heart Foundation National Director, Cardiovascular Health.

“This study highlights that as you put more weight on you become more at risk of doing real damage to your heart.  Which is why it’s incredibly important for all Australians to manage their blood pressure, cholesterol and blood sugar levels, stop smoking, exercise daily and eat a healthy diet,” said Dr Grenfell.

The 45 and Up Study is managed by the Sax Institute in collaboration with partners: Cancer Council NSW; National Heart Foundation of Australia (NSW Division); NSW Ministry of Health; beyondblue; Ageing, Disability and Home Care, Department of Family and Community Services NSW; the Australian Red Cross Blood Service; and UnitingCare Ageing.

The original media release can be viewed at: http://news.anu.edu.au/2013/10/23/rising-body-mass-index-increases-heart-risk/