Category Archives: glycaemic index

Mediterranean style diets rich in wholegrains may help to keep us trim and healthy

There are many studies which have found that following a Mediterranean style diet is associated with a reduced risk of developing chronic diseases e.g. heart disease, dementia, diabetes.  A recent study (1) published in the American Journal of Clinical Nutrition has concluded that “promoting the MDP [Mediterranean Dietary Pattern] as a model of healthy eating may help to prevent weight gain and the development of obesity”.  The study involved over 370,000 individuals aged between 25-70 years old from 10 European countries.  Measurements were taken from the individuals at the start of the study and after about 5 years.  A score between 0 and 18 was used to assess adherence to the Mediterranean Dietary Pattern and then the association between the socre and 5 year with change was assessed.  Results showed that individuals who had high adherence to the Mediterranean Dietary Pattern (11-18 points) had significantly less weight change over 5 years and were less likely to develop overweight or obesity than individuals with a low adherence to the Mediterranean Dietary pattern (0-6 points).

The results are not very surprising since the Mediterranean Diet is a very healthful one which is high in vegetables, fruits, nuts, legumes/beans, fish (especially oily fish), healthy fats and wholegrains and low in processed foods, refined carbohydrates, red meats, and saturated fats.  Such a diet will be providing the body with numerous vitamins, minerals and nutrients needed for optimal health.

Another study (2) in the American Journal of Clinical Nutrition has found that “Daily consumption of 3 portions of whole-grain foods can significantly reduce cardiovascular disease risk in middle-aged people mainly through blood pressure–lowering mechanisms. The observed decrease in systolic blood pressure could decrease the incidence of coronary artery disease and stroke by 15% and 25%, respectively”.  A few months ago I wrote about some evidence which suggested that wholegrain consumption might reduce the risk of developing Type-2-diabetes, a condition linked to being overweight and an increased risk for other conditions such as heart disease.

Wholegrain rice, oats, barley, wheat, quinoa and millet make an easy, healthy replacement for refined carbohydrates.  Whole grains are nutrient dense, they provide the vitamins, minerals, phytochemicals and fibre that are lacking in the white/refined varieties.  A diet high in refined carbohydrates has been linked to an increased risk of health problems.  Refined carbohydrates tend to have a high glycaemic index, they increase blood sugar levels quickly, which can impact the production of insulin and other hormones in the body and may negatively impact health.

As mentioned in previous posts:

High glycaemic index foods (foods that release sugar quickly into the body) include most refined carbohydrates like white bread, long-grain rice, sweets, biscuits, sugary foods and many other processed carbohydrates and processed foods. Foods that release sugar quickly into the bloodstream have what is known as a high Glycaemic Index (GI), meals that favour a spike in blood sugar levels are said to have a high Glycaemic Load (GL).  To identify foods with a high glycaemic index that will contribute to increasing the GL of a meal please view the website The Glycemic Index www.glycemicindex.com, there you will find a database where you can search for specific foods and find out more about GI and health. 

Unbalanced blood sugar levels following a meal (post-prandial dysmetabolism) can cause havoc in the body.  A high post-meal blood sugar level can lead to damaging free radicals (reactive oxygen molecules) being released which are a risk for atherosclerosis (damage to blood vessels) and metabolic syndrome (a big risk factor for heart disease).  The high blood sugar can lead to internal inflammation, dysfunction in the lining of the blood vessels, and may also lead to an increase in triglycerides (blood fats) – all risk factors for heart disease. 

Adding to the evidence, a new study (3) has found that diets high in glycaemic load, glycaemic index and low in fibre were associated with an increased risk for type 2 diabetes.  The authors conclude that “carbohydrate quantity and quality seem to be important factors in diabetes prevention”.

Following a diet which is similar to that of a Mediterranean diet, which includes unrefined, wholegrain carbohydrate sources really does seem to be beneficial to health.

(1) Dora Romaguera D et al.  2010.  Mediterranean dietary patterns and prospective weight change in participants of the EPIC-PANACEA project.  American Journal of Clinical Nutrition.  92: 912-921

 (2) Tighe P et al.  2010.  Effect of increased consumption of whole-grain foods on blood pressure and other cardiovascular risk markers in healthy middle-aged persons: a randomized controlled trial.   American Journal of Clinical Nutrition.  92: 733-740

(3) Sluijs I et al.  2010.  Carbohydrate quantity and quality and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition–Netherlands (EPIC-NL) study. American Journal of Clinical Nutrition.  92: 905-911

 

Written by Ani Kowal

Share

As autumn and winter draw in can we do anything to boost our morning energy levels?

Days are getting shorter and there is just over a month before British Summertime ends on 31st October.  Some people in the UK suffer from Seasonal Affective Disorder, SAD, and find the darker months incredibly difficult (please read my previous posts for more information about SAD).  Many more individuals exhibit symptoms, in autumn/winter, such as tiredness, lethargy and sleep problems without the depression and anxiety felt by SAD sufferers.  There is evidence that some kind of seasonal changes in mood impact much of the general population (1,2) 

SADA Seasonal Affective Disorder Association is the UKs only support organisation that is dedicated to SAD.  SADA say that(1) “ SAD is a type of winter depression that affects an estimated 7% of the UK population every winter between September and April, in particular during December, January and February.  It is caused by a biochemical imbalance in the hypothalamus [part of the brain] due to the shortening of daylight hours and the lack of sunlight in winter.  For many people SAD is a seriously disabling illness, preventing them from functioning normally without continuous medical treatment.  For others, it is a mild but debilitating condition causing discomfort but not severe suffering. We call this subsyndromal SAD or ‘winter blues.’ It is estimated that a further 17% of the UK population have this milder form of condition”.

Even those of us who do not suffer with SAD will often find getting up when it is still dark challenging.  Energy levels may be low and springing out of bed with motivation can be hard.  In the spring and summer the light increases from early morning and stimulates a gradual wake up call, this is absent in the autumn and winter.  The lack of dawn awakening seems to have an impact on our natural, internal body clock – also known as the circadian rhythm.  The circadian rhythm is associated with many biological responses in the body including hormonal release.  Disruption to our body clock may play a part in our feelings of morning lethargy in the autumn and winter months.

Previously when writing about SAD I mentioned the sunrise alarm clocks, or bodyclocks, that are available.  These sunrise alarm clocks usually consist of a unit with a light that gradually increases in intensity over a 30 minute period until it is at its brightest when an alarm usually sounds.  If you find yourself struggling to feel energised in the mornings you might want to think about purchasing one of these bodyclocks.  The thinking behind the system is that if we wake up gradually our circadian rhythm, internal body clock, is less disrupted.   Use of these dawn simulator in individuals with SAD has been positive and studies are beginning to find that they may also be helpful for individuals who don’t suffer from the condition (3,4). 

In addition to light there are many things that can impact how we feel during the darker months.  Please read my previous posts on SAD for more information.  One important factor is breakfast.  Eating a nutrient dense breakfast may well help to prevent feelings of fatigue.  It is tempting to reach for caffeine in order to wake up but this may impact blood sugar levels and lead to further feelings of fatigue and irritability.  In order to keep blood sugar levels balanced a breakfast that is low in sugar and low in processed food is preferable.  Choosing food with a low glycaemic index may be helpful and including a source of protein (e.g. eggs, beans, nuts/seeds) is important e.g.  berries with yoghurt, sprinkled with nuts/seeds or poached eggs on wholegrain toast are two breakfast ideas.  Eating a healthy diet rich in vegetables, fruits, unprocessed wholegrain carbohydrates, unprocessed meats/fish (especially oily fish), beans, eggs, nuts/seeds and other unrefined foods will help to fuel the body through the day and prevent feelings of lethargy and fatigue.  Specific vitamins, minerals and essential fats may also be helpful, especially to those individuals suffering with SAD, please read my previous posts for more information.

1.Rosen LN & Rosenthal NE.  1991.  Seasonal variations in mood and behavior in the general population: a factor-analytic approach. Psychiatry Res.  38(3):271-83.

2.Kasper S et al.  1989.  Epidemiological findings of seasonal changes in mood and behavior. A telephone survey of Montgomery County, Maryland. Arch Gen Psychiatry.   46(9):823-33

3.Leppamaki S et al.  2003.  Effect of simulated dawn on quality of sleep, a community based trial.  BMC Psychiatry.  3:14

4.Thorn L et al.  2004.  The effect of dawn simulation on the cortisol response to awakening in healthy participants.  Psychoneuroendocrinology.  29:925-930

Written by Ani Kowal

Share

Refined carbohydrates linked again with increased risk of heart disease

In February this year I wrote about the links between refined carbohydrate and heart disease and mentioned some studies which suggested that sugary carbohydrates and those which increased blood sugar levels quickly (carbohydrates with a high glycaemic index, or GI) seemed to be a greater risk for heart disease than fat.

A recent study (1) published in the American Journal of Clinical Nutrition has concluded (1)that replacing SFAs [saturated fatty acids] with carbohydrates with low-GI values is associated with a lower risk of MI [myocardial infarction, or heart attack], whereas replacing SFAs with carbohydrates with high-GI values is associated with a higher risk of MI”.  The authors write in their introduction that studies suggest that replacing saturated fatty acids with carbohydrates has been modestly associated with a higher risk of ischemic heart disease, whereas replacing saturated fats with polyunsaturated fatty acids is associated with a lower risk of ischemic heart disease.  However, they point out that it is important to look at the type of carbohydrates consumed since different carbohydrates have very different effects in the body.

High glycaemic index foods (foods that release sugar quickly into the body) include most refined carbohydrates like white bread, long-grain rice, sweets, biscuits, sugary foods and many other processed carbohydrates and processed foods. Foods that release sugar quickly into the bloodstream have what is known as a high Glycaemic Index (GI), meals that favour a spike in blood sugar levels are said to have a high Glycaemic Load (GL).  To identify foods with a high glycaemic index that will contribute to increasing the GL of a meal please view the website The Glycemic Index www.glycemicindex.com, there you will find a database where you can search for specific foods and find out more about GI and health. 

 Briefly, unbalanced blood sugar levels following a meal (post-prandial dysmetabolism) can cause havoc in the body.  A high post-meal blood sugar level can lead to damaging free radicals (reactive oxygen molecules) being released which are a risk for atherosclerosis (damage to blood vessels) and metabolic syndrome (a big risk factor for heart disease).  The high blood sugar can lead to internal inflammation, dysfunction in the lining of the blood vessels and may also lead to an increase in triglycerides (blood fats) – all risk factors for heart disease. 

The authors of this research paper (1) aimed to investigate the risk of heart attack, (myocardial infarction), associated with a high carbohydrate diet, they also looked at the different glycaemic index of the carbohydrates.  The study involved over 53,000 individuals, none of whom had suffered a heart attack at the start of the study.  The individuals were followed for an average of 12 years, during this time almost 2000 heart attacks occurred.  They found that there was a statistically significant positive association between substitution of saturated fats with carbohydrates with high GI values and risk of heart attack.

Again these results only show and association and not cause and effect but the evidence does add to other studies which indicate that replacing fat intake with sugary, refined carbohydrates probably won’t be good for the heart, or the body in general.  Low fat diets really are not all that they were once hyped-up to be.  Please read my previous posts here and here for more information and also any of my posts regarding the healthy omega 3  fats and how important they are for health

As I have written previously, personally I feel that the take home message from studies such as these is that a healthy diet, based around natural unprocessed and unrefined foods, is crucially important to prevent disease risk.  Any health-full diet will be rich in plant foods such as vegetables, fruits, beans and pulses, nuts and seeds and will include unprocessed meats and fish (especially oily fish), wholegrain unprocessed and unrefined carbohydrates.  Particularly I feel that omega 3 fats  are important to health.  I would also suggest that refined carbohydrates are generally unnecessary and quite possibly damaging to health when eaten regularly and consistently.

(1)Jakobsen UM et al.  2010.  Intake of carbohydrates compared with intake of saturated fatty acids and risk of myocardial infarction: importance of the glycemic index.  Am J Clin Nutr 91: 1764-1768

Written by Ani Kowal

Share

More evidence links high sugar diet to increased risk of heart disease

Back in February I wrote a piece about how replacing dietary fat with sugar and refined carbohydrates was potentially damaging to health and more recently I mentioned research which linked high GI diets to an increased risk of heart disease in women.

New evidence (1) published in the Journal of the American Medical Association has found that there was a statistically significant correlation between dietary added sugars and blood lipid [fat] levels among US adults.  In the paper the study authors note that dietary carbohydrates have been associated with dyslipidemia, a blood fat profile known to be associated with an increased cardiovascular disease (Heart disease) risk.  The researchers wanted to look at the association between the consumption of added sugars in the diet and blood fat levels.  The study involved over 6000 individuals who were grouped by their intake of added sugars – less than 5 percent of total calories [reference group], 5 percent to less than 10 percent, 10 percent to less than 17.5 percent, 17.5 percent to less than 25 percent, and 25 percent or more of total calories.  The authors then looked to see how various blood fat levels were affected in the various groups of sugar consumption.  They looked at the ‘good’ cholesterol high-density lipoprotein cholesterol (HDL-C) and various types of blood fat that are known risk factors for heart disease such as triglycerides and low-density lipoprotein cholesterol (LDL-C)

Consuming a higher amount of added sugars in processed or prepared foods was associated with lower levels of the ‘good’high-density lipoprotein cholesterol and higher levels of triglycerides, which are important risk factors for cardiovascular disease (1).

The authors of the study write (1)Monitoring trends in consumption and understanding the effect added sugars have on risk of cardiovascular and other diseases is critically important, because added sugars are a potentially modifiable source of calories,” “Added sugars are food additives that can be recognized by consumers and have been proposed for specific labeling on food and beverage packaging. The results of our study demonstrate that increased added sugars are associated with important cardiovascular disease risk factors, including lower HDL-C levels, higher triglyceride levels, and higher ratios of triglycerides to HDL-C.” 

Evidence seems to be accumulating for the dangers to health of eating too much added sugar and sugary foods.  Although further evidence is needed before firm conclusions can be made it would seem wise that we aim to curb consumption of foods which contain high amounts of added sugar.  The authors echo this sentiment by writing (1)Although long-term trials to study the effect of reducing added sugars and other carbohydrates on lipid profiles are needed, our data support dietary guidelines that target a reduction in consumption of added sugar.”

(1)J A Welsh et al.  2010.  Caloric Sweetener Consumption and Dyslipidemia Among US Adults. JAMA. 2010;303(15):1490-1497

Written by Ani Kowal

Share

Replacing dietary fat with sugar and refined carbohydrates is probably damaging to health

Heart disease is a topic I have written extensively about here in these blog posts.  In 2008 I wrote two posts entitled ‘Do you know how to look after your heart’ part 1 and part 2.  In part two I wrote extensively about refined carbohydrates and blood sugar levels and how these appear to be a greater risk for heart disease than dietary fat.  Eating a diet loaded with foods with a high glycaemic index or high glycaemic load has been increasingly linked with a raised risk for heart disease and other health problems.  High glycaemic index foods (foods that release sugar quickly into the body) include most refined carbohydrates like white bread, long-grain rice, sweets, biscuits, sugary foods and many other processed carbohydrates and processed foods. 



By contrast certain types of fat, especially the long chain omega 3 fatty acids (EPA and DHA) from marine sources have been linked to a reduced risk of heart disease.  Many studies have also found that there is not enough evidence to link heart disease to saturated fat or total fat intakes (e.g.1).  I feel quite strongly that the push to eat ultra low fat diets over the last 50 years has impacted negatively on our health (and mood) since it has often led to diets rich in carbohydrates, especially refined carbohydrates.  Look at a low fat yoghurt for instance, the natural fat is removed and, often, replaced with copious quantities of sugar.  Low fat products in general are often full of sugars.  Actually I think the low fat campaigns have been a BIG FAT LIE.



This month in the American Journal of Clinical Nutrition fat is mentioned in a number of studies (e.g. 2,3,4,5).  In a commentary (2) authors point out that “An independent association of saturated fat intake with CVD [cardiovascular disease] risk has not been consistently shown in prospective epidemiologic studies”, the authors also point out that if saturated fat is removed from the diet and then replaced with a higher carbohydrate intake, particularly a higher intake of refined carbohydrates, this is associated with an increased risk of heart disease – specifically a high carbohydrate diet is associated with increasing problems such as insulin resistance, increased triglycerides (blood fats associated with heart disease), increased levels of a particularly destructive type of cholesterol known as small dense LDL cholesterol.  The authors also note that high carbohydrate diets are also linked to a reduced level of HDL ‘good’ cholesterol (2).  They conclude that “there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate” and “dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia [blood fat disorder linked to health problems] should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity [body fat]”.



A research paper (3) looking at data on saturated fat and cardiovascular disease (which includes coronary heart disease and stroke) evaluated 21 scientific studies which in total involved over 340,000 individuals followed for 5-23 years showed that “there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD [coronary heart disease] or CVD [cardiovascular disease]”.



Two other studies in the March issue of the American Journal of Clinical Nutrition (4,5) looked at the positive health benefits of the long chain omega 3 fatty acids, EPA and DHA, found in oily fish such as mackerel, trout, salmon and sardines.  In the first study (4) scientists show that supplementation with these fatty acids are beneficial in improving blood vessel function in individuals with type 2 diabetes.  In the second study (5) high intakes of EPA and DHA were associated with greatly reducing chronic disease risk. 
 


I am not advocating eating a diet that is packed with saturated fat, not in the slightest, personally I feel that the take home message from studies such as these is that a healthy diet, based around natural unprocessed and unrefined foods, is crucially important to prevent disease risk.  Any health-full diet will be rich in plant foods such as vegetables, fruits, beans and pulses, nuts and seeds and will include unprocessed meats and fish (especially oily fish), wholegrain unprocessed and unrefined carbohydrates.  Particularly I feel that omega 3 fats are important to health.  In a press release (6) the lead author of a study looking into heart disease and diet (7) said: “This isn’t just hype; we now have tremendous and compelling evidence from very large studies, some dating back 20 and 30 years, that demonstrate the protective benefits of omega-3 fish oil in multiple aspects of preventive cardiology“.  I also feel that refined carbohydrates are generally unnecessary and quite probably damaging to health when eaten regularly and consistently.



If you do not regularly, at least twice a week, eat oily fish then it would certainly be worth taking a fish oil supplement in order to provide your body with the essential omega 3 fatty acids.  For vegetarians and vegans a flaxseed oil supplement will provide the short chain omega 3 fatty acid, alpha linolenic acid.  Unfortunately the body is not very good at converting this into the long chain EPA and DHA forms that are crucial for health.  New vegetarian and vegan EPA and DHA supplements, made from algae, are becoming increasingly available and are worth looking in to.


 


(1)Mente A et al.  2009. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease.  Arch Intern Med. 169(7):659-669.
(2) Patty W Siri-Tarino PW et al.  2010.  Saturated fat, carbohydrate, and cardiovascular disease.  American Journal of Clinical Nutrition.  91: 502-509
(3) Patty W Siri-Tarino PW et al.  2010.   Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.   American Journal of Clinical Nutrition.  91: 535-546
(4)Stirban A et al.  2010.  Effects of n–3 fatty acids on macro- and microvascular function in subjects with type 2 diabetes mellitus.  American Journal of Clinical Nutrition.  91:808-813
(5)Makhoul Z et al.  2010.  Associations of very high intakes of eicosapentaenoic and docosahexaenoic acids with biomarkers of chronic disease risk among Yup’ik Eskimos.  American Journal of Clinical Nutrition.  91:777-785
(6)
http://www.sciencedaily.com/releases/2009/08/090803173250.htm.  American College of Cardiology (2009, August 3). Mounting Evidence Of Fish Oil’s Heart Health Benefits. ScienceDaily. Retrieved August 4, 2009, from http://www.sciencedaily.com¬ /releases/2009/08/090803173250.htm
(7)Lavie CJ et al.  2009.  Omega-3 Polyunsaturated Fatty Acids and Cardiovascular Diseases.  J Am Coll Cardiol, 2009; 54:585-594

Written by Ani Kowal

Share

Diet, the brain and behaviour in children

Children everywhere are starting to get ready to go back to school after their long summer holidays.  Nutrition and diet can impact the body and health in many ways, the most apparent concerns for parents of school aged children are immune health and brain function/behaviour.



In July I wrote about probiotics and prevention/treatment of childhood colds and last year I wrote about boosting immune health in children going back to school.  Today I wanted to have another look at behaviour and the brain.  Previously I have written about ADHD, particularly with regards the importance of omega 3 fatty acids for brain function.  The brain is a highly complex organ.  In infancy and childhood the brain is growing rapidly and it requires a lot of energy.  There is a mounting body of evidence to suggest that diet can influence the development and functioning of the brain (1).  This influence may well start with the diet of the mother during pregnancy and then in the infant in early life, however later in childhood nutritional intervention may well make a difference to brain function and cannot be discounted.



There is increasing evidence that the missing of breakfast has negative behavioural and attention consequences later in the morning and it is also thought that meals of a low rather than high glycaemic load are beneficial with regards child behaviour.  There are also findings of an association between a tendency to develop low blood sugar (glucose) and aggression in children(2)


Glycaemic index and glycaemic load are terms used to characterise foods and diets based on their effects on blood glucose levels.  Foods that release sugar quickly into the bloodstream have what is known as a high Glycaemic Index (GI), meals that favour a spike in blood sugar levels are said to have a high Glycaemic Load (GL).  White bread, potatoes, processed/refined carbohydrates have a high glycaemic index i.e. they tend to cause a rapid surge in blood sugar.  Vegetables, whole-grain high-fibre carbohydrates, create a more gradual change in blood sugar levels and are considered to have a low glycaemic index.  For the classification of more food examples please visit the website ‘The Glycemic Index’, there you will find a database where you can search for specific foods and find out more about GI and health.



Certain nutrients have greater effects on brain development than do others and hence may have more of an impact on childhood behaviour and brain function. The important nutrients include protein (which is so important for proper growth in childhood), certain fats (especially omega 3 fats), iron, zinc, copper, iodine, selenium, vitamin A, choline, and folate (3).  There is evidence that sub-clinical deficiencies of vitamins and minerals may influence anti-social behaviour and intelligence but the evidence is still controversial(4).The B vitamins, Folate and B12 (cobalamin), are vital for the brain.  Deficiencies have negative consequences on the developing brain, and behaviour, during infancy; and deficits of both vitamins are associated with a greater risk of depression during adulthood (5).  Recently vitamin D has also received attention with regards brain functioning.  As you can see a myriad of nutrients are important for the brain and they probably work and act synergistically, this makes clinical trials difficult to carry out.  However, there have been three well-designed studies which have reported that vitamin/mineral supplementation in children can reduce anti-social behaviour (2).



It is difficult to conclusively say which vitamins/minerals are most important and whether or not supplementation can help children – this is because behaviour is difficult to standardise and measure in a trial-setting.  Also psychological and environmental influences will be having an effect.  Needless to say our bodies are complex, we require various nutrients in correct proportions in order to stay optimally healthy.  Many children in the UK fall short of achieving recommended 5 portions of fruit and vegetable daily which is worrying for health and many children do not eat oily fish (the best source of omega 3 fatty acids) at all.  If you are concerned that your child is not eating a consistently healthy diet you may wish to consider a food-state multivitamin and mineral supplement that has been formulated specifically for children together with an omega 3 fatty acid supplement – easy to take liquid fish oils are now available for children which are naturally flavoured (usually lemon or orange).  Flaxseed oil and omega 3 supplements produced from algae are available for vegetarian/vegan children.



A UK based study concludes: “Whilst the importance of diet in educational attainment remains under investigation, the evidence for promotion of lower-fat, -salt and -sugar diets, high in fruits, vegetables and complex carbohydrates, as well as promotion of physical activity remains unequivocal in terms of health outcomes for all schoolchildren(6)



(1)Benton D.  2008.  Eur J Nutr.  The influence of children’s diet on their cognition and behavior. Eur J Nutr.  47 Suppl 3:25-37.
(2) Benton D.  2007.  The impact of diet on anti-social, violent and criminal behaviour. Neurosci Biobehav Rev. 31(5):752-74.
(3)Georgieff MK.  2007.  Nutrition and the developing brain: nutrient priorities and measurement.  Am J Clin Nutr.  85(2):614S-620S.
(4)Benton D.  2008.  Micronutrient status, cognition and behavioral problems in childhood.  Eur J Nutr. 47 Suppl 3:38-50.
(5)Black MM.  2008.  Effects of vitamin B12 and folate deficiency on brain development in children.  Food Nutr Bull.  29(2 Suppl):S126-31.
(6)Ells LJ et al.  2008.  A systematic review of the effect of dietary exposure that could be achieved through normal dietary intake on learning and performance of school-aged children of relevance to UK schools. Br J Nutr.  100(5):927-36.


Written by Ani Kowal

Share

Certain types of carbohydrates seem to be linked to the risk of developing breast cancer

In my last post I wrote about cinnamon and how it seems to be useful for blood sugar balance, a factor that is important for overall health.  I also wrote about how the glycaemic index and glycaemic load of food and meals can have an effect on the blood sugar (glucose) levels. 


A very recent study (1) has found a link between the glycaemic index of the foods and the glycaemic load of the meals we eat and the risk of developing breast cancer. As previously mentioned, the links between diet and cancer are widely researched.  The World Cancer Research Fund UK (WCRF UK), a charity dedicated to cancer prevention, estimate that lifestyle factors such as being overweight, eating an unhealthy diet and being inactive are responsible for about a third of all cancers in developed countries (2). 


Gycaemic index and glycaemic load are terms used to characterise foods and diets based on their effects on blood glucose levels.  Foods that release sugar quickly into the bloodstream have what is known as a high Glycaemic Index (GI), meals that favour a spike in blood sugar levels are said to have a high Glycaemic Load (GL).  White bread, potatoes, processed/refined carbohydrates have a high glycemic index i.e. they tend to cause a rapid surge in blood sugar.  Vegetables, whole-grain high-fibre carbohydrates, create a more gradual change in blood sugar levels and are considered to have a low glycemic index.  For the classification of more food examples please visit the website ‘The Glycemic Index’, there you will find a database where you can search for specific foods and find out more about GI and health. 



This recent study (1) took place in Sweeden and looked at data from 61,433 women who completed special food frequency questionnaires in the late 1980s.  After around 17 years there were 2952 women who had developed breast cancer.  Analysis of the date found that eating a diet with high glycaemic load was significantly associated with an increased risk of developing breast cancer.
 
When the data was further analysed: total carbohydrate intake, glycaemic index and glycaemic load were all positively associated with the risk of developing a certain type of breast tumour known as oestrogen receptor (ER+) positive/progesterone receptor (PR-) negative breast cancer (ER+/PR-).  Women with the highest glycaemic index diet had a 44% increased risk of developing ER+/PR- breast cancer compared to women with the lowest glycaemic index diet.  Women in the highest category of glyceamic load had an 81% increased risk of ER+/PR- tumours, and those with the highest carbohydrate intake had a 34% increased risk, compared to those in the lowest groups.  (No associations were observed for ER+/PR+ or ER-/PR- breast tumours)



The investigators speculate that high-glycemic load diets may boost breast cancer risk by increasing concentrations of insulin and sex hormones in the body, which may contribute to the development and spread of breast cancer cells.  The WCRF UK say that the relevance of GI and GL to cancer “might lie in the fact that the rise in blood glucose after a meal is closely linked to that of insulin, which apart from its crucial role in carbohydrate and lipid metabolism, is also one of a family of important growth factors (2)”.  High blood sugar levels after a meal are also related to an increase in inflammation in the body.



A healthy, nutritious diet which is low in processed/refined foods and rich in vegetables, nuts/seeds, beans, pulses, unprocessed meats and fish (especially oily fish such as salmon, mackerel and trout), healthy fats, unrefined wholegrains will generally keep blood sugar levels stable.  Including a source of protein with every meal is also important for blood sugar balance e.g. beans/pulses, unprocessed meat and fish, eggs, nuts/seeds.  For more information on blood sugar balance please read my post on cinnamon which contains relevant links. 



(1)Larsson SC et al.  2009.  Glycemic load, glycemic index and breast cancer risk in a prospective cohort of Swedish women.  International Journal of Cancer.  125: 153-157
(2)WCRF/AICR.  2009.  Policy and action for cancer prevention.  Food, nutrition and physical activity: a global perspective.  Washington DC: AICR, 2009
Written by Ani Kowal

Share

Omega 3 fats and low GI foods may help to satisfy our appetites

In order to successfully lose and maintain a healthy weight it is necessary to eat nutritious foods that satisfy appetite.  Foods that release sugar slowly into the bloodstream, i.e. foods that have a low glycaemic index (GI) help us to keep appetite on an even keel and prevent cravings.  Including protein with each meal also helps since protein tends to help satisfy hunger more than carbohydrate or fat.  If we don’t feel as hungry it is often easier to control our food intake.



Can fish oils help satisfy our appetites?
A recent study (1) looked at long chain omega 3 fatty acids, fish oils, to determine whether intake of these fats affects appetite when given to individuals following a low calorie diet.  These long chain fats (EPA and DHA) are found in oily fish such as salmon, trout, sardines and mackerel.  The study involved individuals aged around 31 years who were overweight (with an average BMI of 28).  Their appetite was explored during the last 2 weeks of an 8 week energy-restricted, balanced diet.  Half of the participants had a low amount of long chain omega 3 fatty acids as part of their diet and half had a high amount (over 1300mg per day).  Blood from the participants was measured to detect any changes in fatty acid levels and a validated assessment was used to measure hunger sensations directly after a 2 hour test meal.  As expected, the omega 3 content in blood cell membranes was lower in the low omega 3 intake group. The validated assessment revealed lower hunger sensations in the high omega 3 fatty acid group immediately after the test dinner and 2 hours later i.e. their appetites appeared to be satisfied and they felt fuller even 2 hours after the meal. 



The authors of the study conclude that long chain omega 3 fatty acid intake regulates after-eating (postprandial) satiety in overweight and obese volunteers during weight loss. Further research is needed to investigate the effects of omega 3 fatty acids in appetite control and weight loss maintenance.



There may be many reasons why omega 3 fatty acids help to prevent hunger and increase feelings of satiety after a meal.  One reason could be that omega 3 fats help to keep our blood sugar levels stable by affecting the way that our bodies deal with the hormone insulin (vitally needed for blood sugar control).  A recent study (2) found that long chain omega 3 fatty acids do indeed have positive effects on insulin control in young overweight individuals on a low calorie diet.



Omega 3 fatty acids are vital for our health and wellbeing.  Eating oily fish at least twice a week will help to keep levels in our body high.  For those who do not regularly eat oily fish then an omega 3 fatty acid supplement which provides around 250-350mg DHA and 250-350mg EPA daily may be beneficial.  Vegetarians and vegans can find short chain omega 3 fatty acids within flaxseeds and walnuts and may consider a flaxseed oil supplement providing 500-1000mg alpha linolenic acid daily.  Some long chain vegetarian omega 3 supplements are now becoming available, these are produced from algae.  Phytoplankton (microscopic marine plants) supplements also contain some EPA and DHA.



Oily fish may be beneficial in reducing appetite levels since it is a low GI food and very rich in protein, both factors which seem to have appetite-sating effects.  In addition to this there is evidence for omega 3 fatty acids being beneficial to our mood and in helping people who deal with depression, perhaps this mood boosting effect helps with self-esteem and hence may be a useful tool in curbing comfort eating?  Studies have not yet been done in this area but it seems like a plausible idea.



Why opt for low GI?


GI stands for Glycaemic Index.  Many supermarkets have now started to label low GI foods, but why is GI important to consider?  GI is a system of classification, or ranking, that is given to carbohydrate foods depending on how they affect our bodily blood sugar levels.  A low GI food or meal takes a longer time to release sugar into the bloodstream.  This means that insulin, the hormone responsible for blood sugar control is released in smaller amounts which helps prevent blood sugar fluctuations and consequent cravings and dips in energy levels.  A high GI food or meal releases sugar very quickly into the bloodstream, in response to this our bodies produce huge quantities of insulin which quickly remove the sugar from the bloodstream, often this leaves us feeling tired and lethargic and can cause cravings for more sugar or carbohydrate – leading to another surge in blood sugar levels and the start of a vicious cycle of insulin release and consequent cravings.



High GI foods include white bread, croissants and cornflakes and most processed or refined carbohydrates.  Low GI foods include most vegetables and fruits, most unrefined wholegrains and foods containing little carbohydrate such as meat, fish, eggs etc.



However, GI does not only affect insulin levels, it also seems to work to specifically reduce appetite.  A new study (3) presented at the annual Society for Endocrinology BES meeting this year has found that eating a meal with a low GI increases the production of a specific gut hormone called glucagon-like peptide 1 (GLP-1).  This hormone is known to help suppress our appetite and helps us to feel full after a meal. This is the first study to provide clues as to how a low GI meal produces satiety after a meal.  The study was small and results need to be verified in larger trials but it is indeed an exciting development. 



Previously I have written about eating to control blood sugar levels and how work stress can affect appetite  Reading these posts may provide you with a few useful ideas on how to keep appetite on an even keel throughout the day.  Essentially a healthy diet that includes an abundant variety of vegetables and fruits, healthy fats from nuts/seeds and oily fish, protein from unprocessed meats, fish, beans and pulses and minimal amounts of refined and processed carbohydrates will go far in boosting health and reducing waistlines.  Eating ‘real food’ satisfies taste buds, provides essential nutrients and keeps us healthy. 



(1)Parra D, et al.  2008.  A diet rich in long chain omega-3 fatty acids modulates satiety in overweight and obese volunteers during weight loss. Appetite.   Jun 14; [Epub ahead of print]
(2)Ramel A et al.  2008. Beneficial effects of long-chain n-3 fatty acids included in an energy-restricted diet on insulin resistance in overweight and obese European young adults. Diabetologia.  51(7):1261-8.
(3)Norouzy A et al.  2009.  Effect of single high vs low glycemic index (GI) meal on gut hormones.  Presented at Society for Endocrinology BES 2009, Harrogate,UK.Endocrine abstracts 19 OC17


The Society for Endocrinology is Britain’s national organisation promoting endocrinology and hormone awareness.  The Society for Endocrinology BES 2009 is Britain’s biggest scientific meeting on hormones, took place at the Harrogate International Centre, Harrogate, from 16-19 March 2009.


Written by Ani Kowal

Share