All Posts tagged energy

The deadliest diets : 10 year study

Two specific eating patterns increase the risk of death for older adults, a 10-year study finds.Compared to people who ate healthy foods, men and women in their 70s had a 40% higher risk of death if they got most of their calories from high-fat dairy foods or from sweets and desserts. University of Maryland researcher Amy L. Anderson, PhD, and colleagues monitored the eating patterns of 2,582 adults aged 70 to 79. They found that these diets fell into six patterns or clusters.

After adjusting for risk factors such as sex, age, race, education, physical activity, smoking, and total calories, “the High-Fat Dairy Products cluster and the Sweets and Desserts cluster still showed significantly higher risk of mortality than the Healthy Foods cluster,” Anderson and colleagues found.

The six dietary patterns were:

  • Healthy Foods: Higher intake of low-fat dairy products, fruit, whole grains, poultry, fish, and vegetables. Lower intake of meat, fried foods, sweets, high-energy drinks, and added fat.
  • High-Fat Dairy Products: Higher intake of ice cream, cheese, and 2% and whole milk and yogurt. Lower intake of poultry, low-fat dairy products, rice, and pasta.
  • Sweets and Desserts: Higher intake of doughnuts, cake, cookies, pudding, chocolate, and candy. Lower intake of fruit, fish and other seafood, and dark green vegetables.
  • Meat, Fried Foods, and Alcohol: Higher intake of beer, liquor, fried chicken, mayonnaise/salad dressings, high-energy density drinks, nuts, snacks, rice/pasta dishes, and added fat. Lower intake of low-fat dairy products, fiber/bran breakfast cereal, and other breakfast cereal.
  • Breakfast Cereal: Higher intake of fiber/bran and other breakfast cereals (especially the latter). Low intake of nuts, refined grains, dark yellow vegetables, and dark green vegetables.
  • Refined Grains: Higher intake of refined grains (such as pancakes, waffles, breads, muffins, and cooked cereals such as oatmeal) and processed meat (such as bacon, sausage, ham, and other lunchmeats). Lower intake of liquor, breakfast cereals, and whole grains.

Several of the groups got an unusually large amount of their total calories from just one food group:

The sweets and desserts cluster got 25.8% of its total energy from sweets.The refined grains cluster got 24.6% of its total energy from refined grains.The breakfast cereal group got 19.3% of its total energy from cold cereals other than those full of fiber and bran.The high-fat dairy products group got 17.1% of its total energy from higher-fat dairy foods.

Overall, people in the healthy foods cluster had more years of healthy life and a lower death rate than all other groups. Moreover, their blood tests came back with significantly more indicators of health than the other groups.

But not all of the study findings were so predictable. “Unexpectedly, in this and in several other studies, a [dietary] pattern higher in red meat was not significantly associated with increased risk of mortality,” Anderson and colleagues note. It's also not entirely clear why the Meat, Fried Food, and Alcohol cluster didn't have a significantly higher death risk, as most diets warn people to limit or avoid such foods.

“In our study, the Meat, Fried Food, and Alcohol cluster did have a slightly higher percentage of total energy from vegetables, fruit, and whole grains than both the High-Fat Dairy Products and Sweets and Desserts clusters, which showed higher risk of mortality,” Anderson and colleagues suggest.

This was by far the most common eating pattern seen in the study: 27% of participants were in the meat, fried food, and alcohol cluster. But Anderson and colleagues do not recommend such a diet. Instead, they point to the fact that 14.5% of study participants were in the healthy foods cluster. “Adherence to such a diet appears a feasible and realistic recommendation for potentially improved survival and quality of life in the growing older adult population,” Anderson and colleagues conclude.

The study appears in the January 2011 issue of the Journal of the American Dietetic Association.

Lack of exercise key to increased BMI in children

The paper directly compared findings from two separate studies: 'The Diets of British Schoolchildren' conducted by the Department of health (DH) in 1983 (Department of Health 1989); and the National Diet and Nutrition Survey (NDNS) from 1997 (Gregory & Lowe, 2000).

Gibson's analysis found that total sugar intake averaged at 115g/day in 1983, compared with 113g/day in 1997. Allowing for exclusions of low and high energy reporters, intake levels were 122g/day (1983) and 127g/day (1997), showing a marginal and insignificant increase over the study period. Contrastingly, mean body weight increased significantly during the period of the DH and NDNS surveys, showing a rise of 1.9kg for 10-11 year olds and 3.4kg among 14-15 year olds. BMI increased from 17.9 to 18.6 units in the younger group, and 20.2 to 21.3 units in the older group. According to these calculations, the prevalence of being overweight (plus obesity), as defined by the International Obesity Taskforce (IOTF) cut-offs (91st percentile) rose from 13% to 21-22% between surveys. Gibson concluded that the slight increase in consumption of total sugars did not account for the significant increase in BMI, equivalent to 2-3 kg over the review period.

During the same period, Gibson found that mean energy intake (EI) was 3% lower in 1997 than in 1983, mainly as a result of lower fat intake. This change in overall energy consumption meant that sugars represented a higher proportion of daily energy intake in 1997 (23.6% versus 22.3%), despite total sugar consumption remaining relatively static in comparison. The review surmises that the most likely cause for the increased BMI is a decline in energy expenditure.

In addition, Gibson's paper found that basal metabolic rate (BMR) increased by approximately 3% between surveys as a result of higher body weights, and it is estimated that EI in relation to basal requirements was even lower at 6%. Gibson found that the paradox of rising BMI, despite a 2-3% rise in BMR and an EI that is static or falling, pointed to declining energy expenditure as an important factor in the change.

The Gibson analysis showed that the key sources of sugars in the diet have changed with a marked shift away from table sugar and smaller falls in consumption of sugars through milk, biscuits and cakes, counterbalanced by a significant increase in sugars consumed in soft drinks and, to a lesser extent, fruit juice and breakfast cereals.

A conclusion of Gibson's reanalysis of data from the DH and NDNS studies, that consumption of total sugars remained relatively static during the period, providing an estimated 22% of energy, is supported by findings from a repeated cross sectional study of children's food and drink intake, conducted in Northumberland in 1989, 1990 and 2000 which looked at trends in children's food and drink intake.

Sigrid Gibson, the paper's author, said: “There are very few studies that have assessed trends in sugar intake over time and particularly over such an extended period. The findings of the reanalysis strongly contradict widespread assumptions that sugar levels in the diet are responsible for rising obesity levels. With dietary sugar intakes relatively static, and overall energy consumption showing decline, increased BMI levels cannot be attributed to sugar consumption.”


Replace Saturated Fat with Polyunsaturated Dat

Over the past several decades, the food industry has reduced the amount of saturated fat in many products, and the public has reduced the amount of saturated fat in their diet. However, there has been a wide variation in the types of nutrients that have replaced this saturated fat. For example, in many products saturated fats were replaced with trans fats, which have since been determined to be detrimental; and in the overall American diet saturated fat was generally replaced with increased consumption of refined carbohydrates and grains.

“The specific replacement nutrient for saturated fat may be very important,” said lead author Dariush Mozaffarian, assistant professor in the department of epidemiology at HSPH and the department of medicine at Harvard Medical School. “Our findings suggest that polyunsaturated fats would be a preferred replacement for saturated fats for better heart health.”

Results from prior individual randomized controlled trials of saturated fat reduction and heart disease events were very mixed, with most showing no significant effects. Other trials focused only on blood cholesterol levels, which are an indirect marker of risk. Large observational studies have also generally shown no relationship between saturated fat consumption and risk of heart disease events; for example, earlier this month in the American Journal of Clinical Nutrition, researchers from HSPH and Children's Hospital Oakland Research Institute performed a pooled meta-analysis of prior observational studies and found no evidence that overall consumption of saturated fat was related to risk of coronary heart disease or stroke events.

Some of these mixed findings may relate to absence of prior focus on the specific replacement nutrient for saturated fat; in other words, was saturated fat replaced primarily with carbohydrate, monounsaturated fats such as in olive oil, or polyunsaturated fats such as in most vegetable oils?

Mozaffarian and his HSPH colleagues, Renata Micha and Sarah Wallace, performed a systematic review and meta-analysis of all randomized controlled trials through June 2009 in which participants specifically increased their polyunsaturated fat consumption as a replacement for saturated fat and in which coronary heart disease events were documented. Eight trials met the inclusion criteria, totaling 13,614 participants with 1,042 coronary heart disease events.

The meta-analysis of the trials showed that increasing polyunsaturated fat consumption as a replacement for saturated fat reduced the risk of coronary heart disease events by 19%. For every 5% increase (measured as total energy) in polyunsaturated fat consumption, coronary heart disease risk was reduced by 10%. This is now just the second dietary intervention–consuming long-chain omega-3 fatty acids is the first — to show a reduction in coronary heart disease events in randomized controlled trials.

Currently, the Institute of Medicine guidelines recommend that a range of 5%-10% energy consumption come from polyunsaturated fats. In addition, some scientists and organizations have recently suggested that consumption of polyunsaturated fats (largely “omega-6” fatty acids) should actually be reduced due to theoretical concerns that such consumption could increase coronary heart disease risk.

The results from this study suggest that polyunsaturated fats from vegetable oils may be an optimal replacement for saturated fats, an important finding for dietary guidelines and for when food manufacturers and restaurants are making decisions on how to reduce saturated fat in their products. The findings also suggest that an upper limit of 10% energy consumption from polyunsaturated fats may be too low, as the participants in these trials who reduced their risk were consuming about 15% energy from polyunsaturated fats.

Support for this study was provided by the National Heart, Lung, and Blood Institute, NIH and a Searle Scholar Award from the Searle Funds at the Chicago Community Trust.


Folate Helps Repair Damage Due to Ageing

Since the 1960s, researchers have been studying how the water-soluble vitamin supports the healthy functioning of cells. They discovered that it's essential for cell division and replication, making it especially important for expectant mothers.

It's also important to proper replication of DNA and RNA — a lack of folate has been linked to genetic mutations that can lead to cancer.

Folate is commonly found in leafy green vegetables like spinach and turnip greens. Since 1998, the U.S. Food and Drug Administration has mandated that many foods, such as rice, flour and cornmeal, be enriched with a synthetic folate known as folic acid.

While folate deficiency is no longer a problem in the U.S., it remains widespread in developing nations and much of Europe, where enriching grain products is not widely practiced.

This new research, funded by the National Science Foundation and originally sparked by funding from the U.S. Department of Energy, links folate to the production or repair of compounds called iron-sulfur clusters through a recently discovered intermediary protein called COG0354.

These clusters are part of the mechanism cells use to produce energy and carry out other vital reactions. But they are also sensitive to a byproduct of the energy-producing process: highly reactive oxygen-based molecules, some of which are called free radicals.

The oxidative stress caused when these molecules pollute a cell has been linked to cell death and aging, as well as to conditions such as atherosclerosis, Parkinson's disease, heart disease, Alzheimer's, fragile X syndrome and many more.

Examining the folate-iron-sulfur cluster link required the team to pull experience from not only UF's microbiology and cell science and food science and human nutrition departments, but also the McKnight Brain Institute and the National High Magnetic Field Laboratory.

Expertise from the latter two institutions was needed because the researchers used nuclear magnetic resonance analysis to observe folate interacting with COG0354 protein — molecular-scale activity that could otherwise only have been shown indirectly, said Arthur Edison, the NHMFL's director of chemistry and biology and an associate professor with UF's biochemistry and molecular biology department.

The researchers have found that COG0354 is present in creatures from each of the six kingdoms of life, from mice and plants to one-cell organisms that may predate bacteria.

The findings will open new avenues of study into the overall mechanism of oxidative stress repair, and may someday lead to new medicines. For now, the researchers emphasize that this is another example of the vitamin's importance in one's diet.


It’s Never Too Late

Good nutrition is important at every stage of life, from infancy through late adulthood. The basics of a balanced diet remain the same but individual nutritional needs change as you grow older. No matter what your age, it is never too late to start living a healthier life.

Whether you are 50 or 85, active or homebound, your food choices will affect your overall health in the years ahead. The risk for certain diseases associated with aging such as heart disease, osteoporosis and diabetes can be reduced with a lifestyle that includes healthy eating. Good nutrition also helps in the treatment and recovery from illness. While healthy living can't turn back the clock, it can help you feel good longer.

Eating healthfully means consuming a variety of good foods each day. Food provides the energy, protein, vitamins, minerals, fiber and water you need for good health. For one reason or another your body may not be getting the right amounts of these nutrients.

There are several factors that indicate an increased risk for poor nutrition. If you have three or more of the risk factors listed below consult with Nastaran or your doctor:

  • ill health
  • poor eating habits
  • unexpected weight gain or loss
  • taking medications
  • poor dental health
  • economic hardship
  • loneliness and lack of social contacts
  • the inability to care for yourself

Be Good to Yourself

Due to loss of loved ones, health problems, trouble paying bills, or other reasons, many older people feel lonely, sad, or stressed in their daily lives. Feelings like these may cause you to lose energy, not feel like doing anything, not eat enough, or overeat. Being good to yourself may help you to cope with your feelings and improve your energy level, eating habits, and health. Here are some ideas for being good to yourself:

  • Get enough sleep.
  • Stay connected with family and friends.
  • Join a walking group, or other social group.
  • Surround yourself with people whose company you enjoy.Volunteer or get active with groups in your community.
  • Try a part-time job at a place you would enjoy working for a few hours a week.
  • Watch a funny movie and laugh.
  • Take up a hobby such as playing cards, gardening, cooking, or dancing.

Remember, it's never too late to improve your eating plan, be more physically active, and be good to yourself for a healthier life. If you need to talk, make an appointment to see Nastaran.


Diet Advice for Doctors

 Q: What evidence is there that diet can make a difference?

A:  As an Accredited Practising Dietitian the advice I give has to be scientifically based. Recommended dietary allowances are set for a population group and includes sub-sectors like infants, children and the elderly.

Dietary advice is often based on epidemiological research that is carried out by public health scientists. It is this kind of research, for example that has suggested the value of the Mediterranean diet in reducing the risk of heart disease and cancer. Another example is selenium. Research suggests that this is a mineral influential in improving our immune systems but also indicates that, given its toxicity level, taking a selenium supplement can’t normally be recommended.

People who consume a varied diet tend to have a wider nutritional profile, and therefore are more likely to achieve recommended nutrient intakes. It is important that no foods are portrayed as good or bad, all foods can be consumed in moderation and food choices should be put in context with an individual’s lifestyle.

Whatever condition you’re treating a patient for, once their basic nutritional needs have been met, research suggests that the biggest difference diet can make will be in relation to weight control. It’s down to mathematics. However, what we need can differ. If you’re in your 20s you may have a different level of physical activity from when you’re in your fifties and therefore your requirements will be different. Normal body weight with a slight increase with age appears to be the most beneficial to health and longevity.

Q: Is there any new evidence emerging, which doctors should be aware of?

A: Because diet is part of the treatment programme for diabetes it is sometimes assumed that diet (sugar intake) causes diabetes. However the idea that sugar causes diabetes/heart disease was dismissed as long ago as 1989. A number of more recent, international expert committees have come to the same conclusion. A very recent report shows no association of sugars or total carbohydrate intake on the risk of cardiovascular disease. Obesity and lack of exercise appear to be the main risk factors.

Modest intakes of alcohol have been shown to increase protective HDL cholesterol levels. Those with an increased risk of CHD are recommended to consume alcohol regularly in small quantities, 1-2 units a day for men and women. However, binge drinking is certainly not recommended. Only modest amounts of alcohol should be included in the diets of patients with hypertriglyceridaemia and sometimes-total alcohol avoidance is advised.

Epidemiological evidence is quite clear that communities with a higher intake of fruit and vegetables have a lower incidence of heart disease and cancer.

Pregnant women need a supplement of folic acid before and throughout pregnancy to reduce the risk of neural tube defects.

Prospective cohort studies have shown that a high consumption of plant-based foods is associated with significantly lower risk of coronary artery disease and stroke. The protective effects are thought to be due to beneficial nutrients within the foods, for example, n-3 fatty acids.  A healthy plant-based diet should include unsaturated fat as the predominant form of dietary fat.  Animal products may be included, such as fish, poultry and low-fat dairy.

Q: Doctors are busy professionals, usually with a range of commitments. What are the things they are most likely to miss out on, as far as diet is concerned?

A: Lack of regular meals is probably the most important factor here. If you eat three meals a day you’ll normally eat a wider variety of foods and will be less likely to graze on fatty foods.

One meal you commonly miss out on if you’re busy is breakfast. Research here is absolutely clear – people who have breakfast cereal tend to be thinner and have a higher nutritional intake.

If you’re very busy you may also end up eating late at night, so have less control over what you eat because you’re hungry. You’ll eat pretty much anything.

If there’s a canteen at work you could end up eating two dinners a day and over consuming.

You may eat more convenience foods and miss out on fruit and vegetables and women doctors may not eat enough calcium and iron rich foods.

Q: What would you suggest to counteract this?

A: Breakfast is the most important meal of the day. Healthy breakfast options include wholemeal bread/toast, breakfast cereal with low fat milk, fresh fruit, fruit juice, tea or coffee.

Research suggests a higher intake of cereals and grains, such as whole wheat and rye, are associated with a lower incidence of cardiovascular disease. People who eat breakfast are also less likely to be overweight.

Fortified cereals can be a significant source of minerals and vitamins – for instance calcium which is essential for bone development. Folic acid is highly recommended to pregnant women or women planning a pregnancy, as it is proven to prevent neural tube defects. And iron which is particularly important for women of menstruation age.

No matter how busy you are, aim to eat three meals a day and have fruit or juice with each meal. Avoid high density energy  snacks.

Contrary to popular belief, carbohydrates are not fattening and in general are either fat free or very low in fat. Recent research has shown that a higher cereal fibre intake in adults aged 65 years and over is associated with lower risk of CVD with the lowest risk appearing to be related to intake of dark breads, such as whole wheat, rye and pumpernickel. Meals should therefore be based around carbohydrate foods. This would include the use of high fibre breakfast cereals especially porridge, brown breads, potatoes, pasta, rice, noodles and pitta bread.

If you eat at the canteen then have a wrap or sandwich at lunch and dinner in the evening, or vice versa.

If you live on your own, plan ahead. Online supermarket shopping can be very helpful here. You can plan a balanced diet for the week ahead, order it online and get it all delivered at one go. Also consider bulk cooking and freezing individual portions to ensure healthy options are readily available especially on those particularly busy, stressful days.

Q: So what is a balanced diet?

A: A well balanced diet is one that provides the body with enough energy, and all the nutrients required in their correct amounts to prevent illness and disease. However, how you translate this into food terms is quite difficult.

The biggest difference diet makes to health is through weight control. If you are maintaining your weight over a period of time then your energy intake is matching your energy output. However, if your weight is increasing slowly over a period of a year then you are eating more than your body actually needs. In reverse, if you are underweight then you are not eating enough food to meet your body’s needs. Most diet related problems are associated with weight, either the risk factors associated with obesity, or the health factors associated with anorexia.

People who consume a varied diet tend to have a wider nutritional profile, and therefore are more likely to achieve recommended nutrient intakes.

A diet high in saturated fat will raise blood cholesterol levels in individuals who have a genetic predisposition for raised cholesterol and most people won’t know whether or not they are genetically predisposed. In some individuals, a low saturated diet is sufficient to control blood cholesterol levels. In others, medication is required.

A low fibre diet is associated with cancer of the bowel, constipation and other bowel disorders

Low intake of fruit and veg is associated with higher incidence of cancer and heart disease.

It is important that no foods are portrayed as good or bad, all foods can be consumed in moderation and food choices should be put in context with an individual’s lifestyle.

The main keys to good health are:

  • Be a good weight. Obesity is a major risk factor for type 2 diabetes and can also induce raised blood pressure. Combined with type 2 diabetes this would become a major risk factor for heart disease.
  • Exercise regularly. Epidemiological evidence shows that people who are physically fit have fewer medical problems and a longer life span that people who dont do any exercise at all. Daily activity, like walking or cycling to work is potentially beneficial to health, especially in terms of type 2 diabetes prevention.
  • Don’t smoke.
  • Drink alcohol but in moderation.

Q: From a dietary perspective what are the three most useful things doctors can do themselves and advise their patients to do, to reduce the risk of a heart attack?

A key dietary message is the value of fish in preventing heart disease. Omega-3 fatty acids found in oily fish are beneficial for blood clotting and platelet aggregation, having an anti-thrombotic and anti-inflammatory effect. Omega-3 fatty acids also reduce plasma triglyceride levels, but have minimal effects on LDL and HDL cholesterol levels.

Oil rich fish include herrings, kippers, salmon, sardines, mackerel, trout, tuna and swordfish. These contain much higher levels of Omega-3 than white fish.

Try to include three or more portions of oily fish a week. Those unwilling to do this should use a fish oil supplement (fish body oil not fish liver oil) that contains 0.5-1.0g of omega-3 fatty acids (DHA and EPA).

Epidemiological evidence has shown that diets rich in fruit and vegetables are protective against CVD, including CHD and stroke. These foods contain many important nutrients. Potassium can help reduce blood pressure, folic acid limits homocysteine formation and soluble fibre helps reduce LDL cholesterol and improves HDL cholesterol. In addition, fruit and vegetables contain anti-oxidants as well as bioactive compounds with anti-oxidant activity such as carotenoids and flavonoids. However, anti-oxidant supplements in whatever form are not recommended to replace fruit and vegetable.

Avoid high intakes of total fat, saturated fat and trans fatty acids, as these are linked to raised blood cholesterol levels especially LDL cholesterol. This means limiting how much cream, butter, mayonnaise, cheese, chocolate and biscuits you eat. Products like biscuits are often produced using cheap vegetable oils, which change their chemical composition when cooked, creating trans fatty acids, which are more damaging than even cholesterol.

A high fat intake is also linked with excess weight and obesity. Women should limit fat intake to 60-70g per day with a maximum of 20g coming from saturated fat. Men should limit fat to 80-90g per day with a limit of 25g saturated fat. If the patient needs to lose weight then fat levels should be cut by half.

Potassium will help reduce blood pressure. Good dietary sources are bananas, orange juice and potatoes.

Cholesterol lowering spreads containing plant sterols or stanols have been shown to lower LDL cholesterol by up to 15%

Consuming alcohol three or more times a week even in small to moderate amounts was associated with reduced risk of coronary heart disease and myocardial infarction.

So, in summary, eat:

  • Three or more portions of oily fish a week
  • Less fat, especially saturated fat
  • More fruit and vegetables

Q: One in three people is diagnosed with cancer at some stage in their lifetime. What changes should doctors be thinking of, in their own diet and that of their patients, to try to reduce the risk of cancer?

The association between diet and cancer is still only in its infancy. Most studies are epidemiological in origin and research trials are sometimes hard to replicate.

The evidence is currently suggesting that isoflavones, which are phytoestrogens present in high quantities in soy products, may play a preventative role in breast cancer.

An abundance of data suggests that consuming diets high in fruit and vegetables and thus anti-oxidants, results in a decreased risk for many cancers including colorectal and lung.

Vitamin C has been associated with a decreased risk of many types of cancers especially stomach cancer.

Selenium supplementation has been associated with a decreased risk of prostate cancer (but given its toxicity levels need to be regulated by the GP).

Resveratrol , a polyphenolic phytoalexin found in grapes is an anti-oxidant that has been shown to exhibit strong anti-inflammatory, cell growth-modulatory and anti carcinogenic effects so can be helpful if there is genetic predisposition.

Some evidence has shown a protective effect of tea on the incidence of stomach and rectal cancers. There is little to associate coffee drinking with cancer. Decaffeinated coffee may be worse for you than ordinary coffee, as a result of the decaffeinating process.

Diets rich in cruciferous vegetables like broccoli,  cabbage, cauliflower, horseradish and mustard seed appear to reduce the risk of cancer of the colon and rectum.

Allium vegetables like garlic and onions appear to be preventative against stomach cancer.

High alcohol intakes are associated with cancers of the mouth, pharynx, larynx, oesophagus and liver.

Based on the most recent evidence, the recommendations to prevent cancer are, that the diet should contain foods of plant origin, they should be varied and nutritionally adequate, 7% of energy should come from fruits and veg and 45-60% from starch and protein foods of plant origin. In addition, the diet should maintain a normal BMI (body mass index) and active lifestyle.

Excess intakes of salt, alcohol, heavily cooked meats and hydrogenated fats should be avoided. To achieve this cut down on barbequed food and cheaper manufactured foods, for instance.

Q: Is there anything diet can do to help boost our immune system?

A: Unknown to many people is the role that vitamin A plays in our immune system. Mild vitamin A deficiency leads to an increased susceptibility to a variety of infectious diseases. However, because it is a fat-soluble vitamin that can be stored in the body, supplements should be used with caution. It is far better to improve the sources in the diet, such as fortified milk with vitamins A and D added to it.

Liver is such a rich source of vitamin A that pregnant women should actually avoid it. Many margarines have vitamin A added to them. Carotenes, which are precursors of vitamin A are found in green, yellow and red fruits and vegetables, and these are also a great source of antioxidants.

Selenium (a mineral) and also an antioxidant plays a major role in immunity. Selenium deficiency is accompanied by loss of immunocompetence. Covert suboptimal selenium status may be widespread in human populations. However, there is a narrow margin between beneficial and harmful intakes of selenium so be careful of supplements. Brazil nuts are a rich source of selenium. Fish, shellfish, liver and kidney as well as milk and eggs are also good sources of selenium.

Zinc deficiency causes increased susceptibility to infections. Meat, (beef and lamb being higher than pork and chicken) seafood (especially oysters and crab) and liver are the main sources of bioavailable zinc.

Q: For doctors working long hours, do you have any diet tips to help maintain energy?

A: A high carbohydrate diet is the only way to maintain energy levels. It depends where you are.

For immediate energy, that is fat free, go for something that is sugar-based like tea or coffee with two spoons of sugar added or a soft drink or sweets like pastilles or wine gums. This is so much better than eating biscuits, chocolate or crisps, which are all high in fat.

If you have time and you can get it, white bread is absorbed the quickest so a bread roll will give you instant energy and is also fat-free. Nutritious energy snacks would include fruit juices, a smoothie, a fruit or wholemeal scone, a wholemeal cereal bar, a piece of fruit or even just a couple of slices of toast.

Q: Do dietary supplements have any value or is the main benefit from what we eat and drink?

A: The aim should be to get all the nutrients that your body needs from your diet. However, this is not always practical. There is a role for supplements but in special situations, not for the general population.

Women who do not eat dairy products should take a calcium supplement. Vegetarians should take an Iron and vitamin B12 supplement. Vitamin D requirements increase in the elderly so a vitamin D supplement could be necessary here. If someone has been ill then a short course of a vitamin supplement would be useful.

Most important of course is folic acid for women who are planning a pregnancy.

But for the rest of us, they really are not necessary.

One other point to bear in mind is the value of the sun, within reason, as a source of vitamin D. We are now hearing of an increase in rickets in children, as a result of very high levels of sunscreen use.

Q:  The word diet sometimes conjures up the idea of weight loss and every year seems to bring the latest celebrity diet. What would your advice be for someone looking to lose weight? 

A: There’s no mystery to dieting. It is simply a question of mathematics. Bigger portions contain more calories, which can contribute to weight gain. So to lose weight, or maintain body weight, reduce portion sizes.

Don’t skip breakfast. Have three regular meals a day – just keep the portion sizes down. If you’re eating in, a smaller plate is an easy way of achieving this.

Q: For doctors studying for examinations is there anything they should include in their diet or avoid to help their concentration?

A: The brain is one of the smallest organs in the body yet it uses up 20% of our daily energy. Keeping a constant supply of glucose to the brain will ensure concentration so, again, don’t skip breakfast. Lack of glucose will reduce your ability to recall and concentrate.

High fire carbohydrate foods will ensure a slow but sustained release of glucose. Foods like high fibre breakfast cereal, brown bread, fruit and vegetables are all recommended.

Q: Would you give different advice to doctors at different stages in their lives and careers? For instance, how might your advice differ, talking to a recently qualified doctor compared with a doctor approaching retirement?

A: The basic nutritional requirements will be pretty much the same throughout your life and career. What is more likely to change is your requirement for energy.

There was probably a time when the pace of life earlier in your career was more frantic but changes in Medicare mean you may now be experiencing a hectic pace throughout most of your career. In the past too, many male medical careers were partly built on having a wife at home looking after the home and children and doing the cooking. With both men and women now having careers, pressures outside work may be growing, hence increasing concerns about achieving a work/life balance.

However, physical activity may still be more likely when you are younger, for instance if looking after young children compared with after they have left home.

Other factors will also be age related. As we grow older our appetite may be reducing, there may be a slight loss of taste and smell, we may be getting a bit bored with and losing interest in the food we have traditionally eaten. All this suggests the value of planning our diet to ensure we continue to eat regularly and enjoy a varied diet as we grow older. I’ve already explained the value of higher cereal fibre intake in adults aged 65 years and over.

Also, as you grow older, if your weight goes up your blood pressure tends to rise, so the diet and exercise advice I mentioned earlier becomes increasingly important.

Q: Food allergies seem to be an increasing problem. Is there anything we can do, through choice of diet, to reduce the risk of developing food allergies?

A: Food allergy is a reaction by the body to a dietary protein like milk, egg or nut. This allergic response produces a lot of IgE antibodies and will make you ill immediately after eating the food. 1 – 2% of the population is believed to have a food allergy.

Food intolerance causes symptoms hours/days after eating the offending food. This response may or may not involve the immune system. Foods like soya, milk, eggs, and wheat; chocolate, caffeine and wine can all be listed as offenders. There is no scientific test to prove food intolerance. Advice is usually to avoid the offending food. If you think you have a food intolerance seek advice from an Accredited Practising Dietitian like myself.