Nutrition and health conference
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Over 500 health professionals attended a conference held in London on November 21-22 to hear about recent developments in nutrition and health. Dr
Pamela Mason reports
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Recognition of nutrition as fundamental to health is “a cause
for celebration”
Dr Pamela Mason is a pharmacist and freelance writer with a special
interest in nutrition
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In the keynote address, Professor Alan Jackson, chairman of the United
Kingdom Scientific Advisory Committee on Nutrition, said that issues
of food, nutrition and health were now taken seriously. Nutrition is
widely recognised as being fundamental to health, with current diet carrying
profound implications for the risk of disease in the short and the long
term. There is also broad agreement on the patterns of diet and the style
of life which are associated with health.
Only by influencing food choice can health be improved |
Over the past decade there has been a systematic approach to developing
the capability to provide people with the best advice and guidance, both
in the UK and more widely across Europe. Most recently, the Curry report
on the future of farming and food made it clear that human health and
well-being should be an underlying driver in the formulation of policies
which determine agricultural production and food availability in the
UK.
“All of this is a cause for celebration,” Professor Jackson said.
However, it does make heavy demands on health professionals. Health professionals
are the most highly respected sources of advice on diet, health and nutrition
and the public expects them to be competent. It is therefore imperative
that the dietary advice provided to the public is clear, reliable and
consistent. The health team must work together in the promotion of this.
However, providing nutritional information is not enough to change the
diet of the population. It is only by influencing food choice that health
can be improved. An effective strategy must therefore address a wide
range of issues that help or hinder good nutrition. To achieve this,
needs a broader, public health approach. All health professionals will
need adequate training, to be safe in their own practice and, equally
importantly, to know how best to use the specialised skills of dietitians
and public health nutritionists.
Professor Jackson went on to say that a wide range of nutritional problems
continue to exist in the UK. One of his own studies on household food
insecurity (the limited or uncertain availability of nutritionally adequate
and safe food) and hunger in the UK has shown that 10 per cent of people
suffer from hunger, 20 per cent live in circumstances of poverty sufficient
to cause hunger and around one million experience food insecurity and
hunger. The highest rates of hunger were found in younger people, those
who find healthy eating expensive and the unemployed. The study also
demonstrated that food insecurity is associated with increased incidence
of obesity and that a combination of food insecurity and hunger is associated
with a greater risk of obesity.
The National Diet and Nutrition Survey in older people found that 5–10
per cent of over 65s have a low body mass index and one in three have
biochemical measures of vitamin deficiency. Poor nutrition in the elderly
is becoming sufficiently common to be a public health problem. This situation
highlights the need to identify those at special risk. For this, the
British Association of Parenteral and Enteral Nutrition (BAPEN) has developed
a screening tool that is evidence-based and effectively identifies those
at special risk of poor nutrition and provides guidance on management.
The tool is a simple five-step process which can be used in different
settings and by all health care workers. Atkins diet — no long-term data
In a presentation about the Atkins diet, Dr Susan Jebb (head of nutrition
and health research, Medical Research Council Human Nutrition Research
Centre, Cambridge) said that there were no long-term data on the effect
of high protein, low carbohydrate diets on clinical outcomes. Although
it is true that individuals consuming such diets do lose weight during
the first six months, evidence shows that beyond that time weight gain
may recur, and adherence to the diet plan wanes.
Claims made that weight loss occurs as a result of ketosis and metabolic
stimulation are theoretically plausible, but practically will make little
impact on energy balance. For example, ketosis certainly leads to loss
of energy (calories) because dietary fat is incompletely metabolised
during the ketotic state. Ketones also have a role in appetite suppression,
but there is little evidence of any major impact of either of these mechanisms
on energy (calorie) balance. In addition, diet induced thermogenesis
(DIT) may be increased by high protein, but DIT represents only 10 per
cent of energy expenditure, so again, the influence on energy balance
is likely to be small.
Most scientists argue that weight loss on the Atkins diet is directly
related to a reduction in energy intake (weight cannot be lost in any
other way). This is facilitated by reduction in variety of foods, the
constraints on the intake of many energy dense foods (eg, biscuits, cakes,
confectionery) and the satiating properties of a relatively high protein
diet. All of these factors may reduce dependence on calorie counting.
However, it is important to remember that successful treatment of obesity
is about more than weight loss. It must also improve overall health and
reduce the risk of chronic disease. Low carbohydrate diets do not meet
the recommended intakes for a range of vitamins and minerals so supplementation
is recommended. “Weight loss does occur with Atkins, at least for
six months, and is similar to that found with an isocaloric low fat diet.
However, we don’t know what the long-term health outcomes with
Atkins are, but we do know the health benefits of a low-fat diet.” New dietetic guidelines
The conference also saw the launch of new dietetic guidelines for the
secondary prevention of cardiovascular disease. Developed by UK Heart
Health and the Thoracic Dietitians Group of the British Dietetic Association,
the guidelines are based on systematic reviews of dietary interventions
in heart health. According to Elsa Griffiths, dietitian, Royal Brompton
and Harefield NHS Trust, London, who provided an explanation of the
guidelines, giving evidence-based dietary information to all people
with coronary heart disease (myocardial infarction or angina) will
save more lives than concentrating dietary advice on those in need
of weight loss or lipid lowering.
Following myocardial infarction, all people should be given advice
on a Mediterranean-style diet |
The guidelines state that all people with existing heart disease should
be advised to increase their omega-3 fat intake. The dose required
is two to three large portions of oily fish per week (or 0.5–1g
of omega-3 fats per day). Saturated fat intake should be reduced, although
this dietary change appears to need to be sustained for more than two
years to reduce cardiovascular events. Saturated fat should be replaced
totally or partially with unsaturated fats (olive oil or rapeseed oil).
In addition, following MI all people should be given advice on a Mediterranean-style
diet, which includes increased omega-3 fats, fruits and vegetables
and
fresh foods, reducing saturated fat and processed food.
“The practice of prioritising dietetic time in secondary prevention to
those with raised lipids is out of date since the advent of statin
therapy. However, there is good systematic review evidence that dietary advice
to all those with coronary heart disease can reduce mortality and morbidity
as well as modify risk factors. Dietary advice that does this most
effectively
should be prioritised.” Cholesterol lowering
Professor David Jenkins, faculty of medicine, University of Toronto,
Canada, asked whether diet could be used like a drug in lowering cholesterol.
Drugs have proved effective in lowering serum cholesterol and reducing
the risk of coronary heart disease, he said. By comparison, the impact
of diet has been considered too small to sustain much clinical interest.
Recently, however, to reverse this trend, the American Heart Association
and the adult treatment panel of the national cholesterol education
programme have advocated the use of specific dietary components, including
viscous fibres, plant sterols, soy protein and nuts. These foods have
also been allowed health claim status by the US Food and Drug Administration
for cardiovascular risk reduction related to their ability to reduce
cholesterol.
Professor Jenkins went on to describe his own trials with these four
ingredients — soy protein foods (soy milk, tofu, soy burgers),
viscous fibre foods (oat bran, barley, psyllium), plant sterols (in enriched
margarines) and almonds — in the same diet. Their combined effect
in a group of hyperlipidaemic men and women was to reduce low-density
lipoprotein cholesterol by approximately 30 per cent, which was the same
as found with lovastatin (20mg daily) and with a reduction in C-reactive
protein, a potential risk factor for heart disease.
“Our studies lead us to believe that by combining foods with cholesterol
lowering properties in the same diet, clinically meaningful reductions
in LDL cholesterol can be achieved, which justify continued interest
in diet as therapy. The use of aspirin, a statin, an ACE inhibitor and
a beta-blocker will become routine for increasing numbers of people unless
we make a major effort in terms of diet and lifestyle,” said Professor
Jenkins Nutrition and bone health
In a presentation about nutrition and bone health, Dr Roger Francis,
chairman of the nutrition forum of the National Osteoporosis Society,
said that although high dietary calcium intake may increase the bone
mass acquired during adolescence and reduce postmenopausal bone loss,
both calcium and vitamin D play a more critical role in the maintenance
of bone health in older
people.
Calcium and vitamin D supplementation has been shown to decrease the
risk of fracture in older people, but studies of the effect of vitamin
D alone on fracture risk have yielded inconsistent results. This suggests
that combined cal-cium and vitamin D supplementation is required to obtain
optimal anti-fracture benefit in older people. Recent studies show that
combined calcium and vitamin D supplementation also decreases postural
sway, improves muscle function and reduces the risk of falls in older
people by 50 per cent. This may contribute to the observed reduction
in fracture risk, he said.
Vitamin K is another nutrient that may also be important for bone health,
according to Dr Margaret Ashwell, of Ashwell Associates, UK. She described
a project funded by the Food Standards Agency that looked at the potential
protective effect of vitamin K, calcium and vitamin D in women over the
age of 60 years.
The two-year intervention study included four arms: (i) placebo, (ii)
vitamin K 200µg, (iii) calcium 1,000mg plus vitamin D 10µg
daily, and (iv) combined supplementation with vitamin K (200µg),
calcium (1,000mg) and vitamin D (10µg). There was a statistically
significant effect of supplementation in the combined calcium, vitamin
K and vitamin D supplementation group for wrist, but not hip, on bone
mineral content. “This suggests significant interaction between
vitamins D and K in reducing bone loss,” she concluded. |
