Dietary sodium and potassium intake and blood pressure.

High blood pressure increases risk of stroke and heart attack. High sodium, or salt intake has been associated with increased risk of high blood pressure but it is not clear whether changing salt intake within the usual range that is realistic in the general community is likely to have an influence on blood pressure. In EPIC-Norfolk, men and women who consumed the least salt, (about 5 grams daily), in every day life had lower average blood pressure and were at half the risk of having hypertension (high blood pressure) compared with those who consumed the most amount of salt, (about 10 grams daily). Even within the usual range of salt intake in the community, small and easily achievable reductions in salt intake, e.g. by less than a teaspoon daily, (about 5 grams), may halve a person's chances of getting high blood pressure. In contrast, high dietary intake of potassium, found in plant foods such as fruit and vegetables appears to protect against high blood pressure.

Khaw KT et al. Blood pressure and urinary sodium in men and women: the Norfolk Cohort of the European Prospective Investigation into Cancer (EPIC-Norfolk). Am J Clin Nutr 2004;80:1397-403.

Physical activity and increased longevity

While physical activity has been associated with improving health, including reducing risk of heart disease and stroke, it is not clear how much physical activity is needed for health benefits. Many studies have only looked at leisure time physical activity but not taken into account work based activity. In EPIC-Norfolk we developed a simple index of physical activity, which combines both work and leisure time physical activity. Men and women who were moderately active or active had about one third lower risk of death from any causes or of having heart disease or strokes over the next eight years compared to men and women who were inactive. Compared to being inactive, (sedentary work, no leisure time physical activity), even those who were moderately inactive, (sedentary work with up to half and hour physical activity such as cycling, swimming, keep fit etc, or standing work such as hairdresser, guard, shop assistant without leisure time activity), had about 20% lower risk of death and cardiovascular disease. Not being completely inactive compared to being inactive was comparable to being about three years younger in terms of longevity. Even relatively small and relatively achievable differences in physical activity are associated with big differences in health.

Khaw KT et al. Work and leisure time physical activity assessed using a simple, pragmatic validated questionnaire and incident cardiovascular disease and all cause mortality in men and women: The European Prospective Investigation into Cancer in Norfolk prospective population study. Int J Epidemiology 2006; in press

Bowel cancer: high dietary fibre protects against effects of high meat intake

There is a much controversy as to whether high meat intake increases risk of bowel cancer. In the European study, we have found that high dietary fibre intake lowers and high meat intake increases risk of bowel cancer. However, there is an interaction between the different foods. Meat intake increases cancer risk only in those people with low intakes of dietary fibre; high dietary fibre or high fish intake appear to protect against the effects of meat intake and risk of bowel cancer.

Norat T et al. Meat, fish, and colorectal cancer risk: the European Prospective Investigation into cancer and nutrition. J Natl Cancer Inst. 2005;97:906-16.
Bingham SA et al. Dietary fibre in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC): an observational study. Lancet 2003;361:1496-501.

Obesity and cancer risk

Obesity appears to be a risk factor for a number of cancers including breast cancer in women after the menopause, and kidney cancer. Avoiding obesity may be one way to reduce risk of a number of cancers. Identifying why obesity may increase cancer risk may help us understand how better to prevent or treat cancer.

Lahmann PH, et al. Body size and breast cancer risk: findings from the European Prospective Investigation into Cancer And Nutrition (EPIC). Int J Cancer 2004;111:762-71.

Pischon T et al. Body size and risk of renal cell carcinoma in the European Prospective Investigation into Cancer and Nutrition (EPIC).
Int J Cancer. 2006;118:728-38. 2:

Sex hormone levels in women and breast cancer risk.

In the Europe wide EPIC study, women who had higher blood levels of sex hormones including testosterone (male hormones) as well as estrogen (female hormone) appear to have higher risk of breast cancer. We know that obesity is associated with higher levels of sex hormones and also higher risk of breast cancer in postmenopausal women. If we can identity dietary and other lifestyle factors that influence sex hormone levels in women, this may indicate ways to lower breast cancer risk.

Kaaks R et al. Serum sex steroids in premenopausal women and breast cancer risk within the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst 2005;97:755-65.]

Rinaldi S et al. Anthropometric measures, endogenous sex steroids and breast cancer risk in postmenopausal women: A study within the EPIC cohort.
Int J Cancer. 2006;118:2832-9.

Prediction of total and hip fracture risk in men and women by quantitative ultrasound of the calcaneus

– Published in the Lancet, January 2004 ( Lancet 363(9404):197-202)

Bone heel ultrasound is fast, safe and cheap and may provide a useful assessment of bone health and future fracture risk. Men and women with measurements in the lowest 10 percent of the distribution of heel ultrasound measurements had about a four and a half times greater risk of fracture over the next two years compared with men and women in the top 30 percent. Current smokers had about a 30 percent increased risk of fracture compared with non smokers.

Imprecise methods may be obscuring a relation between fat and breast cancer

– Published in the Lancet, July 2003 (Lancet 362(9379):212-214)

We studied more than 13 000 women participants and found that those who ate the most saturated fat were almost twice as likely to develop breast cancer as those who ate the least. Saturated fats are found mainly in full-fat milk, meat and products such as biscuits and cakes.

In the past many large studies have failed to find a link between fat intake and breast cancer, possibly due to imprecise methods. Our participants were asked to complete a detailed food diary over the course of seven days. Even the brand of food was recorded so that the nutritional content could be worked out more precisely.

We found that women who ate more than 90 grams of fat per day have twice the risk of developing breast cancer as women who ate less than 40 grams of fat per day. Two thirds pint of full-fat milk contains 16 grams of fat whereas the same volume of semi-skimmed milk contains 7 grams of fat.

Eating fruits and vegetables reduces the risk of an early death

– Published in the Lancet, March 2001 (Lancet 357(9257): 657-663)

We examined the blood levels of vitamin C in almost 20,000 EPIC participants. We found that a rise in the level of vitamin C equivalent to a 50g per day increase in fruit and vegetable consumption could cut the risk of dying early from any cause by 20 per cent. This roughly corresponds to eating an extra apple a day – adding two more daily portions of fruit and vegetables could reduce the risk by as much as half. These findings hold regardless of people's age, blood pressure or whether they smoked.

We also found that men and women with the highest levels of vitamin C were 60 to 70 per cent less likely to die from heart attacks or strokes than those with the lowest levels.

These are some of the largest effects of a small change in diet ever detected. They show that there could be significant health gains from even a small increase in fruit and vegetable consumption

High impact sports may preserve bone density

– Published in the British Medical Journal, January 2001 (BMJ 322(7279): 140-146)

We examined data from over 5,000 EPIC participants aged 45-74 who had attended for a second health check. At the check, ultrasound measurements of the heels were made. Low heel bone ultrasound values (low attenuation) are known to be associated with low bone mineral density.

The participants also completed a questionnaire on their physical activity. From this questionnaire, people's recreational activities were classified into four groups according to levels of impact. Activities with no impact included swimming and snooker. Badminton and step aerobics, for example, were classified into the highest impact group.

We found that reported time spent on high impact physical activity was strongly and positively associated with higher ultrasound levels, regardless of people's age and weight. Men who reported taking part in high impact activities for more than two hours a week had around 10% higher ultrasound levels than men who recorded no activity of this type. For women, the high impact group had levels 3% higher, an effect similar in size to an age difference of four years. Women who climbed stairs more often also had higher ultrasound measurements, and those who spent more time watching television had lower levels.

Our results suggest that participation in high impact activities may help preserve bone density and reduce the risk of fracture for people in mid-life. However, this would not be appropriate for older people, who have thinner bones, as these activities could increase the likelihood of falls and fractures.

Blood glucose levels could help predict risk of heart disease

– Published in the British Medical Journal, January 2001 (BMJ 322(7277): 15-20)

Nearly 5,000 male EPIC participants aged 45 to 79 completed the baseline health examination and had the HbA1c concentration in their blood measured. HbA1c is an indicator of average blood glucose levels over the previous three months. It was previously known that people with diabetes have an increased risk of heart disease and that HbA1c concentrations can predict risk of heart disease in people with diabetes.

We found that around half of the male population studied had an increased risk of fatal heart attacks and strokes because of raised blood glucose levels. The vast majority of these men would not be classified as diabetic. Risk of death from all causes, and from heart disease in particular, was found to increase with increasing HbA1c concentration at all levels. Even mildly elevated blood glucose seemed to predict heart disease.

We also measured HbA1c concentration in women. Women are less likely to develop heart disease than men, and we did not observe enough deaths in the study period to draw any firm conclusions. We would expect similar results to apply to women, though we will have to wait longer to confirm this.

Our findings suggest that blood glucose should be considered with high blood pressure and high cholesterol as an important factor in heart disease. Reducing HbA1c concentration in the whole population by just 0.2 per cent could reduce overall mortality by 10 per cent.

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