887
Dietary Goals important document has just been published the by U.S. Senate Select Committee on Nutrition and Human Needs.l The chairman, Senator GEORGE McGoVERN, expresses his conviction that "the eating patterns of this century represent as critical a public health concern as any now before us. We must acknowledge and recognize that the public is confused about what to eat to maximize health... We have an obligation to provide practical guides to the individual consumer as well as set national dietary goals Such an effort is long over-due". The committee sets out six dietary goals, based on scientific testimony and recent reports, including fifteen sets of guidelines, mostly about prevention of coronary heart-disease, from expert and official bodies. Goal one is to increase carbohydrate consumption to between 53% and 60% of the energy (caloric) intake. The committee shows its professionalism by starting with what should be increased, to compensate for the reductions entailed by the other five goals. Present total carbohydrate consumption in the U.S.A., as in Britain, is 46% of dietary energy, about half in the form of sugar. The increase should be in the form of complex carbohydrates or starchy foods such as vegetables, fruits, and whole grains that also contain many other nutrients including dietary fibre. A day’s allowance of protein from whole-grain cereals, legumes, and nuts costs less than the equivalent amount from most types of meat. This first goal will surprise those (one hopes few of them are medical people) who still imagine that starchy foods are unhealthy or that bread and potatoes are especially fattening. Goal two is to reduce fat consumption from over 40% down to 30% of energy intake. This goal is in the same direction as official British advice 2 but goes further. 30% of fat is rather less than was available in Britain during the 1939-45 war but more than the content in traditional Mediterranean cookery. Fats are the most concentrated source of energy in the diet and so favour obesity. Many fats provide empty calories-they are not associated with the mixture of micronutrients found with complex carbohydrates. There are, in addition, epidemiological associations of breast and AN
...
1
Dietary
3.
Royal College of Physicians of London Coll. Physcns Lond. 1976, 10, 213.
Goals for the United States. U.S. Senate Committee on Nutrition and Human Needs. Washington, D.C., 1977. 2 Diet and Coronary Heart Disease. Report of the advisory panel of the Committee on Medical Aspects of Food Policy (Nutrition). H.M. Stationery
Office, 1974. and British Cardiac
Society. Jl
R.
colon cancer with fat intake, unsaturated as well as saturated. The next two goals concern the nature of the dietary fats. Goal three is that saturated fats should be reduced to 10% of total calories and balanced with around 10% monounsaturated and 10% polyunsaturated fats. For comparison the present British diet4 is 21% saturated, 16% monounsaturated, and 4% polyunsaturated fats (total 41% of energy intake). The reasons for reducing saturated and increasing polyunsaturated fats are well enough known.5-7 The fourth goal is reduction of dietary cholesterol to about 300 mg a day because it too
tends
to
increase
plasma-cholesterol-though
in some individuals than in others seemingly One egg contains some 250 mg of cholesterol in the yolk, but servings of liver and kidney can provide more
more.
The fifth goal is to reduce refined sugar to 15% of dietary energy from the present estimated 24% in the U.S.A. Refined sugar in Britain contributes about 20% of total calories.4While most experts believe that no clear links have been established between sucrose and heart-disease, refined sugars provide empty calories and are associated with dental caries. A major source of refined sugar is soft drinks; in the U.S.A. their consumption has doubled in the past 15 years and the report suggests they should be much reduced or even eliminated from the diet. The sixth goal is reduction of salt intake to approximately 3 g a day. Present consumption in the U.S.A. is 6-18 g, but the physiological requirement probably averages only 0.5g a day. Sodium intake is more and more determined by food processors rather than by the individual. This extensive addition of salt to our foods disturbs the natural balance with potassium and may well favour the development of essential hypertension. Looking at the foods which can be used to achieve these six nutritional goals, the report shows that highly processed foods are the most likely to be high in saturated fat and sugar or salt. In addition they very likely contain unnecessary additives such as colouring. Soft drinks account for more of the artificial colour intake in children than any other type of food or drink. For school and institutional catering, unprocessed foods, cooked on the premises, have sociological and economic as well as nutritional advantages over convenience foods. Nutrition education of the public is poor. The seven (or four) basic food groups are out of date; 4. Household Food Consumption and Expenditure, 1974: annual report of the National Food Survey Committee. H.M. Stationery Office, 1976. 5 Lancet, 1975, ii, 398. 6. Miettinen, M, Karvonen, M. J., Turpeinen, O., Elosno, R., Paavilavien, E. ibid. 1972, ii, 835. 7. O’Brien, J. R., Etherington, M. D., Jamieson, S. ibid. 1976, i, 878. 8. Mistry, P., Nicoll, A., Niehaus, C., Christie, I., Janus, E., Lewis, B. Circulation, 1976, 54, suppl. 11-178.
888
they were not designed to meet current nutritional problems. Television is said to be the primary source of information for the American public today, but the advertisements for food and drink are unbalanced towards alcoholic beverages, confectionery, and highly processed foods while fresh fruit, vegetables, fish, and nuts get hardly any time. A similar picture can be seen in Britain. Food labelling should show not only the essential nutrients but also the percentage and type of fats and of sugar, the amount of cholesterol and of salt, and the caloric content. The new U.S. goals are similar to Scandinavian recommendations on a healthy diet, published in 196810 and subsequently incorporated in the Swedish Diet and Exercise programme and in the proposed Norwegian nutrition and food policy. 11 The American goals will be welcomed by people who have thought seriously about the diet of modern Western man. Their major blind-spot is to ignore alcohol consumption, which is increasing fast along with its pernicious effects. L!
Risk Factors in
Hodgkin’s Disease
IF the presence in tissue of
and
reverse
transcriptase
indicates the prehigh-molecular-weight sence of an R.N.A. virus* then Hodgkin’s disease tissue contains such a virus,2 even though no specific agent has been isolated. Perhaps the right techniques have not been applied to the right person at the right time. Epidemiological probes may show where such investigations might most profitably be applied, for studies of the circumstances in which the disease arises are strengthening the long-held concept that some infectious agent is involved, possibly one that is horizontally transmitted. VIANNA etal. 3-5 concluded that close continued personal association, in schools5 or elsewhere, permitted the spread of such an agent and that transmission could be direct or via a symptomless carrier. Casual R.N.A.
acquaintanceship or fleeting personal contacts were insufficient and the direction of transmission was primarily from young to young, occasionally from young to old, and rarely from old to young.4 Family members living in the same house had
Truswell, A. S. Näringsforskning (Swedish Nutrition Foundation), 1975, 20, suppl. 13, p. 42. 10. Mediciniska sunpunkter på folkkosten i de nordiska landerna. Vår föda, 1968, 20, 3 (for English translation see Davidson, S., Passmore, R., Brock, J. F., and Truswell, A. S. Human Nutrition and Dietetics, p. 652. 9.
Edinburgh, 1975). Royal Norwegian Ministry of Agriculture Report No. 32 to the Storting (1975-76) on Norwegian nutrition and food policy. Oslo. 12. Glatt, M. M. Proc. R. Soc. Med. 1977, 70, 202. 1. Schlom, J., Spiegelman, S. L. Science, 1971, 174, 840. 2. Chezzi, C., Detori, D., Manzeri, V., Agliano, A. M., Sanna, A. Proc. natn. Acad. Sci., U.S.A. 1976, 73, 4694. 3. Vianna, N. J., Greenwald, P., Davies, J. N. P. Lancet, 1971, i, 1209. 4. Vianna, N. J., Greenwald, P., Brady, J., Polan, A. K., Dwork, A., Mauro, J., Davies, J. N. P. Ann. intern. Med. 1972, 77, 169.
11.
shorter intervals between diagnoses than similarly related family members living apart, while affected relatives commonly acquired the same histological disease, perhaps because of subtype of Hodgkin’s 6 genetic factors. These findings pointed to the importance of some environmental factor, probably infective, and the wide differences between times of diagnosis made common-source exposure unlikely. Work on familial cases of Hodgkin’s disease in Boston’ has supported these observations and has provided further clues. The Boston workers obtained their data from hospital records and did not interview the people in question; almost certainly this led them to underestimate the extent of family involvement. If one sib acquired Hodgkin’s disease the risk to other sibs was increased at least seven times. The measure of the risk varied according to the sex of the sibs: in those of the same sex the risk was at least nine-fold; in those of different sex it was fivefold. This difference suggests that there is no wide dispersion of an agent-a conclusion which may lessen fears about the possible infectivity of Hodgkin’s disease.Ii The Boston findings’ emphasise the role of close personal contact in pairs of sibs who acquire Hodgkin’s disease; maybe bedroom-sharing is a factor. If prolonged close contact is indeed necessary for acquisition of Hodgkin’s disease, this may account for the school epidemics reported from New Yorkj- and Connecticut (Hodgkin’s disease but not other lymphomas or leukTmias).9 It may also explain the absence of any occupational risk in teachers, physicians, and nurses whose contact with affected individuals may be only intermittent and moreover may only be at certain phases of the illness.1u Perhaps when the lymph-glands enlarge the possibility of transmission decreases. Evidence of case-to-case or case-contact-case spread of Hodgkin’s disease points to an incubation period of 3 to 5 years, perhaps varying with the closeness of association.11 Further factors increasing susceptibility to the disease include tonsillectomy, I2 13 which may permit the passage of some agent or factor usually bound to the peripheral lymphoid tissue, or alternatively may act by some effect on gammaglobulin fractions,14 15 known to be altered in Vianna, N. J., Polan, A. K. New Engl. J. Med. 1973, 289, 499. Vianna, N. J., Davies, J. N. P., Polan, A. K., Wolfgang, P. Lancet, 1974, ii, 854. 7. Grufferman, S., Cole, P., Smith, P. G., Lukes, R. J. New Engl. J. Med. 1977,
5. 6.
296, 248. Smith, P. G., Pike, M. C. Cancer Res. 1976, 36, 660. Zack, M., Heath, C. W., Andrews, D., Randolph, V. R., Housworth, J. W., Christine, B. W. Am. J. Epidem. 1975, 102, 461. 10. Grufferman, S., Duong, T., Cole, P., J. natn. Cancer Inst. 1976, 57, 1193 11. Vianna, N. J. Cancer Res. 1976, 36, 663. 12. Vianna, N. J., Greenwald, P., Davies, J. N. P. Lancet, 1971, i, 431. 13. Gutensohn, N., Li, F. P., Johnson, R. E., Cole, P. New Engl. J. Med. 1975, 292, 22. 8. 9.
14. 15.
Ogra, P. ibid. 1971, 284, 59. Wagener, D. J., Van Munster, 12, 683.
P.
J. J., Haennen, C. Eur. J. Cancer, 1976,
Dietary Goals important document has just been published the by U.S. Senate Select Committee on Nutrition and Human Needs.l The chairman, Senator GEORGE McGoVERN, expresses his conviction that "the eating patterns of this century represent as critical a public health concern as any now before us. We must acknowledge and recognize that the public is confused about what to eat to maximize health... We have an obligation to provide practical guides to the individual consumer as well as set national dietary goals Such an effort is long over-due". The committee sets out six dietary goals, based on scientific testimony and recent reports, including fifteen sets of guidelines, mostly about prevention of coronary heart-disease, from expert and official bodies. Goal one is to increase carbohydrate consumption to between 53% and 60% of the energy (caloric) intake. The committee shows its professionalism by starting with what should be increased, to compensate for the reductions entailed by the other five goals. Present total carbohydrate consumption in the U.S.A., as in Britain, is 46% of dietary energy, about half in the form of sugar. The increase should be in the form of complex carbohydrates or starchy foods such as vegetables, fruits, and whole grains that also contain many other nutrients including dietary fibre. A day’s allowance of protein from whole-grain cereals, legumes, and nuts costs less than the equivalent amount from most types of meat. This first goal will surprise those (one hopes few of them are medical people) who still imagine that starchy foods are unhealthy or that bread and potatoes are especially fattening. Goal two is to reduce fat consumption from over 40% down to 30% of energy intake. This goal is in the same direction as official British advice 2 but goes further. 30% of fat is rather less than was available in Britain during the 1939-45 war but more than the content in traditional Mediterranean cookery. Fats are the most concentrated source of energy in the diet and so favour obesity. Many fats provide empty calories-they are not associated with the mixture of micronutrients found with complex carbohydrates. There are, in addition, epidemiological associations of breast and AN
...
1
Dietary
3.
Royal College of Physicians of London Coll. Physcns Lond. 1976, 10, 213.
Goals for the United States. U.S. Senate Committee on Nutrition and Human Needs. Washington, D.C., 1977. 2 Diet and Coronary Heart Disease. Report of the advisory panel of the Committee on Medical Aspects of Food Policy (Nutrition). H.M. Stationery
Office, 1974. and British Cardiac
Society. Jl
R.
colon cancer with fat intake, unsaturated as well as saturated. The next two goals concern the nature of the dietary fats. Goal three is that saturated fats should be reduced to 10% of total calories and balanced with around 10% monounsaturated and 10% polyunsaturated fats. For comparison the present British diet4 is 21% saturated, 16% monounsaturated, and 4% polyunsaturated fats (total 41% of energy intake). The reasons for reducing saturated and increasing polyunsaturated fats are well enough known.5-7 The fourth goal is reduction of dietary cholesterol to about 300 mg a day because it too
tends
to
increase
plasma-cholesterol-though
in some individuals than in others seemingly One egg contains some 250 mg of cholesterol in the yolk, but servings of liver and kidney can provide more
more.
The fifth goal is to reduce refined sugar to 15% of dietary energy from the present estimated 24% in the U.S.A. Refined sugar in Britain contributes about 20% of total calories.4While most experts believe that no clear links have been established between sucrose and heart-disease, refined sugars provide empty calories and are associated with dental caries. A major source of refined sugar is soft drinks; in the U.S.A. their consumption has doubled in the past 15 years and the report suggests they should be much reduced or even eliminated from the diet. The sixth goal is reduction of salt intake to approximately 3 g a day. Present consumption in the U.S.A. is 6-18 g, but the physiological requirement probably averages only 0.5g a day. Sodium intake is more and more determined by food processors rather than by the individual. This extensive addition of salt to our foods disturbs the natural balance with potassium and may well favour the development of essential hypertension. Looking at the foods which can be used to achieve these six nutritional goals, the report shows that highly processed foods are the most likely to be high in saturated fat and sugar or salt. In addition they very likely contain unnecessary additives such as colouring. Soft drinks account for more of the artificial colour intake in children than any other type of food or drink. For school and institutional catering, unprocessed foods, cooked on the premises, have sociological and economic as well as nutritional advantages over convenience foods. Nutrition education of the public is poor. The seven (or four) basic food groups are out of date; 4. Household Food Consumption and Expenditure, 1974: annual report of the National Food Survey Committee. H.M. Stationery Office, 1976. 5 Lancet, 1975, ii, 398. 6. Miettinen, M, Karvonen, M. J., Turpeinen, O., Elosno, R., Paavilavien, E. ibid. 1972, ii, 835. 7. O’Brien, J. R., Etherington, M. D., Jamieson, S. ibid. 1976, i, 878. 8. Mistry, P., Nicoll, A., Niehaus, C., Christie, I., Janus, E., Lewis, B. Circulation, 1976, 54, suppl. 11-178.
888
they were not designed to meet current nutritional problems. Television is said to be the primary source of information for the American public today, but the advertisements for food and drink are unbalanced towards alcoholic beverages, confectionery, and highly processed foods while fresh fruit, vegetables, fish, and nuts get hardly any time. A similar picture can be seen in Britain. Food labelling should show not only the essential nutrients but also the percentage and type of fats and of sugar, the amount of cholesterol and of salt, and the caloric content. The new U.S. goals are similar to Scandinavian recommendations on a healthy diet, published in 196810 and subsequently incorporated in the Swedish Diet and Exercise programme and in the proposed Norwegian nutrition and food policy. 11 The American goals will be welcomed by people who have thought seriously about the diet of modern Western man. Their major blind-spot is to ignore alcohol consumption, which is increasing fast along with its pernicious effects. L!
Risk Factors in
Hodgkin’s Disease
IF the presence in tissue of
and
reverse
transcriptase
indicates the prehigh-molecular-weight sence of an R.N.A. virus* then Hodgkin’s disease tissue contains such a virus,2 even though no specific agent has been isolated. Perhaps the right techniques have not been applied to the right person at the right time. Epidemiological probes may show where such investigations might most profitably be applied, for studies of the circumstances in which the disease arises are strengthening the long-held concept that some infectious agent is involved, possibly one that is horizontally transmitted. VIANNA etal. 3-5 concluded that close continued personal association, in schools5 or elsewhere, permitted the spread of such an agent and that transmission could be direct or via a symptomless carrier. Casual R.N.A.
acquaintanceship or fleeting personal contacts were insufficient and the direction of transmission was primarily from young to young, occasionally from young to old, and rarely from old to young.4 Family members living in the same house had
Truswell, A. S. Näringsforskning (Swedish Nutrition Foundation), 1975, 20, suppl. 13, p. 42. 10. Mediciniska sunpunkter på folkkosten i de nordiska landerna. Vår föda, 1968, 20, 3 (for English translation see Davidson, S., Passmore, R., Brock, J. F., and Truswell, A. S. Human Nutrition and Dietetics, p. 652. 9.
Edinburgh, 1975). Royal Norwegian Ministry of Agriculture Report No. 32 to the Storting (1975-76) on Norwegian nutrition and food policy. Oslo. 12. Glatt, M. M. Proc. R. Soc. Med. 1977, 70, 202. 1. Schlom, J., Spiegelman, S. L. Science, 1971, 174, 840. 2. Chezzi, C., Detori, D., Manzeri, V., Agliano, A. M., Sanna, A. Proc. natn. Acad. Sci., U.S.A. 1976, 73, 4694. 3. Vianna, N. J., Greenwald, P., Davies, J. N. P. Lancet, 1971, i, 1209. 4. Vianna, N. J., Greenwald, P., Brady, J., Polan, A. K., Dwork, A., Mauro, J., Davies, J. N. P. Ann. intern. Med. 1972, 77, 169.
11.
shorter intervals between diagnoses than similarly related family members living apart, while affected relatives commonly acquired the same histological disease, perhaps because of subtype of Hodgkin’s 6 genetic factors. These findings pointed to the importance of some environmental factor, probably infective, and the wide differences between times of diagnosis made common-source exposure unlikely. Work on familial cases of Hodgkin’s disease in Boston’ has supported these observations and has provided further clues. The Boston workers obtained their data from hospital records and did not interview the people in question; almost certainly this led them to underestimate the extent of family involvement. If one sib acquired Hodgkin’s disease the risk to other sibs was increased at least seven times. The measure of the risk varied according to the sex of the sibs: in those of the same sex the risk was at least nine-fold; in those of different sex it was fivefold. This difference suggests that there is no wide dispersion of an agent-a conclusion which may lessen fears about the possible infectivity of Hodgkin’s disease.Ii The Boston findings’ emphasise the role of close personal contact in pairs of sibs who acquire Hodgkin’s disease; maybe bedroom-sharing is a factor. If prolonged close contact is indeed necessary for acquisition of Hodgkin’s disease, this may account for the school epidemics reported from New Yorkj- and Connecticut (Hodgkin’s disease but not other lymphomas or leukTmias).9 It may also explain the absence of any occupational risk in teachers, physicians, and nurses whose contact with affected individuals may be only intermittent and moreover may only be at certain phases of the illness.1u Perhaps when the lymph-glands enlarge the possibility of transmission decreases. Evidence of case-to-case or case-contact-case spread of Hodgkin’s disease points to an incubation period of 3 to 5 years, perhaps varying with the closeness of association.11 Further factors increasing susceptibility to the disease include tonsillectomy, I2 13 which may permit the passage of some agent or factor usually bound to the peripheral lymphoid tissue, or alternatively may act by some effect on gammaglobulin fractions,14 15 known to be altered in Vianna, N. J., Polan, A. K. New Engl. J. Med. 1973, 289, 499. Vianna, N. J., Davies, J. N. P., Polan, A. K., Wolfgang, P. Lancet, 1974, ii, 854. 7. Grufferman, S., Cole, P., Smith, P. G., Lukes, R. J. New Engl. J. Med. 1977,
5. 6.
296, 248. Smith, P. G., Pike, M. C. Cancer Res. 1976, 36, 660. Zack, M., Heath, C. W., Andrews, D., Randolph, V. R., Housworth, J. W., Christine, B. W. Am. J. Epidem. 1975, 102, 461. 10. Grufferman, S., Duong, T., Cole, P., J. natn. Cancer Inst. 1976, 57, 1193 11. Vianna, N. J. Cancer Res. 1976, 36, 663. 12. Vianna, N. J., Greenwald, P., Davies, J. N. P. Lancet, 1971, i, 431. 13. Gutensohn, N., Li, F. P., Johnson, R. E., Cole, P. New Engl. J. Med. 1975, 292, 22. 8. 9.
14. 15.
Ogra, P. ibid. 1971, 284, 59. Wagener, D. J., Van Munster, 12, 683.
P.
J. J., Haennen, C. Eur. J. Cancer, 1976,
