Dean wrote:
>However, it seems quite possible that dietary carbohydrate might be a red
>herring, or a smaller ingredient than it is sometimes regarded as. The
>first thing to make me realize this was Staffan Lindeberg's studies on the
>Kitava (and Lindeberg is also a member of this listserv, BTW).
If you wish I am Staffan to any of you.
>The Kitava
>are not hunter/gatherers, but are not exactly agriculturalists either; they
>would best be defined as primitive horticulturalists, as they mostly
>cultivate wild plants ...
Their staple crops are tubers: yam, sweet potato, taro, and tapioca.
>... and do not grow or consume cereal grains (and if I'm
>not mistaken, do not eat dairy either).
Correct. 70% of the daily energy intake in a Western society like Sweden is
provided by foods which are not eaten in Kitava and which were unavailable
during human evolution, namely dairy products, oils, margarine, refined
sugar and cereals.
Table 1. Estimated dietary intakes (daily medians) in Kitava.
-------------------------------------------------------
By weight Protein Fat Carbohydrate Energy
(g) (g) (g) (g) (kJ)
-------------------------------------------------------
Tubers 1200 25 2 300 5600
(Yam, sweet potato, taro)
Fruit 400 3 <1 50 920
Coconut 110 4 43 7 1865
Fish 85 17 4 0 445
Other veg. 200 5 <1 14 360
Western food <1 0 <1 <1 20
Total 2 000 54 50 370 9200
-------------------------------------------------------
>Their diet is relatively high in
>carbohydrate and somewhat low in fat, although saturated fat intake is
>fairly high.
It is high in saturated fat from coconut (not coconut oil which is devoid
of fiber and minerals).
Table 2. Estimated dietary macronutrient composition expressed as per cent
of total energy in Kitava, among the general Swedish population, and as
recommended to general western populations (Recommended dietary allowances,
RDA].
-------------------------------------------------------
Kitava Sweden RDA
-------------------------------------------------------
Total fat 21 37 ¾30
-Saturated 17 16 <10
-Monounsaturated 2 16 >10
-Polyunsaturated 2 5 5-10
Protein 10 12 10-15
Carbohydrate 69 48 55-60
Alcohol 0 2 ?
-------------------------------------------------------
>About 80% of them smoke cigarettes on a daily basis, and
>while they are physically active, they are only somewhat moreso than most
>Westerners. Yet their rates of obesity, diabetes, stroke, and heart
>attacks are vanishingly small. (I don't know if Lindeberg and his team ever
>looked for rheumatoid arthritis or cancer, two common autoimmune diseases
>typical to civilization. Perhaps he can tell us that himself.)
1. In our survey, protracted illness during several months or more was
practically unknown, as were successively growing visible tumours. One of
the few exceptions was an elderly man who was reported to have had an ulcer
at the front of the lower part of one leg, and to have become ill and died
after several years. This case was known to the majority (and was presented
almost identically by the different groups across the island). One man had
heard of an old lady who had had a growth at one of her breasts and who had
died within a rather short time. Another man aged 67, a betel-chewer but
non-smoker, suffered since several months, possibly years, from a dry,
non-tender ulcer at the hard palate, which was examined by me. No other
case corresponding to superficially growing malignancies was known in
Kitava.
Comments: The ulcer of the hard palate was obviously an oral carcinoma,
which has been the most common malignancy among males in PNG [Wallington,
1986 #3676; Atkinson, 1964 #3294; Henderson, 1979 #3296], and which, since
Kitavans are all betel chewers, is probably caused by the highly alkaline
lime component of the betel quid [MacLennan, 1985 #3295; Thomas, 1992
#3570; Boyle, 1990 #1581; Nair, 1990 #1580; Prokopczyk, 1991 #1576; Stich,
1991 #1578; Nishikawa, 1992 #1573; Sharan, 1992 #1570; Sundqvist, 1992
#1662]. The man with a reported leg ulcer probably had a tropical
phagedenic ulcer, which are common in the area (J=FCptner H, personal
communication) and in which squamous cell carcinomas (cancer) occasionally
develop [Meyer, 1991 #3293]. In sub-Saharan Africa, malignant change in
poorly treated tropical ulcers account for up to 10% of all malignant
tumours in some groups [Ziegler, 1991 #3362].
Until the last 10-20 years, women have most of the time been stripped above
their hips, and even today the majority freely uncover their breasts.
Nevertheless, Kitavans were unaware of superficial tumors, with the
possible exception of one reported woman who may have had breast cancer.
J=FCptner, however, observed one case during his five years in the 1960s as
the only general practitioner (serving 12,000 people) in Kiriwina, the main
Trobriand island. This was in a pregnant woman, whose mother and
mother-in-law refused to have her operated, and who developed enlargement
of supraclavicular lymph nodes and died within few months. It thus seems
justified to consider breast cancer to be less common in the Trobriand
Islands than in the USA [Seidman, 1985 #3345]. In contrast, J=FCptner, who
was a trained gynecologist, diagnosed more than 10 cases of ovarian cancer
among 12,000 inhabitants in 5 years, which is a higher incidence than in
the USA (p<0.008) [Heintz, 1985 #3297] or as compared to the rest of Papua
New Guinea (p<0.02) [Mola, 1982 #3298]. It is tempting to speculate that
the high intake of saturated fat from coconut may be an explanation, since
milk, an important source of saturated fat in westerners, has been
suggested to cause ovarian cancer [Rose, 1986 #3581; Mettlin, 1990 #3576],
although much of the debate has concerned lactose rather than saturated fat
[Mettlin, 1991 #3579; Cramer, 1991 #3580; Harlow, 1991 #3583]. J=FCptner
found no case of cervical carcinoma (the most common gynecological cancer
in PNG [Mola, 1982 #3298]) and no other malignancies, but he made very few
autopsies. The absence of growths corresponding to lymphoma is thus
confirmed by J=FCptner. Burkitt's lymphomas are fairly common in those
coastal areas of PNG where malaria transmission is intense [Henderson, 1979
#3296].
2. As to other non-communicable diseases, accidents were reported to be a
fairly common cause of death, and most cases had drowned or fallen from
coconut trees (One 70-year-old non-attending man died after falling from
one tree during our expedition). Five of those who were older than 85, and
who declined to participate, referred to their aching legs, and four of
them suffered from stiffness and pain of hips and/or knees. Two of them had
enlarged circumferences and flexion contractures of the knees, suggestive
of chronic arthritis. One case of severe emphysema in an elderly male
smoker was encountered, but milder cases may well have been present. Two
cases of dementia were noted, most certainly due to mental retardation.
Both subjects were younger than 30 years. All the elderly seemed mentally
well preserved. No case of severe personality disorder was noted, although
during an earlier visit on the island a man aged about 30 was seen who was
highly suspected of suffering from schizophrenia. (In Kiriwina I also met a
man with obvious latent psychosis. Incidentally, he had been separated from
his parents as an infant.)
The majority of Kitavans were, on gross inspection, and by the brief
discussions during the initial selection procedures, in excellent
condition. Starvation had not been experienced except for one month around
1927. Food was abundant and considerable amounts were wasted. Many children
aged 2-7 years had large abdomens, but all appeared healthy. No evidence of
malnutrition was found. Estimated protein intake in adults averaged 55 g
per day.
Comments: Accidents are expected to be common [Barss, 1984 #1613], and the
same is true for infectious arthritides [Theis, 1991 #3328]. There is more
uncertainty regarding primary osteoarthritis, which is reported to be
extremely rare in Japan [Nakamura, 1987 #3329]. According to Theis,
"primary osteoarthritis of the hip is rarely seen among Chinese and
[Asians] Indians, whereas the same condition is very common in the knee"
[Theis, 1991 #3328]. Osteoarthritis, which apparently is not primarily an
inflammatory disorder, obviously affects humans irrespectively of their
lifestyle although unphysiological tearing may worsen it [References
below]. J=FCptner diagnosed a few cases of symmetric polyarthritis, primarily
affecting the knees and occasionally the joints of the hand. This MAY
indicate the presence of rheumatoid arthritis, but other causes are perhaps
more likely.
Among the most probable causes of the large abdomens are firstly intestines
distended by voluminous foods or by worms (Ascaris in particular)
[Schwartzman, 1991 #3349; Barnish, 1992 #3348] and secondly
hepatosplenomegaly (enlarged liver and spleen) from chronic malaria
[Strickland, 1991 #3351; Cattani, 1992 #3350]. Protein-energy malnutrition
or vitamin deficiency has neither been diagnosed nor suspected by my
colleagues J=FCptner, Schiefenh=F6vel and Kame among Trobriand Islanders
(personal communications). In contrast, Stanhope reported, on the basis of
government medical protocols and interviews of former medical officers, two
deaths from malnutrition among 17 deceased children between 1962 and 1967,
and suggested that "in bad yam seasons, malnutrition appears in [Kiriwina]
inland villages and vitamin A deficiency has been reported" [Stanhope, 1969
#1053]. On Kitava, however, there are no inland villages. There is some
evidence indicating that infection of Ascaris lumbricoides may cause
stunting and possibly even impaired vitamin A status in developing
countries [Solomons, 1993 #3682], where carotene intake, however, would be
lower than in the Trobriands. The estimated protein intake in adults is
expected to be sufficient [Garlick, 1993 #3460].
According to J=FCptner, retained placenta was the most common cause of
maternal death in the 1960s. Chronic bronchitis and asthma are prevalent in
PNG even in non-smokers [Anderson, 1992 #3352]. Further comments on
non-communicable diseases are best avoided at this stage.
In conclusion, accidents are thus common causes of death in Kitava.
Malnutrition is virtually non-existent. Whether non-communicable diseases
other than cardiovascular disease (CVD), cancer and malnutrition are
uncommon cannot be assessed from the present findings.
>Genetics
>does not seem to be the explanation, either.
Substantial evidence from other surveys indicates that you are right, Dean,
although the significance of genetic factors for the virtual absence of CVD
was not possible for us to study properly, since the environment was
essentially similar to all Kitavans and since both environment and ethnic
descent differed between Kitava and Sweden. The only migrant available to
us, a man aged 44 who had grown up on Kitava and who was now a businessman
in Alotau, the provincial capital, came for a visit during our expedition.
He differed in several aspects from all other adults regardless of sex: he
had the highest diastolic blood pressure (120/92), the highest body mass
index (28.0), the highest waist to hip ratio (1.06) and the highest PAI-1
activity (possibly indicating decreased clot-resolving capacity). The most
obvious difference in his lifestyle, as compared with non-migrant Kitavans,
was the adoption of western dietary habits.
Although this finding is suggestive, one subject is not much to comment
upon, but some general remarks may be relevant. The risk of developing
hypertension (high blood pressure), obesity, diabetes or CVD in response to
a certain environment undoubtedly differs between humans. Within western
populations, familial heritage apparently is a strong determinant of some
cardiovascular risk factors. For instance, fibrinogen seems largely to be
determined by genetic heritability, which in one study explained an
estimated 50% of the variation of fibrinogen, while the combined effect of
obesity and smoking accounted for only 3% [Hamsten, 1987 #3078].
=46urthermore, genetics may influence the risk of CVD on the population
level, as in some Pacific Islanders who seem to develop diabetes more
easily than other ethnic groups after westernization [King, 1992 #3749;
Zimmet, 1979 #1020], and the same may be true for Maoris in New Zealand
[Prior, 1974 #1032]. Even the higher CVD rates among blacks in the US
[Gillum, 1982 #3374] or Asian Indians in the UK [McKeigue, 1989 #3448] may
hypothetically be due to lower resistance to the Western life style. The
prevalence of inherited disorders such as familial hypercholesterolemia may
exert some influence on overall death rates, for instance in South African
whites [Rossouw, 1984 #430].
However, the environment is obviously more important to explain the vast
differences in extent of coronary atherosclerosis or occurrence of CVD and
diabetes that have been found in cross-cultural surveys, migrant studies
and observations of secular trends [Tejada, 1968 #1835; Solberg, 1972
#3740; Trowell, 1981 #2064; Keys, 1980 #3159; Prior, 1974 #1032;
INTERHEALTH Steering Committee, 1991 #919; O'Dea, 1992 #1538; Dyerberg,
1989 #1637; Kevau, 1990 #1454; Hughes, 1986 #3449; World Health
Organization, 1992 #3759]. It is reasonable to assume that environmental
factors may actually be necessary requirements for the development of CVD,
and that cross-cultural differences only to a minor degree are explained in
terms of population genetics. Papua New Guinea is no exception, as is
evident from the increasing number of myocardial infarctions and diabetics
in urbanized populations [Kevau, 1990 #1454; King, 1985 #3646]. As yet
there are no scientific reports on CVD rates in migrants from the Trobriand
Islands. Sporadic interviews that I made in Kiriwina indicate that at least
one overweight Trobriander in Port Moresby may have been struck by
spontaneous sudden death.
Genetics and environment as causes of CVD are not mutually exclusive
[Smith, 1992 #3665]. Or, as it has been put, "the answer to 'Why does this
particular individual in this population get this disease?' is not
necessarily the same as the answer to 'Why does this population have so
much disease?'" [Rose, 1985 #3645]. The two approaches are not in academic
competition (they only compete for funding).
Conclusion: The findings in the only studied migrant suggest that Kitavans
are not protected from hypertension or androgenic obesity when exposed to
western dietary habits. This would be consistent with the emergence of
obesity, diabetes, hypertension and IHD in Melanesia and other parts the
Pacific.
I am sorry for the long answer.
Staffan Lindeberg
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