Interview with a Kitavan

Kitava is a Melanesian island that has maintained an almost entirely traditional, non-industrial diet until very recently. It was the subject of a study by Dr. Staffan Lindeberg and colleagues, which I have written about many times, in which they demonstrated that Kitavans have a very low (undetectable) rate of heart attack, stroke, diabetes and overweight. Dr. Lindeberg described their diet as consisting mostly of yam, sweet potato, taro, cassava, coconut, fruit, fish and vegetables. Over the seven days that Dr. Lindeberg measured food intake, they ate 69% of their calories as carbohydrate, 21% as fat (mostly from coconut) and 10% as protein.

I recently received an e-mail from a Kitavan by the name of Job Daniel. He's working at the Papua New Guinea Institute of Medical Research in Madang, studying the social and economic impacts of malaria and related health issues in Papua New Guinea. He recalls many details of Dr. Lindeberg's visit to Kitava, which Dr. Lindeberg has confirmed are correct. Job generously offered to answer some of my questions about the traditional Kitavan diet. My questions are in bold, and his responses are below.

How many meals a day do Kitavans eat?
People on the island eat mostly two meals a day. But nowadays, breakfast is mainly comprised of tubers (yam and sweet potato and greens all cooked in coconut cream and salt) and dinner is the same with the inclusion of fish as protein most often. In between these two meals, lunch is seen as a light refreshment with fruits or young coconut only to mention these two popular ones. In between the morning and the evening, we mostly eat fruits as snack or lunch. Generally speaking, there are only two main meals per day, i.e breakfast and dinner.

Do Kitavans eat any fermented food?
There are fermented fruits and nuts like you've said for breadfruit, nuts, yams and not forgetting fish. We ferment them by using the traditional method of drying them over the fire for months. And this fermented foods last for almost one to two years without getting stale or spoiled. Food preservation is a skill inherited from our great grand fathers taking into consideration the island's location and availability of food. Foods such as bread fruit and fish are fermented and preserved to serve as substitutes to fresh food in times of trouble or shortage. Otherwise, they're eaten along the way.

Is this really fermentation or simply drying?
To your query about the fermentation methods we use, apart from drying food over the fire, we also use this method like the Hawaiians do with taro [poi- SJG]. For our case we bury a special kind of fruit collected from the tree and buried in the ground to ripen, which takes about 2 - 3 days. I don't really know the English name, but we call it 'Natu' in vernecular. There's also a certain nut when it falls from the tree, women collect them and peel off the rotten skin, then mumu [earth oven- SJG] them in the ground covered with leaves to protect them from burning from the extreme heat of the fire, both from the open fire on top and hot stones underneath. After a day, the nuts are removed from the mumu and loaded into very big baskets which are then shifted to the sea for fermentation. This takes a week (minimum) to ferment or be ready for consumption at last. After the fermentation period is over, i.e one week some days or two
weeks to be exact, then the nuts are finally ready for eating. The length of time it takes before the nuts are no longer edible is roughly one week.

What parts of the fish are eaten?
As islanders, we eat almost every creature and body part of a sea creature. Especially fish eggs, it is one of the favorites of children. They always prefer it burnt on the fire and consumed greedily. Every part of the fish is eaten except for the feces, gall bladder, bones and the scales.

Is food shortage really rare on Kitava?
Generally speaking it is rare. BUT sometimes we run out of food only if there is a drought and the sea is useless. Otherwise, we tend to use the preserved or fermented foods on the dryer in the kitchen. As you would understand, we have seasons and they affect the type and availability of food on the island. In the beginning of the year, we eat sweet potato, cassava and mostly tuna for protein. During mid year, before yam comes in to replace sweet potato and cassava, taro is then ready for harvest. And then yams are ready for harvesting so the food supply is continued on. OK when yams are harvested, some are eaten, some are stored away for reserve and seedlings. In this way, we don't run out food towards the end of the year before sweet potato would be ready for harvest. So as you can see, the food supply on the island is somewhat planned by our ancestral economists where it continues throughout the year without stopping.

Do Kitavans traditionally eat pork, and if so, how often?
We do eat pork but not that often because pork meat is chiefly regarded important on the island. We only eat pork on special occasions so I'd rather say that pork is only eaten occasionally. In most cases in the middle of the year when the yams are harvested (yam harvest celebrations and towards the end of the year for certain rites and activities). Otherwise the everyday meal is always topped with fish.

How long are infants breast fed on Kitava?
Women breast feed for a minimum of 2 years. But breast feeding is again determined by the size and health situation of the baby. If the baby is looking healthy and big, it is most likely that this baby would be adopted temporarily by someone else so as to be removed from breast milk after two years of age minimum. Child care nowadays is paramount as people start to realize the importance of health and hygiene in general. But Kitavans are well known in that part of the country for their hygiene practices. They also got the provincial and district awards for a 'clean community' in early 90s and right now, they still maintain their hygiene level and awareness.

Are there any other foods that are commonly eaten on Kitava that I might not be aware of?
Bananas, pineapple, corn and watermelons. For watermelon and corn, they are plentiful especially at this time of the year.

Thanks for your help, Job! I know many people will appreciate reading these responses.

"Care and Cost"

Good friends David Kibbe and Brian Klepper have finally started their own blog--aimed at becoming a forum for many contributors to the health care debate.I suggest you add, "Care and Cost"––"Health Care Conversations About Hard Choices and Emerging Solutions" to your bookmarks.

Diet-Heart Controlled Trials: a New Literature Review

Many controlled studies have measured the cardiovascular effects of replacing animal ("saturated") fats with seed oils (predominantly the omega-6 polyunsaturated fat linoleic acid) in humans. A number of these studies recorded heart attacks and total mortality during the following 1-8 years. Several investigators have done meta-analyses (literature reviews) to try to tease out overall conclusions from these studies.

I'm pleased to point out a new meta-analysis of these controlled trials by Dr. Christopher Ramsden and colleagues (1). This paper finally cleans up the mess that previous meta-analyses have made of the diet-heart literature. One recent paper in particular by Dr. Dariush Mozaffarian and colleagues concluded that overall, the controlled trials show that replacing animal fat with linoleic acid (LA)-rich seed oils reduces heart attack risk (2). I disagreed strongly with their conclusion because I felt their methods were faulty (3).

Dr. Ramsden and colleagues pointed out several fundamental flaws in the review paper by Dr. Mozaffarian and colleagues, as well as in the prevailing interpretation of these studies in the scientific literature in general. These overlap with the concerns that I voiced in my post (4):

1. Omission of unfavorable studies, including the Rose corn oil trial and the Sydney diet-heart trial.
2. Inclusion of weak trials with major confounding variables, such as the Finnish mental hospital trial.
3. Failure to distinguish between omega-6 and omega-3 fatty acids.
4. Failure to acknowledge that seed oils often replaced large quantities of industrial trans fats in addition to animal fat in these trials.
   

Dr. Ramsden and colleagues accounted for all of these factors in their analysis, which has never been done before. They chose inclusion criteria* that made sense, and stuck with them. In addition, they did an impressive amount of historical work, digging up old unpublished data from these trials to determine the exact composition of the control and experimental diets. The paper is published in the British Journal of Nutrition, an excellent journal, and overall is written in a scientific and professional manner.

What did they find?

• Interventions that replaced animal and trans fat with seed oils that were rich in LA but low in omega-3 caused a non-significant trend toward increased heart attacks (13% increase) and overall mortality.
  
• Interventions that replaced animal and trans fat with a combination of LA and omega-3 fats significantly reduced heart attacks (by 22%). The numbers for total mortality followed a similar trend.

In other words, LA-rich seed oils do not prevent heart attacks (and may actually promote them), but correcting an omega-3 deficiency and reducing industrial trans fat intake may be protective. This is similar to what I've been saying for a while now, based on my own interpretation of the same studies and others. However, Dr. Ramsden and colleagues have taken the idea to a new level by their thorough and sophisticated detective work and analysis. For example, I didn't realize that in virtually all of these controlled trials, the intervention group reduced its trans fat intake substantially in addition to reducing animal fat. From the paper:

...experimental diets replaced common ‘hard’ margarines, industrial shortenings and other sources of [trans fat] in all seven of the [controlled trials] included in the meta-analysis by Mozaffarian et al. The mean estimated [trans fat] content of the seven control diets was 3·0 [% of calories] (range 1·5–9·6 [%]).
...the displacement of [trans fat], rather than the substitution of mixed n-3/n-6 [polyunsaturated fat] for [saturated fat], may account for some or all of the 22% reduction in non-fatal [heart attacks and heart attack] death in our meta-analysis. By contrast, the increased [heart attack] risks from n-6 specific [polyunsaturated fat] diets in our meta-analysis may be underestimated as n-6 [polyunsaturated fat] also replaced substantial quantities of [trans fat] (Table 3). The consistent trends towards increased [heart attack] risk of n-6 specific [polyunsaturated fat] diets may have become significant if the n-6 [polyunsaturated fat] replaced only [saturated fat], instead of a combination of [saturated fat] and [trans fat].

In other words, it looks like trans fat is probably the issue, not animal fat, but these trials replaced both simultaneously so we can't know for sure. I will note here that trans fat does not generally promote atherosclerosis (thickening and hardening of arteries) in animal models, so if it does truly increase heart attack risk as many studies suggest, it's probably through a mechanism that is independent of atherosclerosis.

The article also contains an excellent discussion of the Finnish mental hospital trial (5, 6) and why it was excluded from the meta-analysis, in which Dr. Ramsden and colleagues point out major design flaws, some of which I was not aware of. For example, trans fat intake was on average 13 times higher in the control groups than in the experimental groups. In addition, one of the control groups received more than twice as much of the antipsychotic drug thioridazine, which is known to be highly toxic to the heart, as any other group. Ouch. I'm glad to see this study finally discussed in an open and honest manner. I discussed my own problems with the Finnish trial in an earlier post (7).

I was also glad to see an open discussion of the Oslo Diet-heart study (8), in which diet changes led to a reduction in heart attack risk over five years. Dr. Mozaffarian and colleagues included it in their analysis as if it were a controlled trial in which animal fat was replaced by seed oils only. In reality, the investigators changed many variables at once, which I had also pointed out in my critique of Dr. Mozaffarian's meta-analysis (9). Here's what Dr. Ramsden and colleagues had to say about it:

First, experimental dieters were instructed to substitute fish, shellfish and ‘whale beef’ for meats and eggs, and were actually supplied with ‘considerable quantities of Norwegian sardines canned in cod liver oil, which proved to be popular as a bread spread’(32)... Second, the experimental group consumed massive amounts of soybean oil, which provided large quantities of both LA (15·6 en %) and ALA (2·7 en %). ALA consumption was about 4·5 times average US intake(42), or about twelve typical flax oil pills (1 g pill ¼ 560 mg ALA) per d. In addition, the fish and cod liver oil consumption provided Oslo (598N latitude) dieters with 610 IU (15·25 mg) of daily vitamin D3, recently linked to lower blood pressure, plaque stabilisation, and reduced [heart attack risk] (64). Furthermore, experimental dieters were encouraged to eat more nuts, fruits, and vegetables; to limit animal fats; and to restrict their intake of refined grains and sugar.

trans fat intake was also reduced substantially by excluding margarine in the experimental group. Other review papers have used this trial as a justification to replace animal fat with seed oils. Hmm... The only reason they get away with this is because the trial was published in 1966 and almost no one today has actually read it.

One criticism I have of Dr. Ramsden's paper is that they used the Oslo trial in their analysis, despite the major limitation described above. However, they were extremely open about it and discussed the problem in detail. Furthermore, the overall result would have been essentially the same even if they had excluded the Oslo trial from the analysis.

Overall, the paper is an excellent addition to the literature, and I hope it will bring a new level of sophistication to the dialogue on dietary prevention of cardiovascular disease. In the meantime, brace yourselves for an avalanche of criticism from the seed oil brigade.


* Guidelines that determine which studies to include in the analysis. For example, you want to exclude any study that wasn't randomized, because it will not be interpretable from a statistical standpoint. You also want to exclude trials where major variables differ between groups besides the specific variable you're trying to test. The Finnish mental hospital trial fails by both criteria.