Friday, August 15, 2008

Cardiovascular Risk Factors on Kitava, Part II: Blood Lipids

The findings in the previous post are all pretty much expected in a population that doesn't get heart disease. However, things started to get interesting when Lindeberg's group measured the Kitavans' serum lipids ("cholesterol"). Kitavan and Swedish total cholesterol is about the same in young men, around 174 mg/dL (4.5 mmol/L). It rises with age in older Swedish men but not Kitavans.

Doctors commonly refer to total cholesterol over 200 mg/dL (5.2 mmol/L) as "high", so Kitavan men are in the clear. On the other hand, Kitavan women should be dying of heart disease left and right with their high middle-age cholesterol of 247 mg/dL (6.4 mmol/L)! That's actually higher than the value for Swedish women of the same age, who are far more prone to heart disease than Kitavans.

The fun doesn't stop there. Total cholesterol isn't a good predictor of heart attack risk, but there are better measures. LDL on Kitava is lower in males than in Sweden, but for females it's about the same until old age.  HDL is slightly lower than Swedes' at middle and old age, and triglycerides are higher on average. Judging by these numbers, Kitavans should have cardiovascular disease (CVD) comparable to Swedes, who suffer from a high rate of cardiovascular mortality.

Kitavan smokers had a lower HDL than nonsmokers, yet still did not develop CVD. Smoking is considered one of the most powerful risk factors for cardiovascular disease in Western populations.  I think it's worth noting, however, that Kitavans tend to be light smokers.

These data are difficult to reconcile with the hypothesis that certain patterns of blood lipids cause CVD. Kitavans, particularly the women, have a blood lipid profile that should have them clutching their chests, yet they remain healthy.

There is a theory of the relationship between blood lipids and CVD that can explain these data. Perhaps blood lipids, rather than causing CVD, simply reflect diet composition and other lifestyle factors. Both on Kitava and in the West, low HDL and elevated triglycerides imply a high carbohydrate intake. Low-carbohydrate diets consistently raise HDL and lower triglycerides. On Kitava, carbohydrate comes mostly from root crops. In the West, it comes mostly from processed grains (typically wheat) and sugar. So the blood lipid pattern that associates best with CVD and the metabolic syndrome in the West is simply a marker of industrial food intake.

11 comments:

Chainey said...

I wonder about the smoking thing - how long have they had access to cigarettes?

It typically takes a few decades for the results to show.

Debs said...

I like your theory about blood lipids being simply a reflection of diet rather than causing CVD. It makes sense, intuitively, and yet I haven't heard it from elsewhere.

If that's true, then drugs like statins that reduce cholesterol are only smoothing over a symptom of an underlying problem, rather than reducing risk for the problem. Sounds like the same old, familiar approach to disease.

Debs
Food Is Love

pspierce said...

I have always wondered that maybe statins were having some kind of impact on inflammation and that accounted for even the minor efficacy that some studies show.

What I am wondering, Stephen, because I tend to agree with you, what differentiates the carbs in grain and the carbs in tubers? Why are the Kitavans not having a metabolic reaction to such a high-carb diet? Is it fiber or perhaps the saturated fat in the coconut has a powerful slowing affect?

BTW, really enjoy the blog. I haven't found too many people that I align with on these issues but I am really ignorant compared to you!

Scott

Dr. B G said...

This is a great piece of information! Thank you for posting.

Have you seen any associated data regarding Kitavan blood levels:
--fasting or random insulin
--Hgba1c or fructosamine
--dietary intake of EPA or DHA (fish, shellfish, gamey meat)?
--dietary intake coconut oils?
--alcohol habits -- what kind? obviously not fermented wheat right!

I agree -- wheat is clearly toxic (more than CIGARETTES!) ha haa!

-G

Aaron said...

I'm still wondering about the true effect on the arteries their diet may have. How do we know that they don't have large arteries (protective factor) and cardiomyopathy like older Massai. Maybe the Kitavans are protected by some sort of minor dietary factor. A heart-scan on older Kitavans would be most warranted. High HDL and low LDL hasn't always -protected people from heart disease (just as small particle LDL doesn't always tigger heart disease either!) - we need to single out all the factors!

Stephan said...

Chainey,

That's a good point. I don't know how long they've had access to cigarettes.

Debs,

I wish I could take credit for the idea that blood lipids are nothing more than a reflection of diet composition, but I didn't come up with it. I just think it fits the data rather well.

Stephan said...

Hi pspierce,

I can only speculate, but here goes. I think that it's not the carbohydrate that's the problem, but the things that come along with it. Grains are loaded with nasty toxins, especially gluten grains like wheat. We aren't adapted to handle them, whereas we've been dealing with tuber toxins for perhaps 2 million years.

Some will chalk it up to the glycemic index or fiber content, but I don't think that explains it. These tubers are very starchy and cooked to death. Their glycemic index and glycemic load are not low. Plus, the Kitavans aren't eating much fat or protein to slow down digestion. In my opinion, the reason they can handle it is because they haven't demolished their pancreas and insulin sensitivity by eating wheat, refined sugar and processed junk. There may also be a role for the fat-soluble vitamins like D, A and K2.

Stephan said...

Hi G,

I'll be posting on their insulin and leptin next. I haven't found any HbA1c data. They eat about 4 g of fish fat and 43 g of coconut fat per day. They don't drink alcohol.

Stephan said...

Hi Aaron,

I don't know what their arteries look like, but frankly if they're not having heart infarctions or stroke, then to me it doesn't matter much. I'm mostly interested in functional outcomes, and pathology only insofar as it relates to outcomes.

As far as protection by a minor dietary factor, I don't think you need to invoke that to explain these results. The data are consistent with other carbohydrate-eating, non-industrial cultures throughout the world like the Kuna.

Although I don't want to rule it out completely as a factor. Vitamin D from sunlight could certainly play a role, for example.

Anesha said...
This comment has been removed by a blog administrator.
LeonRover said...

Hi Stephan

Been researching smoking and Kitavans and noted that Chainey wondered how long Kitavans had the "habit".

In his book Lindeberg states that the islanders have been indulging in tobacco for 100 years.

I cannot find any data on whether the Kitavans have any lung complications - cancer, emphysema etc - often ascribed to use of tobacco in "the West".

I am a non smoker, but approve the use of nicotine patches for a variety of therapeutic reasons.