Thursday, June 05, 2008

Dogmatic Conclusions to Make Your Head Spin

One of the oft repeated concerns about a carbohydrate restricted, high-fat diet is long-term effects. With globalization and a wide-variety of foods available in even remote locations today, it's increasingly difficult to find traditional populations whom may be ideally suited to assess the long-term effect of such a diet.

One such population does exist - the Masai of Africa - for whom meat, milk and blood are their daily dietary staples, a naturally low-carbohydrate diet that has been traditionally consumed for generations. They offer us a unique opportunity to assess how such a diet impacts the 'health risk markers' held dear in modern science and medicine.

Does their diet, high in fat, make them fat?

Does their diet, high in fat, make them hypertensive?

Does their diet, high in fat, lead to high cholesterol levels?

For decades many have assumed that a diet rich with dietary fat leads to obesity, high blood pressure and high cholesterol, which then is assumed to lead to heart disease and other chronic health problems.

In the June 3, 2008 issue of the British Journal of Sports Medicine a study investigating the Masai and their dietary habits and comparing them with rural and urban Bantu consuming different dietary practices is quite enlightening and tells us a story about how consuming dietary fat per se is not the underlying cause of obesity, high blood pressure or high cholesterol.

In the study published, Daily Energy Expenditure and Cardiovascular Risk in Masai, Rural and Urban Bantu Tanzanians, we learn that researchers investigated the dietary habits of three distinct populations within the same country - Tanzania - thus limiting confounding variables due to vastly different cultural conditions.

In total, the researchers investigated the health and health risk markers of 985 Tanzanian men and women - 130 Masai, 371 rural Bantu and 484 urban Bantu - with each group reporting very different dietary habits.

The Masai reported a high-fat, low-carbohydrate dietary pattern.

The rural Bantu reported a low-fat, high-carbohydrate dietary pattern.

The urban Bantu reported a high-fat, high-carbohydate dietary pattern, similar to a Western diet.

Which group to do think fared best?

BMI (average)

Masai = 20.7
Rural Bantu = 23.2
Urban Bantu = 27.4 (as a whole, the group was, on average, overweight)

Incidence of Obesity (BMI at or higher than 30)

Masai = 3%
Rural Bantu = 12%
Urban Bantu = 34%

Waist-Hip Ratio (lower is better)

Masai = 0.87
Rural Bantu = 0.89
Urban Bantu = 0.93

Blood Pressure

Masai = 118/71
Rural Bantu = 134/80
Urban Bantu = 134/82

Prevalence of Hypertention

Masai = 4%
Rural Bantu = 16%
Urban Bantu = 21%

Total Cholesterol

Masai = 3.89mmol/L (152mg/dl)
Rural Bantu = 3.60mmol/L (140mg/dl)
Urban Bantu = 4.50mmol/L (176mg/dl)

HDL (higher is better)

Masai = 1.08mmol/L (42mg/dl)
Rural Bantu = 0.91mmol/L (36mg/dl)
Urban Bantu = 1.08mmol/L (42mg/dl)


Masai = 2.09mmol/L (82mg/dl)
Rural Bantu = 2.13mmol/L (83mg/dl)
Urban Bantu = 2.69mmol/L (105mg/dl)


Masai = 1.36mmol/L (121mg/dl)
Rural Bantu = 1.45mmol/L (129mg/dl)
Urban Bantu = 1.61mmol/L (143mg/dl)

Total Cholesterol/HDL Ratio (less than 4 is 'ideal')

Masai = 3.72
Rural Bantu = 4.38
Urban Bantu = 4.53

LDL/HDL Ratio (the lower the better)

Masai = 2.21
Rural Bantu = 2.46
Urban Bantu = 2.69

ApoB/ApoA-1 Ratio (measure of LDL particle ratios, lower is better)

Masai = 0.74
Rural Bantu = 0.83
Urban Bantu = 0.81

So, there you have the major findings. What did the researchers conclude?

No! It couldn't possibly be their dietary habits, it must be that the "potentially atherogenic diet among the Masai was not reflected in serum lipids and was offset probably by very high energy expenditure levels and low body weight."

Now their level of physical activity certainly may be contributing to their overall health, but it's certainly not independent of their dietary habits. In fact, I would contend that while it's ideal to be active, that is not the driving force in 'health' or lack thereof - it's dietary habits that dominate our health outcomes, our level of activity may be important too, but activity in and of itself is no solution to a piss-poor diet.

We need, before activity, a proper diet to enable us to perform phyisical activity, not the other way around! So while the researchers here could not bring themselves to even consider that the habitual diet of the Masai - high-fat and low-carbohydrate - was the driving force in their good health and enabled high levels of activity, I'll say it!

Here we have evidence that a high-fat, low-carbohydrate diet, consumed habitually does not lead to obesity, high blood pressure and dyslipidemia, and it may, in fact, lead to beneficial long-term health and increased levels of activity in those habitually eating such a diet.


  1. Great post! This study really puts some things into proper perspective. A lowfat diet of more natural foods is indeed better than the typical western diet. So if you compare such a diet to a western diet, it's going to come up smelling like roses. But lowfat diets do NOT look so great when compared head to head with low carb diets. And regarding activity level of Masai...I'm sure the rural Bantu also have a high activity level. So that argument is indeed bogus.

  2. Excellent post Regina. The kind of nonsense concluded from evidence seriously makes you question the mental processes of people out there.

  3. Does the paper discuss how activity levels were assessed? The abstract states the Masai expended "2565 kcal/day over basal requirements", which seems pretty high. What were they doing to burn all of these extra calories anyway?

  4. The "offset by very high energy expenditure levels" part is kind of revealing. If they needed to offset with very high energy expenditure levels, then they must have been consuming very high calorie diets, no? (I realize this is kind of obvious, I just feel that it deserves to be underlined.)
    So dietary fat is good for you, as long as you burn it? That was my plan all along.

  5. Anonymous3:20 PM

    Thanks Regina for this post. I sent a letter to the editor of the Journal as a result!-Eric Westman

  6. Thanks Regina for this post. I sent a letter to the editor of the Journal as a result!-Eric Westman

    ooooh...way cool! Thanks!

  7. To me the take-home message is a diet high in processed crap is worse than a more natural one, whether it's high or low in fat.

  8. Anonymous11:33 PM

    But the Masai do suffer from extensive CHD. George Mann, one of the original researchers that popularized the Masia and a great doubter of the lipid hypothesis, acutally preformed autopsies on Masia men and discovered extensive blood vessel disease. Luckily they were proteced by their exceptional large cornaary arteries (due their genetics and large volumne of medium intensity aerobic exercise).


    Here's the ref:

    Mann, G. V. (Vanderbilt Univ. School of Medicine, Nashville, Tenn. 37203), A. Spoerry, M. Gray, and D. Jarashow. Atherosclerosis in the Masai. Am J Epidemiol 95: 26–37, 1972.–The hearts and aortae of 50 Masai men were collected at autopsy. These pastoral people are exceptionally active and fit and they consume diets of milk and meat. The intake of animal fat exceeds that of American men. Measurements of the aorta showed extensive atherosclerosis with lipid infiltration and fibrous changes but very few complicated lesions. The coronary arteries showed intimal thickening by atherosclerosis which equaled that of old U.S. men. The Masai vessels enlarge with age to more than compensate for this disease. It is speculated that the Masai are protected from their atherosclerosis by physical fitness which causes their coronary vessels to be capacious.

    atherosclerosis; autopsy; cholesterol; coronary artery disease; diet; exercise

    1 From the Nutrition Division, vanderbilt University, Nashville, Tennessee 37203 (G. V. Mann and D. Jarashow), and the Aftrican Medical and Research Foundation, Nairobi (A. Spoerry and M. Gray). Reprint requests to Dr. Mann.

    June 11, 2008 6:28 AM

  9. But the Masai do suffer from extensive CHD.

    I'll let the paper you cite data speak for itself:

    "We examined 600 genetically genuine Masai with clinical methods, including 350 men over the age of 40, and found very little evidence of cardiovascular disease.(6) We have found only one Masai man with unequivocal ECG evidence of an infarction.

    Reference 6 is Mann et al, Cardiovascular Disease in the Masai; J Atheroscler Res 4: 289-312, 1964

    Later in the introduction - "Do the Masai not develop atherosclerosis or do they have it but remain immune to occlusive disease because of some other protective circumstance? The question was answered with autopsy material collected over a five-year period. The Masai do have atherosclerosis but the are almost immune to occlusive disease.

    The paper you cite is the results of fifty autopsies of hearts and vessels.

    Ten of the 50 heart specimens showed evidence of disease or anomalies. Four were scarred in a manner typical of rheumatic carditis (rheumatic fever, not heart disease per se). Two showed evidence of syphilitic aortistis adn two had extensive pericarditis, probably causing their deaths. Three hearts with anomalous patterns of coronary vessels were found but none in none was their evidence of myocardial disease.

    In reviewing table 2, the causes of death of the 50 were: 15 due to combat wounds, 13 due to infection, 8 due to CV renal, 6 due to accidents, 3 due to maligancy, 2 due to instestinal obstruction, 2 due to suicide and 1 due to diabetic coma.

    Of the ten noted to have abnormalities found:

    4 were due to rheumatic heart disease, a condition following rheumatic fever; 2 were symphilitic aortitis, a pathological state of the aorta associated with the tertiary stage of syphilis infection; 2 were pericarditis-constrictive, cause unknown, but commonly caused by tuberculosis infection and/or other inflammatory infection; and two (along with one with rheumatic heart disease) had anamalous coronary vessels, with the two not related to rheumatic heart disease being congenital defects - both coronary arteries arising on the left and one absent a right coronary artery.

    Later, in the discussion section, the researchers note, "We find the Masai vessels do show extensive atherosclerosis; they show coronary intimal thickening which is equal to that seen in elderly Americans. The unique anatomical feature of the Masai is that the coronary vessels enlarge with age so that the lumina are not compromised by intimal thickening.

    They continue, "The three noteworthy factors to be considered in the Masai immunity to CHD are fitness, the hypothetical noxious dietary agent which is unidentified and the fibrous capping explanation which proposed that 15 years of muranhood in young adults allows early lesions to be capped and this gives immunity to subsequent progression."

  10. Anonymous7:50 AM

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  11. There entire Lipid Hypothesis of heart disease is utter nonsense. The LDL:HDL Ratio and TC are completely meaningless measures. It doesn't matter whether your TC is 3mmol/L or 8mmol/L

    Only three things have ever been shown to reduce CHD:

    a) adequate omega 3, vitamin C and selenium intake;

    b) high levels of of moderate physical activity and

    C) low levels of psychosocial stress.

    It is very unlikely that diet has any role at all in CHD. For example Zulu(Bantu) cane cutters examined by Dr TL Cleave had no CHD or obesity on a sugar-laden diet of ~90% carbohydrate.

    The Zulu have low CHD because they walk 25km each day not because of their diet.

  12. Jeff:
    "And regarding activity level of Masai...I'm sure the rural Bantu also have a high activity level. So that argument is indeed bogus."

    This is incorrect. Married Bantu men have exceptionally low levels of physical activity - almost all physical work is done by women.

    The type of physical activity is also very important. Only regular sustained rhythmic activity like brisk walking exercise the heart. Activities like horticulture or infrequent lifting have little or no cardio-protective effect.

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