About two months ago, I did an interview with Jimmy Moore of the Livin' la Vida Low Carb internet empire. I hardly remember what we talked about, but I think it went well. I enjoyed Jimmy's pleasant and open-minded attitude. Head over to Jimmy's website and listen to the interview here.
I do recall making at least one mistake. When discussing heart attacks,I said "atrial fibrillation" when I meant "ventricular fibrillation".
Low Micronutrient Intake may Contribute to Obesity
[2013 update: I'm skeptical of the idea that micronutrient insufficiency/deficiency promotes obesity. Although the trial discussed below suggested it might be a factor, it has not been a general finding that micronutrient supplementation causes fat loss, and the result needs to be repeated to be believable in my opinion. Also, conditions of frank micronutrient deficiency are not usually associated with fat gain]
Lower Micronutrient Status in the Obese
Investigators have noted repeatedly that obese people have a lower blood concentration of a number of nutrients, including vitamin A, vitamin D, vitamin K, several B vitamins, zinc and iron (1). Although there is evidence that some of these may influence fat mass in animals, the evidence for a cause-and-effect relationship in humans is generally slim. There is quite a bit of indirect evidence that vitamin D status influences the risk of obesity (2), although a large, well-controlled study found that high-dose vitamin D3 supplementation does not cause fat loss in overweight and obese volunteers over the course of a year (3). It may still have a preventive effect, or require a longer timescale, but that remains to be determined.
Hot off the Presses
A new study in the journal Obesity, by Y. Li and colleagues, showed that compared to a placebo, a low-dose multivitamin caused obese volunteers to lose 7 lb (3.2 kg) of fat mass in 6 months, mostly from the abdominal region (4). The supplement also reduced LDL by 27%, increased HDL by a whopping 40% and increased resting energy expenditure. Here's what the supplement contained:
Vitamin A(containing natural mixed b-carotene) 5000 IU
Vitamin D 400 IU
Vitamin E 30 IU
Thiamin 1.5 mg
Riboflavin 1.7 mg
Vitamin B6 2 mg
Vitamin C 60 mg
Vitamin B12 6 mcg
Vitamin K1 25 mcg
Biotin 30 mcg
Folic acid 400 mcg
Nicotinamide 20 mg
Pantothenic acid 10 mg
Calcium 162 mg
Phosphorus 125 mg
Chlorine 36.3 mg
Magnesium 100 mg
Iron 18 mg
Copper 2 mg
Zinc 15 mg
Manganese 2.5 mg
Iodine 150 mcg
Chromium 25 mcg
Molybdenum 25 mcg
Selenium 25 mcg
Nickel 5 mcg
Stannum 10 mcg
Silicon 10 mcg
Vanadium 10 mcg
Although the result needs to be repeated, if we take it at face value, it has some important implications:
Does this mean we should all take multivitamins to stay or become thin? No. There is no multivitamin that can match the completeness and balance of a nutrient-dense, whole food, omnivorous diet. Beef liver, leafy greens and sunlight are nature's vitamin pills. Avoiding refined foods instantly doubles the micronutrient content of the typical diet. Properly preparing whole grains by soaking and fermentation is equivalent to taking a multi-mineral along with conventionally prepared grains, as absorption of key minerals is increased by 50-300% (10). Or you can eat root vegetables instead of grains, and enjoy their naturally high mineral availability. Or both.
Lower Micronutrient Status in the Obese
Investigators have noted repeatedly that obese people have a lower blood concentration of a number of nutrients, including vitamin A, vitamin D, vitamin K, several B vitamins, zinc and iron (1). Although there is evidence that some of these may influence fat mass in animals, the evidence for a cause-and-effect relationship in humans is generally slim. There is quite a bit of indirect evidence that vitamin D status influences the risk of obesity (2), although a large, well-controlled study found that high-dose vitamin D3 supplementation does not cause fat loss in overweight and obese volunteers over the course of a year (3). It may still have a preventive effect, or require a longer timescale, but that remains to be determined.
Hot off the Presses
A new study in the journal Obesity, by Y. Li and colleagues, showed that compared to a placebo, a low-dose multivitamin caused obese volunteers to lose 7 lb (3.2 kg) of fat mass in 6 months, mostly from the abdominal region (4). The supplement also reduced LDL by 27%, increased HDL by a whopping 40% and increased resting energy expenditure. Here's what the supplement contained:
Vitamin A(containing natural mixed b-carotene) 5000 IU
Vitamin D 400 IU
Vitamin E 30 IU
Thiamin 1.5 mg
Riboflavin 1.7 mg
Vitamin B6 2 mg
Vitamin C 60 mg
Vitamin B12 6 mcg
Vitamin K1 25 mcg
Biotin 30 mcg
Folic acid 400 mcg
Nicotinamide 20 mg
Pantothenic acid 10 mg
Calcium 162 mg
Phosphorus 125 mg
Chlorine 36.3 mg
Magnesium 100 mg
Iron 18 mg
Copper 2 mg
Zinc 15 mg
Manganese 2.5 mg
Iodine 150 mcg
Chromium 25 mcg
Molybdenum 25 mcg
Selenium 25 mcg
Nickel 5 mcg
Stannum 10 mcg
Silicon 10 mcg
Vanadium 10 mcg
Although the result needs to be repeated, if we take it at face value, it has some important implications:
- The nutrient density of a diet may influence obesity risk, as I speculated in my recent audio interview and related posts (5, 6, 7, 8, 9).
- Many nutrients act together to create health, and multiple insufficiencies may contribute to disease. This may be why single nutrient supplementation trials usually don't find much.
- Another possibility is that obesity can result from a number of different nutrient insufficiencies, and the cause is different in different people. This study may have seen a large effect because it corrected many different insufficiencies.
- This result, once again, kills the simplistic notion that body fat is determined exclusively by voluntary food consumption and exercise behaviors (sometimes called the "calories in, calories out" idea, or "gluttony and sloth"). In this case, a multivitamin was able to increase resting energy expenditure and cause fat loss without any voluntary changes in food intake or exercise, suggesting metabolic effects and a possible downward shift of the body fat "setpoint" due to improved nutrient status.
Does this mean we should all take multivitamins to stay or become thin? No. There is no multivitamin that can match the completeness and balance of a nutrient-dense, whole food, omnivorous diet. Beef liver, leafy greens and sunlight are nature's vitamin pills. Avoiding refined foods instantly doubles the micronutrient content of the typical diet. Properly preparing whole grains by soaking and fermentation is equivalent to taking a multi-mineral along with conventionally prepared grains, as absorption of key minerals is increased by 50-300% (10). Or you can eat root vegetables instead of grains, and enjoy their naturally high mineral availability. Or both.
Nitrate: a Protective Factor in Leafy Greens
Cancer Link and Food Sources
Nitrate (NO3) is a molecule that has received a lot of bad press over the years. It is thought to promote digestive cancers, in part due to its ability to form carcinogens when used as a preservative for processed meat. Because of this (1), nitrate was viewed with suspicion and a number of countries imposed strict limits on its use as a food additive.
But what if I told you that by far the greatest source of nitrate in the modern diet isn't processed meat-- but vegetables, particularly leafy greens (2)? And that the evidence linking exposure to nitrate itself has largely failed to materialize? For example, one study found no difference in the incidence of gastric cancer between nitrate fertilizer plant workers and the general population (3). Most other studies in animals and humans have not supported the hypothesis that nitrate itself is carcinogenic (4, 5, 6), but rather that they are only carcinogenic in the context of processed meats due to the formation of carcinogenic nitrosamines. This, combined with recent findings on nitrate biology, has changed the way we think about this molecule in recent years.
A New Example of Human Symbiosis
In 2003, Dr. K. Cosby and colleagues showed that nitrite (NO2; not the same as nitrate) dilates blood vessels in humans when infused into the blood (7). Investigators subsequently uncovered an amazing new example of human-bacteria symbiosis: dietary nitrate (NO3) is absorbed from the gut into the bloodstream and picked up by the salivary glands. It's then secreted into saliva, where oral bacteria use it as an energy source, converting it to nitrite (NO2). After swallowing, the nitrite is reabsorbed into the bloodstream (8). Humans and oral bacteria may have co-evolved to take advantage of this process. Antibacterial mouthwash prevents it.
Nitrate Protects the Cardiovascular System
In 2008, Dr. Andrew J. Webb and colleagues showed that nitrate in the form of 1/2 liter of beet juice (equivalent in volume to about 1.5 soda cans) substantially lowers blood pressure in healthy volunteers for over 24 hours. It also preserved blood vessel performance after brief oxygen deprivation, and reduced the tendency of the blood to clot (9). These are all changes that one would expect to protect against cardiovascular disease. Another group showed that in monkeys, the ability of nitrite to lower blood pressure did not diminish after two weeks, showing that the animals did not develop a tolerance to it on this timescale (10).
Subsequent studies showed that dietary nitrite reduces blood vessel dysfunction and inflammation (CRP) in cholesterol-fed mice (11). Low doses of nitrite also dramatically reduce tissue death in the hearts of mice exposed to conditions mimicking a heart attack, as well as protecting other tissues against oxygen deprivation damage (12). The doses used in this study were the equivalent of a human eating a large serving (100 g; roughly 1/4 lb) of lettuce or spinach.
Mechanism
Nitrite is thought to protect the cardiovascular system by serving as a precursor for nitric oxide (NO), one of the most potent anti-inflammatory and blood vessel-dilating compounds in the body (13). A decrease in blood vessel nitric oxide is probably one of the mechanisms of diet-induced atherosclerosis and increased clotting tendency, and it is likely an early consequence of eating a poor diet (14).
The Long View
Leafy greens were one of the "protective foods" emphasized by the nutrition giant Sir Edward Mellanby (15), along with eggs and high-quality full-fat dairy. There are many reasons to believe greens are an excellent contribution to the human diet, and what researchers have recently learned about nitrate biology certainly reinforces that notion. Leafy greens may be particularly useful for the prevention and reversal of cardiovascular disease, but are likely to have positive effects on other organ systems both in health and disease. It's ironic that a molecule suspected to be the harmful factor in processed meats is turning out to be one of the major protective factors in vegetables.
Nitrate (NO3) is a molecule that has received a lot of bad press over the years. It is thought to promote digestive cancers, in part due to its ability to form carcinogens when used as a preservative for processed meat. Because of this (1), nitrate was viewed with suspicion and a number of countries imposed strict limits on its use as a food additive.
But what if I told you that by far the greatest source of nitrate in the modern diet isn't processed meat-- but vegetables, particularly leafy greens (2)? And that the evidence linking exposure to nitrate itself has largely failed to materialize? For example, one study found no difference in the incidence of gastric cancer between nitrate fertilizer plant workers and the general population (3). Most other studies in animals and humans have not supported the hypothesis that nitrate itself is carcinogenic (4, 5, 6), but rather that they are only carcinogenic in the context of processed meats due to the formation of carcinogenic nitrosamines. This, combined with recent findings on nitrate biology, has changed the way we think about this molecule in recent years.
A New Example of Human Symbiosis
In 2003, Dr. K. Cosby and colleagues showed that nitrite (NO2; not the same as nitrate) dilates blood vessels in humans when infused into the blood (7). Investigators subsequently uncovered an amazing new example of human-bacteria symbiosis: dietary nitrate (NO3) is absorbed from the gut into the bloodstream and picked up by the salivary glands. It's then secreted into saliva, where oral bacteria use it as an energy source, converting it to nitrite (NO2). After swallowing, the nitrite is reabsorbed into the bloodstream (8). Humans and oral bacteria may have co-evolved to take advantage of this process. Antibacterial mouthwash prevents it.
Nitrate Protects the Cardiovascular System
In 2008, Dr. Andrew J. Webb and colleagues showed that nitrate in the form of 1/2 liter of beet juice (equivalent in volume to about 1.5 soda cans) substantially lowers blood pressure in healthy volunteers for over 24 hours. It also preserved blood vessel performance after brief oxygen deprivation, and reduced the tendency of the blood to clot (9). These are all changes that one would expect to protect against cardiovascular disease. Another group showed that in monkeys, the ability of nitrite to lower blood pressure did not diminish after two weeks, showing that the animals did not develop a tolerance to it on this timescale (10).
Subsequent studies showed that dietary nitrite reduces blood vessel dysfunction and inflammation (CRP) in cholesterol-fed mice (11). Low doses of nitrite also dramatically reduce tissue death in the hearts of mice exposed to conditions mimicking a heart attack, as well as protecting other tissues against oxygen deprivation damage (12). The doses used in this study were the equivalent of a human eating a large serving (100 g; roughly 1/4 lb) of lettuce or spinach.
Mechanism
Nitrite is thought to protect the cardiovascular system by serving as a precursor for nitric oxide (NO), one of the most potent anti-inflammatory and blood vessel-dilating compounds in the body (13). A decrease in blood vessel nitric oxide is probably one of the mechanisms of diet-induced atherosclerosis and increased clotting tendency, and it is likely an early consequence of eating a poor diet (14).
The Long View
Leafy greens were one of the "protective foods" emphasized by the nutrition giant Sir Edward Mellanby (15), along with eggs and high-quality full-fat dairy. There are many reasons to believe greens are an excellent contribution to the human diet, and what researchers have recently learned about nitrate biology certainly reinforces that notion. Leafy greens may be particularly useful for the prevention and reversal of cardiovascular disease, but are likely to have positive effects on other organ systems both in health and disease. It's ironic that a molecule suspected to be the harmful factor in processed meats is turning out to be one of the major protective factors in vegetables.
Fermented Grain Recipes from Around the World
In my last two posts on grains, I described how traditional food processing methods make grains more nutritious and digestible (1, 2). I promised to briefly describe a few recipes from around the world, then got distracted by other things. Here they are.
Africa: Ogi
Grain fermentation is widespread in Africa and is probably nearly as old as agriculture on the continent. The nutritional importance of fermentation is suggested by the amount of time and effort that many African cultures put into it, when they could save themselves a lot of trouble by simply soaking and cooking their grains.
Ogi is a common West African porridge that's eaten as a staple food by people of all ages. It's even used as a weaning food. It's made in essentially the same manner from corn, sorghum or millet.
Whole grain is soaked in water for one to three days. It's then wet milled, mixed with water and sieved to remove a portion of the bran. Extra bran is fed to animals, while the white, starchy sediment is fermented for two to three days. This is then cooked into a thin or thick porridge and eaten.
South America: Pozol
At first glance, some people may think I left the 'e' off the word 'pozole', a traditional Mexican stew. However, pozol is an entirely different beast, an ancient food almost totally unknown in the US, but which fueled the Mayan empire and remains a staple food in Southeastern Mexico.
To make pozol, first the corn must be 'nixtamalized': whole kernels are boiled in a large volume of water with calcium hydroxide (10% w/v). This is a processing step in most traditional South American corn recipes, as it allows a person to avoid pellagra (niacin deficiency)! The loosened bran is removed from the kernels by hand.
The kernels are then ground into dough, formed into balls and placed into banana leaves to ferment for one to 14 days. Following fermentation, pozol is diluted in water and consumed raw.
Europe: Sourdough Bread
Sourdough bread is Europe's quintessential fermented grain food. Before purified yeast strains came into widespread use in the 20th century, all bread would have been some form of sourdough.
Although in my opinion wheat is problematic for many people, sourdough fermentation renders it more nutritious and better tolerated by those with gluten/wheat sensitivity. In an interesting series of studies, Dr. Marco Gobbetti's group, among others, has shown that fermentation partially degrades gluten, explaining the ability of fermentation to decrease the adverse effects of gluten in those who are sensitive to it (3). They even showed that people with celiac disease can safely eat wheat bread that has been long-fermented with selected bacteria and yeasts under laboratory conditions (4). Rye contains about half the gluten of bread wheat, and is generally nutritionally superior to wheat, so sourdough rye is a better choice in my opinion.
To make sourdough bread, first the dry grains are ground into flour. Next, the flour is sifted through a screen to remove a portion of the bran. The earliest bread eaters probably didn't do this, although there is evidence of the wealthy eating sifted flour in societies as old as ancient Egypt and ancient Rome. I don't know what the optimum amount of bran to include in flour is, but it's not zero. I would be inclined to keep at least half of it, recognizing that the bran is disproportionately rich in nutrients.
Next, a portion of flour is mixed with water and a "sourdough starter", until it has a runny consistency. The starter is a diverse culture of bacteria and yeast that is carefully maintained by the bread maker. This culture acidifies the batter and produces carbon dioxide gas. The mixture is allowed to ferment for 8-12 hours. Finally, flour and salt are added to the batter and formed into dough balls. These are allowed to ferment and rise for a few hours, then baked.
My Experience
I've tried making ogi (millet) and pozol, and I have to admit that neither attempt was successful. Pozol in particular may depend on local populations of bacteria and yeast, as the grains' microorganisms are killed during processing. However, I do eat fermented grains regularly in the form of homemade brown rice 'uthappam' and sourdough buckwheat 'crepes'. The buckwheat crepes are tasty and easy to make. I'll post a recipe at some point.
The first two recipes are from the FAO publication Fermented Cereals: a Global Perspective (5).
Africa: Ogi
Grain fermentation is widespread in Africa and is probably nearly as old as agriculture on the continent. The nutritional importance of fermentation is suggested by the amount of time and effort that many African cultures put into it, when they could save themselves a lot of trouble by simply soaking and cooking their grains.
Ogi is a common West African porridge that's eaten as a staple food by people of all ages. It's even used as a weaning food. It's made in essentially the same manner from corn, sorghum or millet.
Whole grain is soaked in water for one to three days. It's then wet milled, mixed with water and sieved to remove a portion of the bran. Extra bran is fed to animals, while the white, starchy sediment is fermented for two to three days. This is then cooked into a thin or thick porridge and eaten.
South America: Pozol
At first glance, some people may think I left the 'e' off the word 'pozole', a traditional Mexican stew. However, pozol is an entirely different beast, an ancient food almost totally unknown in the US, but which fueled the Mayan empire and remains a staple food in Southeastern Mexico.
To make pozol, first the corn must be 'nixtamalized': whole kernels are boiled in a large volume of water with calcium hydroxide (10% w/v). This is a processing step in most traditional South American corn recipes, as it allows a person to avoid pellagra (niacin deficiency)! The loosened bran is removed from the kernels by hand.
The kernels are then ground into dough, formed into balls and placed into banana leaves to ferment for one to 14 days. Following fermentation, pozol is diluted in water and consumed raw.
Europe: Sourdough Bread
Sourdough bread is Europe's quintessential fermented grain food. Before purified yeast strains came into widespread use in the 20th century, all bread would have been some form of sourdough.
Although in my opinion wheat is problematic for many people, sourdough fermentation renders it more nutritious and better tolerated by those with gluten/wheat sensitivity. In an interesting series of studies, Dr. Marco Gobbetti's group, among others, has shown that fermentation partially degrades gluten, explaining the ability of fermentation to decrease the adverse effects of gluten in those who are sensitive to it (3). They even showed that people with celiac disease can safely eat wheat bread that has been long-fermented with selected bacteria and yeasts under laboratory conditions (4). Rye contains about half the gluten of bread wheat, and is generally nutritionally superior to wheat, so sourdough rye is a better choice in my opinion.
To make sourdough bread, first the dry grains are ground into flour. Next, the flour is sifted through a screen to remove a portion of the bran. The earliest bread eaters probably didn't do this, although there is evidence of the wealthy eating sifted flour in societies as old as ancient Egypt and ancient Rome. I don't know what the optimum amount of bran to include in flour is, but it's not zero. I would be inclined to keep at least half of it, recognizing that the bran is disproportionately rich in nutrients.
Next, a portion of flour is mixed with water and a "sourdough starter", until it has a runny consistency. The starter is a diverse culture of bacteria and yeast that is carefully maintained by the bread maker. This culture acidifies the batter and produces carbon dioxide gas. The mixture is allowed to ferment for 8-12 hours. Finally, flour and salt are added to the batter and formed into dough balls. These are allowed to ferment and rise for a few hours, then baked.
My Experience
I've tried making ogi (millet) and pozol, and I have to admit that neither attempt was successful. Pozol in particular may depend on local populations of bacteria and yeast, as the grains' microorganisms are killed during processing. However, I do eat fermented grains regularly in the form of homemade brown rice 'uthappam' and sourdough buckwheat 'crepes'. The buckwheat crepes are tasty and easy to make. I'll post a recipe at some point.
The first two recipes are from the FAO publication Fermented Cereals: a Global Perspective (5).
Does Red Wine Protect the Cardiovascular System?
The 'French paradox' rears its ugly head again. The reasoning goes something like this: French people eat more saturated animal fat than any other affluent nation, and have the second-lowest rate of coronary heart disease (only after Japan, which has a much higher stroke rate than France). French people drink red wine. Therefore, red wine must be protecting them against the artery-clogging yogurt, beef and butter.
The latest study to fall into this myth was published in the AJCN recently (1). Investigators showed that 1/3 bottle of red wine per day for 21 days increased blood flow in forearm vessels of healthy volunteers, which they interpreted as "enhanced vascular endothelial function". The novel finding in this paper is that red wine consumption increases the migration of certain cells into blood vessels that are thought to maintain and repair the vessels. There were no control groups for comparison, neither abstainers nor a group drinking a different type of alcohol.
The investigators then went on to speculate that the various antioxidant polyphenols in red wine, such as the molecule resveratrol, could be involved. This could be true, but there's another possible mechanism here...
Ethanol-- plain old alcohol. You could drink a 40 oz bottle of malt liquor every night and it might do the same thing.
No matter what the source, alcohol consumption is associated with a lower risk of cardiovascular disease out to about 3-4 drinks per day, after which the risk goes back up (2, 3)*. The association is not trivial-- up to a 62% lower risk associated with alcohol use. Controlled trials have shown that alcohol, regardless of the source, increases HDL cholesterol and reduces the tendency to clot (4).
Should we all start downing three drinks a day? Not so fast. Although alcohol does probably decrease heart attack risk, the effect on total mortality is equivocal. That's because it increases the risk of cancers and accidents. Alcohol is a drug, and my opinion is that like all drugs, overall it will not benefit the health of a person with an otherwise good diet and lifestyle. That being said, it's enjoyable, so I have no problem with drinking it in moderation. Just don't think you're doing it for your health.
So does red wine decrease the risk of having a heart attack? Probably, yes, just like malt liquor does. I do think it's interesting to speculate about why alcohol (probably) reduces heart attack risk. Could it be because it relaxes us? I'm going to ponder that over a glass of whiskey...
* The first study is really interesting. For once, I see no evidence of "healthy user bias". Rates of healthy behaviors were virtually identical across quintiles of alcohol intake. This gives me a higher degree of confidence in the results.
The latest study to fall into this myth was published in the AJCN recently (1). Investigators showed that 1/3 bottle of red wine per day for 21 days increased blood flow in forearm vessels of healthy volunteers, which they interpreted as "enhanced vascular endothelial function". The novel finding in this paper is that red wine consumption increases the migration of certain cells into blood vessels that are thought to maintain and repair the vessels. There were no control groups for comparison, neither abstainers nor a group drinking a different type of alcohol.
The investigators then went on to speculate that the various antioxidant polyphenols in red wine, such as the molecule resveratrol, could be involved. This could be true, but there's another possible mechanism here...
Ethanol-- plain old alcohol. You could drink a 40 oz bottle of malt liquor every night and it might do the same thing.
No matter what the source, alcohol consumption is associated with a lower risk of cardiovascular disease out to about 3-4 drinks per day, after which the risk goes back up (2, 3)*. The association is not trivial-- up to a 62% lower risk associated with alcohol use. Controlled trials have shown that alcohol, regardless of the source, increases HDL cholesterol and reduces the tendency to clot (4).
Should we all start downing three drinks a day? Not so fast. Although alcohol does probably decrease heart attack risk, the effect on total mortality is equivocal. That's because it increases the risk of cancers and accidents. Alcohol is a drug, and my opinion is that like all drugs, overall it will not benefit the health of a person with an otherwise good diet and lifestyle. That being said, it's enjoyable, so I have no problem with drinking it in moderation. Just don't think you're doing it for your health.
So does red wine decrease the risk of having a heart attack? Probably, yes, just like malt liquor does. I do think it's interesting to speculate about why alcohol (probably) reduces heart attack risk. Could it be because it relaxes us? I'm going to ponder that over a glass of whiskey...
* The first study is really interesting. For once, I see no evidence of "healthy user bias". Rates of healthy behaviors were virtually identical across quintiles of alcohol intake. This gives me a higher degree of confidence in the results.
Sweet Potatoes
We can debate the nutritional qualities of a food until we're blue in the face, but in the end, we still may not have a very accurate prediction of the health effects of that food. The question we need to answer is this one: has this food sustained healthy traditional cultures?
I'm currently reading a great book edited by Drs. Hugh Trowell and Denis Burkitt, titled Western Diseases: Their Emergence and Prevention. It's a compilation of chapters describing the diet and health of traditional populations around the world as they modernize.
The book contains a chapter on Papua New Guinea highlanders. Here's a description of their diet:
How was their health? Like many non-industrial societies, they had a high infant/child mortality rate, such that 43 percent of children died before growing old enough to marry. Surprisingly, protein deficiency was rare. No obvious malnutrition was observed in this population, although iodine-deficiency cretinism occurs in some highlands populations:
There was no evidence of coronary heart disease or diabetes. Average blood pressure was on the high side, but did not increase with age. Investigators administered 100 gram glucose tolerance tests and only 3.8 percent of the population had glucose readings above 160 mg/dL, compared to 21 percent of Americans. A study of 7,512 Papuans from several regions with minimal European contact indicated a diabetes prevalence of 0.1 percent, a strikingly low rate. For comparison, in 2007, 10.7 percent of American adults had diabetes (1).
I'm not claiming it's optimal to eat nothing but sweet potatoes. But this is the strongest evidence we're going to come by that sweet potatoes can be eaten in quantity as part of a healthy diet. However, I wish I knew more about the varieties this group ate. Sweet potatoes aren't necessarily sweet. Caribbean 'boniato' sweet potatoes are dry, starchy and off-white. In the US, I prefer the yellow sweet potatoes to the orange variety of sweet potato labeled 'yams', because the former are starchier and less sweet. If I could get my hands on locally grown boniatos here, I'd eat those, but boniatos are decidedly tropical.
Instead, I eat potatoes, but I'm reluctant to recommend them whole-heartedly because I don't know enough about the traditional cultures that consumed them. I believe there are some low-CHD, low-obesity African populations that eat potatoes as part of a starch-based diet, but I haven't looked into it closely enough to make any broad statements. Potatoes have some nutritional advantages over sweet potatoes (higher protein content, better amino acid profile), but also some disadvantages (lower fiber, lower in most micronutrients, toxic glycoalkaloids).
I'm currently reading a great book edited by Drs. Hugh Trowell and Denis Burkitt, titled Western Diseases: Their Emergence and Prevention. It's a compilation of chapters describing the diet and health of traditional populations around the world as they modernize.
The book contains a chapter on Papua New Guinea highlanders. Here's a description of their diet:
A diet survey was undertaken involving 90 subjects, in which all food consumed by each individual was weighed over a period of seven consecutive days. Sweet potato supplied over 90 percent of their total food intake, while non-tuberous vegetables accounted for less than 5 percent of the food consumed and the intake of meat was negligible... Extensive herds of pigs are maintained and, during exchange ceremonies, large amounts of pork are consumed.They ate no salt. Their calories were almost entirely supplied by sweet potatoes, with occasional feasts on pork.
How was their health? Like many non-industrial societies, they had a high infant/child mortality rate, such that 43 percent of children died before growing old enough to marry. Surprisingly, protein deficiency was rare. No obvious malnutrition was observed in this population, although iodine-deficiency cretinism occurs in some highlands populations:
Young adults were well built and physically fit and had normal levels of haemoglobin and serum albumin. Further, adult females showed no evidence of malnutrition in spite of the demands by repeated cycles of pregnancy and lactation. On the basis of American standards (Society of Actuaries, 1959), both sexes were close to 100 percent standard weight in their twenties.
The Harvard Pack Test carried out on 152 consecutive subjects demonstrated a high level of physical fitness which was maintained well into middle-age. Use of a bicycle ergometer gave an estimated maximum oxygen uptake of 45.2 ml per kilogram per minute and thus confirmed the high level of cardiopulmonary fitness in this group.Body weight decreased with age, which is typical of many non-industrial cultures and reflects declining muscle mass but continued leanness.
There was no evidence of coronary heart disease or diabetes. Average blood pressure was on the high side, but did not increase with age. Investigators administered 100 gram glucose tolerance tests and only 3.8 percent of the population had glucose readings above 160 mg/dL, compared to 21 percent of Americans. A study of 7,512 Papuans from several regions with minimal European contact indicated a diabetes prevalence of 0.1 percent, a strikingly low rate. For comparison, in 2007, 10.7 percent of American adults had diabetes (1).
I'm not claiming it's optimal to eat nothing but sweet potatoes. But this is the strongest evidence we're going to come by that sweet potatoes can be eaten in quantity as part of a healthy diet. However, I wish I knew more about the varieties this group ate. Sweet potatoes aren't necessarily sweet. Caribbean 'boniato' sweet potatoes are dry, starchy and off-white. In the US, I prefer the yellow sweet potatoes to the orange variety of sweet potato labeled 'yams', because the former are starchier and less sweet. If I could get my hands on locally grown boniatos here, I'd eat those, but boniatos are decidedly tropical.
Instead, I eat potatoes, but I'm reluctant to recommend them whole-heartedly because I don't know enough about the traditional cultures that consumed them. I believe there are some low-CHD, low-obesity African populations that eat potatoes as part of a starch-based diet, but I haven't looked into it closely enough to make any broad statements. Potatoes have some nutritional advantages over sweet potatoes (higher protein content, better amino acid profile), but also some disadvantages (lower fiber, lower in most micronutrients, toxic glycoalkaloids).
Pastured Dairy may Prevent Heart Attacks
Not all dairy is created equal. Dairy from grain-fed and pasture-fed cows differs in a number of ways. Pastured dairy contains more fat-soluble nutrients such as vitamin K2, vitamin A, vitamin E, carotenes and omega-3 fatty acids. It also contains more conjugated linoleic acid, a fat-soluble molecule that has been under intense study due to its ability to inhibit obesity and cancer in animals. The findings in human supplementation trials have been mixed, some confirming the animal studies and others not. In feeding experiments in cows, Dr. T. R. Dhiman and colleagues found the following (1):
In a recent article from the AJCN, Dr. Liesbeth Smit and colleagues examined the level of CLA in the body fat of Costa Rican adults who had suffered a heart attack, and compared it to another group who had not (a case-control study, for the aficionados). People with the highest level of CLA in their body fat were 49% less likely to have had a heart attack, compared to those with the lowest level (2).
Since dairy was the main source of CLA in this population, the association between CLA and heart attack risk is inextricable from the other components in pastured dairy fat. In other words, CLA is simply a marker of pastured dairy fat intake in this population, and the (possible) benefit could just as easily have come from vitamin K2 or something else in the fat.
This study isn't the first one to suggest that pastured dairy fat may be uniquely protective. The Rotterdam and EPIC studies found that a higher vitamin K2 intake is associated with a lower risk of heart attack, cancer and overall mortality (3, 4, 5). In the 1940s, Dr. Weston Price estimated that pastured dairy contains up to 50 times more vitamin K2 than grain-fed dairy. He summarized his findings in the classic book Nutrition and Physical Degeneration. This finding has not been repeated in recent times, but I have a little hunch that may change soon...
Vitamin K2
Cardiovascular Disease and Vitamin K2
Can Vitamin K2 Reverse Arterial Calcification?
Cows grazing pasture and receiving no supplemental feed had 500% more conjugated linoleic acid in milk fat than cows fed typical dairy diets.Fat from ruminants such as cows, sheep and goats is the main source of CLA in the human diet. CLA is fat-soluble. Therefore, skim milk doesn't contain any. It's also present in human body fat in proportion to dietary intake. This can come from dairy or flesh.
In a recent article from the AJCN, Dr. Liesbeth Smit and colleagues examined the level of CLA in the body fat of Costa Rican adults who had suffered a heart attack, and compared it to another group who had not (a case-control study, for the aficionados). People with the highest level of CLA in their body fat were 49% less likely to have had a heart attack, compared to those with the lowest level (2).
Since dairy was the main source of CLA in this population, the association between CLA and heart attack risk is inextricable from the other components in pastured dairy fat. In other words, CLA is simply a marker of pastured dairy fat intake in this population, and the (possible) benefit could just as easily have come from vitamin K2 or something else in the fat.
This study isn't the first one to suggest that pastured dairy fat may be uniquely protective. The Rotterdam and EPIC studies found that a higher vitamin K2 intake is associated with a lower risk of heart attack, cancer and overall mortality (3, 4, 5). In the 1940s, Dr. Weston Price estimated that pastured dairy contains up to 50 times more vitamin K2 than grain-fed dairy. He summarized his findings in the classic book Nutrition and Physical Degeneration. This finding has not been repeated in recent times, but I have a little hunch that may change soon...
Vitamin K2
Cardiovascular Disease and Vitamin K2
Can Vitamin K2 Reverse Arterial Calcification?
Malocclusion Posts Translated into German
It's nice to see on my website statistics program that Whole Health Source has a solid international following. As commonly as English is spoken throughout the world however, there are many people who do not have access to this blog due to a language barrier.
A gentleman by the name of Bertram has translated/summarized my series on the causes and prevention of malocclusion (misaligned teeth) into German. His site is OriginalHealth.net, and you can find the first post here, with links to the subsequent 8. It looks like an interesting site-- I wish I could read German. Thanks Bertram!
A gentleman by the name of Bertram has translated/summarized my series on the causes and prevention of malocclusion (misaligned teeth) into German. His site is OriginalHealth.net, and you can find the first post here, with links to the subsequent 8. It looks like an interesting site-- I wish I could read German. Thanks Bertram!
Intervew with Chris Kresser of The Healthy Skeptic
Last week, I did an audio interview with Chris Kresser of The Healthy Skeptic, on the topic of obesity. We put some preparation into it, and I think it's my best interview yet. Chris was a gracious host. We covered some interesting ground, including (list copied from Chris's post):
- The little known causes of the obesity epidemic
- Why the common weight loss advice to “eat less and exercise more” isn’t effective
- The long-term results of various weight loss diets (low-carb, low-fat, etc.)
- The body-fat setpoint and its relevance to weight regulation
- The importance of gut flora in weight regulation
- The role of industrial seed oils in the obesity epidemic
- Obesity as immunological and inflammatory disease
- Strategies for preventing weight gain and promoting weight loss
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