Tag Archives: saturated fat

August 31, 2016 · 4:22 AM

Ghee is making a comeback, at least in India

Also known as clarified butter, ghee is a traditional food in India. I’ve been reading about it for several years but I haven’t tried it yet.

From Times of India:

“Clarified butter remained India’s culinary star for centuries till it was sidelined in the 1980s by vegetable oils because of its high saturated fat. The new oils were aggressively marketed as superior and heart-healthy. Of late, research has shown that saturated fats have no link to obesity, heart disease or early death. In January 2015, the US dietary guidelines declared for the first time that total dietary fat and cholesterol intake are not a concern for healthy people. Now, on the back of some recent studies which maintain that it reduces fat and lower cholesterol, ghee too is making a big comeback in India. It is also making a splash abroad in alternative health circuits.”

Source: Ghee with glee – Times of India

You can make your own ghee. Alton Brown has a recipe, as does Michelle Tam.

If you still think saturated fat is bad, here’s the research proving otherwise.

Steve Parker, M.D.

PS: If you fear saturated fat, rest assured there’s none in my books.

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June 11, 2016 · 9:30 PM

Should You Reduce Saturated Fat Consumption If You Have Heart Disease?

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Most heart attacks occur in folks with pre-existing coronary artery disease that’s been present for years

For the bulk of my medical career, physicians thought that saturated fat caused heart disease, specifically coronary artery disease and heart attacks. Most doctors still think that. In 2009, I spent 80 hours reviewing the scientific literature supporting the saturated fat/heart disease connection. The evidence was very weak, if not nonexistent.

But what if you are already a heart disease patient? Would continuing saturated fat consumption have any effect on your longevity and risk of future heart attacks? If you already have coronary artery disease, Dr. Axel Sigurdsson says that ongoing saturated fat intake probably doesn’t matter, in terms of future cardiac events (like heart attacks) or risk of death from any cause.

Dr. Sigurdsson is a cardiologist in Iceland.

Some quotes from his blog:

For decades, cardiologists have advised patients with heart disease to restrict the intake of saturated fats and dietary cholesterol. Many patients still believe this to be the cornerstone of their lifestyle modification.

The main reason for avoiding saturated fats is the assumption that they adversely affect the lipid profile of our patients.

*   *   *

Recent studies suggest that the recommendation to avoid saturated fats may have been premature and not based on solid scientific evidence.

Now, a recently published Norwegian study shows that dietary intake of saturated fatty acids was not associated with risk of future events or death among patients with established coronary artery disease.

It is important to keep in mind that most of the patients were receiving secondary prevention drug therapy including aspirin, beta blockers and statins.

Anyhow, the results of the study certainly suggest that high intake of saturated fats is not a risk factor among patients with coronary heart disease receiving modern-day treatment.

These recent scientific data don’t imply that we should urge our patients to consume high amounts of saturated fats. They only tell us that there is no association and accordingly, restriction won’t help.

So, it’s certainly a lifeline for those who believe red meat, whole-fat milk, cheese, cream, butter and eggs can be a part of a healthy diet.

On the other hand we must realise that scientific studies often provide contradictory results. A US study published last year suggested that greater adherence to a low carbohydrate diet high in animal sources of fat and protein was associated with higher all-cause and cardiovascular mortality following acute heart attack.

It appears the jury is still out…

RTWT.

Steve Parker, M.D.

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August 3, 2014 · 3:57 AM

Do Low-Carb Diets Cause Premature Death?

Adult life is a battle against gravity. Eventually we all lose.

Adult life is a battle against gravity. Eventually we all lose.

Japanese researchers say low-carb diets are causing premature death. I’m skeptical.

The potentially healthful side effects linked to low-carb eating include reduced weight, higher HDL cholesterol, and lower triglycerides and blood pressure. The Japanese investigators wondered if the improved cardiovascular risk factors seen with low-carb diets actually translate into less heart disease and death.

How Was the Study At Hand Done?

The best way to test long-term health effects of a low-carb diet (or any diet) is to do a randomized controlled trial. You take 20,000 healthy and very similar people—not rodents—and randomize half of them to follow a specific low-carb diet while the other half all eat a standard or control diet. Teach them how to eat, make damn sure they do it, and monitor their health for five, 10, or 20 years. This has never been, and never will be, done in humans. The Nazis may have done it, but it’s not published. In the old days, we could do this study on inmates of insane asylums or prisons.

What we have instead are observational studies in which people voluntarily choose what they’re eating, and we assume they keep eating that way for five or 10+ years. You also assume that folks who choose low-carb diets are very similar to other people at the outset. You depend on regular people to accurately report what and how much they’re eating. You can then estimate how much of their diet is derived from carbohydrate and other macronutrients (protein and fat), then compare health outcomes of those who were in the top 10% of carb eaters with those in the bottom 10%. (We’ve made a lot of assumptions, perhaps too many.)

Of the observational studies the authors reviewed, the majority of the study participants were from the U.S. or Sweden. So any true conclusions may not apply to you if you’re not in those countries. In looking for articles, they found no randomized controlled trials.

The observational studies estimated carb consumption at the outset, but few ever re-checked to see if participants changed their diets. That alone is a problem. I don’t know about you, but I’ve had significant changes in my diet depending on when I was in college and med school, when I was a bachelor versus married, when my income was higher or lower, and when I had young children versus teenagers. But maybe that’s just me.

The researchers looked at all-cause mortality, deaths from cardiovascular disease, and incidence of cardiovascular disease. They don’t bother to define cardiovascular disease. I assume heart attack, strokes, and peripheral vascular disease. (But aren’t aneurysms, deep vein thrombosis, and pulmonary embolism vascular diseases, too?) Wouldn’t you think they’d carefully define their end-points? I would. Since they were going to all this trouble, why not look at cancer deaths, too?

What Did the Investigators Conclude?

Very low-carbohydrate dieters had a 30% higher risk of death from any cause (aka all-cause mortality) compared to very high-carb eaters. The risk of cardiovascular disease incidence or death were not linked with low-carb diets. Nor did they find protection against cardiovascular disease.

Finally, “Given the facts that low-carbohydrate diets are likely unsafe and that calorie restriction has been demonstrated to be effective in weight loss regardless of nutritional composition, it would be prudent not to recommend low-carbohydrate diets for the time being.”

If Low-Carb Dieters Die Prematurely, What Are They Dying From?

The top four causes of death in the U.S. in 2011, in order, are:

  1. heart attacks
  2. cancer
  3. chronic lower respiratory tract disease
  4. stroke

You’ll note that two of those are cardiovascular disease (heart attacks and stroke). So if low-carb diets promote premature death, it’s from cancer, chronic lung disease, or myriad other possibilities. Seventy-five percent of Americans die from one of the top 10 causes. Causes five through 10 are:

  • accidents
  • Alzheimer disease
  • diabetes
  • flu and pneumonia
  • kidney disease
  • suicide

Problem is, no one has ever linked low-carb diets to higher risk of death from any specific disease, whether or not in the top ten. Our researchers don’t mention that. That’s one reason I’m very skeptical about their conclusion. If you’re telling me low-carb diets cause premature death, tell me the cause of death.

Another frustration of mine with this report is that they never specify how many carbohydrates are in this lethal low-carb diet. Is it 20 grams, 100, 150? The typical American eats 250-300 grams of carb a day. If you’re going to sound the alarm against low-carb diets, you need to specify the lowest safe daily carb intake.

For most of my career—like most physicians—I’ve been wary of low-carb diets causing cardiovascular disease. That’s because they can be relatively high in total fat and saturated fat. In 2009, however, I did my own review of the scientific literature and found little evidence of fats causing cardiovascular disease.

If you’re looking for a reason to avoid low-carb diets, you can cite this study and its finding of premature death. I’m not convinced. I’ll turn it around on you and note this study found no evidence that low-carb diets cause cardiovascular disease. The risk of cardiovascular disease had been the traditional reason for physicians to recommend against low-carb diets.

Steve Parker, M.D.

Reference: Noto, Hiroshi et al. Low-Carbohydrate diets and all-cause mortality: A systematic review and meta-analysis of observational studies. PLoS One, 2013; 8(1): e55050

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November 29, 2012 · 5:40 AM

Low-Carb Research Update

“What about that recent study in American Journal of Clinical Nutrition…?”

As much as possible, I base my nutrition and medical recommendations on science-based research published in the medical literature.  Medical textbooks can be very helpful, but they aren’t as up-to-date as the medical journals.

In the early 2000s, a flurry of research reports demonstrated that very-low-carb eating (as in Dr. Atkins New Diet Revolution) was safe and effective for short-term weight management and control of diabetes.  I was still concerned back then about the long-term safety of the high fat content of Atkins.  But 80 hours of literature review in 2009 allowed me to embrace low-carbohydrate eating as a logical and viable option for many of my patients.  The evidence convinced me that the high fat content (saturated or otherwise) of many low-carb diets was little to worry about over the long run.

By the way, have you noticed some of the celebrities jumping on the low-carb weight-management bandwagon lately?  Sharon Osbourne, Drew Carey, and Alec Baldwin, to name a few.

My primary nutrition interests are low-carb eating, the Mediterranean diet, and the paleo diet.  I’m careful to stay up-to-date with the pertinent scientific research.  I’d like to share with you some of the pertinent research findings of the last few years.

Low-Carb Diets

  • Low-carb diets reduce weight, reduce blood pressure, lower triglyceride levels (a healthy move), and raise HDL cholesterol (another good trend).  These improvements should help reduce your risk of heart disease.  (In the journal Obesity Reviews, 2012.)
  • Dietary fat, including saturated fat, is not a cause of vascular disease such as heart attacks and atherosclerosis (hardening of the arteries).  (Multiple research reports.)
  • If you’re overweight and replace two sugary drinks a day with diet soda or water, you’ll lose about four pounds over the next six months.  (American Journal of Clinical Nutrition, 2012.)
  • United States residents obtain 40% of total calories from grains and added sugars.  Most developed countries are similar.  Dr. Stephan Guyenet notes that U.S. sugar consumption increased steadily “…from 6.3 pounds [2.9 kg] per person per year in 1822 to 107.7 pounds [50 kg] per person in 1999.  Wrap your brain around this: in 1822 we ate the amount of added sugar in one 12-ounce can of soda every five days, while today we eat that much sugar every seven hours.”
  • A very-low-carb diet improves the memory of those with age-related mild cognitive impairment. Mild cognitive impairment is a precursor to dementia.  (University of Cincinnati, 2012.)
  • High-carbohydrate and sugar-rich diets greatly raise the risk of mild cognitive impairment in the elderly. (Mayo Clinic study published in the Journal of Alzheimers’ Disease, 2012.)
  • Compared to obese low-fat dieters, low-carb dieters lose twice as much fat weight.  (University of Cincinnati, 2011.)
  • Diets low in sugar and refined starches are linked to lower risk of age-related macular degeneration in women.  Macular degeneration is a major cause of blindness.  (University of Wisconsin, 2011.)
  • A ketogenic (very-low-carb) Mediterranean diet cures metabolic syndrome (Journal of Medicinal Food, 2011.)
  • For type 2 diabetics, replacing a daily muffin (high-carb) with two ounces (60 g) of nuts (low-carb) improves blood sugar control and reduces LDL cholesterol (the “bad” cholesterol). (Diabetes Care, 2011.)
  • For those afflicted with fatty liver, a low-carb diet beats a low-fat diet for management. (American Journal of Clinical Nutrition, 2011.)
  • For weight loss, the American Diabetes Association has endorsed low-carb (under 130 g/day) and Mediterranean diets, for use up to two years. (Diabetes Care, 2011.)
  • High-carbohydrate eating doubles the risk of heart disease (coronary artery disease) in women.  (Archives of Internal Medicine, 2010.)
  • One criticism of low-carb diets is that they may be high in protein, which in turn may cause bone thinning (osteoporosis).  A 2010 study shows this is not a problem, at least in women.  Men were not studied.  (American Journal of Clinical Nutrition.)
  • High-carbohydrate eating increases the risk of developing type 2 diabetes (American Journal of Clinical Nutrition, 2010.)
  • Obesity in U.S. children tripled from 1980 to 2000, rising to 17% of all children.  A low-carb, high-protein diet is safe and effective for obese adolescents.  (American Journal of Clinical Nutrition, 2010.)

Mediterranean Diet

The traditional Mediterranean diet is well established as a healthy way of eating despite being relatively high in carbohydrate: 50 to 60% of total calories.  It’s known to prolong life span while reducing rates of heart disease, cancer, strokes, diabetes, and dementia.  The Mediterranean diet is rich in fresh fruits, vegetables, nuts and seeds, olive oil, whole grain bread, fish, and judicious amounts of wine, while incorporating relatively little meat.  It deserves your serious consideration.  I keep abreast of the latest scientific literature on this diet.

  • Olive oil is linked to longer life span and reduced heart disease.  (American Journal of Clinical Nutrition, 2012.)
  • Olive oil is associated with reduced stroke risk.  (Neurology, 2012).
  • The Mediterranean diet reduces risk of sudden cardiac death in women.  (Journal of the American Medical Association, 2011.)
  • The Mediterranean diet is linked to fewer strokes visible by MRI scanning.  (Annals of Neurology, 2011.)
  • It reduces the symptoms of asthma in children.  (Journal of the American Dietetic Association, 2011.)
  • Compared to low-fat eating, it reduces the incidence of type 2 diabetes by 50% in middle-aged and older folks.  (Diabetes Care, 2010.)
  •  A review of all available well-designed studies on the Mediterranean diet confirms that it reduces risk of death, decreases heart disease, and reduces rates of cancer, dementia, Parkinson’s disease, stroke, and mild cognitive impairment.  (American Journal of Clinical Nutrition, 2010.)
  • It reduces the risk of breast cancer.  (American Journal of Clinical Nutrition, 2010.)
  • The Mediterranean diet reduces Alzheimer’s disease.   (New York residents, Archives of Neurology, 2010).
  • It slows the rate of age-related mental decline.  (Chicago residents, American Journal of Clinical Nutrition, 2010.)
  • In patients already diagnosed with heart disease, the Mediterranean diet prevents future heart-related events and preserves heart function.  (American Journal of Clinical Nutrition, 2010.)

Clearly, low-carb and Mediterranean-style eating have much to recommend them.  Low-carb eating is particularly useful for weight loss and management, and control of diabetes, prediabetes, and metabolic syndrome.  Long-term health effects of low-carb eating are less well established.  That’s where the Mediterranean diet shines.  That’s why I ask many of my patients to combine both approaches: low-carb and Mediterranean.  Note that several components of the Mediterranean diet are inherently low-carb: olive oil, nuts and seeds, fish, some wines, and many fruits and vegetables.  These items easily fit into a low-carb lifestyle and may yield the long-term health benefits of the Mediterranean diet.  If you’re interested, I’ve posted on the Internet a Low-Carb Mediterranean Diet that will get you started.

Steve Parker, M.D.

Disclaimer:  All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physician before making any dietary or exercise changes.

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June 14, 2012 · 2:00 AM

Are Dietary Saturated Fats Dangerous?

This is an epic post from my old Advanced Mediterranean Diet blog, originally dated July 6, 2009. That was a watershed year for me because of the ideas in this article.  If you or your doctor think low-carb eating is dangerous because it may be higher in saturated fat, this post should convince you otherwise.

I’ve been thinking a lot lately about saturated fats. Weird, huh?

No saturated fat in grapes

The American Heart Association recommends that Americans limit the amount of saturated fats they eat to less than 7 percent of total daily calories. If you eat 2,000 calories a day, no more than 140 of them should come from saturated fats. That’s about 16 grams of saturated fats.

In over two decades of clinical practice, I’ve never run across a patient willing to do that calculation. Not many physicians could tell you the “seven percent rule.”

One of the two major themes of Gary Taubes’ book, Good Calories, Bad Calories, is that dietary saturated fats are not particularly harmful to our health, if at all. From what I’ve been taught, this is sacrilegious. “Saturated fats are a major cause of heart disease and strokes,” I’ve heard and read over and over. In brief, this is the Diet-Heart Hypothesis or the “lipid hypothesis”: Dietary saturated fat, total fat, and cholesterol are directly related to coronary heart disease and other forms of atherosclerosis (aka hardening of the arteries).

In his review of Taubes’ book, Dr. George Bray didn’t even address Taubes’ point about saturated fats, writing instead, “read and decide for yourself.”

That started me thinking either that the Diet-Heart Hypothesis is indefensible or that Dr. Bray is lazy. I don’t think he’s lazy. Dr. Bray is a Grand High Pooh-Bah in the fields of obesity and nutrition.

The American Heart Association in 1957 recommended that polyunsaturated fats replace saturated fats.

U.S. public health recommendations in 1977 were to reduce fat intake to 30% of total calories to lower the risk of coronary heart disease. Slowly, some fats were replaced mostly with carbohydrates, highly refined ones at that. This shift tends to raise triglycerides and lower HDL cholesterol levels, which may themselves contribute to atherosclerosis. Current recommendations are, essentially, to keep saturated fatty acids as low as possible.

One concern about substituting carbohydrates for fats is that blood sugar levels rise, leading to insulin release from the pancreas, in turn promoting growth of fat tissue and potentially leading to weight gain. Some believe that the public health recommendation to reduce total fat (which led to higher carbohydrate intake) is the reason for the dramatic rise in overweight and diabetes we’ve seen over the last 30 years.

Note that if intake of saturated fats is inadequate, our bodies can make the saturated fats it needs from carbohydrates. These are generally the same saturated fats that are present in dietary fats of animal origin. The only exceptions are the two essential fatty acids: alpha-linolenic acid and linoleic acid.

Why would saturated fats be harmful? Apparently because they raise blood levels of cholesterol (including LDL cholesterol – “bad cholesterol”), which is thought to be a cause of atherosclerosis, which increases the risk of coronary heart disease and stroke. I don’t recall seeing any mention of a direct toxic effect of saturated fats (or fatty acids) on arterial walls, where the rubber meets the road. (Saturated fats are broken down in the small intestine to glycerol and fatty acids.)

Dietary saturated fats also raise HDL cholesterol – “good cholesterol” – although not to the degree they raise LDL.

You needed a break

Let’s not forget many other factors that cause, contribute to, or predict coronary heart disease and atherosclerosis: smoking, family history, high blood pressure, obesity, diabetes, oxidative stress, homocysteine level, systemic inflammation, high-glycemic index diets, C-reactive protein, lack of exercise, and others. I discussed dietary factorsin my April 14, 2009, blog post.

Often overlooked in discussion of dietary fat effects is the great variability of response to fats among individuals. Response can depend on genetics, sex, fitness level, overweight or not, types of carbohydrates eaten, amount of total dietary fat, etc. And not all saturated fats affect cholesterol levels.

Many of the journal articles listed as references below support the idea that the link between dietary saturated fats and coronary heart disease is not strong, and may be nonexistent. Read them and you’ll find that:

  • Some studies show no association between dietary saturated fats and coronary heart disease.
  • Some studies associate lower rates of coronary heart disease with higher saturated fat intake.
  • Higher saturated fat intake was associated with less progression of coronary atherosclerosis in women.
  • Lowering saturated fat intake did not reduce total or coronary heart disease mortality.

“Read and decide for yourself,” indeed. I think you’ll begin to question the reigning dogma.

For example, here’s a conclusion from the Hooper article (from 2001):

In this review we have tried to separate out whether changes in individual fatty acid fractions are responsible for any benefits to health (using the technique of meta-regression). The answers are not definitive, the data being too sparse to be convincing. We are left with a suggestion that less total fat or less of any individual fatty acid fraction in the diet is beneficial.

And a conclusion of the J.B. German article:

At this time [2004], research on how specific saturated fatty acids contribute to coronary artery disease and on the role each specific saturated fatty acid play in other health outcomes is not sufficient to make global recommendations for all persons to remove saturated fats from their diet. No randomized clinical trials of low-fat diets or low-saturated fat diets of sufficient duration have been carried out; thus, there is a lack of knowledge of how low saturated fat intake can be without the risk of potentially deleterious health outcomes.

Zarraga and Schwartz (2006) conclude:

Numerous studies have been conducted to help provide dietary recommendations for optimal cardiovascular health. The most compelling data appear to come from trials that tested diets rich in fruits, vegetables, MUFAs [monounsaturated fatty acids], and PUFAs [polyunsaturated fatty acids], particularly the n-3 PUFAs. In addition, some degree of balance among various food groups appears to be a more sustainable behavioral practice than extreme restriction of a particular food group.

Here’s another of my favorite quotes on this topic, from the J.B. German article:

If saturated fatty acids were of no value or were harmful to humans, evolution would probably not have established within the mammary gland the means to produce saturated fatty acids . . . that provide a source of nourishment to ensure the growth , development, and survival of mammalian offspring.

Take-Home Points

The connection between dietary saturated fat and coronary heart disease is weak.

I may be excommunicated from the medical community for uttering this. You won’t hear it from most physicians or dietitians. They don’t have time to spend 80 hours on this topic, so they stick with the party line. And maybe I’m wrong anyway.

The scientific community is slowly moving away from the original Diet-Heart/Lipid Hypothesis. It is being replaced with stronger anti-atherosclerosis theories that promote:

  • fruit and vegetable intake
  • whole grain intake
  • low-glycemic index eating
  • increased consumption of plant oils and fish
  • moderate intake of nuts
  • ? moderate intake of low-fat diary (e.g., DASH diet) (less consensus on this point)

So, saturated fats and dietary cholesterol are being crowded out of the picture, or ignored. In many cases, saturated fats have literally been replaced by poly- and monounsaturated fats (plant oils). Several clinical studies indicate that’s a healthy change, but it may be related more to the healthfulness of the plant oils than to detrimental effects of saturated fats.

The original Diet-Heart Hypothesis won’t die until the American Heart Association and U.S. public health agencies put a gun to its head and pull the trigger. That will take another 10 years or more.

If you want to hedge your bets, go ahead and limit your saturated fat intake. It probably won’t hurt you. It might help a wee bit. By the same token, I’m not going on an all-meat and cheese, ultra-high-saturated fat diet; I don’t want to miss out on the healthy effects of fruits, vegetables, whole grains, fish, nuts, and low-glycemic index carbohydrates. Some would throw red wine into the mix. This “prudent diet” reflects what I hereby christen The 21st Century Diet-Heart Hypothesis.

If you’re worried about coronary heart disease and atherosclerosis, spend less time counting saturated fat grams, and more time on other risk-reducing factors: diet modification as above, get regular exercise, control your blood pressure, achieve a healthy weight, and don’t smoke. More bang for the buck.

What do you think?

Steve Parker, M.D.

Disclaimer: All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status. Always consult your personal physician before making any dietary or exercise changes.

Selected References Contradicting or Questioning the Diet-Heart Hypothesis (updated February 19, 2012):

Astrup, A., et al (including Ronald Krause, Frank Hu, and Walter Willett). The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010. American Journal of Clinical Nutrition, 93 (2011): 684-688. (The authors believe that replacing saturated fats with polyunsaturated fats (but not carbohydrates) can reduce the risk of coronary heart disease (CHD). For the last four decades, low-fat diets replaced fat with carbohydates. So they believe saturated fatty acids cause CHD or polyunsaturated fatty acids prevent it. I see no mention of total fat intake in this article written by major names in nutritional epidemiology and lipid metabolism. “In countries following a Western diet, replacing 1% of energy intake from saturated fatty acids with polyunsaturated fatty acids has been associated with a 2–3% reduction in the incidence of CHD.” “Furthermore, the effect of particular foods on CHD cannot be predicted solely by their content of total saturated fatty acids because individual saturated fatty acids may have different cardiovascular effects and major saturated fatty acid food sources contain other constituents that could influence coronary heart disease risk.”) A Feb. 19, 2012, press release from the Harvard School of Public Health covered much of the same ground. It’s titled “Time to Stop Talking About Low-Fat, say HSPH Nutrition Experts.”

Siri-Tarino, Patty, et al. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, January 13, 2010. doi:10.3945/ajcn.2009.27725

Skeaff, C. Murray and Miller, Jody. Dietary fat and coronary heart disease: Summary of evidence from prospective cohort and randomised controlled trials. Annals of Nutrition and Metabolism, 55 (2009): 173-201.

Halton, Thomas, et al. Low-carbohydrate-diet score and the risk of coronary heart disease in women. New England Journal of Medicine, 355 (2006): 1,991-2,002.

German, J. Bruce, and Dillard, Cora J. Saturated fats: What dietary intake? American Journal of Clinical Nutrition, 80 (2004): 550-559.

Ravnskov, U. The questionable role of saturated and polyunsaturated fatty acids in cardiovascular disease. Journal of Clinical Epidemiology, 51 (1998): 443-460.

Ravsnskov, U. Hypothesis out-of-date. The diet-heart idea. Journal of Clinical Epidemiology, 55 (2002): 1,057-1,063.

Ravnskov, U, et al. Studies of dietary fat and heart disease. Science, 295 (2002): 1,464-1,465.

Taubes, G. The soft science of dietary fat. Science, 291 (2001): 2535-2541.

Zarraga, Ignatius, and Schwartz, Ernst. Impact of dietary patterns and interventions on cardiovascular health. Circulation, 114 (2006): 961-973.

Mente, Andrew, et al. A Systematic Review of the Evidence Supporting a Causal Link Between Dietary Factors and Coronary Heart Disease. Archives of Internal Medicine, 169 (2009): 659-669.

Parikh, Parin, et al. Diets and cardiovascular disease: an evidence-based assessment. Journal of the American College of Cardiology, 45 (2005): 1,379-1,387.

Bray, G.A. Review of Good Calories, Bad Calories. Obesity Reviews, 9 (2008): 251-263. Reproduced at the Protein Power website of Drs. Michael and Mary Dan Eades.

Hooper, L., et al. Dietary fat intake and prevention of cardiovascular disease: systematic review. British Medical Journal, 322 (2001): 757-763.

Weinberg, W.C. The Diet-Heart Hypothesis: a critique. Journal of the American College of Cardiology, 43 (2004): 731-733.

Mozaffarian, Darius, et al. Dietary fats, carbohydrate, and progression of coronary atherosclerosis in postmenopausal women. American Journal of Clinical Nutrition, 80 (2004): 1,175-1,184.

Related editorial: Knopp, Robert and Retzlaff, Barbara. Saturated fat prevents coronary artery disease? An American paradox. American Journal of Clinical Nutrition, 80 (2004): 1.102-1.103.

Yusuf, S., et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet, 364 (2004): 937-952. (ApoB/ApoA1 ratio was a risk factor for heart attack, so dietary saturated fat may play a role if it affects this ratio.)

Hu, Frank. Diet and cardiovascular disease prevention: The need for a paradigm shift. Journal of the American College of Cardiology, 50 (2007): 22-24. (Dr. Hu de-emphasizes the original diet-heart hypothesis, noting instead that “. . . reducing dietary GL [glycemic load] should be made a top public health priority.:)

Oh, K., et al. Dietary fat intake and risk of coronary heart disease in women: 20 years of follow-up of the Nurses’ Health Study. American Journal of Epidemiology, 161 (2005): 672-679.

Parker, Steve. Time to abandon the diet-heart hypothesis? Advanced Mediterranean Diet Blog, May 1, 2009.

Parker, Steve. New study confirms the heart-healthy Mediterranean diet. Advanced Mediterranean Diet Blog, April 14, 2009. (Examination of the Mente study listed above.)

Selected References Supporting the Diet-Heart Hypothesis (by no means exhaustive)

Ascherio, A. Epidemiologic studies on dietary fats and coronary heart disease. American Journal of Medicine, 113 (supplement) (2002): 9S-12S.

Griel, Amy and Kris-Etherton, Penny. Beyond saturated fat: The importance of the dietary fatty acid profile on cardiovascular disease. Nutrition Reviews, 64 (2006): 257-262. (Primarily a response to the Mozaffarian article above.)

Erkkila, Arja, et al. Dietary fatty acids and cardiovascular disease: An epidemiological approach. Progress in Lipid Research, 47 (2008): 172-187.

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April 1, 2011 · 2:00 AM

Origins and Definition of the Mediterranean Diet

ORIGINS

It all starts with Ancel  Keys.

Keys was the leader of the team who put together the Seven Countries Study, which seemed to demonstrate lower rates of coronary heart disease in countries consuming less saturated fat.  [Coronary heart disease is the leading cause of death in Western cultures.]  He also found that cardiovascular disease rates rose in tandem with blood cholesterol  levels.  The two countries particularly illustrative of these connections were Italy and Greece, both Mediterranean countries.

The other countries he analyzed in Seven Countries were the United States, Yugoslavia, Japan, Finland, and the Netherlands.

Keys and his wife Margaret, a biochemist, drilled deeper in to the “Mediterranean diet” that was characteristic of Italy, Greece, and other countries on or near the Mediterranean Sea in the 1950s and 1960s.  [“Diet” in this context refers to the usual  food and drink of a person, not a weight-loss program.]  Their efforts culminated in the publication of several best-selling Mediterranean diet books in the 1970s, and Keys’ photo on the cover of Time magazine in 1961.

Thus began the still-popular healthy Mediterranean diet.

Oldways Preservation Trust re-invigorated the Mediterranean diet around 1990, helping the public incorporate Mediterranean diet principals into everyday life.  Oldways founder, K. Dun Gifford, passed away within the last year.

DEFINITION

There is no monolithic, immutable, traditional Mediterranean diet.  But there are similarities among many of the regional countries that tend to unite them, gastronomically speaking.  Greece and southern Italy are particularly influential in this context.

So here are the characteristics of the traditional Mediterranean diet  of the mid-20th century:

•It maximizes natural whole foods and minimizes highly processed ones

•Small amounts of red meat

•Less than four eggs per week

•Low to moderate amounts of poultry and fish

•Daily fresh fruit

•Seasonal locally grown foods with minimal processing

•Concentrated sugars only a few times per week

•Wine in low to moderate amounts, and usually taken at mealtimes

•Milk products (mainly cheese and yogurt) in low to moderate amounts

•Olive oil as the predominant fat

•Abundance of foods from plants: vegetables, fruits, beans, potatoes, nuts, seeds, breads and other whole grain products

•Naturally low in saturated fat, trans fats, and cholesterol

•Naturally high in fiber, phytonutrients, vitamins (e.g., folate), antioxidants, and minerals (especially when compared with concentrated, refined starches and sugars in a modern Western diet)

•Naturally high in monounsaturated and polyunsaturated fats, particularly as a replacement for saturated fats

CONTROVERSIES

Keys has been criticized for “cherry-picking” the data that linked saturated fat consumption with increased heart disease.  In other words, the allegation is that he used information if it supported his theory, while ignoring data that was contrary or neutral.  Subsequent studies indicate a weak link, if any, between saturated fat consumption and heart disease.  A list of the pertinent studies de-linking heart disease and saturated fat is at my Advanced Mediterranean Diet Blog.

The Seven Countries Study included only men.  It’s practical implications, therefore, may not apply to women.

The traditional Mediterranean diet is increasingly a thing of the past as Mediterranean countries adopt the Western diet characterized by “fast food” and highly processed foods.

FUN FACTS FOR FOOD GEEKS

Ever heard of K rations used by the U.S. military in World War II?  Keys invented them.  He earned Ph.D.s in biology and physiology.  Keys lived to age 100 and was said to be intellectually active through his 97th year.

Steve Parker, M.D.

PS:  The Mediterranean diet has too many carbohydrates (55% of total energy) for for most people with diabetes.  Hence, the Low-Carb Mediterranean Diet.

References:

Keys, Ancel.  Coronary heart disease in seven countries.  Circulation, 41, (1970) supplement I: I-1 through I-211.

Keys, Ancel.  Seven Countries:  A Multivariate Analysis of Death and Coronary Artery Disease.  Harvard University Press, 1980.

Oldways website.

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January 12, 2011 · 2:00 AM

Asian Strokes Are Not Same as Western

The higher the consumption of saturated fat, the lower the risk of death from stroke, according to Japanese researchers in a recent American Journal of Clinical Nutrition. 

Most physicians in the West would have predicted the opposite: saturated fats increase your risk of stroke.  Western physicians tend to think most strokes and heart attacks are caused by the same process, atherosclerosis, and would be aggravated by saturated fat consumption.  We’re learning that ain’t necessarily so.

Most strokes in the Western world are thought to be linked to atherosclerosis (hardening of the arteries) of relatively large arteries. In Japan, most strokes not caused by bleeding in the head are actually lacunar infarctions involving small arteries in the brain, not necessarily involving atherosclerosis. 

Another major difference between East and West is that saturated fat consumption in Japan is far lower than in the West.

Are you confused yet?

It seems to me that comparing strokes in Japan versus the West is comparing apples to oranges.  The take-away point to me is that we have to be quite wary of generalizing the research results applicable to one culture or ethnic group, to others.

By the way, stroke had been the third leading cause of death in the U.S. for the last 50 years.  It was recently demoted to fourth place by chronic lower respiratory disease.  The traditional Mediterranean diet is one way to reduce your risk of stroke, and the DASH diet works for women.  Keeping your blood pressure under 140/90 is another.  And don’t smoke.

Steve Parker, M.D.

Reference:  Yamagishi, Kazumasa, et al.  Dietary intake of saturated fatty acids and mortality from cardiovascular disease in Japanese: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk Study.  American Journal of Clinical Nutrition, August 4, 2010.  doi: 10.3945/ajcn.2009.29146

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December 14, 2010 · 11:07 AM

Book Review: Why We Get Fat

Gary Taubes’s new book, Why We Get Fat: And What To Do About It, comes on the market later this month.  I give it five stars per Amazon.com’s ranking system (I love it).

♦   ♦   ♦

At the start of my medical career over two decades ago, many of my overweight patients were convinced they had a hormone problem causing it.  I carefully explained that’s rarely the case.  As it turns out, I may have been wrong.  And the hormone is insulin.

Mr. Taubes wrote this long-awaited book for two reasons: 1) to make the ideas in his 2007 masterpiece (Good Calories, Bad Calories) more accessible to the public, and 2) to speed up the process of changing conventional wisdom on overweight.  GCBC was the equivalent of a college-level course on nutrition, genetics, history, politics, science, physiology, and biochemistry. Many nutrition science geeks loved it while recognizing it was too difficult for the average person to digest.

Paradigm Shift

The author hopes to convince us that “We don’t get fat because we overeat; we overeat because we’re getting fat.”  We need to think of obesity as a disorder of excess fat accumulation, then ask why the fat tissue isn’t regulated properly.  A limited number of hormones and enzymes regulate fat storage; what’s the problem with them?

Mr. Taubes makes a great effort convince you the old “energy balance equation” doesn’t apply to fat storage.  You remember the equation: eat too many calories and you get fat, or fail to burn up enough calories with metabolism and exercise, and you get fat.  To lose fat, eat less and exercise more.  He prefers to call it the “calories-in/calories-out” theory.  He admits it has at least a little validity.  Problem is, the theory seems to have an awfully high failure rate when applied to weight management over the long run.  We’ve operated under that theory for the last half century, but keep getting fatter and fatter.  So the theory must be wrong on the face of it, right?  Is there a better one?

So, Why DO We Get Fat?

Here is Taubes’s explanation.  The hormone in charge of fat strorage is insulin; it works to make us fatter, building fat tissue.  If you’ve got too much fat, you must have too much insulin action.  And what drives insulin secretion from your pancreas?  Dietary carbohydrates, especially refined carbs such as sugars, flour, cereal grains, starchy vegetables (e.g., corn, beans, rice, potatoes), liquid carbs.  These are the “fattening carbs.”  Dozens of enzymes and hormones are at play either depositing fat into tissue, or mobilizing the fat to be used as energy.  It’s an active process going on continously.  Any regulatory derangement that favors fat accumulation will CAUSE gluttony (overeating) or sloth (inactivity).  So it’s not your fault. 

What To Do About It

Cut back on carb consumption to lower your fat-producing insulin levels, and you turn fat accumulation into fat mobilization.

Before you write off Taubes as a fly-by-night crackpot, be aware that he’s received three Science-in-Society Journalism Awards from the National Association of Science Writers.  He’s a respected, professional science writer.  Having read two of his books, it’s clear to me he’s very intelligent.  If he’s got a hidden agenda, it’s well hidden.

One example  illustrates how hormones control growth of tissues, including fat tissue.  Consider the transformation of a skinny 11-year-old girl into a voluptuous woman of 18. Various hormones make her grow and accumulate fat in the places we now see curves.  The hormones make her eat more, and they control the final product.  The girl has no choice.  Same with our adult fat tissue, but with different hormones. If some derangement is making us grow fatter, it’s going to make us more sedentary (so more energy can be diverted to fat tissue) or make us overeat, or both.  We can’t fight it.  At not least very well, as you can readily appreciate if look at the people around you at any American shopping mall.

This’N’That

Taubes’s writing is clear and persuasive.  He doesn’t beat you over the head with his conclusions. He lays out a logical series of facts and potential connections and explanations, helping you eventually see things his way.  If insulin controls fat storage by building and maintaining fat tissue, and if carboydrates drive insulin secretion, then the way to reduce overweight and obesity is carbohydrate-restricted eating, especially avoiding the fattening carbohydrates.  I’m sure that’s true for many folks, perhaps even a majority.

If you’re overweight and skeptical about this approach, you could try out a very-low-carb diet for a couple weeks or a month at little expense and risk (but not zero risk).  If Mr. Taubes and I are right, there’s a good chance you’ll lose weight.  At the back of the book is a university-affiliated low-carb eating plan.

If cutting carb consumption is so critical for long-term weight control, why is it that so many different diets—with no focus on carb restriction—seem to work, if only for the short run?  Taubes suggests it’s because nearly all diets reduce carb consumption to some degree, including the fattening carbs.  If you reduce your total daily calories by 500, for example, many of those calories will be from carbs.  Simply deciding to “eat healthy” works for some people: stopping soda pop, candy bars, cookies, desserts, beer, etc.  That cuts a lot of fattening carbs right there.

Losing excess weight or controlling weight by avoiding carbohydrates was the conventional wisdom prior to 1960, as documented by Mr. Taubes.  Low-carb diets for obesity date back almost 200 years.  The author attributes many of his ideas to German internist Gustav von Bergmann (1908).   

Taubes discusses the Paleolithic diet, mentioning that the average paleo diet derived about a third of total calories from carbohdyrates (compared to the standard American diet’s 55% of calories from carb).  My prior literature review  found 40-45% of paleo diet calories from carbohydrate.  I’m not sure who’s right.

Minor Bone of Contention RE: Coronary Heart Disease

Mr. Taubes provides numerous scientific references to back his assertions.  I checked out one in particular because it didn’t sound right.  Some background first. 

Reducing our total fat and saturated fat consumption over the last 40 years was supposed to lower our LDL cholesterol, thereby reducing the burden of coronary heart disease, which causes heart attacks.  Instead, we’ve experienced the obesity epidemic as those fats were replaced by carbohydrates.  Taubes mentions a 2009 medical journal article by Kuklina et al, in which Taubes says Kuklina points out the number of heart attacks has not decreased as we’ve made these diet changes.  Kuklina et al don’t say that.  In fact, age-standardized heart attack rates have decreased in the U.S. during the last decade. 

Furthermore, autopsy data document a reduced prevalence of anatomic coronary heart disease in people aged 20-59 from 1979 to 1994, but no change in prevalence for those over 60. The incidence of coronary heart disease decreased in the U.S. from 1971 to 1998 (the latest reliable data).  Death rates from heart disease and stroke have been decreasing steadily over the last 40 years in the U.S.; coronary heart disease death rates are down by 50%.  I do agree with Taubes that we shouldn’t credit those improvements to reduced total and saturated fat consumption.  [Reduced trans fat consumption may play a role, but that’s off-topic.] 

I think Mr. Taubes would like to believe that coronary artery disease is either more severe or unchanged in the last few decades because of low-fat, high-carb eating.  That would fit nicely with some of his theories, but it’s not the case.  Coronary artery disease is better now thanks to a variety of factors, but probably not diet (setting aside the trans-fat issue).

Going Forward

Low-carb dieting was vilified over the last half century partly out of concern that the accompanying high fat consumption would cause premature heart attacks, strokes, and death.  We know now that total dietary fat and saturated fat have little to do with coronary heart disease and atherosclerosis (hardening of the arteries), which sets the stage for a resurgence of low-carb eating.  

I advocate Mediterranean-style eating as the healthiest, in general.  It’s linked with prolonged life and lower risk of heart disease, stroke, dementia, diabetes, and cancer.  On the other hand, obesity is a strong risk factor for premature death and development of heart disease, stroke, diabetes, and cancer.  If consistent low-carb eating cures the obesity, is it healthier than the Mediterranean diet?  Maybe so.  Would a combination of low-carb and Mediterranean be better?  Maybe so.  I’m certain Mr. Taubes would welcome a decades-long interventional study comparing low-carb with the Mediterranean diet.  But that’s probably not going to happen in our lifetimes. 

Gary Taubes rejects the calories-in/calories-out theory of overweight that hasn’t done a very good job for us over the last 40 years.  Taubes’s alternative ideas deserve serious consideration.

Steve Parker, M.D.

Update December 18, 2010: I found Mr. Taubes’s reference for stating that Paleolithic diets provide about a third of calories from carbohydrate (22-40%), based on modern hunter-gatherer societies).  See References below.   

References:
Coronary heart disease autopsy data:  American Journal of Medicine, 110 (2001): 267-273.
Reduced heart attacks:  Circulation, 12 (2010): 1,322-1,328.
Reduced incidence of coronary heart disease:  www.UpToDate.com, topic: “Epidemiology of Coronary Heart Disease,” accessed December 11, 2010.
Death rates for coronary heart disease:  Journal of the American Medical Association, 294 (2005): 1,255-1,259.

Cordain, L., et al.  Plant-animal subsistance ratios and macronutrient energy estimations in worldwide hunter-gatherer diets.  American Journal of Clinical Nutrition, 71 (2000): 682-692.

Disclosure:  I don’t know Gary Taubes.  I requested from the publisher and received a free advance review copy of the book.  Otherwise I received nothing of value for this review.

Disclaimer:   All matters regarding your health require supervision by a personal physician or other appropriate health professional familiar with your current health status.  Always consult your personal physician before making any dietary or exercise changes.

Update April 22, 2013: 

As mentioned above, WWGF was based on Taubes’ 2007 book, Good Calories, Bad Calories. You may be interested in a highly critical review of GCBC by Seth at The Science of Nutrition.

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September 1, 2010 · 2:00 AM

Are Refined Carbs Worse for Your Heart Than Saturated Fat?

To reduce coronary heart disease, we need to focus on reducing consumption of refined carbohydrates rather than fat and cholesterol, according to Dr. Frank Hu.

Dr. Hu is not a wild-eyed, bomb-throwing radical. He’s a Harvard professor of nutrition and epidemiology with both M.D. and Ph.D. degrees.  High-glycemic-index carbs in particular are the bad boys, he writes in an editorial published in the American Journal of Clinical Nutrition earlier this year.

Additional details are at my April 26, 2010, post at the Self/NutritionData Heart Health Blog.

Steve Parker, M.D.

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