Category Archives: Fat in Diet

Supplemental Omega-3 Fats’ Effect on Heart Disease, Stroke, Cancer, and Death: No Relationship In a General Population

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

I’ve been sitting on this research report a few years, waiting until I had time to dig into it. That time never came. The full report is free online (thanks, British Medical Journal!). I scanned the full paper to learn that nearly all the studies in this meta-analysis used fish oil supplements, not the cold-water fatty fish the I recommend my patients eat twice a week.

Here’s the abstract:

Objective: To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer.

Data sources: Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies.

Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate.

Results: Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded.

Conclusion: Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Reference: Hooper, Lee et al. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ  2006;332:752-760 (1 April), doi:10.1136/bmj.38755.366331.2F (published 24 March 2006).

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Filed under coronary heart disease, Diabetes Complications, Fat in Diet, Fish, Heart Disease, Longevity, Stroke

Low-Carb Diet Improves Glucose Control in Japanese Type 2 Diabetics

Mt. Fuji in Japan

Mt. Fuji in Japan

I don’ know anything about Japanese T2 diabetes. I’ve never studied it. Their underlying physiology may or may not be the same as in North American white diabetics, with whom I am much more familiar.

For what it’s worth, a small study recently found improvement of blood sugar control and triglycerides in those on a carbohydrate restricted diet versus a standard calorie-restricted diet.

Only 24 patients were involved. Half were assigned to eat low-carb without calorie restriction; the other half ate the control diet. The carbohydrate-restricted group aimed for 70-130 grams of carb daily, while eating more fat and protein than the control group. The calorie-restricted guys were taught how to get 50-60% of calories from carbohydrate and keep fat under 25% of calories. At the end of the six-month study, the low-carbers were averaging 125 g of carb daily, compare to 200 g for the other group. By six months, both groups were eating about the same amount of calories.

Average age was 63. Body mass index was 24.5 in the low-carb group and 27 in the controls. (If you did the research, I bet you’d find Japanese T2 diabetics have lower BMIs than American diabetics.) All were taking one or more diabetes drugs.

The calorie-restricted group didn’t change their hemoglobin A1c (a standard measure of glucose control) from 7.7%. The low-carb group dropped their hemoglobin A1c from 7.6 to 7.0% (statistically significant). The low-carb group also cut their triglycerides by 40%. Average weights didn’t change in either group.

Bottom Line

This small study suggests that mild to moderate carbohydrate restriction helps control diabetes in Japanese with type 2 diabetes. The improvement in hemoglobin A1c is equivalent to that seen with initiation of many diabetes drugs. I think further improvements in multiple measures would have been seen if carbohydrates had been restricted even further.

Steve Parker, M.D.

Link to reference.

h/t Dr Michael Eades

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Filed under Carbohydrate, Fat in Diet

Can You Manage Your Type 2 Diabetes Without Drugs?

David Mendosa says you can. I’m not quite that optimistic, but probably a majority can, if they have the knowledge, discipline, and willpower. Here are some snippets from David’s blog:

You can use drugs to bring your A1C level down to normal. That’s a good thing. But this strategy does have its costs, and those costs aren’t just money out of your pocket or your checkbook. The worst of those costs are the potential side effects of the drugs.

***

But some of us think we have a safer strategy of managing our diabetes without drugs. Back in 2007 I joined this group with the encouragement of a good friend of mine who is a Certified Diabetes Educator. Before that, I had 14 years of experience taking a wide range of diabetes drugs, including two different sulfonylureas (Diaßeta and Amyrl), Glucophage (metformin), and Byetta. For the past six years I haven’t taking any diabetes drugs, and yet I keep my diabetes in control with an A1C level usually about 5.4.

I had to make three big changes in my life when I went off the diabetes drugs, and they are hard at first. But now they are a routine part of my life, and I would never go back to my old ways. The changes that I had to make are those that almost everyone who has diabetes has to make. In order of importance, I had (1) to lose weight, (2) eat fewer carbohydrates, and (3) exercise more.

Read the whole enchilada. It’s brief.

Steve Parker, M.D.

 

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Filed under Exercise, Fat in Diet

Large Breakfast Rich in Protein and Fat Beats a Small Breakfast Strategy in Type 2 Diabetes

…according to research reported at MedPageToday.  This was a relatively small study with about 30 participants in each treatment arm. A snippet:

Patients in the big-breakfast group were instructed to consume 33% of their daily calories in their morning meal — that included up to 30% protein, up to 37% fat, and the rest in carbohydrates. Patients in the small-breakfast group were instructed to consume 12.5% of their daily calories at breakfast — with up to 70% in the form of carbohydrates.

Average fasting glucose decreased 14.51 mg/dL in the big breakfast group and decreased 4.91 mg/dL in the small breakfast group (P=0.011), she said at the annual meeting of the European Association for the Study of Diabetes.

The big breakfast group also saw a significant drop in systolic blood pressure (almost 10 mmHg), although probably not to the point it created a problem.

Read the whole enchilada.

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Periodic Tests, Treatments, and Goals for PWDs (Persons With Diabetes)

If you don't like your physician, find a new one

If you don’t like your physician, find a new one

So, you’ve got diabetes. You’re trying to deal with it or you wouldn’t be here. You’ve got a heck of a lot of medical information to master.

Unless you have a good diabetes specialist physician on your team, you may not be getting optimal care. Below are some guidelines you may find helpful. The goal is to prevent diabetes complications. Many primary care physicians will not be up-to-date on the guidelines. Don’t hesitate to discuss them with your doctor. Nobody cares as much about your health as you do.

Annual Tests

The American Diabetes Association (ADA) recommends the following items be done yearly (except as noted) in non-pregnant adults with diabetes. (Incidentally, I don’t necessarily agree with all ADA guidelines.) The complete ADA guidelines are available on the Internet.

  • Lipid profile (every two years if results are fine and stable)
  • Comprehensive foot exam
  • Screening test for distal symmetric polyneuropathy: pinprick, vibration, monofilament pressure sense
  • Serum creatinine and estimate of glomerular filtration rate (MDRD equation)
  • Test for albumin in the urine, such as measurement of albumin-to-creatinine ratio in a random spot urine specimen
  • Comprehensive eye exam by an ophthalmologist or optometrist (if exam is normal, every two or three years is acceptable)
  • Hemoglobin A1c at least twice a year, but every three months if therapy has changed or glucose control is not at goal
  • Flu shots

Other Vaccinations, Weight Loss, Diabetic Diet, Prediabetes, Alcohol, Exercise, Etc.

Additionally, the 2013 ADA guidelines recommend:

  • Pneumococcal vaccination. “A one time re-vaccination is recommended for individuals >64 years of age previously immunized when they were <65 years of age if the vaccine was administered >5 years ago.” Also repeat the vaccination after five years for patients with nephrotic syndrome, chronic kidney disease, other immunocompromised states (poor ability to fight infection), or transplantation.
  • Hepatitis B vaccination to unvaccinated adults who are 19 through 59 years of age.
  • Weight loss for all overweight diabetics. “For weight loss, either low-carbohydrate, low-fat calorie-restricted, or Mediterranean diets may be effective in the short-term (up to two years).” For those on low-carb diets, monitor lipids, kidney function, and protein consumption, and adjust diabetic drugs as needed. The optimal macronutrient composition of weight loss diets has not been established. (Macronutrients are carbohydrates, proteins, and fats.)
  • “The mix of carbohydrate, protein, and fat may be adjusted to meet the metabolic goals and individual preferences of the person with diabetes.” “It must be clearly recognized that regardless of the macronutrient mix, total caloric intake must be appropriate to weight management goal.”
  • “A variety of dietary meal patterns are likely effective in managing diabetes including Mediterranean-style, plant-based (vegan or vegetarian), low-fat and lower-carbohydrate eating patterns.”
  • “Monitoring carbohydrate, whether by carbohydrate counting, choices, or experience-based estimation, remains a key strategy in achieving glycemic control.”
  • Limit alcohol to one (women) or two (men) drinks a day.
  • Limit saturated fat to less than seven percent of calories.
  • During the initial diabetic exam, screen for peripheral arterial disease (poor circulation). Strongly consider calculation of the ankle-brachial index for those over 50 years of age; consider it for younger patients if they have risk factors for poor circulation.
  • Those at risk for diabetes, including prediabetics, should aim for moderate weight loss (about seven percent of body weight) if overweight. Either low-carbohydrate, low-fat calorie-restricted, or Mediterranean diets may be effective in the short-term (up to 2 years). Also important is exercise: at least 150 minutes per week of moderate-intensity aerobic activity. “Individuals at risk for type 2 diabetes should be encouraged to achieve the U.S. Department of Agriculture (USDA) recommendation for dietary fiber (14 g fiber/1,000 kcal) and foods containing whole grains (one-half of grain intake).” Limit intake of sugar-sweetened beverages.
  • “Adults with diabetes should be advised to perform at least 150 min/week of moderate-intensity aerobic physical activity (50–70% of maximum heart rate), spread over at least 3 days/week with no more than two consecutive days without exercise. In the absence of contraindications, adults with type 2 diabetes should be encouraged to perform resistance training at least twice per week.”
  • Screening for coronary artery disease before an exercise program is depends on the physician judgment on a case-by-case basis. Routine screening is not recommended.
Steve Parker MD, low-carb diet, diabetic diet

Olive, olive oil, and vinegar: classic Mediterranean foods

Obviously, some of my dietary recommendations conflict with ADA guidelines. The experts assembled by the ADA to compose guidelines were well-intentioned, intelligent, and hard-working. The guidelines are supported by 528 scientific journal references. I greatly appreciate the expert panel’s work. We’ve simply reached some different conclusions. By the same token, I’m sure the expert panel didn’t have unanimous agreement on all the final recommendations. I invite you to review the dietary guidelines yourself, discuss with your personal physician, then decide where you stand.

General Blood Glucose Treatment Goals

The ADA in 2013 suggests these therapeutic goals for non-pregnant adults:

  • Fasting blood glucoses: 70 to 130 mg/dl (3.9 to 7.2 mmol/l)
  • Peak glucoses one to two hours after start of meals: under 180 mg/dl (10 mmol/l)
  • Hemoglobin A1C: under 7%
  • Blood pressure: under 140/80 mmHg
  • LDL cholesterol: under 100 mg/dl (2.6 mmol/l). (In established cardiovascular disease: <70 mg/dl or 1.8 mmol/l may be a better goal.)
  • HDL cholesterol: over 40 mg/dl (1.0 mmol/l) for men and over 50 mg/dl (1.3 mmol/l) for women
  • Triglycerides: under 150 mg/dl (1.7 mmol/l)

The American Association of Clinical Endocrinologists (AACE) in 2011 proposed somewhat “tighter” blood sugar goals for non-pregnant adults:

  • Fasting blood glucoses: under 110 mg/dl (6.11 mmol/l)
  • Peak glucoses 2 hours after start of meals: under 140 mg/dl (7.78 mmol/l)
  • Hemoglobin A1C: 6.5% or less

The ADA reminds clinicians, and I’m sure the AACE guys agree, that diabetes control goals should be individualized, based on age and life expectancy of the patient, duration of diabetes, other diseases that are present, individual patient preferences, and whether the patient is able to easily recognize and deal with hypoglycemia. I agree completely.

Steve Parker, M.D.

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Filed under Diabetes Complications, Exercise, Fat in Diet, Fiber, Mediterranean Diet, Overweight and Obesity, Prediabetes, Prevention of T2 Diabetes

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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Filed under Carbohydrate, Fat in Diet, Health Benefits, Heart Disease, ketogenic diet, Mediterranean Diet, nuts, olive oil, Stroke, Vegetables, Weight Loss

Lower Risk of Death and Heart Disease With Olive Oil

 

Olive oil and vinegar

Olive oil consumption is linked to lower risk of death and heart disease in a Spanish population, according to the American Journal of Clinical Nutrition.

Olive oil figures prominently in my Ketogenic Mediterranean Diet and Low-Carb Mediterranean Diet.

-Steve

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Sources of Calories in U.S. Diet Over Last Four Decades

Italian seaside totally unrelated to this post

Do you ever wonder how many of your total calories come from added sugars? Grains? Dairy products? Added fats?

Deriving your personal numbers would require detailed nutrient analysis, but if you’d like U.S. averages, see this cool infographic at Civil Eats.

It also shows how many calories are or were available for consumption per capita over time (without accounting for wastage in restaurants). It’s based on U.S. Department of Agriculture data.

A superficial glance suggests that U.S. per capita daily calorie consumption has increased by about 600 from the 1970s until now. But remember, these numbers don’t discount for restaurant wastage. Nor do I see an adjustment for children versus adults. I’ve seen other calculations of and extra daily 150 calories (women) to 300 calories (men). Even the lower numbers could explain our explosion of overweight and obesity.

Steve Parker, M.D.

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Filed under Dairy Products, Fat in Diet, Grains, Overweight and Obesity, Sugar

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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Filed under Fat in Diet, Heart Disease

Random Thoughts On Paleo Eating for People With Diabetes

Not really pertinent, but I like buffalo

I was interviewed a couple months ago by Amy Stockwell Mercer, author of Smart Woman’s Guide to Diabetes. All I knew beforehand was that she was interested in my thoughts on the paleo diet as applied to diabetes.  I think she had run across my PaleoDiabetic blog.

In preparation, I collected some random thoughts and did a little research.

What’s the paleo diet?

Fresh, minimally processed food. Meat (lean or not? supermarket vs yuppiefied?), poultry, eggs, fish, leafy greens and other vegetables, nuts, berries, fruit, and probably tubers.

Non-paleo: highly processed, grains, refined sugars, industrial plant/seed oils, legumes, milk, cheese, yogurt.

The paleo diet is also called Old Stone Age, caveman, ancestral, hunter-gatherer, and Paleolithic diet.

Is the paleo diet deficient in any nutrients?

A quick scan of Loren Cordain’s website found mention of possible calcium and vitamin D deficits. Paleoistas will get vitamin D via sun exposure and fish (especially cold-water fatty fish). Obtain calcium from broccoli, kale, sardines, almonds, collards. (I wonder if the Recommended Dietary Allowance for calcium is set too high.)

What About Carbohydrates and Diabetes and the Paleo Diet?

Diabetes is a disorder of carbohydrate metabolism. In a way, it’s an intolerance of carbohydrates. In type 1 diabetes, there’s a total or near-total lack of insulin production on an autoimmune basis. In type 2 diabetes, the body’s insulin just isn’t working adequately; insulin production can be high, normal or low. In both cases, ingested carboydrates can’t be processed in a normal healthy way, so they stack up in the bloodstream as high blood sugars. If not addressed adequately, high blood glucose levels sooner or later will poison body tissues . Sooner in type 1, later in type 2. (Yes, this is a gross over-simplification.)

Gluten-rich Neolithic food

If you’re intolerant of lactose or gluten, you avoid those. If you’re intolerant of carbohydrates, you could avoid eating them, or take drugs to help you overcome your intolerance. Type 1 diabetics must take insulin. Insulin’s more optional for type 2’s. We have 11 classes of drugs to treat type 2 diabetes; we don’t know the potential adverse effects of most of these drugs. Already, three diabetes drugs have been taken off the U.S. market or severely restricted due to unacceptable toxicity: phenformin, troglitazone, and rosiglitazone.

Humans need two “essential fatty acids” and nine “essential” amino acids derived from proteins. “Essential” means we can’t be healthy and live long without them. Our bodies can’t synthesize them. On the other hand, there are no essential carbohydrates. Our bodies can make all the carbohydrate (mainly glucose) we need.

Since there are no essential carbohydrates, and we know little about the long-term adverse side effects of many of the diabetes drugs, I favor carbohydrate restriction for people with carboydrate intolerance. (To be clear, insulin is safe, indeed life-saving, for those with type 1 diabetes.)

That being said, let’s think about the Standard American Diet (SAD) eaten by an adult. It provides an average of 2673 calories a day. Added sugars provide 459 of those calories, or 17% o the total. Grains provide 625 calories, or 23% of the total. And most of those sugars and grains are in processed, commercial foods. So added sugars and grains provide 40% of the total calories in the SAD. (Figures are from an April 5, 2011, infographic at Civil Eats.)

Anyone going from the SAD to pure Paleo eating will be drastically reducing intake of added sugars and grains, our current major sources of carbohydrate. Question is, what will they replace those calories with?

That’s why I gave a thumbnail sketch of the paleo diet above. Take a gander and you’ll see lots of low-carb and no-carb options, along with some carb options. For folks with carbohydrate intolerance, I’d favor lower-carb veggies and judicious amounts of fruits, berries, and higher-carb veggies and

Will these cause bladder cancer? Pancreatitis?

tubers. “Judicious” depends on the individual, considering factors such as degree of residual insulin production, insulin sensitivity, the need to lose excess weight, and desire to avoid diabetes drugs.

Compared to the standard “diabetic diet” (what’s that?) and the Standard American Diet, switching to paleo should lower the glycemic index and glycemic load of the diet. Theoretically, that should help with blood sugar control.

A well-designed low-carb paleo diet would likely have at least twice as much fiber as the typical American diet, which would also tend to limit high blood sugar excursions.

In general, I favor a carbohydrate-restricted paleo diet for those with diabetes who have already decided to “go paleo.” I’m not endorsing any paleo diet for anyone with diabetes at this point—I’m still doing my research. But if you’re going to do it, I’d keep it lower-carb.  E.g., under 100 g of digestible carb daily. It has a lot of potential.

Are There Any Immediate Dangers for a Person With Diabetes Switching to the Paleo Diet?

It depends on three things: 1) current diet, and 2) current drug therapy, and 3) the particular version of paleo diet followed.

Remember, the Standard American Diet provides 40% of total calories as added sugars and grains (nearly all highly refined). Switching from SAD to a low-carb paleo diet will cut carb intake and glycemic load substantially, raising the risk of hypoglycemia if the person is taking certain drugs.

Drugs with potential to cause hypoglycemia include insulin, sulfonylureas, meglitinides, pramlintide, and perhaps thiazolidinediones.

Who knows about carb content of the standard “diabetic diet”? Contrary to poplular belief, there is no monolithic “diabetic diet.” There is no ADA diet (American Diabetes Association). My impression, however, is that the ADA favors relatively high carbohydrate consumption, perhaps 45-60% of total calories. Switching to low-carb paleo could definitely cause hypoglycemia in those taking the aforementioned drugs.

One way to avoid diet-induced hypoglycemia is to reduce the diabetic drug dose.

A type 2 overweight diabetic eating a Standard American Diet—and I know there are many out there—would tend to see lower glucose levels by switching to probably any of the popular paleo diets. Be ready for hypoglycemia if you take those drugs.

Paleo diets are not necessarily low-carb. Konner and Eaton estimate that ancestral hunter-gatherers obtained 35 to 40% of total calories from carbohydrates. I’ve seen other estimates as low as 22%. Reality likely falls between 22 and 65%. When pressed for a brief answer as to how many carbohydrate calories are in the paleo diet, I say “about a third of the total.” By comparison, the typical U.S. diet provides 50% of calories from carbohydrate.

Someone could end up with a high-carb paleo diet easily, by emphasizing tubers (e.g., potatoes), higher-carb vegetables, fruits, berries, and nuts (especially cashews). Compared with the SAD, this could cause higher or lower blood sugars, or no net change.

A diabetic on a Bernstein-style diet or Ketogenic Mediterranean Diet (both very-low-carb) but switching to paleo or low-carb paleo (50-150 g?) would see elevated blood sugars. Perhaps dangerously high glucoses.

Any person with diabetes making a change in diet should do it in consultation with a personal physician or other qualified healthcare professional familiar with their case.

Steve Parker, M.D.

Fun Facts!

  • A typical carbonated soda contain the equivalent of 10 tsp (50 ml) of sugar.
  • The typical U.S. adult eats 30 tsp (150 ml) daily of added sweeteners and sugars.
  • U.S total grain product consumption was at record lows in the 1970s, at 138 pounds per person. By 2000, grain consumption was up by 45%, to 200 pounds per person.
  • Total caloric sweetener consumption (by dry weight) was 110 pounds per person in the 1950s. By 2000, it was up 39% to 150 pounds.
  • Between 1970 and 2003, consumption of added fats and oils rose by 63%, from 53 to 85 pounds. [How tasty would that be without starches and sugars? Not very.]
  • In 2008, “added fat” calories in the U.S. adult diet were 641 (24% of total calories).

Fun Facts provided by the U.S. Department of Agriculture.

 

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Filed under Carbohydrate, Dairy Products, Drugs for Diabetes, Fat in Diet, Glycemic Index and Load, Grains, Paleo diet