Tag Archives: cardiovascular disease

June 12, 2010 · 4:42 AM

Whole Grains in Diabetics: A Double-Edged Sword

 Whole grain and bran consumption are linked to reduced overall death rates and cardiovascular disease deaths in white women with type 2 diabetes, according to recent research from Boston-based investigators.

This is an important association since diabetics are prone to develop cardiovascular disease and suffer premature death.  Anything that can easily counteract those trends is welcome.

Several prior studies have found lower rates of cardiovascular disease in the general public eating whole grains.  I’m referring to fewer heart attacks and strokes, and fewer deaths from cardiovascular disease.

On the other hand, the carbohydrate content of whole grain products has the potential to complicate day-to-day management of diabetes by spiking blood sugars too high.  Too-high blood sugars aren’t healthy.  So, there’s the double edge.

What’s the Evidence That Whole Grains and Bran Prevent Death in Diabetics ?

ResearchBlogging.orgThe Harvard researchers followed 7,822 type 2 diabetic women in the massive Nurses’ Health Study over 26 years, during which 852 women died from any cause, including 295 from cardiovascular disease (195 from coronary heart disease, 100 from stroke).  Food-frequency questionnaires were administered periodically to the participants, with attention to whole grain and its components: cereal fiber, bran, and germ.  The hard clinical end-point in this study was death—from any and all causes, and from cardiovascular disease.   

Results

  • After adjustment for age and lifestyle and other dietary factors, only bran consumption was inversely associated with all-cause mortality: 25% lower risk of death for those eating an average of 10 g per day compared to 1 g per day.  In other words,the women who ate the most bran had the lowest risk of dying from any cause.
  • After adjustment for age and lifestyle and other dietary factors, whole grain intake trended towards protection against all-cause death, but not quite to the point of statistical significance.  Average highest consumption was 33 g per day, compared to lowest intake at 5 g per day. 
  • Bran consumption was consistently associated with lower risk of cardiovascular death: 35% lower risk comparing highest (10 g/day) with lowest consumption (1 g/day). 
  • “Added bran” was as protective against cardiovascular death as naturally occuring bran. 
  • Whole grain tended to protect against cardiovascular death, but did not reach statistical significance in the model adusting for lifestyle and other dietary variables (even when comparing 33 g/day to 5 g/day)
  • Whole grain and cereal fiber were inversely associated with all-cause and cardiovascular mortality when the investigators adjusted only for age, disregarding the possible effects of smoking, alcohol, overweight, physical activity, family history of heart disease, hormone therapy, duration of diabetes, total energy intake, fat intake (polyunsatrurated, trans-, saturated), magnesium, and folate.

The Researchers’ Conclusions

Whole-grain and bran intakes were associated with reduced all-cause and cardiovascular disease-specific mortality in women with diabetes mellitus. These findings suggest a potential benefit of whole-grain intake in reducing mortality and cardiovascular risk in diabetic patients.

The authors point out that whole grain and its components may be protective since they:

  • reduce blood lipids
  • lower blood pressure
  • reduce hyperinsulinemia and improve glucose control
  • improve performance of the arterial wall lining (endothelium)
  • reduce oxidative stress and iflammation

My Comments

Whole grain and bran consumption may indeed protect against death and cardiovascular disease in diabetic white women, but the effect is by no means dramatic.  I had speculated earlier whether whole grain intake might be particularly protective in diabetics, but this study suggests not.  Clearly, whole grains are no panacea. 

Diabetics hoping to avoid cardiovascular disease are well-advised to pay attention to—and modify—non-dietary risk factors for heart disease, such as obesity, smoking, and sedentary lifestyle.  Non-dietary issues probably outweigh the effects of diet, assuming blood sugars are reasonably controlled.

The traditional Mediterranean diet—prominently featuring whole grains—is associated with longer lifespan and less cardiovascular disease.   Canadian researchers in 2009 found moderately strong evidence that whole grains protect against coronary heart disease in the general population.  Yet a 2009 study did not find cereals contributing to the longer lifespan. 

I’m starting to think that the effect of diet on chronic disease is not as powerful as we have hoped.  

Steve Parker, M.D.

Reference: 
He, M., van Dam, R., Rimm, E., Hu, F., & Qi, L. (2010). Whole-Grain, Cereal Fiber, Bran, and Germ Intake and the Risks of All-Cause and Cardiovascular Disease-Specific Mortality Among Women With Type 2 Diabetes Mellitus Circulation, 121 (20), 2162-2168 DOI: 10.1161/CIRCULATIONAHA.109.907360

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April 24, 2010 · 8:21 AM

Whole Grains Reduce Heart Attacks and Strokes

Whole grain consumption is associated with a 21% reduction in cardiovascular disease when compared to minimal whole grain intake, according to a 2008 review article in Nutrition, Metabolism, and Cardiovascular Disease.   

Coronary heart disease is the No. 1 killer in the developed world.  Stroke is No. 3.  The term “cardiovascular disease” lumps together heart attacks, strokes, high blood pressure,  and generalized atherosclerosis (hardening of the arteries). 

Investigators at Wake Forest University reviewed seven pertinent studies looking at whole grains and cardiovascular disease.  The studies looked at groups of people, determining their baseline food consumption via questionnaire, and noted disease development over time.  These are called “prospective cohort studies.” 

None of these cohorts was composed purely of diabetics.

The people eating greater amounts of whole grain (average of 2.5 servings a day) had 21% lower risk of cardiovascular disease events compared to those who ate an average of 0.2 servings a day.  Disease events included heart disease, strokes, and fatal cardiovascular disease.  The lower risk was similar in degree whether the focus was on heart disease, stroke, or cardiovascular death.

Note that refined grain consumption was not associated with cardiovascular disease events. 

Why does this matter?

The traditional Mediterranean diet is rich in whole grains, which may help explain why the diet is associated with lower rates of cardiovascular disease.  If we look simply at longevity, however, a recent study found no benefit to the cereal grain component of the Mediterranean diet.  Go figure . . . doesn’t add up. 

Readers here know that over the last four months I’ve been reviewing the nutritional science literature that supports the disease-suppression claims for consumption of fruits, vegetables, and legumes.  I’ve been disappointed.  Fruit and vegetable consumption does not lower risk of cancer overall, nor does it prevent heart disease.  I haven’t found any strong evidence that legumes prevent or treat any disease, or have an effect on longevity.  Why all the literature review?  I’ve been deciding which healthy carbohydrates diabetics and prediabetics should add back into their diets after 8–12 weeks of the Ketogenic Mediterranean Diet.

The study at hand is fairly persuasive that whole grain consumption suppresses heart attacks and strokes and cardiovascular death.  [The paleo diet advocates and anti-gluten folks must be disappointed.]  I nominate whole grains as additional healthy carbs, perhaps the healthiest.

But . . .

. . .  for diabetics, there’s a fly in the ointment: the high carbohydrate content of grains often lead to high spikes in blood sugar.  It’s a pity, since diabetics are prone to develop cardiovascular disease and whole grains could counteract that.  We need a prospective cohort study of whole grain consumption in diabetics.  It’ll be done eventually, but I’m not holding my breath.

[Update June 12, 2010: The aforementioned study has been done in white women with type 2 diabetes.  Whole grain and bran consumption do seem to protect them against overall death and cardiovascular death.  The effect is not strong.]

What’s a guy or gal to do with this information now?

Non-diabetics:  Aim to incorporate two or three servings of whole grain daily into your diet if you want to lower your risk of heart disease and stroke. 

Diabetics:  Several options come to mind:

  1. Eat whatever you want and forget about it [not recommended].
  2. Does coronary heart disease runs in your family?  If so, try to incorporate one or two servings of whole grains daily, noting and addressing effects on your blood sugar one and two hours after consumption.  Eating whole grains alone will generally spike blood sugars higher than if you eat them with fats and protein.  Review acceptable blood sugar levels here.
  3. Regardless of family history, try to eat one or two servings of whole grains a day, noting and addressing effects on your blood sugar.  Then decide if it’s worth it.  Do you have to increase your diabetic drug dosages or add a new drug?  Are you tolerating the drugs?  Can you afford them?    
  4. Assess all your risk factors for developing heart disease: smoking, sedentary lifestyle, high blood pressure, age, high LDL cholesterol, family history, etc.  If you have multiple risk factors, see Option #3.  And modify the risk factors under your control.   
  5. Get your personal physician’s advice.    

Steve Parker, M.D.

Extra Credit:  The study authors suggest a number of reasons—and cite pertinent scientific references—how whole grains might reduce heart disease:

  • improved glucose homeostasis (protection against insulin resistance, less rise in blood sugar after ingestion [compared to refined grains], improved insulin sensitivity or beta-cell function)
  • advantageous blood lipid effects (soluble fiber from whole grains [especially oats] reduces LDL cholesterol, lower amounts of the small LDL particles thought to be particularly damaging to arteries, tendency to raise HDL cholesterol and trigylcerides [seen with insulin resistance in the metabolic syndrome])
  • improved function of the endothelial cells lining the arteries (improved vascular reactivity)

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.

Reference: Mellen, P.B, Walsh, T.F., and Herrington, D.M.  Whole grain intake and cardiovascular disease: a meta-analysis.  Nutrition, Metabolism and Cardiovascular Disease, 18 (2008): 283-290.

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January 18, 2010 · 2:00 AM

Grains and Legumes: Any Effect on Heart Disease and Stroke?

Several scientific studies published in the first five years of this century suggest that whole grain consumption protects agains coronary heart disease and possibly other types of cardiovascular disease, such as stroke. 

Note that researchers in this field, especially outside the U.S., use the term “cereal” to mean “a grass such as wheat, oats, or corn, the starchy grains of which are used as food.”  They also refer frequently to glycemic index and glycemic load, spelled “glycaemic” outside the U.S.  Most of the pertinent studies are observational (aka epidmiologic): groups of people were surveyed on food consumption, then rates of diseases were associated with various food types and amounts.  “Association” is not proof of causation. 

Here are highlights from a 2006 review article in the European Journal of Clinical Nutrition: 

The researchers concluded that a relationship between whole grain intake and coronary heart disease is seen with at least a 20% and perhaps a 40% reduction in risk for those who eat whole grain food habitually vs those who eat them rarely.

Whole grain products have strong antioxidant activity and contain phytoestrogens, but there is insufficient evidence to determine whether this is beneficial in coronary heart disease prevention.

Countering the positive evidence for whole grain and legume intake has been the Nurses Health Study in 2000 that showed women who were overweight or obese consuming a high glycaemic load (GL) diet doubled their relative risk of coronary heart disease compared with those consuming a low GL diet.

The intake of high GI carbohydrates (from both grain and non-grain sources) in large amounts is associatied with an increased risk of heart disease in overweight and obese women even when fiber intake is high but this requires further confirmation in normal-weight women.

Promotion of carbohydrate foods should befocused on whole grain cereals because these have proven to be associatied with health benefits.

Whether adding bran to refined carbohydrate foods can improve the situation is also not clear, and it was found that added bran lowered heart disease risk in men by 30%.

Recommendation:  Carbohydrate-rich foods should be whole grain and if theyare not, then the lowest GI product available should be consumed.

My Comments

This journal article focuses on whole grains rather than legumes, and promotes whole grains more than legumes.  For people with diabetes, this may be a bit of a problem since grains—whole or not—generally have a higher glycemic index than legumes, which may have adverse effects on blood sugar control.  Keep in mind that highly refined grain products, like white bread, have a higher glycemic index than whole grain versions.

Did you notice that the abstract doesn’t recommend a specific amount of whole grains for the general population?  My educated guess would be one or two servings a day. 

Grains are high in carbohydrate, so anyone on a low-carb diet may have to cut carbs elsewhere. 

Diabetes predisoses to development of coronary heart disease.  Whole grains seem to help prevent heart disease, yet may adversely affect glucose control, contributing to diabetic complications.  It’s a quandary.  “Caught between the horns of a dilemma,” you might say.  So, what should a diabetic do with this information in 2010, while we await additional research results?

Several options come to mind:

  1. Eat whatever you want and forget about it.
  2. Note whether coronary heart disease runs in your family.  If so, try to incorporate one or two servings of whole grains daily, noting and addressing effects on your blood sugar.
  3. Try to eat one or two servings of whole grains a day, noting and addressing effects on your blood sugar.  Then decide if it’s worth it.  Is there any effect?  Do you have to increase your diabetic drug dosages or add a new drug?  Are you tolerating the drugs?    
  4. Assess all your risk factors for developing heart disease: smoking, sedentary lifestyle, high blood pressure, age, high LDL cholesterol, family history, etc.  If you have multiple risk factors, see Option #3.  And modify the risk factors under your control.   
  5. Get your personal physician’s advice.    

Before you stress out over this, be aware that we don’t really know whether a diabetic who doesn’t eat grains will have a longer healthier life by starting a daily whole grain habit.  Maybe . . . maybe not.  The study hasn’t been done.    

Steve Parker, M.D.

References:

Flight, I. and Clifton, P.  Cereal grains and legumes in the prevention of coronary heart disease and stroke: a review of the literature.  European Journal of Clinical Nutrition, 60 (2006): 1,145-1,159.

Malik, V. and Hu, Frank.  Dietary prevention of atherosclerosis: go with whole grains.  American Journal of Clinical Nutrition, 85 (2007): 1,444-1,445.

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November 9, 2009 · 2:00 AM

Walnuts: More Evidence in Favor of Health Benefits

MPj03095770000[1]Nuts are a time-honored component of the Mediterranean diet and may contribute to the lower risk of cardiovascular disease  associated with the diet. 

Regular nut consumption lowers total cholesterol and LDL (“bad cholesterol”) by 5 to 15%, which would tend to lower heart disease risk.  Walnuts are particularly high in alpha-linolenic acid, an omega-3 fatty acid.

Bix over at Fanatic Cook links to three scientific studies showing that walnuts:

  • improved arterial function in people with type 2 diabetes
  • improved arterial function in people with high cholesterol eating a Mediterranean diet
  • decreased fasting insulin levels in people with type 2 diabetes
  • decreased LDL cholesterol in people with type 2 diabetes who were on a low-fat diet

The “dose” of walnuts in these studies was 1–2 ounces (28–56 g) daily.

For good reason, nuts have a prominent role in both the Advanced Mediterranean Diet and Ketogenic Mediterranean Diet. 

I don’t know Bix, but he or she seems to base many of his/her nutrition opinions on scientific principles, which I appreciate.

Steve Parker, M.D.

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September 7, 2009 · 2:08 AM

Do Grape Products Other Than Wine Affect Heart Disease Risk?

"Grapes may be just as healthful as wine"

"Grapes may be just as healthful as wine"

Grape products favorably affect four risk factors for heart disease, according to a scientific review published last year.

The “French Paradox” refers to the fact that certain regions of France have low levels of heart disease despite high consumption of saturated fats that supposedly cause heart disease.  Some have explained away the paradox by noting high consumption of red wine in those areas, which could counteract the adverse effects of saturated fats.  Others have used the paradox to indict the Diet-Heart Hypothesis itself. 

Wine, especially red wine, is an integral part of the Ketogenic Mediterranean Diet.  However, many people just don’t like wine, and others shouldn’t be drinking it.  So, I’ve been wondering if grape products other than wine might have the healthy effects of wine.

The reference article below reviewed grape product trials published over the previous 13 years: 34 studies in animals, 41 in humans.  In addition to wine, grape products included grape juice, grape seed, grape skin, grape pomace, and polyphenol-rich extracts.  The authors conclude that grape products have the following beneficial effects on cardiovascular risk factors:

  • lower blood pressure, mainly due to release of nitric oxide from cells lining the arteries
  • reduced levels of total cholesterol, LDL cholesterol (“bad cholesterol”), and trigylcerides, especially if these values are high at baseline
  • reduced development of early-stage atherosclerosis (less LDL oxidation and plaque formation)
  • improved antioxidant status

Here are some grape product “fun facts” from the article:

  • healthy effects are primarily attributed to polyphenols, which are strong antioxidants that disable free radicals and chelate metals
  • major grape polyphenols are anthocyanins in red grapes, flavon-3-ols in white grapes
  • red grapes have more total polyphenols than white grapes
  • the main polyphenols in wine are resveratrol, tannins, flavan-3-ols, flavan-3,4-diols, anthocyanins, flavonols, flavones, anthocyanins, and anthocyanidins
  • red wine has a much higher phenolic content than white wine

Unfortunately, the authors never make any specific recommendations for people wanting to substitute alcohol-free grape products for wine.  

But I bet if you went down to your local vitamin or health food store, you could find some grape extracts or other grape products to try.  Anyone on a very low-carb diet would want to be sure the grape product wouldn’t supply more than 3-4 grams of digestible carbohydrate per day.  For those not on such a diet, purple grape juice like Welch’s—4 to 8 fl oz a day—is a good alternative to wine.  Welch’s has 42 g of carbohydrate per 8 fl oz. 

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.

Reference:  Perez-Jimenez, Jara and Saura-Calixto, Fulgencio.  Grape products and cardiovascular disease risk factors.  Nutrition Research Reviews, 21 (2008): 158-173.

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June 21, 2009 · 2:00 AM

Adverse Health Effects of Obesity

"I'm not fat, I'm chubby"

"I'm not fat, I'm chubby"

As a physician, I see many illnesses and conditions that are caused or aggravated by overweight and obesity.  Both terms refer to excess body fat; obesity is a greater degree of fat.

Body mass index (BMI) is used to define overweight and obesity.  Your BMI is your weight in kilograms divided by your height in meters squared.  A BMI between 18.5 and 25 is considered healthy.  BMIs between 25 and 30 are overweight.  Here’s an online BMI calculator.  For example, a 5-foot, 4-inch person enters obesity territory – BMI over 30 – when weight reaches 174 pounds (79 kilograms).  A 5-foot, 10-incher is obese starting at 208 pounds (94.5 kilograms).

People trying to lose excess fat typically have days when willpower, discipline, and commitment waver.  On those days, it can help to remember why they started this adventure in the first place.  The reasons for many involve improved health and longevity.  Even if you have just 20 pounds of excess fat to lose, it will often take twenty weeks.  Your weight-loss goal is one to one-and-a-half pounds a week. 

This race is won not by the swift, but by the slow and steady.

Here’s a laundry list of obesity-related conditions to remind you why you want to avoid obesity:

  • Premature death.  It starts at BMI of 30, with a major increase in premature death at BMI over 40.  The U.S. has 200,000 yearly deaths directly attributable to obesity.
  • Arthritis, especially of the knees.
  • Type 2 diabetes melllitus.  Eight-five percent of people with type 2 diabetes are overweight.
  • Increased cardiovascular disease risk, especially with an apple-shaped fat distribution as compared to pear-shaped.  Cardiovascular disease includes heart attacks, high blood pressure, strokes, and peripheral arterial disease (poor circulation).
  • Obstructive sleep apnea.
  • Gallstones are three or four times more common in the obese.
  • High blood pressure.  At least one third of cases are caused by excess body fat.  Every 20 pounds of excess fat raises blood pressure 2-3 points (mmHg).
  • Tendency to higher total and LDL cholesterol, higher triglycerides, while lowering HDL cholesterol.  These lipid changes are associated with hardening of the arteries – atherosclerosis – which can lead to heart attacks, strokes, and peripheral arterial disease.
  • Increased cancers.  Prostate and colorectal in men.  Endometrial, gallbladder, cervix, ovary, and breast in women.  Kidney and esophageal adenocarcinoma in both sexes.  Excess fat contributes to 14-20% of all cancer-related deaths in the U.S.  Over 550,000 people die from cancer in the U.S. yearly.  Twenty percent of us will die from cancer.
  • Strokes.
  • Low back pain.
  • Gout.
  • Varicose veins.
  • Hemorrhoids.
  • Blood clots in legs and lungs.
  • Surgery complications: poor wound healing, blood clots, wound infection, breathing problems.
  • Pregnancy complications: toxemia, high blood pressure, diabetes, prolonged labor, greater need for C-section.
  • Fat build-up in liver.
  • Asthma.
  • Low sperm counts.
  • Decreased fertility.
  • Delayed or missed diagnosis due to difficult physical examination or weight exceeding the limit of diagnostic equipment.

I hope you find this information motivational rather than depressing.  For those already obese, weight loss can significantly improve, alleviate, or prevent these conditions.  Many obesity-related medical conditions and metabolic abnormalities are improved with loss of just five or 10% of total body weight.  For instance, a 240 pound man with mild diabetes and high blood pressure may be able to reduce or avoid drug therapy by losing just 12 to 24 pounds.  He’s still obese, but healthier.

Steve Parker, M.D. 

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