Category Archives: Fruits

Longevity Components of the Mediterranean Diet

According to Greek researchers, the components of the Mediterranean diet that contribute to longer lifespan are:

  • moderate alcohol consumption
  • low consumption of meat
  • high consumption of vegetables, fruits, nuts, olive oil, and legumes

The following didn’t seem to contribute much, if any:

  • cereals (the grain of a grass such as wheat, corn, oats)
  • dairy products
  • fish and seafood

Investigators at the University of Athens examined the Greek portion of the European Prospective Investigation into Cancer (EPIC) and Nutrition, which included 23,349 men and women free of diabetes, cancer, and coronary heart disease at the outset.  Food habits were documented by questionnaire. 

The focus of this particular study was death rates over an average follow-up of 8.5 years.  Adherence to the traditional Mediterranean diet ranged from minimal to high, as would be expected. 

As with numerous other studies of the Mediterranean diet, higher adherence to the Mediterranean diet was associated with lower chance of death. 

My Comments

The lack of benefit from fish is unexpected.  I have no explanation.  A preponderance of evidence elsewhere suggests fish consumption helps prolong life via lowered rates of heart disease.

Alcohol can be dangerous, of course.  Some people should not partake, ever.     

For people with diabetes who wish to avoid the carbohydrate load in cereals and dairy products, you don’t need to worry much about cutting those out of an otherwise Mediterranean-style diet.

Steve Parker, M.D. 

Reference:  Trichopoulou, Antonia, et al.  Anatomy of health effects of the Mediterranean diet: Greek EPIC prospective cohort studyBritish Medical Journal, 338 (2009): b2337.  DOI: 10.1136/bmj.b2337.

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Filed under Alcohol, Dairy Products, Fish, Fruits, Grains, Health Benefits, legumes, Mediterranean Diet, nuts, olive oil, Vegetables

Fruits and Vegetables DON’T Prevent Heart Disease

Fruit and vegetable consumption does not seem to reduce the risk of heart attacks (coronary heart disease), according to a recent literature review by French epidemiologists.

I recently wrote about a study that found no overall reduced risk of cancer via consumption of fruits and vegetables.

Heart attacks and cancer are the first and second leading causes of death in the developed world.

So just why, again, are we supposed to be eating our fruits and vegetables?

Here’s most of the abstract written by the epidemiologists:

This Review summarizes the evidence for a relationship between fruit and vegetable consumption and the occurrence of coronary heart disease…Most of the evidence supporting a cardioprotective effect comes from observational epidemiological studies; these studies have reported either weak or nonsignificant associations.  Controlled nutritional prevention trials are scarce and the existing data do not show any clear protective effects of fruit and vegetables on coronary heart disease.  Under rigorously controlled experimental conditions, fruit and vegetable consumption is associated with a decrease in blood pressure, which is an important cardiovascular risk factor.  However, the effects of fruit and vegetable consumption on plasma lipid levels, diabetes, and body weight have not yet been thoroughly explored.  Finally, the hypothesis that nutrients in fruit and vegetables have a protective role in reducing the formation of atherosclerotic plaques and preventing complications of atherosclerosis has not been tested in prevention trials.  Evidence that fruit and vegetable consumption reduces the risk of cardiovascular disease remains scarce thus far.

What do they mean by controlled prevention trials?  Here’s an example.  Find 20,000 people with similar characteristics.  Randomly assign half of them to eat significantly more fruits and vegetables, and make sure they do it.  The other half eats their usual way, and make sure they do it.  Analyze the entire group’s health and food consumption after 10 years and see which half has more or less heart disease.   

Such a study is very difficult and costly.  Even if the fruit and veggie group had less heart disease, someone would argue that the heart benefit was gained because of what they cut out of their eating to make way for the fruits and veggies!  “They quit eating Cheetos; that’s why they had fewer heart attacks.”

Bottom Line

Fruits and vegetables don’t prevent heart disease, according to these researchers.

Fruits and vegetables are components of overall healthy diet patterns such as the Mediterranean diet, the DASH diet, and the “prudent diet.”  Is it possible they reduce the risk of stroke, the second leading cause of death?  I’ll leave that for another day.

I’m starting to think if I read enough nutritional literature, I won’t know anything with certainty.

Steve Parker, M.D. 

Dauchet L., Amouyel, P., and Dallongeville, J. (via MedScape).  Fruits, vegetables and coronary heart disease.  Nature Reviews Cardiology, 6 (2009): 599-608.  doi: 1011038/nrcardio.2009.131

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Filed under coronary heart disease, Fruits, Vegetables

Vinegar to Treat Diabetes?

Vinegar reduces blood sugar elevations after meals containing complex carbohydrates, according to the Department of Nutrition at Arizona State University.

Meals containing carbohydrates (and to a lesser extent, proteins) raise blood sugar after meals in people with or without diabetes.  [I’ve written previously about the normal ranges of blood sugars.]  Previous studies established that a single vinegar dose around mealtime lowers postprandial (after meal) blood sugar levels by up to 50%.  Arizona investigators wanted to know the best dose and timing for reducing postprandial blood sugar elevations.

They ran multiple tests on about 40 adults who reported they were generally healthy except nine had type 2 diabetes (not taking insulin). 

Findings

Mealtime vinegar ingestion reduced postprandial (two hours after meal)  blood sugars by about 20% compared to placebo.  The test meal was white bagel (variable amounts), 20 g of butter, and 200 g of juice. 

The most effective dose of vinegar was 10 g (about two teaspoons or 10 ml) of 5% acetic acid vinegar (either Heinz apple cider vinegar or Star Fine Foods raspberry vinegar).  This equates to two tablespoons of vinaigrette dressing (two parts oil/1 part vinegar) as might be used on a salad.  The authors also say that “…two teaspoons of vinegar could be consumed palatably in hot tea with lemon at mealtime.”

Discussion

The study authors suggest that the blood-sugar-lowering effect of vinegar may be related to inhibition of digestive enzymes or to a slower rate of empyting by the stomach.  Remember that most of digestion and absorption of nutrients occurs in the small intestine; the stomach first has to empty food into the small intestine.  Vinegar seems to inhibit digestion of starch but not of simple (monosaccharide) sugars.

They also note another study that found vinegar slowed the rate of stomach emptying by almost 40% in type 1 diabetics with gastoparesis, potentially raising the risk of low blood sugar.

Take-Home Points

The development of cardiovascular disease, like heart attacks and strokes, seems to be tied especially to elevations of blood sugar after meals as compared to before-meal or fasting sugar levels.  This may be related to formation of free radicals  and inflammatory mediators.  So reduction of postprandial blood sugar elevations by vinegar may be particularly helpful in preventing heart disease.  It will be many years before we can prove this by a clinical study, if ever. 

Diabetics, especially type 2’s without gastroparesis, may better tolerate grains, fruits, and legumes—in terms of lower blood sugar spikes—if they eat them in a meal that includes two teaspoons of vinegar. 

Steve Parker, M.D.

Reference:  Johnston, Carol, et al.  Examination of the antiglycemic properties of vinegar in healthy adults.  Annals of Nutrition and Metabolism, 56 (2010): 74-79.

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Filed under Drugs for Diabetes, Fruits, Grains, legumes

Another Sacred Cow Slaughtered: Fruits and Vegetables DON’T Prevent Cancer

We’ve been told by the authorities repetitively that eating plenty of fruits and vegetables will lower our risk of cancer.  However, a recent study in the American Journal of Clinical Nutrition says that ain’t so.

Fire up the grill—we’re havin’ steak tonight!

Researchers looked at data from over 450,000 participants (men and women over 50) in the National Institutes of Health—AARP Diet and Health Study.  Diet data was collected by self-administered questionnaire.  State-level cancer registries identified the cancers that developed during the average follow-up of seven years.

Their conclusions and selected comments:

Intake of fruit and vegetables was generally unrelated to total cancer incidence in this cohort.

However, on the basis of animal studies, human case control and cohort studies, and randomized controlled trials, there is likely no harm associated with the consumption of fruit and vegetables and their consumption may prevent cardiovascular disease.

Indeed, analyses in this cohort and in others that have investigated dietary patterns rich in fruit and vegetables have found reduced risks of colorectal cancer [three references cited] and mortality, including death from cardiovascular disease and all cancers [one reference was cited supporting reduced deaths from CVD and all cancers—a Mediterranean diet study].

As in all good science reports, the researchers compare and contrast their findings with similar published research.  They note that theirs is one of only four large cohort studies that have examined this issue.  Two of the other three (see references below) also found no association between total cancers and fruit and vegetable consumption.  The one that did find a beneficial linkage was the smallest of the four, so not as compelling.

Before this research was published, some experts suggested that adequate fruit and vegetable intake could prevent between 5 and 12% of cancers.

Eat your fruits and vegetables because they taste good, provide myriad nutrients, and may have some other healthful properties.  But not to lower overall cancer risk.  

Steve Parker, M.D.

References:

George, Stephanie, et al.   Fruit and vegetable intake and risk of cancer: a prospective cohort studyAmerican Journal of Clinical Nutrition, 89 (2009): 347-353. 

Hung, H.C., et al.  Fruit and vegetable intake and risk of major chronic disease.  Journal of the National Cancer Institute, 96 (2004): 1,577-1,584.

Takachi, R., et al.  Fruit and vegetable intake and risk of total cancer and cardiovascular disease [in Japan].  American Journal of Epidemiology, 167 (2008): 59-70.

Benetou, V., et al.  Vegetables and fruit in relation to cancer risk: evidence from the Greek EPIC Cohort Study.  Cancer Epidemiology, Biomarkers, and Prevention, 17 (2008): 387-392.

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Filed under cancer, Fruits, Mediterranean Diet, Vegetables

Eat the Right Carbs to Alleviate Diabetes and Heart Disease

Harvard’s Dr. Frank Hu in 2007 called for a paradigm shift in dietary prevention of heart disease, de-emphasizing the original diet-heart hypothesis and noting instead that “. . . reducing dietary GL [glycemic load] should be made a top public health priority.”  Jim Mann at the University of Otago (Dunedin, New Zealand) authored a 2007 review of carbohydrates and effects on heart disease and diabetes.  Here are highlights from the article summary in the European Journal of Clinical Nutrition:

The nature of carbohydrate is of considerable importance when recommending diets intended to reduce the risk of type II diabetes and cardiovascular disease and in the treatment of patients who already have established diseases. Intact fruits, vegetables, legumes and whole grains are the most appropriate sources of carbohydrate. Most are rich in [fiber] and other potentially cardioprotective components.  Many of these foods, especially those that are high in dietary fibre, will reduce total and low-density lipoprotein cholesterol and help to improve glycaemic control in those with diabetes.

Frequent consumption of low glycaemic index foods has been reported to confer similar benefits, but it is not clear whether such benefits are independent of the dietary fibre content of these foods or the fact that low glycaemic index foods tend to have intact plant cell walls.

A wide range of carbohydrate intake is acceptable, provided the nature of carbohydrate is appropriate. Failure to emphasize the need for carbohydrate to be derived principally from whole grain cereals, fruits, vegetables and legumes may result in increased lipoprotein-mediated risk of cardiovascular disease, especially in overweight and obese individuals who are insulin resistant.

Why does this matter to me and readers of this blog?  Dietary carbohydrates are a major determinant of blood sugar levels, tending to elevate them.  Chronically high blood sugar levels are associated with increased complication rates from diabetes.  People with diabetes are prone to develop heart disease, namely coronary artery disease, which causes heart attacks, weakness of the heart muscle, and premature death. 

Steve Parker, M.D.

References: 

Mann, J.  Dietary carbohydrate: relationship to cardiovascular disease and disorders of carbohydrate metabolismEuropean Journal of Clinical Nutrition, 61 (2007): Supplement 1: S100-11.

Hu, Frank.  Diet and cardiovascular disease prevention: The need for a paradigm shift.  Journal of the American College of Cardiology, 50 (2007): 22-24.

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Filed under Carbohydrate, coronary heart disease, Fiber, Fruits, Glycemic Index and Load, Grains, legumes, Vegetables

Does Diet Influence Risk of Stroke?

Harvard researchers suggest that our food consumption does indeed influence our risk of suffering a stroke.  This matters since stroke is the third leading cause of death in the U.S.

Scientists looked carefully at 121 different studies—published between 1979 and 2004—on the relationship between dietary factors and stroke.  High blood pressure is a major modifiable risk factor for stroke, so it also was considered.  Dietary factors included fats, minerals, animal protein, cholesterol, fish, whole grains, fiber, carbohydrate quality, fruits and vegetables, antioxidants, B vitamins, and dietary patterns.

I quote their conclusions:

Diets low in sodium and high in potassium lower blood pressure which will likely reduce stroke risk.

Consumption of fruits and vegetables, whole grains, folate, and fatty fish are each likely to reduce stroke risk.

A prudent or traditional Mediterranean dietary pattern, which incorporates these individual dietary components as well as intake of legumes and olive oil, may also prevent stroke.

Evidence is limited or inconsistent regarding optimal levels of dietary magnesium, calcium, antioxidants, total fat, other fat subtypes, cholesterol, carbohydrate quality, or animal protein for stroke prevention.

A diet low in sodium, high in potassium, and rich in fruits, vegetables, whole grains, cereal fiber, and fatty fish will likely reduce the incidence of stroke.

Take Home Points

The article abstract does not address the optimal intake amount of these various foods, vitamins, and minerals.  That’s probably not known with any certainty.

The traditional Mediterranean diet incorporates many of these stroke-preventing foods.  The Advanced Mediterranean Diet helps people lose weight while teaching how to eat Mediterranean-style.

The very low-carb Ketogenic Mediterranean Diet includes these stroke-preventing foods and minerals, except for whole grains and a tendency to be low in potassium.  The KMD is high in total fat and animal protien, and potentially high in cholesterol; this study indicates those issues are nothing to worry about in terms of future strokes.

I’ll use articles such as this to recommend long-term food consumption for followers of any future Diabetic Mediterranean Diet.

Steve Parker, M.D.

Reference:  Ding, E.L, and Mozaffarian, D.  Optimal dietary habits for the prevention of stroke. Seminars in Neurology, 26 (2006): 11-23.

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Filed under Fish, Fruits, Grains, Health Benefits, legumes, Mediterranean Diet, olive oil, Stroke, Vegetables

Diabetes + Overweight and Obesity = Diabesity

Mark Hyman, M.D., blogged about diabesity at the Huffington Post December 24, 2009.  He defines diabesity as a problem with glucose regulation associated with overweight and obesity.  The glucose physiology problem ranges from metabolic syndrome to prediabetes to full-blown type 2 diabetes.

“Diabesity” has been in circulation for a few years, but hasn’t caught on yet. 

What interested me about his blog post was that he advocates the Mediterranean diet as both therapeutic and prophylactic.  To quote Dr. Hyman:

The optimal diet to prevent and treat diabesity includes:

  • Fruits
  • Vegetables
  • Nuts
  • Seeds
  • Beans
  • Whole grains
  • Healthy fats such as olive oil, nuts, avocados, and omega-3 fats
  • Modest amounts of lean animal protein including small wild fish such as salmon or sardines

This is commonly known as a Mediterranean diet.  It is a diet of whole, real, fresh food. It is a diet of food you have to prepare and cook from the raw materials of nature.  And it has broad-ranging benefits for your health.

Food for thought, no doubt. 

Steve Parker, M.D.

Reference:  Hyman, Mark.  The diabesity epidemic part III:  Treating the real causes instead of the symptoms.  The Huffington Post, December 24, 2009

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Filed under Causes of Diabetes, Fish, Fruits, Grains, legumes, nuts, Overweight and Obesity, Prevention of T2 Diabetes