Category Archives: Vegetables

June 7, 2023 · 8:50 AM

Do You Absolutely Hate Broccoli?

If so, it may well be because of your genes according to an article at SBS.com. Particular genes determine whether you can detect a bitter chemical (called PTC) in broccoli and other brassicas like cauliflower and brussels sprouts.

“Free broccoli and carrot in frying“/ CC0 1.0

“On average, about 70% of us can taste something bitter in broccoli or PTC, but those with two copies of the bitter sensitivity gene are closer to 20%, and they are much more likely to hate it.”

U.S. President George H.W. Bush said in March 1990, “I do not like broccoli. And I haven’t liked it since I was a little kid and my mother made me eat it. And I’m President of the United States and I’m not going to eat any more broccoli!” He banned it on Air Force One.

Most of us at the Parker Compound like broccoli. My wife usually sautes it in olive oil and seasons with garlic, other herbs, and salt.

Steve Parker, M.D.

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October 3, 2013 · 2:00 AM

Experts Debate Composition of the Mediterranean Diet

…but they have some good ideas as to the healthy components, according to a report in MedPageToday. A sample:

Through a subtractive statistical technique, the EPIC investigators calculated that the biggest chunk of the health advantage—24%—came from moderate alcohol consumption (predominantly wine).

The other relative contributions were:

  • 17% from low consumption of meat and meat products
  • 16% from high vegetable consumption
  • 11% from high fruit and nut consumption
  • 11% from high monounsaturated-to-saturated lipid ratio (largely due to olive oil consumption)
  • 10% from high legume consumption

Here’s my definition of the Mediterranean diet.

Steve Parker, M.D.

Reference:
Sofi F, et al “Ideal consumption for each food group composing Mediterranean diet score for preventing total and cardiovascular mortality” EuroPRevent 2013; Abstract P106.

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April 6, 2013 · 2:00 AM

Which Diseases Do Vegetables and Fruits Prevent?

Potential answers are in the American Journal of Clinical Nutrition (2012).  I quote:

For hypertension, coronary heart disease, and stroke, there is convincing evidence that increasing the consumption of vegetables and fruit reduces the risk of disease. There is probable evidence that the risk of cancer in general is inversely associated with the consumption of vegetables and fruit. In addition, there is possible evidence that an increased consumption of vegetables and fruit may prevent body weight gain. As overweight is the most important risk factor for type 2 diabetes mellitus, an increased consumption of vegetables and fruit therefore might indirectly reduces the incidence of type 2 diabetes mellitus. Independent of overweight, there is probable evidence that there is no influence of increased consumption on the risk of type 2 diabetes mellitus. There is possible evidence that increasing the consumption of vegetables and fruit lowers the risk of certain eye diseases, dementia and the risk of osteoporosis. Likewise, current data on asthma, chronic obstructive pulmonary disease, and rheumatoid arthritis indicate that an increase in vegetable and fruit consumption may contribute to the prevention of these diseases. For inflammatory bowel disease, glaucoma, and diabetic retinopathy, there was insufficient evidence regarding an association with the consumption of vegetables and fruit.

It bothers me that vegetables and fruits are lumped together: they’re not the same.

All of my diets—Advanced Mediterranean, Low-Carb Mediterranean, and Ketogenic Mediterranean—provide plenty of fruits and vegetables.

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December 15, 2012 · 2:00 AM

Comprehensive List of Low-Carb Vegetables

A half cup of sliced bell pepper has about 2 grams of digestible carbohydrate

Laura Dolson over at About.com has a helpful list of low-carb veggies.  Helpful if you:

  • experience excessive blood sugar spikes from high-carb items
  • are restricting carbs for weight management
  • are eating a Paleo Diabetic diet

-Steve

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December 5, 2012 · 2:01 AM

What’s Dr. Bernstein Got Against Tomatoes?

Eat greens for vitamin K

Looks reasonable to me

Dr. Richard Bernstein cautions his diabetic patients and readers of Diabetes Solution to keep a tight lid on consumption of tomatoes.  An excerpt from page 149:

If you have them uncooked in salad, limit yourself to one slice or a single cherry tomato per cup of salad.

His concern is that tomatoes will raise your blood sugar too high.

That doesn’t make sense to me.  A 3-inch diameter tomato has 7 grams of carbohydrate, 2 of which are fiber.  So the digestible carb count is only 5 grams.  That’s not much.  So do tomatoes have a high glycemic index?  Unlikely, although it’s hard to be sure.  Good luck finding a reliable GI for tomatoes on the Internet.

I think Dr. Bernstein’s wrong about this one, which is rare.  I suppose it’s possible that tomatoes deliver some other substance to the bloodstream that interferes with carbohydrate metabolism, but Dr. Bernstein doesn’t mention that.

Do tomatoes play havoc with your blood sugars?

Steve Parker, M.D.

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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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January 7, 2011 · 7:48 AM

Low-Carb Diets Killing People?

Animal-based low-carb diets are linked to higher death rates, according to a recent study in the Annals of Internal Medicine.  On the other hand, a vegetable-based low-carb diet was associated with a lower mortality rate, especially from cardiovascular disease.

As always, “association is not causation.”

It’s just a matter of time before someone asks me, “Haven’t you heard that low-carb diets cause premature death?”  So I figured I’d better take a close look at the new research by Fung and associates.

It’s pretty weak and unconvincing.  I have little to add to the cautious editorial by William Yancy, Matthew Maciejewski, and Kevin Schulman published in the same issue of Annals.

The study at hand was observational over many years, using data from the massive Nurses’ Health Study and Health Professionals’ Follow-up Study.  To find the putative differences in mortality, the researchers had to compare the participants eating the most extreme diets.  The 80% of study participants eating in between the extremes  were neutral in terms of death rates.

They report that “…the overall low-carbohydrate diet score was only weakly associated with all-cause mortality.”  Furthermore,

These results suggest that the health effects of a low-carbohydrate diet may depend on the type of protein and fat, and a diet that includes mostly vegetable sources of protein and fat is preferable to a diet with mostly animal sources of protein and fat.

In case you’re wondering, all these low-carb diets derived between 35 and 42% of energy (total calories) from carbohydrate, with an average of 37%.  Anecdotally, many committed low-carbers chronically derive 20% of calories form carbohydrate (100 g of carb out of 2,000 calories/day).  The average American eats 250 g of carb daily, 50-60% of total calories.

Yancy et al point out that “Fung and coworkers did not show a clear dose-response relationship in that there was not a clear progression of risk moving up or down the diet deciles.”  If animal proteins and fats are lethal, you’d expect to see some dose-response relationship, with more deaths as animal consumption gradually increases over the deciles.

ResearchBlogging.orgThe Fung study is suggestive but certainly not definitive.  Anyone predisposed to dietarycaution who wants to eat lower-carb might benefit from eating fewer animal sources of protein and fat, and more vegetable sources.  Fung leaves it entirely up to you to figure out how to do that. Compared to an animal-based low-carb diet, the healthier low-carb diet must subsitute more low-carb vegetables and higher-fat plants like nuts, seeds, seed oils and olive oil, and avocadoes, for example.  What are higher-protein plants?  Legumes?

You can see how much protein and fat are in your favorite vegetables at the USDA Nutrient Database.

The gist of Fung’s study dovetails with the health benefits linked to low-meat diets such as traditional Mediterranean and DASH.  On the other hand, if an animal-based low-carb diet helps keep a bad excess weight problem under control, it too may by healthier than the standard American diet.

See the Yancy editorial for a much more detailed and cogent analysis.  As is so often the case, “additional studies are needed.”

Steve Parker, M.D.

Reference: Fung TT, van Dam RM, Hankinson SE, Stampfer M, Willett WC, & Hu FB (2010). Low-carbohydrate diets and all-cause and cause-specific mortality: two cohort studies. Annals of internal medicine, 153 (5), 289-98 PMID: 20820038

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July 15, 2010 · 10:01 AM

Maybe Diet Prevents Alzheimer Dementia After All

I blogged about a study by Gu et al on April 30, 2010, that found significantly lower incidence of Alzheimer dementia in people in Manhattan who followed this dietary pattern:

  • relatively high consumption of salad dressing, nuts, fish, tomatoes, fruits, dark green leafy vegetables, and cruciferous  vegetables
  • relatively low consumption of poultry, red meat, butter, and high-fat dairy

About the same time, a National Institutes of Health expert panel pooh-poohed the possibility that diet had any effect one way or the other on Alzheimer’s. 

Why does this matter?  Five million U.S. adults have Alzheimer dementia already, and it’s going to get much worse over the coming decades.

A June, 2010, issue of Journal of the American Medical Association has a commentary by two doctors (Martha Morris, Sc.D., and Christine Tangney, Ph.D.), experts in the field of nutrition.  Here’s their explanation of the NIH panel’s negative findings:

Many of the inconsistencies among studies of dietary factors can be attributed to the complexity of nutrition science and the omission of nutrition expertise in the design and analysis of both epidemiological and randomized controlled trials.

Morris and Tangney think the findings of Gu et al are valid, confirming prior studies showing benefit to diets high in vitamin E (from food) and low in saturated fat from animals.  They point out that the animal foods may simply be displacing beneficial nutrients in other foods, rather than directly causing harm.

Until we have further data, anyone at risk for Alzhiemer’s may be better off following the dietary pattern above, or the Mediterranean diet.  The two are similar.

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 physican before making any dietary or exercise changes. 

Reference: Morris, M., & Tangney, C.  Diet and Prevention of Alzheimer Disease.  The Journal of the American Medical Association, 303 (2010): 2,519-2,520.    doi: 10.1001/jama.2010.844

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April 11, 2010 · 2:00 AM

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 study.  British Medical Journal, 338 (2009): b2337.  DOI: 10.1136/bmj.b2337.

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April 10, 2010 · 2:00 AM

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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