Advanced Mediterranean Diet

I’ve found that nearly everbody’s eyes glaze over if I try to explain how, physiologically, the Mediterranean diet promotes health and longevity.  Below are some of the boring details, for posterity’s sake, from my 2007 book, The Advanced Mediterranean Diet: Lose Weight, Feel Better, Live Longer.

Many of the nutrient-disease associations I mention below are just that: associations, linkages, not hard proof of a benefit.  Available studies are often contradictory.  For instance, there may be 10 observational studies linking whole grain consumption with reduced deaths from heart disease, while three other studies find no association, or even suggest  higher death rates. (I’m making these numbers up.)  If you want hard proof, you’ll have to wait.  A long time.  Such is nutrition science.  Take it all with a grain of salt. 

Also note that the studies supporting my claims below are nearly all done in non-diabetic populations.

Coronary Heart Disease

Coronary heart disease, also known as coronary artery disease, is the No.1 cause of death in the world. It’s responsible for 40% of deaths in the United States and other industrialized Western countries. The Mediterranean diet is particularly suited to mitigating the ravages of coronary heart disease. Mediterranean diet cardiac benefits may be related to its high content of monounsaturated fat (in olive oil), folate, and antioxidants.

The predominant source of fat in the traditional Mediterranean diet is olive oil, which is rich in monounsaturated fatty acids. High intake of olive oil reduces blood levels of triglycerides, total cholesterol, and LDL (”bad”) cholesterol. HDL or “good” cho-lesterol is unaffected. Olive oil tends to lower blood pressure in hypertensive people. Monounsaturated fatty acids reduce cardiovascular risk substantially, particularly when they replace simple sugars and easily digestible starches. Monounsaturated fatty acids and olive oil may also reduce breast cancer risk. The cardioprotective (good for the heart) and cancer-reducing effects of olive oil may be partially explained by the oil’s polyphenolic compounds.
    
Nuts are another good source of monounsaturated fatty acids and polyunsaturated fatty acids, including some omega-3 polyunsaturated fatty acids. Nuts have been proven to be cardioprotective. They lower LDL and total cholesterol levels, while providing substantial fiber and numerous micronutrients, such as vitamin E, potassium, magnesium, and folic acid. Compared with those who never or rarely eat nuts, people who eat nuts five or more times per week have 30 to 50% less risk of a fatal heart attack. Lesser amounts of nuts are also cardioprotective, perhaps by reducing lethal heart rhythm dis-turbances. 
    
Another key component of the Mediterranean diet is fish. Fish are excellent sources of protein and are low in cholesterol. Fatty, cold-water fish are particularly good for us because of their omega-3 polyunsaturated fatty acids: eicosapentaenoic acid (EPA) and docosahexanaenoic acid (DHA). The other important omega-3 polyunsaturated fatty acid is alpha-linolenic acid (ALA), available in certain plants. Our bodies can convert ALA into EPA and DHA, but not very efficiently. Fish oil supplements, which are rich in EPA, lead to lower total cholesterol and triglyce-ride levels. Fish oil supplements have several properties that fight atherosclerosis (hardening of the arteries). In people who have already had a heart attack, the omega-3 polyunsaturated fatty acids have proven to dramatically reduce cardiac deaths, especially sudden death, and nonfatal heart attacks. So omega-3 polyunsaturated fatty acids are “cardioprotective.”

The first sign of underlying coronary heart disease in many people is simply sudden death from a heart attack (myocardial infarction) or heart rhythm disturbance. These unfortunate souls had hearts that were ticking time bombs. I have little doubt that a significant number of such deaths can be prevented by adequate intake of cold-water fatty fish. As a substitute for fish, fish oil supplements might be just at beneficial. The American Heart Association also recommends fish twice weekly for the general population, or fish oil supplements if whole fish isn’t feasible. Compared with fish oil capsules, whole fish are loaded with vitamins, minerals, and protein. The richest fish sources of omega-3 polyunsaturated fatty acids are albacore (white) tuna, salmon, sar-dines, trout, sea bass, sword-fish, herring, mackerel, anchovy, halibut, and pompano.
    
Cardioprotective omega-3 polyunsaturated fatty acids (mainly ALA) are also provided by plants, such as nuts and seeds, legumes, and vegetables. Rich sources of ALA include walnuts, butternuts, soy-beans, flaxseed, almonds, leeks, purslane, pinto beans, and wheat germ. Purslane is also one of the few plant sources of EPA. Several oils are also very high in ALA: flaxseed, canola, and soybean. Look for them in salad dressings, or try cooking with them.

Macular Degeneration

Omega-3 fatty acid and fish consumption may also be “eye-protective.” Eating fish one to three times per week apparently helps prevent age-related macular degeneration (AMD), the leading cause of blindness in people over 50 in the United States. While AMD has a significant hereditary component, onset and progression of AMD are affected by diet and lifestyle choices. For instance, smoking cigarettes definitely increases your risk of developing AMD. Other foods associated with lower risk of AMD are dark green leafy vegetables, orange and yellow vegetables and fruits: spinach, kale, collard greens, yellow corn, broccoli, sweet potatoes, squash, orange bell peppers, oranges, mangoes, apricots, peaches, honeydew melon, and papaya. Two unifying phytochemicals in this food list are lutein and zeaxanthin, which are also found in red grapes, kiwi fruit, lima beans, green beans, and green bell peppers. Increasing your intake of these foods as part of the Advanced Mediterranean Diet may well help preserve your vision as you age.      
    
Alzheimer’s Dementia
    
Another exciting potential benefit of fish consumption is prevention or delay of Alzheimer’s dementia. Several recent epidemiologic studies have suggested that intake of fish once or twice per week significantly reduces the risk of Alzheimer’s. Types of fish eaten were not specified. No one knows if fish oil capsules are equivalent. For now, I’m sticking with fatty cold-water fish, which I call my “brain food.”
    
Vitamin E supplements may slow the progression of established Alzheimer’s disease; clinical studies show either modest slowing of progression or no benefit. As a way to prevent Alzheimer’s, however, vitamin E supplements have been disappointing. On the other hand, high dietary vitamin E is associated with reduced risk of developing Alzheimer’s. Good sources of vitamin E include vegetable oils (especially sunflower and soybean), sunflower seeds, nuts, shrimp, fruits, and certain vegetables: sweet potatoes, asparagus, beans, broccoli, Brussels sprouts, carrots, okra, green peas, sweet peppers, spinach, and tomatoes. All of these are on your new diet. 

Wine

For centuries, the healthier populations in the Mediterranean region have enjoyed wine in light to moderate amounts, usually with meals. Epidemiologic studies there and in other parts of the world have associated reasonable alcohol consumption with prolonged lifespan, reduced coronary artery disease, diminished Alzheimer’s and other dementias, and possibly fewer strokes. Alcohol tends to increase HDL cholesterol, have an antiplatelet effect, and may reduce C-reactive protein, a marker of arterial inflammation. These effects would tend to reduce cardiovascular disease. Wine taken with meals provides antioxidant phytochemicals (polyphenols, procyanidins) which may protect against atherosclerosis and some cancers. 

What’s a “reasonable” amount of alcohol? An old medical school joke is that a “heavy drinker” is anyone who drinks more than the doctor does. Light to moderate alcohol consumption is generally consi-dered to be one or fewer drinks per day for a woman, two or fewer drinks per day for a man. One drink is 5 ounces of wine, 12 ounces of beer, or 1.5 ounces of 80 proof distilled spirits (e.g., vodka, whiskey, gin). The optimal health-promoting type of alcohol is unclear. I tend to favor wine, a time-honored component of the Mediterranean diet. Red wine in particular is a rich source of resveratrol, which is thought to be a major contributor to the cardioprotective benefits associated with light to moderate alcohol consumption. Grape juice may be just as good—it’s too soon to tell.
    
I have no intention of overselling the benefits of alcohol. If you are considering habitual alcohol as a food, be aware that the health benefits are still somewhat debatable. Consumption of three or more alcoholic drinks per day is clearly associated with a higher risk of breast cancer in women. Even one or two drinks daily may slightly increase the risk. Folic acid supplementation might mitigate the risk. If you are a woman and breast cancer runs in your family, strongly consider abstinence. Be cautious if there are alcoholics in your family; you may have inherited the predisposition. If you take any medications or have chronic medical conditions, check with your personal physician first. For those drinking above light to mod-erate levels, alcohol is clearly perilous. Higher dosages can cause hypertension, liver disease, heart failure, certain cancers, and other medical problems. And psychosocial problems. And legal problems. And death. Heavy drinkers have higher rates of violent and accidental death. Alcoholism is often fatal. You should not drink alcohol if you:
            ■  have a history of alcohol abuse
                or alcoholism
            ■  have liver or pancreas disease
            ■  are pregnant or trying to become
                pregnant
            ■  may have the need to operate
                dangerous equipment or machinery,
                such as an automobile, while under
                the influence of alcohol
            ■  have a demonstrated inability to
                limit yourself to acceptable
                intake levels
            ■  have personal prohibitions due
                to religious, ethical, or other
                reasons. 
    
Cancer

Do you ever worry about cancer? You should. It’s the second leading cause of death. Over 500,000 people die from cancer each year in the United States. One third of people in the United States will develop cancer. Twenty percent of us will die from cancer. About half the deaths are from cancer of the lung, breast, and colon/rectum. Are you worried yet?

According to the American Cancer Society, one third of all cancer deaths can be attributed to diet and inadequate physical activity. So we have some control over our risk of developing cancer. High consumption of fruits and vegetables seems to protect against cancer of the lung, stomach, colon, rectum, oral cavity, and esophagus, although other studies dispute the protective linkage. Data on other cancers is limited or inconsistent. If you typically eat little or no fruits and vegetables, you can start today to cut your cancer risk by up to one half. Five servings of fresh fruits and vegetables a day seems to be the protective dose against cancer. Make it a life-long habit. The benefits accrue over time. Fruits and vegetables contain numerous phytochemicals thought to improve or maintain health, such as carotenoids (e.g., lycopene), lignans, phytosterols, sulfides, isothyocyanates, phenolic compounds (including flavonoids, resveratrol, phytoestrogens, antho-cyanins, and tannins), protease inhibitors, capsaicin, vitamins, and minerals. 
   
In addition to cancer prevention properties, fruits and vegetables provide fiber, which is the part of plants resistant to digestion by our enzymes. The other source of fiber is grain products, especially whole grains. Liberal intake of fiber helps prevent constipation, diverticular disease, hemorrhoids, irritable bowel syndrome, and perhaps colon polyps. Soluble fiber helps control blood sugar levels in diabetics. It also reduces LDL cholesterol levels, thereby reducing risks of coronary heart disease. Whether or not related to fiber, high fruit and vegetable intake may reduce the risks of coronary heart disease and stroke. Legume consumption in particular has been associated with a 10 to 20% lower risk of coronary heart disease, with the effective dose being around four servings per week. 

Fiber and Whole Grains

Processed, refined grain products have much less fiber than do whole grains. For instance, white all-purpose enriched flour has only about one fourth the fiber of whole wheat flour. The milling process removes the bran, germ, and husk (chaff), leaving only the endosperm as the refined product, flour. Endosperm is mostly starch and 10–15% protein. Many nutrients are lost during processing. The germ is particularly rich in vitamins (especially B vitamins), polyunsaturated fatty acids, antioxidants, trace minerals, and phytochemicals. Phytochemicals protect us against certain chronic diseases. Bran is high in fiber and nutrients: B vitamins, iron, magnesium, copper, and zinc, to name a few. Enriched grain products are refined grains that have had some, but certainly not all, nutrients added back, typically iron, thiamin, niacin, riboflavin, and folate. Why not just eat the whole grain? Whole grain products retain nearly all the nutrients found in the original grain. Hence, they are more nutritious than refined and enriched grain products.
    
Liberal intake of high-fiber whole grain foods, as contrasted with refined grains, is linked to lower risk of death and lower incidence of coronary heart disease and type 2 diabetes mellitus. For existing diabetics, whole grain consumption can help im-prove blood sugar levels. Three servings of whole grains per day cut the risk of coronary heart disease by about 25 percent compared with those who rarely eat whole grains. Regular consumption of whole grains may also substantially reduce the risk of sev-eral forms of cancer.

Average adult fiber intake in the United States is 12 to 15 grams daily. Expert nutrition panels and the American Heart Association recommend 25 to 30 grams daily from whole grains, fruits, and vegetables.

The health benefits of the Mediterranean diet likely spring from synergy among multiple Mediteranean diet components, rather than from a single food group or one or a few food items. 

Steve Parker, M.D.

Dietitian Melanie Thomassian at her Dietriffic blog April 27, 2010, notes that nuts are not fattening, contrary to popular belief.  This is documented in a guest post by Matthew Denos.  Most of the evidence refers to almonds, so I’m not sure other nuts would be equally non-fattening. 

We’re talking about one or two ounces (up to 60 grams) a day.  Could someone gain fat weight eating more than that?  Probably, especially if they have a high-carbohydrate eating pattern.  Do I have scientific studies to back me up?  No. 

Nuts are a classic component of the traditional Mediterranean diet, which is one reason I included them in the Ketogenic Mediterranean Diet.  The other reason is that nut consumption is associated with lower heart disease risk.

Steve Parker, M.D.

Nut consumption is strongly linked to reduced coronary heart disease, with less rigorous evidence for several other health benefits, according to a recent article in the American Journal of Clinical Nutrition.

This is why I’ve included nuts as integral components of the Ketogenic Mediterranean Diet and the Advanced Mediterranean Diet.

Regular nut consumption is associated with health benefits in observational studies of various populations, within which are people eating few nuts and others eating nuts frequently.  Health outcomes of the two groups are compared over time.  Frequent and long-term nut consumption is linked to:

• reduced coronary heart disease (heart attacks, for example)
• reduced risk of diabetes in women (in men, who knows?)
• less gallstone disease in both sexes
• lower body weight and lower risk of obesity and weight gain 

The heart-protective dose of nuts is three to five 1-ounce servings a week.

Steve Parker, M.D.

Reference:  Sabaté, Joan and Ang, Yen.  Nuts and health outcomes: New epidemiologic evidence.  American Journal of Clinical Nutrition, 89 (2009): 1,643S-1,648S.

Researchers at Harvard and the University of Athens (Greece) report that the following specific components of the Mediterranean diet are associated with lower rates of death:

• moderate ethanol (alcohol) consumption
• low meat and meat product intake
• high vegetable consumption
• high fruit and nut consumption
• high ratio of monounsaturated fat to saturated fat
• high legume intake

Minimal, if any, contribution to mortality was noted with high cereal, low dairy, or high fish and seafood consumption. 

The researchers examined diet and mortality data from over 23,000 adult participants in the Greek portion of the European Prospective Investigation into Cancer and nutrition.  You’ll be hearing more about the EPIC study for many years.  Over an average follow-up of 8.5 years, 1,075 of participants died.  652 of these deaths were of participants in the lower half of Mediterranean diet adherence; 423 were in the upper half.

Alcohol intake in Greece is usually in the form of wine at mealtimes. 

The beneficial “high ratio of monounsaturated fat to saturated fat” stems from high consumption of olive oil and low intake of meat. 

It’s not clear if these findings apply to other nationalities or ethnic groups.  Other research papers have documented the health benefits of the Mediterranean diet in at least eight other countries over three continents. 

The researchers don’t reveal in this report the specific causes of death.  I expect those data, along with numbers on diabetes, stroke, and dementia, to be published in future articles, if not published already.  Prior Mediterranean diet studies indicate lower death rates from cardiovascular disease and cancer.   

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.

Additional Information:  Childs, Dan.  Take it or leave it?  The truth about 8 mediterranean diet staples.  ABC News online, June 24, 2009.  Accessed June 25, 2009.

Update June 26, 2009:

Here’s a direct quote from the study at hand:

Among the presumed beneficial components of the Mediterranean diet score, high consumption of all but fish and seafood was inversely associated with mortality, although none of these associations was statistically significant.

“. . . none of these associations was statistically significant.”  So I can understand some skepticism about this journal article. The researchers had to use some very sophisticated statistical manipulation to come up with the “healthy components” list. I’m not saying that’s wrong. I will admit that the statistical analysis is beyond my comprehension, so I’m trusting the authors and peer-review process to be honest and effective. My college statistics course was too many years ago.

The take-home point for me is that the health benefits of the Mediterranean diet probably stem from an overall combination of multiple foods rather than any single component.

Steve Parker, M.D.

And remember to exercise regularly, maintain a healthy weight (BMI 18.5-25), keep your blood pressure under 140/90, and don’t smoke.

-Steve

Major media outlets in the last 48 hours have reported a new Canadian study that confirms the heart-healthy characteristics of the Mediterranean diet.  Examples are Forbes.com (Review Confirms Links Between Diet, Heart Health, April 12, 2009), UPI.com (Vegetables, nuts, Med Diet good for heart, April 14, 2009), and the Wall Street Journal (Heart Health: Mediterranean Diet Good, Trans Fats Bad, April 13, 2009).

Canadian researchers sought to systematically evaluate the strength of the evidence supporting links between dietary factors and coronary heart disease.  Coronary heart disease (CHD) is the number one cause of death in Western societies.

It’s important to understand the two types of studies meta-analyzed by the Canadians.

Prospective cohort studies can be used to identify a dietary factor that may be associated with a disease or outcome.  For example, researchers could study the health of 20,000 people over the course of 10 years, giving them questionnaires to find out what foods they typically ate.  They might find after 10 years that the people who ate the most saturated fat tended to die earlier and had more heart attacks and strokes compared to the people who ate the least saturated fat.  This would establish an association between dietary saturated fat and premature death, heart attacks, and strokes.  It does not prove that saturated fats cause those outcomes, it’s just an association.

Randomized trials, often called randomized controlled trials (RCTs), typically take two groups of people and apply an intervention to one group but not the other.  The groups are followed over time to see if there is a difference in outcome.  For example, take another group of 20,000 people.  Randomly assign 10,000 of them to eat more-than-usual saturated fat.  The other 10,000 similar people serve as the control group, eating their usual amount of saturated fat.  Follow these 20,000 people over 10 years, then compare their health outcomes: death, heart attacks, strokes.  If the high-saturated-fat group has worse outcomes, you are much closer to proving that dietary saturated fat causes premature death, heart attacks, and strokes.

Methodology 

The scientists located and analyzed every English-language prospective cohort study (146 studies) or randomized trial (43) investigating food intake and coronary heart disease (CHD), from 1950 through June, 2007.  They wrote:

We used the Bradford Hill guidelines to derive a causation score based on four criteria (strength, consistency, temporality, and coherence) for each dietary exposure in cohort studies and examined for consistency with the findings of randomized trials.

The different dietary patterns evaluated in studies were noted.  The “Mediterranean” dietary pattern emphasizes a higher intake of vegetables, legumes, fruits, nuts, whole grains, cheese or yogurt, fish, and monounsaturated relative to saturated fatty acids.  The “prudent” dietary pattern is characterized by a high intake of vegetables, fruit, legumes whole grains, and fish and other seafood.  The “western” pattern is characterized by a high intake of processed meat, red meat, butter, high-fat dairy products, eggs, and refined grains.

Results

Strong evidence (four Bradford Hill criteria satisfied) supported protection against CHD with consumption of:

• vegetables
• nuts
• monounsaturated fatty acids [prominent in olive oil, for example]
• Mediterranean diet
• prudent diet

Modertately strong evidence (three criteria satisfied) supported protection against CHD with consumption of:

• fish
• marine omega-3 fatty acids
• folate
• whole grains
• dietary vitamins E and C (as opposed to vitamin supplements)
• beta carotene
• alcohol
• fruit
• fiber

Strong evidence supported the following as harmful dietary factors, in terms of CHD:

• trans-fatty acids
• foods with a high-glycemic index or load
• western diet

Researchers found insufficient evidence (two or less criteria) to support an association between CHD and:

• total fat
• saturated and polyunsaturated fatty acids
• eggs
• meat
• milk
• vitamin supplements E and C
• alpha-linolenic acid

Selected Comments of the Researchers  [my comments in brackets]

Cohort studies provide abundant evidence of an association with total mortality for many dietary exposures.  Randomized controlled trials corroborate these associations for the consumption of omega-3 fatty acids and a Mediterraneandiet because most of the other dietyary factors have not been evaluated to date.

Among the dietary exposures with strong evidence of causation from cohort studies, only a Mediterranean dietary pattern is related to CHD in randomized trials.  [The association is inverse: Higher adherence to the Mediterranean diet leads to lower rates of CHD.]

A wealth of epidemiologic studies have evaluated associations between dietary exposures and CHD.  The general consensus from the evidence currently available is that a reduced consumption of saturated and trans-fatty acids and a higher intake of fruits and vegetables, polyunsaturated fatty acids including omega-3 fatty acids, and whole grains are likely beneficial.  This is reflected in the revised Dietary Guidelines for Americans 2005 from the US Departments of Health and Human Services and Agriculture.  However, little direct evidence from RCTs supports these recommendations.  [Emphasis added.]  In some cases, RCTs have not been conducted, and RCTs that have been conducted have generally not been adequately powered or have evaluated surrogate end points rather than clinical outcomes.

Single-nutrient RCTs have yet to evaluate whether reducing saturated fatty acid intake lowers the risk of CHD events.

More recently, the lack of benefit of diets of reduced total fat has been established [in women only? (reference below)], and the evidence supporting the adverse effect of trans-fatty acids on cholesterol levels and CHD has increased, which is reflected in our findings.  [This is the only mention of cholesterol in the report.]

My Comments

I wonder about vegetarian/vegan diets.  Have they been tested for efficacy against CHD?  What about Dr. Dean Ornish’s program?

Although not mentioned in the text of the article, Table 3 on page 664 shows that the positive association between CHD and high-glycemic index/load is much stonger in women than in men.  Relative risk for women on a high-glycemic index/load diet was 1.5 (95% confidence interval = 1.29-1.71), and for men the relative risk was 1.06 (95% confidence interval = 0.91-1.20).  I question whether the association for men is statistically significant. 

Why wasn’t there discussion of dietary cholesterol?  The public and physicians have been told for years that dietary cholesterol causes or aggravates coronary heart disease.  In a near-future post, I quote one expert stating that people at risk for coronary heart disease (aren’t we all?) should limit cholesterol to 200 mg/day.  Is there no evidence?

I’m a little surprised, but some of you won’t be, that the researchers found no clear association between CHD and saturated and total fat intake.  In traditional medical circles, these findings are considered sacrilegious!

Medical schools and cardiologists have been teaching for thirty or more years that they are related positively.  “Positively” means the more saturated and total fat in your diet, the more likely you are to develop atherosclerosis, which in the heart is coronary heart disease.  Dietary cholesterol is often thrown into the equation.  The is the dogmatic Diet-Heart Hypothesis.

Steve Parker, M.D.

References:

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.

van Dam, R.M., et al.  Dietary glycemic index in relation to metabolic risk factors and incidence of coronary heart disease: the Zutphen Elderly Study.  European Journal of Clinical Nutrition, 54  (2000): 726-731.

Howard, B.V., et al.  Low-fat dietary pattern and risk of cardiovascular disease: the Women’s Health Initiative Randomized Controlled Dietary Modification Trial.  Journal of the American Medical Association, 295 (2006): 655-666.

This is an April 16 update to my April 14 post which was based solely on the journal article abstract.  I have reviewed the full article. 

I frequently check in at CalorieLab for up-to-date nutrition news.

Karen Collins, M.S., R.D., C.D.N., is a guest contributor there today, writing about the potential health benefits of nuts.  I was aware of the cardiovascular benefits; she taught me about possible salutary effects on cancer and diabetes.

From my own literature review, the cardiac benefits are associated with a nut ”dose” of three to five 1-ounce servings a week.

Last December, I blogged about reversal of metabolic syndrome with a Mediterranean Diet supplemented with nuts.

I recommend Ms. Collins’ article to you. 

Steve Parker, M.D.

Albert, Christine, et al.  Nut consumption and decreased risk of sudden cardiac death in the Physicians’ Health Study.  Archives of Internal Medicine, 162, (2002): 1,382-1,387.

An article published yesterday by Bloomberg.com presents results of a recent scientific study in Spain that showed reduction in “metabolic syndrome” by the Mediterranean diet supplemented with nuts.  CBSnews.com, Reuters, and others helped spread the news.  The Bloomberg article was written by Nicole Ostrow.

Metabolic syndrome is a constellation of clinical factors that are associated with increased risk of type 2 diabetes and atherosclerotic complications such as heart attack and stroke.  [Sometimes metabolic sydrome is called Syndrome X, which I sorta like.  Oh, the mystery!]  One in six Americans have the syndrome.  Diagnosis requires at least three of the following five conditions:

• High blood pressure (130/85 or higher, or using a high blood pressure medication)
• Low HDL cholesterol:  under 40 mg/dl in a man, under 50 in a women (or either sex taking a cholesterol-lowering drug)
• Triglycerides over 150 mg/dl (or taking a cholesterol-lowering drug)
• Abdominal fat:  waist circumference 40 inches or greater in a man, 35 inches or greater in a woman
• Fasting blood glucose over 100 mg/dl

The scientific study at hand is part of the PREDIMED study being conducted in Spain.  For this portion of the study, 1,224 participants at high risk for cardiovascular disease were randomized to follow a 1) low-fat diet (considered the control group), 2) Mediterranean diet plus 1 liter virgin olive oil per week, or 3) Mediterranean diet plus 30 gm daily of mixed nuts.

Note that the nuts used in this study were walnuts, almonds, and hazelnuts.  Half of all nuts were walnuts; a quarter of the nuts were almonds and a quarter were hazelnuts.

Participants were 55-80 years old, and 61% had metabolic syndrome at baseline.  Participants could eat all they wanted, and there was no increase in physical activity for any of the groups.  Participants were given instructions at baseline and quarterly.

After one year of intervention, the prevalence of metabolic syndrome  was reduced by 14% in the Mediterranean diet plus nuts group compared to the control, low-fat diet group.  The Mediterranean diet plus extra olive oil group reduced prevalence of metabolic syndrome by 7%, but this did not reach statistical significance (P=0.18).

New cases of metabolic syndrome continued to develop at about the same rate in all three groups.  I.e., incident rates were not significantly different.  So, the lower prevalence of metabolic syndrome after one year reflected reversion or clearing of the syndrome in many people who had it at baseline.  Compared to the control group, people in the nutty group were 70% more likely to resolve their metabolic syndrome.  Individuals in the oily group were 30% more likely than controls to resolve the condition.

[Feel free to consult a dictionary for definitions of “prevalence” and “incidence.”]

The researchers conclude that:

A traditional Mediterranean diet enriched with nuts could be a useful tool in the management of the metabolic syndrome. 

My Comments:

Thirty grams (daily) of nuts is a decent-sized snack of about 180 calories.  Thirty grams of almonds formed a heap in the palm of my hand, not touching my fingers.  This is more than the “two tablespoons” reported by CBSnews.com December 9.

If you have metabolic syndrome, you might want to try reversing it with all the usual methods (e.g., lose excess fat weight, exercise more) along with a traditional Mediterranean diet enriched with 30 gm of mixed nuts daily.  As usual, check with your personal healthcare provider first.  Be aware that many of them won’t know about this study.

The puzzling thing to me is:  If the Mediterranean diet plus extra nuts is so effective in reversing metabolic syndrome, why didn’t that study cohort see fewer new cases of metabolic syndrome?

Steve Parker, M.D., author of The Advanced Mediterranean Diet

Additional reference:  Salas-Salvado, Jordi, et al.  Effect of a Mediterranean Diet Supplemented With Nuts on Metabolic Syndrome Status: One-Year Results of the PREDIMED Randomized Trial.  Archives of Internal Medicine, 168 (2008): 2,449-2,458.