More Good News for the Mediterranean Diet

For years, the standard nutritional advice for cardiovascular disease prevention has been to follow a low-fat diet.  This is still the official recommendation of the American Heart Association.  However, more and more evidence is pointing to the fact that it may be the quality, not quantity, of the fats we consume that is good for our hearts.

A few weeks ago, I wrote about a new study showing that detrimental effects of red meat consumption on our gut bacteria.  This could be one of the keys that links higher risk of cardiovascular disease to hiding meat intake.  The Mediterranean diet, which is low in meat, has just gotten some new support for its effectiveness in primary prevention of cardiovascular disease.  The Mediterranean diet is definitely not low in fat; it just relies more on different types of fat than the standard American diet (S.A.D.).  Instead of high levels of animal-based saturated fats from meat and dairy, the Mediterranean approach relies more on the healthful unsaturated fats in nuts and olive oil.

This new study from Spain, called PREDIMED (1), differs from previous research, in that it was a randomized controlled trial, involving over 7000 older men and women without any established cardiovascular disease.  This means that the investigators assigned a different diet to different groups of subjects -- either Mediterranean, or the AHA low-fat diet.  Most previous research was a retrospective -- that is, it looked at people's dietary habits in the past, based on recall or diet diaries.

The exciting finding from PREDIMED is that the Mediterranean diet, with a special focus on either olive oil or nuts, resulted in about a 30% lower risk of heart attack, stroke, or cardiovascular death compared to the low-fat approach.  Perhaps surprisingly, there are no studies of similar quality to support the benefits of a low-fat diet.  This recommendation of the AHA could be classified as a medical myth.

Dr Ramón Estruch, one of the lead researchers in this study, summarized his recommendations this way:

"People should know that the Mediterranean diet is a diet healthier than others and should know the key components of this food pattern. The plan should be to increase the intake of the key foods (vegetables, fruit, nuts, fish, legumes, extra virgin olive oil, and red wine in moderation), also increase the intake of white meat, and decrease the intake of red and processed meat, soda drinks, whole dairy products, commercial bakery goods, and sweets and pastries."

He continued: "To achieve a score of 14 in the 14-item adherence scale to traditional Mediterranean diet [laid out in a supplemental appendix in the paper] is more or less impossible, but to upgrade two to three points in this score is enough to reduce your cardiovascular risk by 30%."

 1.  Estruch R, Ros E, Salas-Salvadó J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med 2013; DOI:10.1056/NEJMoa200303. 

Just Say NO to High Blood Pressure!

It has long been known that compounds known as nitrates have a beneficial effect for the cardiovascular system.  The most common example of this is nitroglycerin, a drug that is used for angina (chest pain due to spasm of blood vessels).  Nitrates are transformed by bacteria in the mouth to nitrites, which are then converted in the blood into nitric oxide (NO).  NO relaxes blood vessels, which can lower blood pressure.

In addition to pharmaceutical nitrates, attention has been focused recently on whole foods sources of nitrates.  Two studies took a look at the effects of beetroot juice on blood pressure.  In 2012, Australian researchers (1) found that consuming beetroot juice significantly lowered systolic blood pressure for up to 6 hours, compared to placebo.  Beets are a good source of nitrates, which the body can convert into NO.

But 500 g of beetroot juice is quite a bit.  Some clever Brits (2) therefore compared drinking liquid beetroot juice to consuming a special beetroot enriched bread.  They found that both were equally effective in lowering blood pressure, and the bread may be more palatable.  Furthermore, in their study, they noticed that the blood pressure lowering benefits persisted for 24 hours.

One caveat to keep in mind is that both of these studies were performed with healthy subjects.  However, eating more vegetables is definitely good for your health anyway, so increasing your beet intake is a good idea if you're trying to lower your blood pressure.  You can also look at other vegetables that are high in nitrates, such as radishes, carrots, and lettuce.  And don't forget the blood pressure lowering benefits of chocolate for dessert!

1.  Coles, L and Clifton, P.  Effect of beetroot juice on lowering blood pressure in free-living, disease-free adults: a randomized, placebo-controlled trial.  Nutr J. 2012; 11: 106.

2.  Hobbs DA, et al. Blood pressure-lowering effects of beetroot juice and novel beetroot-enriched bread products in normotensive male subjects. Br J Nutr. 2012 Dec 14;108(11): 2066-74. Epub 2012 Mar 14.

Red Meat and Heart Health: The Gut Bacteria Connection

There's been a lot of debate over the years as to whether or not red meat consumption increases our risk of developing heart disease. In the past, much of the research has focused on the high levels of saturated fat and red meat, and their impact on blood cholesterol levels. A new study just published this month in Nature Medicine suggests a new mechanism: the difference in the type of gut bacteria between meat eaters and non-meat eaters.  A nice summary of the study was discussed recently on the National Public Radio show, Science Friday.

The main focus of this new study is a compound called L-carnitine, which is found in abundance in red meat. The intestinal bacteria found in omnivorous humans (compared to vegetarians or vegans) are more likely to metabolize L-carnitine into a compound called trimethylamine-N-oxide (TMAO).  High levels of TMAO accelerate the process of atherosclerosis.

The findings of this study are consistent with the well-known pattern of the Mediterranean diet, which places a great emphasis on plant-based foods, and recommends red meat only once or twice per month (see the pyramid diagram below). The Mediterranean diet is the pattern of eating among people in Italy, Greece, and other Mediterranean regions, that has been associated with protection against chronic disease, and greater lifespan.  This study has generated considerable outrage and debate, especially among proponents of high-meat diets, such as the Paleo diet. However, there is much more research about the health benefits of a Mediterranean eating pattern.

Once again, we're just beginning to scratch the surface of the importance of the ecosystem living in our intestinal tract.  I recently reported that the normal flora living in our gut can have an influence on obesity and weight loss.  If the first hundred years of nutrition research has focused on identifying nutrient compounds, deficiency conditions, and toxicity, then the next hundred years could be looking more at the effects of normal flora on our health.

Intestinal microbiota metabolism of L-carnitine, a nutrient in red meat, promotes atherosclerosis.  

Nature Medicine

 

(2013)

 

doi:10.1038/nm.3145.  

Published online

 

07 April 2013

Coffee: Pain Reduction, Weight Loss, and More

For decades, it's been a given in natural health circles that coffee is a no-no. It's commonly one of the first things that people are asked to give up when going on a detox program, or any other recommendations for improving their health. Over the past decade or so, though, evidence has been mounting that there are actually many health benefits for that morning cup of joe.

One of the latest findings is that coffee may help to reduce pain.  In 2012, Norwegian researchers found that coffee drinkers reported about a 25% lower pain score than non-coffee drinkers in a simulated office work environment. This difference was true whether participants had chronic pain or not.

Other benefits that have been reported for coffee in recent years include:

• decreased risk of endometrial cancer, Parkinson's disease, Alzheimer's disease, and type 2 diabetes
• enhanced muscle growth
• assistance with weight loss (with green coffee bean extract)

The research on green coffee extract for weight loss was a small human trial, involving only 16 subjects. Doses used were in the range of 700 to 1000 mg per day.  However, the results were striking, and so far, and this supplement seems safe. It is inexpensive, and worth a try for a few months.

The main benefits of coffee seem to be related to its phytonutrient content-- those health promoting compounds found in plants that have antioxidant and other beneficial effects on the human body. These benefits seem to hold true whether the coffee contains caffeine or not. So if you're concerned about caffeine, due to its acute blood pressure raising effects, or its detrimental effects on sleep, you can drink decaf, and still enjoy the preventive medicine aspects of coffee.

One last thing to keep in mind: many of the health benefits of coffee can be counteracted if you add a lot of milk and sugar to it. The high saturated fat and empty calories would be more than enough to outweigh the phytonutrient effects.

For me, I'll be enjoying my cup of black half-caf in the morning all the more.

Chocolate: Health Food or Not?

At this time of year, perhaps you've finished off your Valentine's Day chocolate, only to be looking forward to some chocolate in your Easter basket soon.  Americans definitely need to cut down on sweets:  The high sugar and saturated fat content in most milk chocolate can be a contributor to obesity and metabolic syndrome (a combination of insulin resistance, high blood pressure, and abnormal blood lipid levels).

On the other hand, the evidence for the health benefits of chocolate have been accumulating more and more in recent years.  The perks seem to be related to the flavanol content of the cocoa bean (Theobroma cacao).  The higher the cocoa (cacao) content, the better:  and dark chocolate (55% cacao or higher) is your best bet.  Eating an average of about one ounce per day can really boost cardiovascular and general health, including:

• Decreasing stroke risk by 14% for women (1) or 17% for men (2)
• Decreasing risk of heart failure in older women by 26-32% (3)
• Modestly reducing blood pressure (4-7)
• Decreasing "bad" cholesterol (LDL), and increasing "good" cholesterol (HDL) (8-9)
• Improving cognitive function (10)
• Most surprising of all:  decreasing body mass index (BMI) (11).  In other words, chocolate can lead to weight loss!

Just remember to enjoy your dark chocolate in moderation, as part of an overall nutrient-dense Mediterranean-type diet, including lots of fruits and veggies, nuts, legumes, lean protein, and healthy fats such as extra virgin olive oil.

1. Larsson SC, Virtmo J, Wolk A. Chocolate consumption and risk of stroke in women. J Am Coll Cardiol. 2011;58:1828-1829.
2. Larsson SC, Virtamo J, Wolk A. Chocolate consumption and risk of stroke: a prospective cohort of men and meta-analysis. Neurology. 2012;79:1223-1229.
3. Mostofsky E, Levitan EB, Wolk A, Mittleman MA. Chocolate intake and incidence of heart failure: a population-based prospective study of middle-aged and elderly women. Circ Heart Fail. 2010;3:612-616.
4. Ried K, Sullivan TR, Fakler P, Franks OR, Stocks NP. Effect of cocoa on blood pressure. Cochrane Database Syst Rev. 2012;8:CD008893.
5. Buijsse B, Weikert C, Drogan D, Bergmann M, Boeing H. Chocolate consumption in relation to blood pressure and risk of cardiovascular disease in German adults. Eur Heart J. 2010;31:1616-1623.
6. Taubert D, Roesen R, Lehmann C, Jung N, Schömig E. Effects of low habitual cocoa intake on blood pressure and bioactive nitric oxide: a randomized controlled trial. JAMA. 2007;298:49-60.
7. Buijsse B, Feskens EJ, Kok FJ, Kromhout D. Cocoa intake, blood pressure, and cardiovascular mortality: the Zutphen Elderly Study. Arch Intern Med. 2006;166:411-417.
8. Jia L, Liu X, Bai YY, et al. Short-term effect of cocoa product consumption on lipid profile: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2010;92:218-225.
9. Mursu J, Voutilainen S, Nurmi T, et al. Dark chocolate consumption increases HDL cholesterol concentration and chocolate fatty acids may inhibit lipid peroxidation in healthy humans. Free Radic Biol Med. 2004;37:1351-1359.
10. Desideri G, Kwik-Uribe C, Grassi D, et al. Benefits in cognitive function, blood pressure, and insulin resistance through cocoa flavanol consumption in elderly subjects with mild cognitive impairment: the Cocoa, Cognition, and Aging (CoCoA) study. Hypertension. 2012;60:794-801.
11. Golomb BA, Koperski S, White HL. Association between more frequent chocolate consumption and lower body mass index. Arch Intern Med. 2012;172:519-521.

Good Bacteria = Smaller Waistline?

Research in the area of normal flora -- the "good," or beneficial bacteria that live in our gut -- has been exploding in recent years.  It has been known for a long time that supplementing with probiotics (those friendly bacteria like Lactobacillus and Bifidus) can help with conditions ranging from eczema to allergies to irritable bowel syndrome.  But the list of benefits of proper microbial balance keeps growing -- and it seems like the more we know, the more we realize how much we don't know yet.

Recently, Chinese researchers (1) found a connection between the microbes in our gut and the problem of obesity.  Mice that were bred to be resistant to obesity, in spite of a high-fat diet, rapidly gained weight when injected with a bacteria from the human gut called Enterobacter cloacae.  They hypothesize that a harmful substance produced by these bacteria, called endotoxin, contributes to insulin resistance.  Insulin resistance is a major contributor to overeating and obesity, and the hallmark of type 2 diabetes.  Think of insulin as a key to open the door to your cells so they can take in blood sugar for energy; insulin resistance is where the lock on the cell doors gets worn and rusty, making it more difficult for insulin to do its job.  Insulin levels rise, which contributes to widespread inflammation in the cardiovascular system, and promotes fat storage.

In the same article, the researchers report a case study of a man who lost 66 pounds in 9 weeks by switching to a diet that promoted good bacteria growth in the intestinal tract.  The harmful Enterobacter was reduced to undetectable levels.

Now before you pop an acidophilus supplement or grab a Yoplait, expecting miraculous weight loss, we need to look a little more closely at the diet supplied to this test subject.  It was very high in fiber, to feed the good bacteria in the gut, and also included traditional Chinese fermented foods that might seem challenging to our palates.  Fermented foods are beginning to look more important than probiotic supplements, simply because of sheer numbers:  supplements might have anywhere from 1 billion to 20 billion bacteria per serving, which sounds like a lot, until you realize that there are about 100 trillion bacteria in your gut!  Traditional fermented foods have much higher levels of good bacteria than supplements.  We're not talking about most commercial yogurts, which are crammed with sugar and have questionable amounts of active bacterial cultures; we're talking about plain yogurt, kefir, miso, traditional sauerkraut, and kimchi, to name a few.

We've barely scratched the surface on research into our normal flora -- not just in the gastrointestinal tract, but also on the skin, respiratory tract, and genitourinary tract.  It makes sense that they would have such a huge influence on our health:  there are ten times as many bacterial cells as human cells in our bodies!  We are really more of an ecosystem rather than a single organism.  Perhaps in the future there will be much less emphasis on therapeutic nutrition, except as it applies to how it influences our flora.

1.  An opportunistic pathogen isolated from the gut of an obese human causes obesity in germfree mice.  The ISME Journal advance online publication 13 December 2012; doi: 10.1038/ismej.2012.153

To Calcium or Not to Calcium?

Two big studies that came out recently have muddied the waters on the one nutritional supplement that even conventional medicine has rallied behind:  calcium.

We've all heard that supplemental calcium is good for the bones, and may even protect against colon cancer in older adults.  Seems like a logical recommendation.  But like hormone replacement therapy, whose cardiovascular benefits were disproven ten years ago by the Women's Health Initiative study, calcium supplements are now being called into question.

The first chink in the armor came a few weeks ago when a study sponsored by the National Institutes of Health (NIH) (1) found that supplemental calcium boosts the risk of death by cardiovascular disease (CVD) in men, but not women.  Men who consumed 1000 mg/day of calcium supplement had a 20% higher risk of CVD death than those who took no calcium.

OK, great... men, ditch the calcium; women, keep popping those ginormous horse pills.  Until February 13, when BMJ (British Medical Journal) (2) published the findings of Swedish scientists, who found that calcium supplements increased death rates in women, too.  Examining the findings more closely, though, we find some important details:  the all-cause mortality rates were doubled in women with a calcium intake of  more than 1400 mg/day, compared to those getting 600-1000 mg/day.  A further complication is that risk of death was increased if the calcium came from supplements rather than food.

The US Preventive Services Task Force (3) has also chimed in, with a re-analysis of older data that showed that 400 IU of vitamin D plus 1000 mg of calcium per day did not significantly prevent fractures in healthy older women.

These studies add more weight to hints that have been accumulating over the years, that just increasing calcium intake is not necessarily better for health.  Some cultures of the world have very low levels of calcium intake, but very little osteoporosis.  Meanwhile, the US recommendations for daily calcium have climbed over the years, so that now the RDA for women over age 50 is 1200 mg/day.  When it comes to bone health, just adding more calcium is like throwing more bricks on a construction site, and hoping that they'll form a building.  You also need an architect and foreman -- namely, vitamin D and vitamin K.

So how do we parse all this confusion about calcium, health, and disease for older adults?  Here's my bottom line:

• Men:  Keep your daily calcium intake under 1000 mg/day.  For most men, this means skipping the calcium supplements altogether.
• Women:  Ditch the high-dose calcium supplements that provide 1000-1500 mg/day.  Aim for that 600-1000 mg/day range total between dietary and supplemental calcium, with an emphasis on dietary sources (dairy, leafy greens, sardines).
• Men and women:  Get your blood tested for 25-hydroxyvitamin D on a regular basis; aim for a level between 40-80 ng/ml.  If it is low, you may safely take higher levels of supplemental vitamin D3 (consult your doctor for the right amount -- I usually recommend anywhere from 2,000-10,000 IU per day).  If you have CVD, osteoporosis, or risk factors for these conditions, be sure to get extra vitamin K along with vitamin D3.

Stay tuned; like all of nutritional science, the landscape and recommendations are constantly in flux.

1.  Xiao Q, Murphy RA, Houston DK, Harris TB, Chow WH, Park Y. Dietary and supplemental calcium intake and cardiovascular disease mortality. JAMA Intern Med 2013; DOI:10.1001/jamainternmed.2013.3283. 

2.  Long term calcium intake and rates of all cause and cardiovascular mortality: community based prospective longitudinal cohort study.  BMJ 2013; 346 doi: http://dx.doi.org/10.1136/bmj.f228 (Published 13 February 2013)

3.  

Vitamin D and Calcium Supplementation to Prevent Fractures in Adults: U.S. Preventive Services Task Force Recommendation Statement.  Ann Intern Med. 26 February 2013