Reams of research suggest that plant foods rich in antioxidants support optimal health.
This explains why berries, cocoa, grapes, leafy greens, onions, and other plant foods have stimulated so much buzz and – as with pomegranates – more than a little hype.
In fact, their “antioxidants” – almost all of which belong to the polyphenol family – don't really benefit the body in the way that term suggests. (To learn more, see our sidebar, “The truth about ‘antioxidants' in foods”.)
And some foods rich in beneficial polyphenols – including beans, nuts, and whole grains – rarely make the list of good sources.
Nuts are strongly linked to better heart health, and the polyphenols concentrated in their skins may be one reason why.
But they contain relative small amounts … too little to explain the links between nuts and heart health. A new study suggests that people who eat a handful (one ounce) of nuts daily are more likely to live longer, compared with people who rarely eat nuts.
The truth about “antioxidants” in foods|
The polyphenol and carotenoid compounds in whole plant foods are commonly called “antioxidants” because they behave that way in test tube experiments.
But in general, these health allies do not exert direct antioxidant effects in the body… at least not to a very substantial extent.
Instead, polyphenols appear to exert strong indirect effects on oxidation and inflammation via so-called “nutrigenomic” effects on gene switches (e.g., transcription factors) in our cells.
Polyphenols' nutrigenomic effects tend to moderate inflammation and stimulate the body's own antioxidant network … which includes enzymes, lipoic acid, CoQ10, melatonin, and vitamins C and E.
The richest known food source of polyphenols are raw (non-alkalized / non-“Dutched”) cocoa, berries, plums, prunes, tea, coffee, extra virgin olive oil, beans, and whole grains.
(Highly beneficial procyanidin-type polyphenols abound in cocoa, dark-hued berries – e.g., blackberries, blueberries açaí berries – grapes, red wine, and tea. Comparably beneficial anthocyanin-type polyphenols abound in cherries and most berries.)
Extra virgin olive oil is uniquely rich in hydroxytyrosol, oleuropein, oleocanthal, and other tyrosol esters … a particularly potent class of polyphenols with clinically documented vascular and brain benefits.
Population study indicates nuts may extend life
The new study comes from researchers at Boston's Brigham and Women's Hospital, Harvard Medical School, and Dana-Farber Cancer Institute.
They examined diet and health data collected from 76,464 women in the Nurses' Health Study and 42,498 men in the Health Professionals Follow-up Study.
The 118,962 participating nurses and doctors were in their 30s and 40s when the study began, and they completed diet surveys every two to four years over several decades.
Those who reported eating a handful of peanuts or tree nuts daily were significantly more likely to reach their 70s, compared with people who didn't eat nuts so regularly.
According to lead author, Ying Bao, MD, ScD, “Compared with those who did not eat nuts, individuals who consumed [one ounce of] nuts seven or more times per week had a 20 percent lower death rate and this association was dose-dependent.”
The benefit also held true for the risk of death due to cancer, heart disease, and respiratory disease.
When Dr. Bao said that the association was “dose-dependent,” he meant that the more nuts people reported eating, the longer they lived.
And the apparent life-extending effect of nuts was independent of other predictors for longevity, such as activity levels and overall diet.
The volunteers who consumed more nuts were also leaner, and tended to have a healthy lifestyle, such as smoking less and exercising more, but the analysis accounted for the known life-extending effects of those factors.
This suggests that – all other thing being equal – adding nuts to your daily diet may make a real difference to your risk of early death.
This was the largest study to date on the relation between nut consumption and risk of death, and the results are consistent with those of previous studies.
In 2003, the Food and Drug Administration approved a food label claim stating that for most nuts, consumption of 43 grams (1.5 oz) per day, as part of a low-fat diet, “may reduce the risk of heart disease.”
We should note that although most of the funds came from the National Institutes of Health, the researchers also accepted a grant from the International Tree Nut Council's education foundation.
Why would nuts extend life?
Prior research indicates that nuts make people feel fuller, faster, and nuts help control blood sugar.
As co-author Charles Fuchs told National Public Radio, “What we think nuts do is that they affect metabolism," he explains.
Dr. Fuchs also noted that if nuts deter overeating, that alone would tend to reduce the risk of diabetes and cardiovascular disease.
Nuts provide unsaturated fats, protein, fiber, vitamins (vitamin E, folate and niacin) minerals (magnesium, calcium, and potassium), phytosterols, and polyphenol-type “antioxidants”.
All of these nutrients help protect against cardiovascular disease and cancer … and the high blood sugar, oxidative damage (from free radicals), and chronic inflammation that drive both diseases.
What about nuts' contribution to American's “omega imbalance”?
Most nuts – except macadamia nuts – are very high in omega-6 polyunsaturated fatty acids.
While these are every bit as essential as omega-3 fatty acids, the American diet is overloaded with omega-6s.
Omega-6 fats predominate in the cheap vegetable oils that started replacing butter and lard in the 1960's – corn, soy, cottonseed, sunflower, and safflower oils – in a misguided, largely failed attempt to reduce heart disease risks.
Ample evidence shows that this sharp turn from animal fats to vegetable oils high in omega-6 fats – and the great majority packaged and takeout foods made with them – had seriously unhealthful consequences.
However, the small amount of omega-6 fatty acids in a handful of nuts is no problem, as long as your diet is not overloaded with these fats.
You can redress this imbalance in three ways:
At home, replace the vegetable oils highest in omega-6s – corn, soy, cottonseed, sunflower, and safflower oils – with olive, macadamia nut, and “hi-oleic” sunflower oils. Canola oil is a better choice, but is still high in omega-6 fats, and be aware that most of it comes from genetically modified rapeseed plants.
Cut back on prepared and packaged meals, snacks, and desserts, which are almost always made with these cheap, high-omega-6 oils.
Add more omega-3s to your diet, from seafood and fish oils. Some plant foods – dark, leafy greens, walnuts, and flaxseed – provide omega-3s, but they must compete with omega-6s for absorption in to our cells. Seafood is the only food source of the long-chain omega-3s our bodies actually use, and fatty fish like salmon, sardines, tuna, and sablefish offer the highest levels, by far.
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