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How healthy are roasted nuts (the ones you buy from a store, like Kirkland Signature)?


InquilineKea

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E.g. Kirkland Signature Whole Cashews or Planters Peanuts?

 

I often snack on them. But are they often roasted? If so, do their oils contain significant amounts of advanced lipoperoxidation endproducts? Is that a major concern?

 

A lot of studies show positive effects of eating nuts, and most of the nuts that are available do seem to be somewhat processed.

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  • 4 weeks later...

Good question.

 

For sure, raw nuts are preferable; but, in the Wikopedia entry on "peanut butter", it is claimed that peanuts actually gain a benefit from being roasted -- supposedly the "goodies" in the peanuts are more easily absorbed when the peanuts are in the form of roasted peanut butter.  (This may be true; I don't know.  If so, an analogy comes to mind:  lycopene is better absorbed from cooked tomatoes, or tomatoe paste, than from raw tomatoes.)

 

  -- Saul

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  • 3 weeks later...

Conversely Science Daily had a report   http://www.sciencedaily.com/releases/2015/06/150610190920.htm

 

Nuts and peanuts -- but not peanut butter -- linked to lower mortality rates, study finds

 

Summary:

A study confirms a link between peanut and nut intake and lower mortality rates, but finds no protective effect for peanut butter. Men and women who eat at least 10 grams of nuts or peanuts per day have a lower risk of dying from several major causes of death than people who don't consume nuts or peanuts

 

I did not see anything in the article on the original question of roasted vs raw.

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I've requested a copy of the article in the International Jornal of Epidemiology that is summarized in the Science Daily article.  It's availalble to me online here at the University of Rochester -- I'll post back when I've received and read the article.

 

It is a very interesting question -- whether roasted or raw nuts are better -- and, of course, it's unclear if the answer will be the same for every kind of nut.

 

In the meantime, the Science Daily article had one useful observation:  It was claimed that 1/2 handful of nuts had the beneficial effects -- more had no additional effect.

 

(Also, it would be nice to know how large a study this was -- is it statistically significant?  (I think that the Sciencw Daily article suggested that that is so.)

 

  -- Saul

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Hi All!

 

I've recieved a .pdf of the original article that is summarized in the Science Daily article.  I would like to make it available to all; but apparently I have to put it into "My Media" before I can do this -- and I don't know how to put something into "My media". 

Here's a (very brief) summary of some of the material:  The original paper does not indicate whether the tree nuts and peanuts consumed were raw or roasted (or salted).  Overall, the Scince Daily summary is correct -- but many causes of death showed continuing lowering of mortality rates with larger amounts of consumed nuts.

 

One surprising finding:  For non-alcohol consuming subjects, there was no association found between nut-eating and improvements in mortality.  But for alcohol consumers, that inverse association remained.

 

The authors of the study indicate that further work would be needed to validate the observation for non-alcohol consumers -- possibly because of low numbers of "non-alcohol consumers" in the study -- but this inforemation was not given in the article.

 

Another interesting detail:  The study was for people adhering to "The Mediterranean Diet" -- so it appears that those eating less nuts were probably eating more olive oil, in order to balance %fat (I would guess).

 

If so, the study would appear to suggest that nuts (tree nuts, peanuts, but not peanut butter) are better sources of MUFA than olive oil -- however, I am not sure that I'm interpreting that correctly.  I'd like Michael Rae's opinion and analysis of the article; he's much better at this than I am.

 

(Also, I'm worried whether or not I'd be violating Copyright Laws by publishing the .pdf on thew List).

 

So, I'm going to ewmail it to Michael, for his much more scholarly anaslysis.

 

  -- Saul

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I think the questions we need to answer are:

  • What about raw (or any) nuts provide a benefit to our health?
  • Does roasting impair #1 by either A) reducing the health-promoting benefits or B} creating new harmful substances
  • Are raw nuts per se healthy, or is it something else (diet/lifestyle) associated with raw nut consumption?

My quick response to the above:

  • Raw nuts are difficult to digest and slow absorption, and also result in less overall calorie absorption. Roasting increases digestibility and calorie extraction. Many phytochemicals exist in raw nuts that seem to be destroyed or modified with roasting, though from what I recall the general physiological beneit from these phytonutrients/antioxidants/etc. isn't substantially changed with roasting. Nuts in general contain unsaturated fats, especially PUFA, which seem to provide some metabolic benefits when replacing SFA or processed carbohydrate. Nuts also contain various anti-nutrients that may actually provide benefit, though some people may be sensitive to them. Nuts also contain fiber and phytosterols.
     
  • Many components of #1 don't change with roasting, but some do. A) I believe roasting (and soaking) reduces the anti-nutrient content of nuts. This could increase overall nutrient absorption, but also reduces the potential benefits anti-nutrients may provide. Roasting also reduces vitamin E content. B} Roasting does increase oxidation of unsaturated fats and (I think) reduces vitamin E content, though I don't recall these specifically greatly reducing the epidemiological benefits of nut consumption. Roasting may also induce novel carcinogenic compounds, but again without significant epidemiological impact.

    Roasting is often accompanied by salting, which may increase palatability and over-consumption and exacerbate salt-related conditions, altering the epidemiological/associative data. As Cory posted above, nut butters most often contain sugar, salt, and trans-fats, having a similar effect on our interpretation of the data.
     
  • Nut consumption, especially raw, is associated with higher socioeconomic status, and often income, education, access to health-care, and is definitely associated with health-conscious diet and lifestyle choices.

Overall, I think you'd be statistically fine consuming raw or roasted nuts. Given the choice I think raw may be better, but perhaps not meaningfully so in the context of the rest of your diet and CR.

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Here is some info I dug up:
 
PDF of a medical professional summary (with references) on effects of roasting nuts: Roasting Nuts--Practice Issue; Evidence Summary
[This one is definitely worth reading!]

 

Overall, nothing directly comparing roasted vs. unroasted that I could find. Only epidemiological evidence, and that seems to mostly show no difference.

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Hi again, James!

A careful reading of the full article from which the Science Daily article refers to, indicates:

This large, professional study, for the most part, doesn't distinguish between roasted vs. raw nuts -- and whether or not salted.

Concerning peanut butter: they found no effect (positive or negative) on all cause, or specific cause (from a long list) mortality from consuming peanut butter. However, they note that Dutch peanut butter (the study was in Holland) is usually heavily salted, and usually contains trans-saturated fatty acids -- so that "effect" might mean "positive, enough to neutralize the negative effects of the trans fats".

Also: A direct comparison is made between consuming walnuts vs. peanuts regulary: both are good, but peanuts are slightly better (I think not statistically significantly).

The interesting thing here: They don't say it, but walnuts are, to the best of my knowledge, almost always eaten raw. So this is PROBABLY a comparison, for the most part, of a raw nut vs. a roasted one.

-- Saul

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  • 3 weeks later...

All:
 

A lot of studies show positive effects of eating nuts, and most of the nuts that are available do seem to be somewhat processed.

 
I agree, and it is worth paying attention to the specifics of the epidemiology; and it's surprising that no one seems to have really looked into this question. It would be nice to have at least short-term studies on the effects of raw vs. roasted nuts on well-established risk factors, like the ones done on high- vs. low-phenolic olive oil. Still, in a case like this, where the chemical effects of roasting are clearly pretty deleterious (see all the research on glycotoxin consumption), my strong inclination is to assume that while consumption of roasted (and usually salted) nuts may be healthier than abstention from all nuts, consumption of raw, unsalted nuts is healthier still.
 
Adding to the information on raw vs. nuts already offered by James:
 

Food Chem. 2015 Aug 1;180:77-85. doi: 10.1016/j.foodchem.2015.02.017. Epub 2015 Feb 11.
Influence of roasting conditions on health-related compounds in different nuts.
Schlörmann W, Birringer M, Böhm V, Löber K, Jahreis G, Lorkowski S, Müller AK, Schöne F, Glei M.

 
... The composition of hazelnuts, almonds, macadamia nuts, pistachios and walnuts regarding health-promoting and potentially harmful compounds was examined before and after roasting under different time and temperature conditions. Fatty acid compositions were not affected by roasting. Malondialdehyde increased with higher roasting temperatures (17-fold in walnuts). Levels of tocopherol isomers were reduced after roasting (α-T: 38%, β-T: 40%, γ-T: 70%) and hydrophilic antioxidant capacity decreased significantly in hazelnuts (1.4-fold), macadamia nuts (1.7-fold) and walnuts (3.7-fold). Increasing roasting temperatures supported the formation of significant amounts of acrylamide only in almonds (1220 μg kg(-1)). In general, nuts roasted at low/middle temperatures (120-160°C) exhibited best sensory properties. Therefore, desired sensory quality along with a favourable healthy nut composition may be achieved by roasting over a low to medium temperature range.

PMID: 25766804

 
 

One surprising finding:  For non-alcohol consuming subjects, there was no association found between nut-eating and improvements in mortality.  But for alcohol consumers, that inverse association remained.
 
The authors of the study indicate that further work would be needed to validate the observation for non-alcohol consumers -- possibly because of low numbers of "non-alcohol consumers" in the study -- but this inforemation was not given in the article.

 
This is a curious finding; as they note, "To our knowledge, this is the first report of a significant and rather strong interaction between nuts and alcohol intake. Nevertheless, subgroup findings are to be interpreted with caution because of possible chance findings; they need to be verified first in other studies."  The only thing I can think of is maybe a beneficial effect of both on HDL. I think Saul is probably right to suggest an underpowering: they do mention that "Nut consumers ... on average ... drank more alcohol," but as you can see in Table 1 there was substantial alcohol consumption in all groups: for men, alcohol intake in g ±SD is 12.5 (16.7) for nonconsumers of nuts (this is already one standard "drink" a day), and rises by quartile of nut intake:13.5 (16.9), 16.7 (19.0), 20.1 (17.7).
 

Another interesting detail:  The study was for people adhering to "The Mediterranean Diet" -- so it appears that those eating less nuts were probably eating more olive oil, in order to balance %fat (I would guess).
 
If so, the study would appear to suggest that nuts (tree nuts, peanuts, but not peanut butter) are better sources of MUFA than olive oil -- however, I am not sure that I'm interpreting that correctly.

 
First,  neither the study as a whole nor the benefit of nuts was (just) for people adhering to the Med diet: if you look at Supplmentary Table 2, there are statistically significant reductions in mortality by nut intake in low/non-, medium-, and high-Med diet scoring groups. I think you may have been misled by either their statement that “In sensitivity analyses with adjustment for Mediterranean diet adherence (excluding nuts) instead of adjusting for alcohol, vegetables and fruit, essentially similar results were seen”, or their noting that “In the Netherlands Cohort Study (NLCS), an inverse association between nut intake as a component of the Mediterranean diet and overall mortality in both men and women was found”: the latter refers to a previous report in this cohort, and even in that previous study, it’s not as if there was a finding of no benefit found of nut consumption in non-Med eaters: rather, that nuts were assigned points on the Med diet score and the analysis was for overall Med diet adherence by points.
 
I'm am pretty skeptical of your guess that "those eating less nuts were probably eating more olive oil, in order to balance %fat." Certainly it  has no basis in the report: the investigators adjusted for total energy intake and a range of other variables, but not % fat -- and, of course, people do vary in the %fat in the diet, just as they do for particular fat sources. In the PREDIMED trial,(1) the group assigned to consume more olive oil increased their % fat and did not decrease their mean nut intake; the group assigned to consume more nuts also increased their %fat, and increased their olive oil intake even though they weren't asked to.
 

Also: A direct comparison is made between consuming walnuts vs. peanuts regulary: both are good, but peanuts are slightly better (I think not statistically significantly).
The interesting thing here: They don't say it, but walnuts are, to the best of my knowledge, almost always eaten raw. So this is PROBABLY a comparison, for the most part, of a raw nut vs. a roasted one.

 I don't see anywhere where they compare the effects of particular kinds of nuts: they do compare the nutrient profiles of nuts and walnuts, but nowhere do I see an analysis of their respective effects on total or disease-specific mortality.

 

Reference

1. Estruch R, Ros E, Salas-Salvadó J, Covas MI, Corella D, Arós F, Gómez-Gracia E, Ruiz-Gutiérrez V, Fiol M, Lapetra J, Lamuela-Raventos RM, Serra-Majem L, Pintó X, Basora J, Muñoz MA, Sorlí JV, Martínez JA, Martínez-GonzálezMA; PREDIMED Study Investigators. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013 Apr 4;368(14):1279-90. doi: 10.1056/NEJMoa1200303. Epub 2013 Feb 25. PubMed PMID: 23432189.

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Thanks, Michael.

 

"Guest's" suggestion of emailing the authors might be a good idea -- but I'm 99% sure that they didn't distinguish between raw or roasted in the study.

 

Also, the study was done in the Netherlands:  It is noted that peanuts consumed there are almost always roasted and heavily salted.  There is no information given about other nuts on the subject of raw or roasted.

 

  -- Sauk

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I don't think the mysterious Guest_guest_'s suggestion would help: whether they used raw or roasted nuts in PREDIMED (and I suspect they would have used raw walnuts but roasted almonds and probably hazelnuts, since that's usual for those nuts), it wouldn't tell you how much better or worse raw nuts are than roasted, which is what's at issue.

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