Nuts vary in the amount & composition of their fats & micronutrients, to the point where it makes no sense to make broad claims for "nuts" as a category in itself.
The fatty acid breakdowns shown below come from the USDA database. I have skipped mention of any fat type that is less than 5% by weight. I find it amusing when experts promote nuts as part of a healthy diet, but then praise the nuts that have the lowest fat content, & warn against eating too many. I don't suppose the Dean Ornish 10% fat diet allows for many nuts at all.
I have included polyphenol data when I could find it. Polyphenols are mostly found in the skins. Proanthocyanidins "are estimated to be the most abundant polyphenols in tree nuts", but we have almost no detailed data. [Z1]
Total phenol content comes from the USDA database & (Phenol-Explorer database) & are given as gallic acid equivalents [GAE]. Pecans have the most: 2,016 (1,816) GAE, & Pine nuts the least: 68 (58) GAE. More GAE is thought to be better.
Epidemiological PCa-nutrition studies that I have seen do not refer to specific nuts. Seeds are sometimes included in the 'nuts' category. Peanuts (a legume) may or may not be included - the studies are sometimes vague. It didn't seem worth including the few I found. PCa incidence has been reported to be lower in those who eat nuts, but which nuts - & how many?
PCa aside, people who consume nuts seem to have better mortality stats, but that doesn't help someone with a particular condition locate the best nuts & steer clear of nuts that might have no benefit.
I suppose that a significant consumption of nuts can be read as code for 'healthy lifestyle', although one study showed that men who were asked to incorporate nuts into their diets generally failed to adjust for the high energy content. They became an added snack.
But if nuts are incorporated into meals, rather than used as snacks, their high calorie content should cause men to cut down on other foods. But which? Benefits due to nut consumption might actually be due to the absence of the displaced foods.
Nuts, below, are in alphabetical order & I have nothing much to say about them until the last one (walnuts).
It's interesting to compare the fatty acids. I suspect that some will be turned off a particluar nut because of the amount of omega-6 fatty acid; others because of the saturated fat content; & still others because of the sheer amount of fat.
Dr Myers, who favors an interpretation of the Mediterranean diet, stresses that it is in no way a low-fat diet. He has mentioned that the carb:fat:protein ratio he aims for is pretty much what Barry Sears has been pushing in his Zone diet for decades. Nuts are a convenient way of balancing a meal that would otherwise be low in fat.
- Saturated fats. Brazil nuts are 10% palmitic acid & 6% stearic acid. Only one other nut approaches 5% for a specific saturated fatty acid: pistachios (5% palmitic acid).
Palmitic acid is the preferred fuel of prostate cells & that continues into PCa. However, the body converts excess carbs to palmitic acid, so carbs are more of an issue than Brazils, IMO. At least for those who shop for No-Fat/Lo-Fat products or follow Dean Ornish.
Stearic acid gets a bad name (you can make candles out of it), but it has been proven to be heart-neutral. Whatever the pros & cons of other saturated fats, one can no longer blame stearic acid for CVD. An interesting thing about cancer is that the stearic:oleic acid ratio goes down as the disease becomes more serious. This is disconcerting, since beef tallow is supposed to be unhealthy & oleic acid healthy.
- Monounsaturated fat. This is mostly oleic acid & it ranges from 9% (walnuts) to 44/45% (macadamias/hazelnuts). Continuing the discussion of the change in the stearic:oleic acid ratio (more oleic / less stearic), it makes one wonder if olive oil is such a healthy oil when PCa is advanced. However, the two fatty acids are only one processing step away from each other in the body. They both have backbones of 18 carbons. Stearic acid has no double bonds, since it is fully saturated, whereas oleic has one in the middle, i.e. 9 from the end (it is an omega-9). The body can convert one to the other. Just why the circulating ratio is altered in cancer is a mystery to me.
- Polyunsaturated fat. Mostly linoleic acid [LA], the "bad" omega-6. It ranges from 0% (macadamia) to 38% (walnuts). Walnuts are alone in having a significant amount of the "bad" omega-3 - alpha-linolenic acid [ALA] (9%) But see the discussion in the walnut section.
Nuts as a source of vitamin E. I am impressed that some nuts are good sources of gamma tocopherol, without the burden of alpha tocopherol. These include pecans, walnuts & pistachios.
Cutting to the chase, I'm surprised to find that there is more of a case for walnuts than almonds. This revolves around the type of vitamin E in each. I pretty much discount the ALA content since the LA is four times larger. LA is nominally "bad" because it can convert to arachidonic acid [AA]. However, the body doesn't create large amounts of AA just because it has a lot of LA. More significant to the balance of AA is intake of marine omega-3 fatty acids, IMO. Pecans have a better profile than walnuts - more gamma tocopherol without the ALA. More polyphenols. Pecans are my choice. (That was my summary, by the way.)
[A] Almonds. ( Prunus amygdalus )
Fatty acids, total monounsaturated: 32%
- Oleic acid: 31%
Fatty acids, total polyunsaturated: 12%
- Linoleic acid: 12%
Phytochemicals:
"The polyphenol content and antioxidant activity of Nonpareil, Carmel, Butte, Sonora, Fritz, Mission, and Monterey almond cultivars harvested over three seasons in California were examined. LC–MS was employed to quantify 16 flavonoids and two phenolic acids in acidified methanol extracts of almond skins. The 3-year mean polyphenol content of cultivars ranged from 4.0 to 10.7 mg/100 g almonds. Isorhamnetin-3-O-rutinoside was the most abundant flavonoid, present at 28–49% of total polyphenols among cultivars. Almonds from 2006 and 2007 had 13% fewer polyphenols than 2005, but FRAP and total phenols were comparable. Cultivar, but not season, had a differential impact on individual polyphenol synthesis. Using the results of polyphenol, total phenol, and FRAP, multivariate analysis distinguished harvest years and most cultivars with 80% confidence. Flavonoid content and antioxidant activity of almonds may be more dependent on cultivar than on seasonal differences." [A1]
"Combining {various} reports yields an average of 25·01 mg flavonoids/100 g almonds." [Z1]
Total phenol content: 418 (287) GAE.
Proanthocyanidins: 184 mg/100g. [Z1]
Almonds are rich in alpha tocopherol vitamin E (26mg / 100g). In my view, this makes them a poor choice, since alpha tocopherol drives down the beneficial gamma tocopherol. Walnuts are a far better choice for vitamin E.
"Almonds are currently subjected to mandatory pasteurisation or roasting treatments before consumption due to food safety concern." [Z1]
[B] Brazils - dried. ( Bertholletia excelsa ) ... actually, a seed!
Fatty acids, total saturated: 16%
- Palmitic acid: 10%
- Stearic acid: 6%
Fatty acids, total monounsaturated: 24%
- Oleic acid: 24%
Fatty acids, total polyunsaturated: 24%
- Linoleic acid: 24%
Phytochemicals:
Total phenol content: 310 (244) GAE.
Brazils famously contain a huge amount of selenium: 1,917 µg per 100g.
[C] Cashews. ( Anacardium occidentale )
Fatty acids, total saturated: 8%
Fatty acids, total monounsaturated: 24%
- Oleic acid: 24%
Fatty acids, total polyunsaturated: 8%
- Linoleic acid: 8%
Phytochemicals:
Total phenol content: 269 (233) GAE.
Proanthocyanidins: 9 mg/100g. [Z1]
[D] Chestnuts. ( Castanea )
Only 1% total fat.
[F] Filberts. ( Corylus maxima ) ... as for Hazelnuts.
[H] Hazelnuts. ( Corylus avellana )
Fatty acids, total monounsaturated: 46%
- Oleic acid: 45%
Fatty acids, total polyunsaturated: 8%
- Linoleic acid: 8%
Phytochemicals:
Total phenol content: 835 (687) GAE.
"Hazelnuts have an appreciable content of flavonoids with 18 mg/100 g" [Z1]
Proanthocyanidins: 500 mg/100g. [Z1]
Contains genistein.
[M] Macadamia. ( Macadamia integrifolia )
Fatty acids, total saturated: 12%
Fatty acids, total monounsaturated: 59%
- Palmitoleic acid: 13%
- Oleic acid: 44%
Phytochemicals:
Total phenol content: 156 (126) GAE.
[P] Pecans. ( Carya illinoiensis )
Fatty acids, total saturated: 6%
Fatty acids, total monounsaturated: 41%
- Oleic acid: 41%
Fatty acids, total polyunsaturated: 22%
- Linoleic acid: 21%
Phytochemicals:
Total phenol content: 2,016 (1,816) GAE.
"Pecans have the highest total flavonoid content among nuts at 34 mg/100 g, consisting mostly of flavan-3-ols and anthocyanins." [Z1]
Proanthocyanidins: 494 mg/100g. [Z1]
Source of ellagic acid.
Pecans contain gamma tocopherol vitamin E: 24 mg, versus 1.4 mg alpha tocopherol.
[Q] Pine nuts - dried. ( Pinaceae ) ... seeds, not nuts.
Fatty acids, total saturated: 5%
Fatty acids, total monounsaturated: 19%
- Oleic acid: 18%
Fatty acids, total polyunsaturated: 34%
- Linoleic acid: 33%
Phytochemicals:
Total phenol content: 68 (58) GAE.
[R] Pistachios. ( Pistacia vera )
Fatty acids, total saturated: 6%
- Palmitic acid: 5%
Fatty acids, total monounsaturated: 23%
- Oleic acid: 23%
Fatty acids, total polyunsaturated: 14%
- Linoleic acid: 14%
Phytochemicals:
Total phenol content: 1,657 (1420) GAE.
"Pistachios are the only tree nut with reported stilbene content, with 803 μg/100 g."
"Resveratrol and piceid are the only stilbenes thus far identified in tree nuts" [Z1].
"Pistachios have the highest isoflavone content of nuts at 3·63 mg/100 g mainly as daidzein and genistein, more than 100-fold greater than levels of other nuts" [Z1].
Proanthocyanidins: 237 mg/100g. [Z1]
[W] Walnuts, English. ( Juglans regia )
Fatty acids, total saturated: 6%
Fatty acids, total monounsaturated: 9%
- Oleic acid: 9%
Fatty acids, total polyunsaturated: 47%
- Linoleic acid [LA]: 38%
- Alpha Linolenic acid [ALA]: 9%
Phytochemicals:
Total phenol content: 1,556 (1,576) GAE.
Proanthocyanidins: 67 mg/100g. [Z1]
A source of ellagic acid
Walnuts are the only nut listed here with ALA (9%). The PCa litereature against ALA is substantial. I believe that Dr. Myers advises against walnuts.
It should be noted that the men who fared worst in one big study, were those who had high ALA & low LA. The two fatty acids compete for enzymes & it appears that ALA is a problem when it is dominant. With LA:ALA in a 4:1 ratio, I'm not convinced that walnuts have to be excluded, if there are other reasons to eat them. ...
Walnuts contain gamma tocopherol vitamin E: 21 mg, versus 1 mg alpha tocopherol. But for the ALA, this would make them a very attractive source of vitamin E.
"Walnuts ... are rich in polyphenols, mainly ellagitannins (ETs) that after consumption are hydrolyzed to release ellagic acid (EA). EA is further metabolized by microbiota to form urolithins, such as A and B, which are absorbed." [W1]
[W1] (2014 - Spain) ... note "AR" = Androgen Receptor
"... urolithins inhibit AR-mediated PSA expression at the transcriptional level."
"... urolithins decreased AR binding to its consensus response element."
"Additionally, urolithins induced apoptosis in LNCaP cells ..."
[W2] (2008 - U.S.)
"We assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). Subjects (n = 21) consumed (in random order) their usual diet +/- a walnut supplement (75 g/d) that was isocalorically incorporated in their habitual diets. Prior to the supplement study, 5 fasted subjects participated in an acute timecourse experiment and had blood taken at baseline and 1, 2, 4, and 8 h after consuming walnuts (75 g)." {Seems excessive - ~25% total energy?}
"... although PSA did not change, the ratio of free PSA:total PSA increased and approached significance ..."
"The alpha-T: gamma-T ratio decreased significantly .., partly reflecting an increase in serum gamma-T, which approached significance ..."
"The ratio of serum α-T:γ-T, which decreased almost four-fold, is of particular interest ..."
"A previous study identified a higher ratio of serum α-T:γ-T as an important difference between patients with heart disease and healthy controls. Thus, a lower ratio of serum α-T:γ-T may be protective against heart disease, and walnuts may be beneficial in lowering this ratio."
-Patrick
[A1] ncbi.nlm.nih.gov/pmc/articl...
[W1] ncbi.nlm.nih.gov/pubmed/252...
They feed my delusions. Yum. I eat lots of almonds. I started becuase I wanted the empty square transparent containers. Now I have no idea. The container project has gone by the boards.
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