This is the second installment in a discussion of dietary fats, with respect to prostate cancer. See also:
"Foods/Supplements-Vitamins: Fats - [1] Oleic & Stearic Acids – (Olive Oil & Animal Fat)"
A. Summary.
High levels of palmitic acid are associated with increased risks for PCa & cardiovascular disease.
It is the preferred fuel for normal prostatic cells, & this does not change in PCa. (Note that palmitic acid does not drive the growth rate.)
Palmitic acid is found in fats of animal & plant origin. Limiting fat intake would be counterproductive, since excess carbohydrates convert to palmitic acid. Far better to accept a certain amount in the fat component of a low-carb diet.
Ultimately, the cancer may be responsible for higher levels, & control might involve inhibiting the enzyme used to generate palmitic acid.
B. Introduction.
"Palmitic acid ... is the most common saturated fatty acid found in animals {&} plants ..." [Ba] It was first discovered in palm oil - hence the name. It has a chain of 16 carbons.
Palmitoleic acid is derived from palmitic acid by the addition of a double bond 7 carbons from the end. i.e. it is an omega-7 monounsaturated fatty acid of 16 carbons.
Extra Virgin Olive oil is 7.5-20% palmitic & 0.3-3.5% palmitoleic.
In contrast, Macadamia oil is 7-10% palmitic & 14-22% palmitoleic.
High levels of palmitic acid (& palmitoleic acid) increase PCa risk.
"According to the World Health Organization, evidence is "convincing" that consumption of palmitic acid increases the risk of developing cardiovascular disease, based on studies indicating that it may increase LDL levels in the blood." [Ba]
"... palmitic acid is a major body component of animals. In humans, one analysis found it to make up 21–30% (molar) of human depot fat ..."
It is not possible to avoid palmitic acid, since the body manufactures it. "Palmitic acid is the first fatty acid produced during fatty acid synthesis and is the precursor to longer fatty acids."
However, high carbohydrate diets should be avoided IMO, since: "Excess carbohydrates in the body are converted to palmitic acid."
C. PCa Studies.
C1. Studies that assessed intake.
[C1a] (2008 - Japan)
"Relative risks ... on comparison of the highest with the lowest quartiles of ... palmitic acid were ... 1.53 ..."
C2. Studies that measured blood levels.
[C2a] (2008 - Europe - EPIC study)
"We found a positive association between palmitic acid and risk of total, localized, and low-grade prostate cancer. The risk of prostate cancer for men in the highest quintile compared with the lowest quintile of palmitic acid was 1.47"
[C2b] (2008 - Australia)
"Prostate cancer risk ... (Q5 to Q2 vs. Q1) {was} significantly elevated for {% plasma phospholipid} palmitic acid."
[C2c] (1997 - Norway)
"Blood donors to the Janus serum data bank in Norway, who later developed prostate cancer, were matched to blood donors without prostate cancer (141 matched sets) ..."
"Increasing risk for prostate cancer was found with increasing quartiles of palmitoleic {and} palmitic ... acid."
Risk factors - Palmitic: 1.0 1.2 1.4 2.3; Palmitoleic: 1.0 1.7 1.2 2.8
[C2d] (2013 - U.S.)
"De novo lipogenesis has been implicated in prostate carcinogenesis, and blood levels of specific saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) could reflect activity of this pathway."
"Blood levels of 16:1n-7 were associated with higher prostate cancer incidence, with rate ratios for men in increasing quintiles of 1.00, 1.40, 1.35, 1.44, and 1.97"
'16:1n-7' is palmitoleic acid. (Decoded: 16 carbons, 1 double bond, omega-7.)
"Furthermore, 16:1n-7 levels were positively related to incidence of high-grade (Gleason score ≥7) tumors (rate ratioQ5-Q1 = 3.92 ...) but not low-grade tumors ..."
"Higher activity of enzymes involved in de novo lipogenesis, as reflected in blood levels of 16:1n-7, could be involved in the development of high-grade prostate cancer."
C3. Cell Studies.
[C3a] (2010 - U.S.)
"Prostate cancer is characterized by a low rate of glycolysis and glucose uptake. We hypothesize that fatty acid is dominant over glucose in uptake by prostate cells."
"Uptake of palmitate {palmitic acid} in all 3 prostate cell lines was significantly higher than that of glucose at all incubation times ... But in malignant cell lines, neither glucose nor palmitate uptake was quantitatively higher than that in the benign cell line."
"Prostate cells are characterized by a dominant uptake of fatty acid over glucose ..."
C4. Fatty Acid Synthase [FAS, FASN].
FAS is the enzyme used to synthesize palmitic acid. Its presence in PCa cells is troubling, since it implies that the cells are manufacturing their preferred fuel.
[C4a] (2014 - Japan)
"A total of 46 patients (57.5%) with biopsy GS 5-6 were upgraded to GS ≥7 at RP. FAS expression was significantly associated with clinical T stage ... and positive core rate ..."
"Increased FAS expression in prostate biopsy cores could be a novel parameter for upgrading from biopsy GS 5-6 to GS ≥7 at RP."
[C4b] (2006, U.S.)
"Cancer cells frequently exhibit a significant increase in overexpression and activity of fatty acid synthase (FASN). Elevated FASN pathway activity also occurs in prostate cancer"
"... we observed gene copy gain in 24% of all prostate adenocarcinoma specimens examined with concurrent increased FASN protein expression. Immunohistochemistry alone showed 59% of prostate cancer specimens in the same tissue microarray with high FASN expression. Increased FASN gene was observed in 53% of all prostate tissues expressing elevated FASN protein levels and in 2 of 5 prostate tumor cell lines tested. These findings suggest that FASN gene copy number increases may be involved in the resultant increase in FASN protein expression observed in prostatic disease."
...
"Our ... studies demonstrated that {Tannic acid} is a natural FAS inhibitor whose inhibitory activity is stronger than that of classical FAS inhibitors, such as C75 and cerulenin." [C4c]
"Cerulenin is an antifungal antibiotic that inhibits fatty acid and steroid biosynthesis." [C4d]
In a liver cancer study, curcumin proved to be a FAS inhibitor. [C4e]
-Patrick
[Ba] en.wikipedia.org/wiki/Palmi...
[C1a] ncbi.nlm.nih.gov/pubmed/183...
[C2a] ncbi.nlm.nih.gov/pubmed/189...
[C2b] onlinelibrary.wiley.com/doi...
[C2c] onlinelibrary.wiley.com/doi...
[C2d] ncbi.nlm.nih.gov/pmc/articl...
[C3a] ncbi.nlm.nih.gov/pubmed/203...
[C4a] ncbi.nlm.nih.gov/pubmed/241...
[C4b] ncbi.nlm.nih.gov/pubmed/165...
[C4c] ncbi.nlm.nih.gov/pubmed/263...
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