So, while browsing the CR Society Archives today, I ran across a post about a paper comparing the plasma concentrations of several organochlorines in a vegan group and an omnivore group. Since I am eating mostly vegan, this piqued my interest.The paper also includes a look at the olestra compound, but I’m not going to discuss this study in my post; if you are interested the paper can be read though the link I provide below. Keep in mind this link goes to a text only version of the paper since the full version with pics is still pay only. So, my post will be what it can without pics, although I would really like to see the graphs for this data.
I am going to focus on Study 1, the vegan vs. omnivore study. Study 1 included 9 vegans (vegans at least 4 years with the mean of 10.2 years and a standard deviation of 4.8 years) and 15 omnivores. A total of 26 organochlorines (OC) were tested for in the plasma of the study participants and include the following:
ß-hexachlorocyclohexane
p, p’-dichlorodiphenyldichloroethane (p, p’-DDE)
p, p’-dichlorodiphenyltrichloroethane (p, p’-DDT)
Hexachlorobenzene (HCB)
Mirex
Aldrin
?-chlordane (not sure exactly what this is, the # where the ? is didn’t c/p correctly)
?-chlordane (not sure exactly what this is, the # where the ? is didn’t c/p correctly)
Oxychlordane
Polychlorinated biphenyl (PCB) #28, 52, 99, 101, 105, 118, 128, 138, 153, 156, 170, 180, 183 and 187
Cis-nonachlor
Trans-nonachlor
Aroclor 1260
For five of the OCs {Aroclor 1260, PCB 99, PCB 138, PCB 153, and PCB 180}, the researchers reported that the vegans had significantly lower plasma concentration compared to the omnivores. Also, PCB 99 was less detectable in the vegans.
Nine OCs were completely undetectable in both groups {Aldrin, ?-chlordane, ?-chlordane, Cis-nonachlor, PCB 52, PCB 101, PCB 105, PCB 128, and PCB 183}.
Now, let’s look at the data backing this conclusion. I’m going to just post the P-values for the OCs of interest, and if you want to see the raw data just go to the post. For those of you that may not have had a probability course, the P-value used in determining data trends is representative of how likely the results are due to chance. If a P-value is less than 0.05, this is considered statistically significant, but for data with a P-value above 0.05 there is considered no significant data trend. Now, lets look at some P-values.
P-Values for Vegans vs. Omnivores, Table 2
p,p’ 0-DDE = 0.92
HCB ====== 0.076
Aroclor ==== 0.024
PCB 138 === 0.025
PCB 153 === 0.020
PCB 180 === 0.031
P-Values for Vegans vs. Omnivores, Table 3
ß-HCH ======= 1.00
p,p’ 0-DDT ==== 0.51
Mirex ======== 1.00
Oxychlordane === 0.092 (close)
Trans-nonachlor = 0.36
PCB 28 ====== 0.26
PCB 99 ====== 0.033
PCB 118 ===== 0.36
PCB 156 =====1.00
PCB 170 =====0.68
PCB 187 ===== 0.40
Notes from the Discussion portion of the paper:
The researchers conclude that vegans are significantly less polluted than omnivores; however they do note the small size of their study. Some reasons why they didn’t find significant differences in all the plasma OC concentrations include the fact that the vegans may have been breast fed as infants (exposing them to the OCs in their mother), and most vegans make the dietary shift in adulthood resulting in OC exposure all throughout childhood and adolescence. In addition, the vegans in this study tended to be older. Finally, contamination may come though environmental concerns in addition to diet. Location of residence, water sources, and food source as well as type are all factors in OC exposure.
There is also a positive correlation between body fat mass and OC concentration. Because OCs are fat soluble, greater fat mass on the body leads to an increased dilution space and likely retention of OCs. Also, other studies have reported that changes in OC concentration affect thyroid hormone levels. These reserachers, in a different study, reported that fat loss is related to an greater predicted decrease in T3 concentration.
As a final note, the researchers expect to see more significant data between omnivores and people who have practiced veganism for more than 10 years. Considering PCB half lives are 5-25 years, these substances could be detected in the body long after the exposure has ended.
