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Janae Decker
Annotated Bibliography
Group Topic: Obesity and Weight Management
Headline: Losing 10 pounds could boost your immunity
Cottam DR. Schaefer PA, Shaftan GW, et al. Dysfunctional Immune-Privilege In Morbid
Obesity: Implications and Effect of Gastric Bypass Surgery. Obesity Surgery. 2003;13:49-57.
The researchers tested the blood levels of 15 subjects with a BMI <25, and 27 subjects with a
BMI >40. In this experimental study, the obese subjects underwent bariatric surgery and had
their blood levels tested for one year. The blood levels were taken preoperatively and
postoperatively at 1, 3, 6, and 12 months and were tested for markers of immune function. After
the study was completed, the researchers discovered that in obese subjects CD62L (an adhesion
molecule on T-cells responsible for lymphocyte circulation) depression of 9.6% suggests a
functional decrease in the ability of lymphocytes to migrate and circulate to sites of infection,
inflammation, and tumors. The severe depression of CD62L was reversed with gastric bypass
surgery, increasing the levels to those similar to the control group.Researchers also found that
chronic inflammation seen in obesity causes a 13.4% increase of CD95 antigen expression on
polymorphonucleocytes and lymphocytes. The higher level of CD95 increases the risk of cell
death especially when the cell has to deal with inflammation from infection or Fas lignin
expression. In this study, the correction of the CD95 levels was seen through the intervention of
bariatric surgery. One year after surgery, the levels were CD95 were near the levels of the
control group.
Because this study is an experimental study its strength is that it can observe cause and effect.
The study can say that losing weight through bariatric surgery in obese subjects causes a
correction of the levels of CD62L and CD95 on lymphocytes to normal levels. The researchers in
this study state that limitations would include a diversity of diseases and medications affecting
the patient population. Also, since obesity is always tied to comorbidities, conditions that occur
paired with obesity, it is impossible to run the study from a population of “healthy” obese
patients.
The results of this study support the idea that morbid obesity is associated with unfavorable
decreases in the functioning of certain white blood cells in the immune system. The fact that
bariatric surgery showed the rapid reverse of unfavorable levels in certain cells strongly supports
the idea that obesity is correlated with decreased immune function. The discrepancy between the
news headline and this article is that the headline states that losing ten pounds will boost your
immunity. This study cannot be applied to everyone, only those who are obese. The blood levels
of the subjects were compared against the control group which had BMI’s < 25. If you have a
BMI < 25, then your immunity does not have any adjusting to occur according to this study.
Nieman DC, Henson DRUA, Nehlsen-Cannarella SL, et al. Influence of obesity on immune
function. Journal of the American Dietetic Association. 1999;99(3):294-99.
Using community subjects, the researchers took 116 obese (ranging from mildly to severely
obese) and 41 nonobese Caucasian women and ran complete blood panels, VO2max tests, BMI,
body composition, and psychological well-being tests. This cross sectional study was done to
compare measures of immune function in obese and nonobese subjects. The researchers found
from these tests that T and B lymphocyte counts were decreased by 19-32% in obese subjects,
and that monocyte and granulocyte phagocytosis and oxidative burst activity were 13-16%
higher in obese subjects.The elevated activity of these cells is important because these cells can
release potentially damaging substances, free radicals, and proteolysis enzymes. All of which are
found to promote atherosclerosis.BMI appeared to be the most important correlating factor for
immune parameters.
This study has strong findings showing that obese subjects had unfavorable levels of white blood
cell (WBC) compared to the nonobese subjects with normal WBC levels. The primary weakness
of this study is that it cannot be applied to the entire population because it was a correlational
study. Correlation does not mean causation. The occurrence of WBC levels in this population
can be considered as a possible outcome of obesity, but it cannot prove that WBC alterations and
obesity are connected. The results could be specific to this certain area or region. Another
limitation linked to this study is that it was done completely on a population of women, which
again limits its applicability to the general public.
This study supports the idea that immunity function and obesity may be related. The significant
differences in the white blood cell levels and their activity in the obese and nonobese subjects
point to a strong correlation between the functioning of the immune system and the BMI of
anindividual. This study implies that obese people have altered immune functions when their
WBC levels are compared to normal weight individuals. There is no evidence in this article that
losing weight will boost your immune system. It simply shows that those who are obese have
unfavorable levels of white blood cells compared to the nonobese population. It can be inferred
that if one loses weight, WBC levels will adjust to normal levels, but the study cannot state this.
If this study is paired with the above study on Dysfunctional Immune-Privilege In Morbid
Obesity: Implications and Effect of Gastric Bypass Surgery a conclusion could be drawn that
losing weight could possibly improve your immune system, but only for those that have a BMI>
40. It cannot be applied to the general population, as the headline “Losing 10 pounds could boost
your immunity” implies.
Viardot A, Samaras K. The effects of weight loss and gastric banding on the innate and adaptive
immune system in type 2 diabetes and prediabetes. J ClinEndocrinolMetab. 2010;95(6):2845-50.
In this study,the researchers used 7 male and 6 female morbidly obese (BMI > 35) subjects over
age 18 with either type 2 diabetes or impaired glucose tolerance. This experimental study had a
24-week protocol of energy restriction with gastric banding surgery at 12 weeks.The subject’s
blood was tested and compared to 10 normal weight subjects, matched for age and sex, at the
beginning of the study and at 12 and 24-weekintervals.At week 12 after a protocol of energy
restriction, the subjects underwent gastric banding surgery. After the study was completed the
researchers observed significant differences in the Th1 level which is a proinflammatory
lymphocyte. At week 1, the obese levels of Th1 were 5.3 +/- 1.6 compared to the control groups
levels of 2.2 +-/0.9. After the energy restriction, gastric banding surgery, and weight loss the Th1
levels of the obese subjects significantly fell to 0.8 +/- 0.2. The researchers also looked at the
Th1 to Th2 ratio. According to the levels, the ratio can mean that the subject is in an antiinflammatory or proinflammatory state. The anti-inflammatory state ratio was found in the
nonobese group with levels at 1.0 +/- 0.3. At the beginning of the study the obese subjects had
levels around 2.6 +/-0.6. After energy restriction, gastric banding surgery, and weight loss the
levels shifted to anti-inflammatory levels of .05 +/- 0.1. Researchers observed that in morbidly
obese persons with type 2 diabetes or impaired glucose intolerance, a severe energy restriction
paired with 13.5% weight loss reduced proinflammatory markers in the blood and levels shifted
toward anti-inflammatory ratios similar to the control group’s levels after 24 weeks.
Because this study is a human intervention trial, it appears that losing weight can cause an
improvement in the ratios of WBC responsible for a properly functioning immune system.
Although this study has very promising results, there are many limitations. There is lack of a
control group undergoing dietary energy restriction without weight loss to test the immune
function. Because this cannot be done, the effects of weight loss, energy restrictions, and gastric
banding cannot be isolated. We do not know which intervention is responsible for the immune
system changes if it is one in particular or if it is all of the interventions. Another limitation of
this study is that it doesn’t apply to everyone. It was only performed on Caucasians with diabetes
or impaired glucose tolerance. It cannot be applied to obese individuals without these conditions.
This study partially supports the statement that losing 10 pounds could boost your immunity.
While the study does indicate that the subjects that lost 13.5% of their weight reduced the
proinflammatory markers in their blood, which points to a boost in the immunity state of the
subject, it cannot be applied to the general population. The study applies to the morbidly obese
with type 2 diabetes and impaired glucose tolerance. Another issue affecting its applicability to
the general public is that the effects seen in the study only occurred after gastric banding surgery
paired with extreme caloric restriction, not just weight loss.