By Faith Franz. Oncologists use several different factors to determine how well a patient will respond to treatment. Surgeons evaluate the stage and borders of a patient’s tumor to determine which patients are good candidates for surgery, while medical oncologists look for certain biomarkers to estimate how well a patient will respond to chemotherapy. Now, a new study indicates that doctors can predict quality of life (QoL) outcomes based on the patient’s nutritional status.
Antioxidant Supplements and Cancer Chemotherapy
There is much debate whether or not antioxidant supplementation during cancer chemotherapy alters the efficacy of chemotherapy drugs. The review by Block et al. (2007), evaluating Randomized Clinical Trials (RCT), looks at RCTs that measured survival and/or treatment response levels of patients who took antioxidants while on chemotherapy in order to see if antioxidants amplify or impinge on the efficacy of the chemotherapy…
Introduction
Block et al. (2007) start their review by citing no less than ten references about the use of Complementary and Alternative Medicine (CAM), showing that an estimated 13% to 87% of cancer patients use antioxidant supplements.
Antioxidants, while taken during chemotherapy are thought to
- a) hinder the cytotoxicity of chemotherapy by quenching the reactive oxygen species (ROS, a.k.a. free radicals), thus rendering the drug less effective, or
- b) help protect healthy cells from the onslaught of free radicals during chemotherapy (Block et al. (2007).
The Catch-22 for a cancer patient then is to understand if antioxidant therapy can improve Quality of Life (QoL) by protecting healthy tissue or gravely interfere with the outcome of cancer.
On the other hand, antioxidants might improve clinical outcomes by helping patients tolerate an uninterrupted treatment regimen with full doses of chemotherapy (Block et al., 2007).
Methods
Patients in the studies were either on an orally or intravenously administered antioxidants and chemotherapy. Block et al. (2007) make it clear that all types of cancers were included and chemotherapies that use ROS generating mechanism, while studies using whole herbs, multi-component herbals, and synthetic antioxidants were excluded. Trials were given Jadad scores to distinguish between weak and strong study designs. A limitation pointed out by Block et al. (2007) is the fact that “…bias in preferential publication of positive trials cannot be excluded” (p. 409).
Brief Overview of Outcomes
Out of 845 trials 19 were included in their review, using antioxidants Glutathione (7), Melatonin (4), Vitamin A (2), Mixed (2), Vitamin C (1), N-Acetylcysteine (1), Vitamin E (1), and Ellagic Acid (1).
Block et al. (2007) did not find any evidence that substantiated the concern that antioxidant supplementation given while on ROS generating chemotherapy lessened the efficacy of chemotherapy in a population of advanced or relapsed patients. On the contrary, 17 of the 19 reviews established
“…statistically significant advantage or non- significantly higher survival and/or treatment response in those patients given antioxidants. Specifically, of 13 reports on survival, all showed similar or better (four being statistically significant) survival rates for the antioxidant group over the control group” (Block et al., 2007, p. 415).
Block et al. (2007) continue with their findings:
“Additionally, while one study reported similar survival results between the antioxidant arm and control overall, the largest subgroup (stage III patients taking antioxidants) was found to have a statistically significant survival advantage compared to the control group” (p. 415).
And possibly the most reassuring statement:
“No studies reported significantly worse survival or response in the antioxidant supplement group” (Block et al., 2007, p. 415).
Limitations of the Block et al. (2007) Paper
Because of the small size of studies, these studies should be construed as treatment response data, and can’t be yet generalized to a wider population. Larger trials would be needed for such a generalization.
And because statistical power calculations performed either before or after trials, one can not say of important clinical effects were missed in these smaller trials.
The Bottom Line
This paper by Block et al. (2007) hints towards evidence that antioxidant supplementation helps reduce side effects of chemotherapy such as “…neurotoxicity, thrombocytopenia, diarrhea” (p. 416) and because of that, patients who probably would have dropped out of chemotherapy were able to complete their drug regimen.
Block et al. (2007) point to research by Neugut et al. (2006) studying colon cancer patients over age 65 and the effects of the entire five to seven months of chemotherapy regimen. These patients had higher survival rates than those who only received one to four months of treatment.
Also worthwhile considering is the finding that “…among the 30% of patients who dropped out of chemotherapy treatment early, mortality rates were twice those of the group who completed therapy” (Block et al. (2007, p. 416).
In other words, whether or not to use antioxidant supplementation during chemotherapy should probably be a conversation you and your primary care provider or oncologist should have.
However, just in case you are wondering going out to your local health food store to stock up on the antioxidants mentioned in this blog entry consider the following:
Block et al. (2007) clearly make mention of antioxidants administered intravenously, right? So this should give the reader pause and consider the dosages needed to achieve the desired effects.
References:
Block, K. I., Koch, A. C., Mead, M. N., Tothy, P. K., Newman, R. A., & Gyllenhaal, C. (2007). Impact of antioxidant supplementation on chemotherapeutic efficacy: A systematic review of the evidence from randomized controlled trials. Cancer Treatment Reviews, 33(5), 407–418. doi: 10.1016/j.ctrv.2007.01.005
Neugut, A. I., Matasar, M., Wang, X., McBride, R., Jacobson, J. S., Tsai, W.-Y., Grann, V. R., et al. (2006). Duration of adjuvant chemotherapy for colon cancer and survival among the elderly. Journal of clinical oncology: official journal of the American Society of Clinical Oncology, 24(15), 2368–2375. doi:10.1200/JCO.2005.04.5005
Cancer the killer. (n.d.). Description: A comic book on the history of the disease and warning signs of cancer. Retrieved from the Images From The History Of Medicine website at http://ihm.nlm.nih.gov/luna/servlet/view/search?q=A024304
Writing an essay, paper, or report? Cite this story:
APA: W Absenger. (2012.06.16). Block et al. (2007). Impact of antioxidant supplementation on chemotherapeutic efficacy [Web log post]. Retrieved from The Alternative Medicine Blog at http://amacf.org/2012/06/block-et-al-2007-impact-of-antioxidant-supplementation-on-chemotherapeutic-efficacy.html
MLA: Absenger, Werner. “Block et al. (2007). Impact of antioxidant supplementation on chemotherapeutic efficacy” The Alternative Medicine Blog. The Alternative Medicine Blog., 16 JUNE. 2012. Web. Insert your date of access here.
08-Marathon Training, Miami 2010: Why Vitamin B6 Should Be Part Of The Antioxidant Network & 9 Miles (hills again!)
Below is a map of my hilly route (mapmyrun.com, 2009). It is an awesome run up and down Fruitport road. Elevation ranges from 574 ft to 663 ft. The ascent is 112 ft and difference in elevation is about 90 feet or equivalent to a 9 story climb. The starting point once again is the Spring Lake Rite Aid. This course is getting even prettier as the leaves are starting slowly to turn color exposing a runner to an awesome display of fall colors. A 1:30 hours run that literally nourishes body and mind!
Now that we have taken care of nourishing the mind, how about some info on nourishing the body as well? After today’s stats we’ll cover vitamin B-6.
07-ING Marathon Training, Miami 2010: The Sweat Rate: a Crucial Measure of Dehydration During Exercise & 4 Mile Run
Today’s preparation for the 2010 ING Miami Marathon consisted of a short, easy four mile run. Nothing big, just enough to get the weekly mileage up. On another note, today as promised, we will be discussing loss of body weight during exercise or as nutritionists call it: The Sweat Rate. The sweat rate is an important indicator and gives us very important information about the body’s state of dehydration during exercise. The sweat rate also allows us to calculate optimum fluid replacement. Of course optimum fluid replacement is extremely important not only for recovery, but also to restore glycogen homeostasis and prepare us for the next bout of exercise. But firs today’s stats, followed by an explanation of “The Sweat Rate.”
06-26.2 Marathon Training, Miami 2010: 13 Mile Long Run & The Hottest Thing Since Sliced Bread: “Bambou” Underwear!
So, OK! Let’s start today’s training update with another Gear Check. You thought that this was all serious business about training for the 2009 ING Miami Marathon? Not quite. This post however, has to do with marathon running. There are other important things to optimum performance, such as proper shoes, (covered here) clothing, gadgets, music, etc. I usually don’t “wash my laundry in public” but this stuff I gotta share. Today’s Gear Check is absolutely awesome, and if you are an inspiring runner, or even a couch surfing hipster, you might want to check today’s Gear Check on proper running attire: bamboo underwear.
05-26.2 Training Miami 2010: 5 miles running against wind gusts of up to 60 mph & today’s Antioxidant: Vitamin E
Yesterday’s 5 mile run was nuts. On the way back I was battling unbelievable wind gusts. Come to find out, there was a High Wind Advisory in effect for most of West Michigan! I figure that carving my way through the wind was a great workout that will help me prepare to run 26.2 miles. After the stats please find info on the fat soluble antioxidant Vitamin E.
04-26.2 Training Miami 2010: 9 Miles Going Up And Down Hills. Plus This Run’s Nutrition Topic: Antioxidant Vitamin C
Sunday's run was absolutely awesome. It took me up Fruitport Road with it’s many hills. The temp was just right, with very little wind. Awesome conditioning workout. Here are the stats, followed by today’s Antioxidant: Vitamin C why you should make sure you get enough, good sources of Vitamin C and some precautions on Vitamin C.
003-26.2 Training Miami 2010: Very easy 4 miles & Nutrition and Exercise. Today we’ll start to explore Network Antioxidants…
Many of you might be familiar with the concept of the “Free Radical Theory” of aging. In short, free radicals are an unavoidable product of an organism that deals with aerobic respiration, such us humans. When oxygen is involved the very process of living and breathing creates free radicals. Free radicals can in turn, over time, do considerable damage to cells and cell membranes. Enter antioxidants. There is good scientific research out there that certain nutrients have the ability to quench free radicals and thus make them less dangerous to our cells. Individual cells are the building blocks for every tissue such as muscles and organs such as the heart. Running of course depends very heavily on aerobic respiration, and thus, the potential to increase free radical circulation. Over the next couple of “runs”…
Factors Influencing the Restoration of Fluid and Electrolyte Balance After Exercises in the Heat
Purpose: The creators of this study tried to find the best way to rehydrate after strenuous exercise in the heat. All the experiments were performed under controlled conditions in a laboratory in which researchers experimented with different rehydration techniques.
Because potassium is thought of to help rehydration after exercise because potassium is a major component of cytosol and ingestion of potassium after exercise might help retain water in the intracellular space, researchers set up an experiment to find out if that indeed was the case.
Type of study: This practice would make them intervention trials. No control subjects where used in these trials.
Research methodology: The experimenters used clear-cut definitions of dehydration and rehydration. For example, they defined dehydration as, ”a decrease in body mass of about 2% of initial value for a 70kg person.” After 30 minutes of the end of the exercise subjects were allowed to consume varying beverages with different volumes over 1 hour, after which no further food or beverage intake was allowed until the end of the study period. Measurements seemed also clear cut with Urine volume and composition, plasma measurements such as electrolyte balance, hormone levels, osmolality, blood and plasma volume throughout the study clearly defined.
It looks as the researchers did a good job in setting up the study by trying to measure “hydration” or “dehydration” from varying angles.
Summary of results: This particular study was set up by dehydrating eight male volunteers by 2.1% of body mass using intermittent cycle ergometer exercise in the heat. 45 minutes after the end of the exercise, researchers gave the subjects a glucose beverage (90mmol/l), a sodium beverage (NaCl 60mmol/l), a potassium beverage (25mmol/l KCl), and a beverage including all three electrolytes over a period of 30 minutes. The drink volume was equal to the amount of sweat lost in all experiments which was about 1.6L. Plasma volume was decreased by 4.4% in all dehydration experiments. Then researchers collected urine over six hours.
Smaller amounts of urine were collected for electrolyte drinks versus the electrolyte free drink. After researchers gave the subjects drinks, plasma volume increased in all trials, but interestingly, recovery was slower when KCl was consumed. But by the end of the study period, which was six hours after rehydration period there was no difference in an increase of plasma volume. The results were 5.1% for glucose- electrolyte beverage, 6.2% for NaCl beverage, 5.1% for KCl, and 2% for the drink containing all three electrolytes.
This research shows that potassium is not necessarily better in rehydration than other electrolyte containing drinks. In fact, the authors suggest that a rehydration drink should contain relatively high amounts of sodium, a minimum of 50mmol/L and some potassium. Further more the studies show that sodium is a superior medium to rehydrate compared to other electrolytes.
Critique: Researchers tackled this topic of rehydration from multiple angles, trying to cover as much ground as possible under controlled conditions of heat exposure. In general, they tried to measure as many data points possible before, dehydration, the rehydration period, and after rehydration was thought to be completed. Furthermore researchers state, that in order to optimally rehydrate for the next event, fluid losses through sweat should not only be replaced, by a surplus should be consumed.
There is only a couple of questions I have concerning the quality of this study. Why didn’t the researchers try to recruit more subjects for this study? Eight people seem to be a small number to draw conclusions for an entire population of athletes and weekend warriors alike. Why did researchers choose different molarities for their potassium study? (90mmol/L glucose, 60mmol/L NaCl, and 25mmol/L KCl) I understand it was a British study, but looking at the National Research councils recommendations of 60mmol/L for NaCl makes the intake short 5mmol/L of the suggested adequate intake. It gets even worse with potassium. The 25mmol/L administered are short of a whopping 95mmol/L of the suggested adequate daily intake. I would think that athletes incur an increased requirement electrolyte requirement because of their strenuous activities.
Implications for Future Research: Even though researchers did a good job with this series of study, future research could focus more on potassium for rehydration. I would think researchers could also use more test subjects. Trying this out on several sports teams during competition would be a great way to really get to the bottom of rehydration. Implications for the “weekend warrior” are clearly defined here. Rehydrate with more fluid than lost through perspiration, and make sure you use a NaCl-KCl medium to do that.
Beste Gesundheit,
Werner
Reference:
Maughan R., Leiper J., Shirreffs S. (1997). Factors influencing the restoration of fluid and electrolyte balance after exercises in the heat. Br J Sports Med. 31p.175-82
Vitamin B3 (Niacin) & High Cholesterol
Health care providers have been prescribing Vitamin B3, more specifically, the nicotinic acid form of vitamin B3 since the mid 50’s [1].
The Coronary Drug Project (CDP) followed over 8,000 men who had at least one heart attack for six years. When researchers compared findings with placebo, they found that 3g of nicotinic acid per day was responsible for [2]:
10% reduction in total serum cholesterol (nicotinic acid significantly increased HDL cholesterol {the good}, while decreasing LDL cholesterol {the bad}),
26% reduction in triglycerides,
27% reduction in recurrent nonfatal heart attacks
26% reduction in strokes and transient ischemic attacks.