(RxWiki News) Dairy, calcium and vitamin D have been shown to help prevent colorectal cancer. But can they help people who’ve already had colorectal cancer?
A large study of patients with colorectal cancer (cancer of the colon and rectum) compared their diet and vitamin supplements with how long they lived after their cancer diagnosis.
This study revealed that milk and calcium intake after diagnosis were linked to a lower risk of death in colorectal cancer patients.
"Ask your oncologist before taking dietary supplements or vitamins."
The lead author of this research was Peter T. Campbell, PhD, from the American Cancer Society.
Dr. Campbell and colleagues collected data on 2,284 patients diagnosed with colorectal cancer who participated in the Cancer Prevention Study II Nutrition Cohort, a study that began in 1992.
There were 1,274 men and 1,010 women in the study conducted by Dr. Campbell and his team. At the start of the study, patients were an average of 64 years old.
The participants were given a questionnaire when they began the study and again in 1999 and 2003. The questionnaire assessed the diet of the patients and asked the patients about any vitamins or dietary supplements they took after their colorectal cancer diagnosis.
The research team also tracked survival of the patients. Patients were followed until 2009 or 2010.
During the study, 949 patients died. Of these, 408 died from colorectal cancer.
To compare the milk, vitamin D and dairy consumed by the patients, the research team categorized the patients into four groups, from those consumed the most to those who consumed the least.
In the group consuming the lowest amount of calcium, men ate less than 578 milligrams (mg) per day and women ate less than 553 mg per day.
In the group consuming the highest amount of calcium, men ate 1,044 mg or more per day and women ate 1,156 mg or more per day.
In patients who consumed the least amount of vitamin D, men got less than 105 IU per day and women got than 90 IU per day. In the highest vitamin D groups, men received 226 IU per day or more and women received 202 IU per day or more.
The researchers found that the patients who consumed the most calcium had a 28 percent reduced risk of death compared to those in the lowest calcium intake group.
Colorectal cancer patients in the group who consumed the most milk also had a 28 percent lower risk of death than those in the group consuming the least amount of milk.
The authors noted that milk may have improved survival because it is a good source of calcium and vitamin D.
“In addition, milk is a primary dietary source of conjugated linoleic acid, which was found to inhibit colorectal cancer cell growth in vitro,” the authors explained.
An editorial commentary on this research was written by Donald I. Abrams, MD, of the San Francisco General Hospital and University of California San Francisco Osher Center for Integrative Medicine.
Dr. Abrams commented on conflicting results in the scientific literature regarding the effect of different food and vitamin supplements on cancer and survival.
“Taking a more holistic view, maybe it was the contribution of the overall dietary pattern and not a single nutrient,” Dr. Abrams wrote.
Dr. Abrams summed up the conclusion of Dr. Campbell and his co-authors, writing, "[T]he investigators found that the patients with the best outcomes were those who conformed to the American Institute for Cancer Research/World Cancer Research Fund recommendation that ‘after treatment, cancer survivors should follow the recommendations for cancer prevention.'"
This research was published online June 23 in the Journal of Clinical Oncology.
Funding for the research was provided by the American Cancer Society.
The researchers declared no conflicts of interest.