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In the news: Calcium & Colon Health: Fish Oil & Mental Function

Can Adequate Calcium Intake Support Colon Health?

A good deal of evidence suggests that drinking milk may decrease the risk of colorectal cancer, which is the third most commonly diagnosed cancer in the U.S.

While a number of nutrients found in milk – vitamin D, some fats and organic acids – could be affording some of the apparent protection, calcium is believed by many to be the major contributing factor since its content is so high in milk, and there are plausible ways it could be acting.

Despite this likelihood, the results of population-health studies and clinical trials testing the effects of calcium supplements on markers of colon health have been inconsistent.

To better understand the relationship between calcium and colorectal cancer risk, researchers at Harvard School of Public Health conducted a dose-response meta-analysis of 15 prospective observational studies looking at calcium intake and involving over 12,300 cases of colorectal cancer.

In this meta-analysis (1), the authors found calcium to be responsible for this protective effect, with every 300 mg increase in total calcium intake daily associated with an 8% decrease in risk. They also compared dietary with supplemental calcium intake, and found that both sources provide similar benefits.

Since the National Health and Nutrition Examination Survey estimates that the median daily calcium intake from food alone for people over 50 years of age is 650 mg, the meta-analysis findings suggest that supple-mental calcium could help offset dietary calcium gaps and contribute to risk reduction.

The researchers conclude that randomized controlled trials of calcium supplements with at least 10 years of follow-up are warranted in order to confirm a benefit of supplementation on colorectal cancer risk.

Fish Oil Linked to Better Cognitive Test Scores and Brain Volume

Researchers from Brown University took a retrospective look at the relationship between use of fish oil supplements, cognitive decline and brain atrophy in over 800 participants of the NIH-funded Alzheimer’s Disease Neuroimaging Initiative (2).

Older adults (229 cognitively normal individuals, 397 patients with mild cognitive impairment, and 193 patients with Alzheimer's disease) were assessed with neuropsychological tests and brain magnetic resonance imaging (MRI) every 6 months for a 4-year period. The researchers examined cognitive function and brain atrophy in those who reported routine use of fish oil supplements versus non-users.

Compared to non-users, fish oil use during follow-up was associated with better cognitive test scores. It was also linked with less atrophy (smaller volume with a loss of neurons and the connections between them), in critical areas of the brain used in thinking and memory. The benefits were seen only in those who were initially normal, and were not observed in those who were already mildly impaired or had Alzheimer’s. Another group that did not seem to benefit were people who carried the APOE-4, a genetic risk factor for Alzheimer’s.

The associations seen in this study suggest that fish oil use may help preserve brain volume and cognition in some individuals. But the evidence overall is mixed, with some studies suggesting benefit for those with mild cognitive impairment or mild Alzheimer’s, and others finding none. The inconsistency in findings highlights the need for further research to see if the omega-3 fats can influence brain function and structure as we age, and which groups might be the beneficiaries.

References

1. Keum N, et al. Calcium intake and colorectal cancer risk: dose-response meta-analysis of prospective observational studies. Int J Cancer 135:1940-8, 2014.
2. Daiello LA, et al. Association of fish oil supplement use with preservation of brain volume and cognitive function. Alzheimers Dementia June 18, 2014 [Epub ahead of print].