August 27, 2012

Dietary Supplements: Vitamin D and Fish Oil

What dietary supplements -- if any -- should we take? Here's an update with recent findings on two of the most popular: vitamin D and fish oil. I'll cover others tomorrow.

DHA Supplements vs. Vitamins D and B12 for Brain Health
When you hear about DHA, fish oil, or omega-3 fatty acids, it's basically the same thing when it comes to supplements. "Fish oils" is the umbrella term. These oils include the Omega 3 fatty acids EPA and DHA.

In a recent report, Johns Hopkins Medicine noted that vitamin D, vitamin B12, and omega-3 fatty acids have been studied for their potential brain-fortifying results... with mixed results. Of the three, docosahexaenoic acid (DHA) -- an omega-3 fatty acid found in fish oil -- seems to hold the most promise, according to the report:
While a study in the Journal of the American Medical Association found that fish-oil supplements do not slow the progression of Alzheimer's disease once it has begun, another placebo-controlled study published in Alzheimer's and Dementia found that 900mg of DHA per day, taken for 24 weeks, helped improve memory and brain function in people over age 55 with mild cognitive impairment. This suggests that to help the brain, these supplements should be started early, before a mental decline progresses too much.
I searched the Mayo Clinic's "Drugs and Supplements" site for DHA and found a report confirming the possible benefits of DHA for brain health:
Research has linked certain types of omega-3s to a reduced risk of heart disease, stroke, dementia and cognitive decline. The Food and Drug Administration (FDA) permits supplements and foods to display labels with "a qualified health claim" for two omega-3s called docosahexaenoic acid (DHA) and elecosapentaenoic acid (EPA). The FDA recommends taking no more than a combined total of 3 grams of DHA or EPA a day with no more than 2 grams from supplements.
The Mayo Clinic notes that preliminary evidence shows that omega-3s may help reduce symptoms of depression. "It's thought this is because it's an essential nutrient for brain function."

Both EPA and DHA are found in fatty fish (such as salmon, sardines, herring), and it's often recommended that we eat at least two servings of fatty fish each week.

Another recent study found that omega-3 fatty acid supplements can lower inflammation in healthy, but overweight, middle-aged older adults. (There are millions of us!) Chronic inflammation is linked to numerous conditions, including coronary heart disease, type 2 diabetes, arthritis, and Alzheimer's... and to the frailty and functional decline that accompany aging.

That did it! Fish-oil supplements for me. Fortunately, I like fatty fish and eat a can of sardines or a helping of grocery store marinated herring for lunch at least twice a week.

"The Benefits of Vitamin D"
That's the title of a special report from the School of Public Health at the University of California, Berkeley.

The editors of the report note that a major debate has been going on about the potential health benefits of Vitamin D supplements. On one side are researchers who for years have been advocating higher intakes and blood levels of vitamin D. On the other side are those who fear that the vitamin D bandwagon has gotten too far ahead of the research. This group fears a crash, as happened to the bandwagon for antioxidant supplements, when long-awaited clinical trials failed to find benefit and sometimes even suggestred harm.

Here's the official Institute of Medicine recommendation for daily intakes of Vitamin D -- whether from sun, food or supplements:
  • 400 IU for infants up to one year of age
  • 600 IU for everyone up to the age of 70
  • 800 IU for those over 70.
The Berkeley report identifies these groups as "at risk" for vitamin D deficiency:
  • Breastfed infants
  • Pregnant and breastfeeding women
  • People over 50
  • Dark-skinned people
  • People who spend nearly all of their time indoors, especially those who are housebound or institutionalized
  • People living in northern latitudes
  • Obese people
  • People taking certain drugs, such as anti-convulsants or HIV medications
  • Anyone with a chronic condition that interferes with the body's ability to absorb fat, such as Crohn's disease
The bottom line: The Berkeley report confirms vitamin D's role in bone health, but indicates continuing uncertainty about claims that vitamin D might prevent, treat, or delay a wide variety of other conditions.

For example, it has been suggested that high vitamin D levels might help protect against Parkinson's disease. But there's no evidence now that the supplement might improve symptoms or slow progression for those of us who already have the disease.  

"What's needed are large, long-term, well-designed clinical trials on vitamin D," the report says. That's a refrain we hear all the time when it comes to supplements, and one that is less likely to be answered when Big Pharma has little interest in studying low-cost supplements, and when hospitals, universities, and other medical facilities are seeing their funding dry up.

Vitamin D testing:  It's still too soon to recommend vitamin D testing for everyone, the report says.  But it does suggest talking to your doctor about a vitamin D test if you are in any of the risk groups listed above. 

Without my raising the issue, my internist scheduled a vitamin D test as  part of the blood work at my annual physical in April and, based on the results, recommended that I take a 1000mg vitamin D supplement every day. I've found a supplement that combines 1000mg of vitamin D with 1200 mg of fish oils, of which 360mg are the EPA and DHA omega-3 fatty acid oils.

If you are not tested, the reports suggests these three options:
  1. Follow the IOM's recommendation, which suggests that most people don't need to worry about vitamin D. This option is especially appropriate if you want to be cautious, don't like to take supplements, get some sun (but not too much) and  consume a lot of vitamin D fortified milk, cereals and other food products.
  2. If you are at elevated risk for vitamin D deficiency (see above list) and want to be more proactive, you might want t follow the advice of experts who suggest higher intakes (1,000 to 2,000 IU a day) to achieve blood levels of at least 30ng/ml, since there little risk of harm, and the possibility of benefits.
  3. A sensible middle ground would be to take 800 to 1,000 IU a day plus modest amounts of sun exposure.
That's a summary of the latest research findings and recommendations for vitamin D and fish oils. Tomorrow I'll recap the current thinking on some of the other most popular supplements.

1 comment:

Praveen said...

Thanx for Sharing
such a hugefull information and lots of benifits of Fish
Oil
. ya u r ryt, Fish
Oil
is the one of the best nutrician , it has been show to provide
a number of health benifits, and recomended by many health autorities as a
part of balanced diet. Fish
oil
contains omega-3 fatty acids, specifically docosahexaenoic acid
(DHA) and eicosapentaenoic acid (EPA).One of the health benefits linked to
Fish
Oil
is a low risk of heart attack. very healpfull for blood
circulations.

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