Study under review: Effect of Omega-3 Fatty Acids, Lutein/ Zeaxanthin, or Other Nutrient Supplementation on Cognitive Function - The AREDS2 Randomized Clinical Trial
Dementia affects 5% of adults in the US population aged 71-79 years, with a nearly 5-fold rise to 24% in those aged 80-89 years and a sharper rise still to 37% in those over 90-years. Additionally, about one-fifth of all adults older than 71-years have some form of cognitive impairment without signs of dementia, and 10% of these people progress to dementia every year. In other words, a large segment of the elderly population suffers from cognitive impairment and either has dementia or is at a high risk of progressing to it. The brain is the most lipid-dense organ in the body, with 50-60% of its total mass coming from phospholipids alone. Depending on the type of phospholipid, DHA concentrations range from 20-30% of the total fat content and appear to increase with age, displacing omega-6 fatty acids. It has been argued that humans are adapted to consume higher levels of DHA than we currently do, and that a displacement of DHA from the diet driven by excessive consumption of omega-6 fatty acids has resulted in the gradual depletion of DHA from membrane phospholipids and the subsequent rise of modern diseases. It has been proposed that DHA be considered at least “conditionally essential.”
Nine observational studies now support that increased dietary intake of fish is associated with reduced risk for cognitive decline or dementia, and in the Framingham Heart Study the highest quartile of serum DHA concentrations was associated with a significant 47% reduction in the risk of developing all-cause dementia. Additionally, DHA deficiency is linked to various maladies, including Alzheimer’s disease, schizophrenia, psychosis, and anxiety. Some of the mechanisms by which DHA may help are shown in Figure 1. However, DHA is a polyunsaturated fatty acid that is by nature unstable and prone to oxidation. The oxidation of DHA is proposed to be one of the factors leading to dysregulations seen in Alzheimer’s disease
Lutein and zeaxanthin are carotenoids found in green leafy vegetables and brightly colored fruit. These plant pigments are the sole carotenoids in the retina, where they exist in ∼500-fold higher concentrations than in other body tissues and are believed to be protective through their roles as blue-light filters and antioxidants. Lutein and zeaxanthin are also among the dominant carotenoids in human brain tissue, where they account for 66–77% of total carotenoid concentration. It has been shown in animal models that lutein is able to protect against DHA oxidation within the brain, and higher lutein status is related to better cognitive performance in adults.
The current study was an attempt to evaluate how long-term supplementation with EPA and DHA and/or lutein and zeaxanthin affects aspects of cognition in an elderly population.
DHA is a primary fatty acid within the brain, and low levels have been linked to cognitive disorders. Lutein and zeaxanthin are the primary carotenoids within the brain that serve an important protective role against DHA oxidation. The current study sought to evaluate whether supplementation with these compounds would benefit cognition in the elderly.
Other Articles in Issue #11 (September 2015)
A shot to the gut
Alcohol intake and gut impacts have been researched before, but we still aren’t sure what exactly goes on after people drink. This study looked at what happens with gut bacterial products when people have multiple drinks at one sitting ... aka “binge drinking”.
Tea time means only tea for optimal EGCG absorption
Many people drink green tea for health, and some take green tea or EGCG supplements in an attempt to shed extra fat. While these topics have been researched at length, there hasn’t been as much research on timing. This study looks at EGCG absorption with and without food.
The study that didn’t end the low-fat/low-carb diet “wars”
A recent metabolic ward study set the low-carb world on fire, and produced many inaccurate media headlines disparaging low-carb diets. We cover the study and its implications, detail by detail.
- Interview: Dylan Dahlquist, MSc(c)
When is breakfast the most important meal of the day?
With an increasing amount of research pointing to benefits of intermittent fasting, breakfast has been shunned by more and more people. But for those with type 2 diabetes, blood sugar is a central issue, and breakfast may play a major role in regulating it.
What to Expect When We’re Expecting: Fetal Programming and the Development of Taste Preferences
By Margaret Leitch, Ph.D.
Gluten-intolerant? There’s a pill for that
Some people are lactose intolerant, but still drink milk thanks to the availability of lactase enzymes. That setup isn’t yet possible for those who don’t handle gluten well. This study examines the efficacy of a promising enzymatic adjunct to a gluten-free diet.
Vitamin D(efense) against Crohn’s disease?
Immune benefits are often listed among the multitude of possible vitamin D effects. Most of the time, this is simplified to “defense against colds and flu”. But many conditions have an immune component — this particular study examines potential mechanisms by which vitamin D may help Crohn’s disease.
Green tea: a potential pain in the neck
Though it may not be as effective for fat loss as early studies suggested, green tea is still seen as extremely healthy. But animal evidence has pointed to possible thyroid side effects from excessive green tea consumption. How convincing is this evidence?