Enhances the Action of Microglia
Up until 2017 there were no reports of any ingredient in beer having dementia preventing properties. But in that year Japanese scientists connected the first dots. Alpha acids are the main bittering agent in hops. When heated they become iso-alpha acids which are even more intensely bitter. The Japanese study focused on these particular compounds. In earlier work, iso-alpha acids were found to bind and activate PPAR, a protein that regulates many cell processes. By doing so it helps enhance the action of microglia. As long-time readers know, these immune cells are triggered into action when cellular debris needs to be cleared from the brain, a process called phagocytosis. One type of microglia called M2 also helps calm inflammation. In the 2017 study, the researchers found that in mice with the human equivalent of Alzheimer's disease, the bitter compounds upregulated microglia to reduce brain inflammation, improve phagocytosis, reduce amyloid beta plaques by 21% in the cerebral cortex, and enhance cognition. These extremely positive results encouraged them to conduct another study. Since obesity is a risk factor for dementia, they next looked at what happens when iso-alpha acids are included in the daily diet of mice after they have been fattened up with a high fat diet (HFD) compared to those on an HFD diet alone without the supplement. There were three main findings. First, brain inflammation caused by the HFD was suppressed in the hippocampus, a key memory and learning area of the brain. Second, there was a reduction in cognitive decline caused by the high fat diet. Finally, body weight and blood fats were significantly lowered -- other positive effects of activating the PPAR protein by adding the iso-alpha acids to the diet.Boosts Hippocampal Memory
The group’s third study was published in The FASEB Journal in April this year. This time they were interested in the specific effects of iso-alpha acids on cognition. To evaluate this, normal mice were injected with a drug to induce memory impairment, and then given a test of spatial memory by having to wander around a maze. They were also given an object recognition test. The researchers found iso-alpha acids prevented the deficit in short-term spatial memory induced by the drug and enhanced long-term object recognition memory. Further experiments revealed iso-alpha acids act through the vagus nerve — which connects the brain stem to the body — to increase total and extracellular levels of dopamine in the hippocampus. The higher dopamine was responsible for the observed memory improvements. Spatial memory and object recognition memory are both hippocampus-dependent functions. The scientists concluded, "Stimulation of the vagus nerve by food material is safe and easy and may be a new strategy for improving cognitive functions and reversing cognitive declines."Drink Beer?
To improve memory function, according to the scientists, a person weighing 70 kg (154 pounds) would need between 2 and 20 mg of the iso-alpha acids found in hops. I’m not sure why the range is so wide. It does lead to a problem in determining a “clinical dose” of beer. To achieve that requires drinking between 0.13 and 1.3 liters (just over a quarter of a pint to two and three-quarter pints), assuming the beer has an average content of these acids. Some beers like India pale ales can have a lot more. Two and three-quarters pints of beer a day is too much, in my humble opinion. If you don't like beer or want to avoid alcohol, extracts of hops standardized to 30% alpha and iso-alpha acids are available as supplements. That would be my choice, because alcohol is a contentious issue in alternative health. The evidence is conflicting. Some alcoholic products have some benefits, as this article would suggest, but the weight of the evidence is against more than a serving a day. Two at the outside, depending on your body weight.