It’s not unusual to hear of a new study finding a link between the development of Alzheimer’s Disease (AD) and… well, pretty much anything: drinking too much alcohol, not drinking any alcohol, having a stroke, pre-eclampsia, not exercising enough, head trauma earlier in life, having high blood pressure, taking opioids, taking beta-blockers, eating soy, eating too many carbs and unhealthy fats, having diabetes, having herpes virus…the list goes on. As does the list of things to do to prevent Alzheimer’s Disease: exercise more, stay social, drink moderate amounts of alcohol, eat a Mediterranean-style diet, eating soy (yes, that one is on both lists!), stay off of prescription drugs, and taking any number of supplements—L-lysine, CoQ10, alpha lipoic acid, ginko biloba, Omega 3 fatty acid, to name a few. With so many factors to consider (many of which are under-studied) and with growing rates of the disease in our population, it is extremely important to be able to track your own health and determine if your personal lifestyle choices and supplement use are helping or hurting you.
AD can be linked to so many diverse factors because the cause of the disease can be attributed to multiple sources. Some people are genetically predisposed to developing the disease, some cases are cause by inflammation in the brain, some cases are caused by an infection in the brain—specifically herpes simplex type1 virus (HSV-1), and most cases are probably a mix of those. Regardless of the initiating cause, the result is the same—the characteristic amyloid beta plaques, tau tangles, and a loss of memory and brain function.
For this article, we’ll focus specifically on the relationship between AD and HSV-1 and evidence supporting the use of L-lysine in combating the disease.
L-lysine is an essential amino acid that is not produced by the human body and thus must be obtained from your diet. Lysine-rich foods include fish, eggs, meat and dairy products, with smaller amounts found in foods derived from plants. You may have heard of the supplement used as a general immune-booster, but did you know that it could be a huge part of keeping your brain healthy into old age?
The use of lysine in combating herpes outbreaks is well-established in the literature. Lysine competes with arginine (another amino acid), and HSV-1 needs an arginine-rich environment to replicate. In 1982, it was first suggested by Melvyn Ball that HSV-1 may be involved in the development of Alzheimer’s Disease due to the fact that the characteristic plaques and tangles are mostly found in the same regions of the brain where HSV-1 takes up residence. Additonal research has strengthened this hypothesis, noting (in part) that HSV-1 is found in 70-90% of the elderly population, although not always in the active form. The virus is able to take up residence and remain inactive, and when conditions become favorable for it, it will begin to replicate and make itself known. The virus is also associated with inflammation, which is seen in AD patients. According to Dr. Robert Moir from Harvard Medical School, the amyloid beta plaques and tau tangles associated with AD are likely the body’s immune response to a foreign invader (such as HSV-1)—so the features of AD that drug companies are trying to attack and get rid of may actually be your body’s attempt to attack the disease (and in fact, there are drugs that successfully rid the brain of these structures in AD patients, but the symptoms of the disease remain, furthering the evidence that they aren’t what’s causing the problem to begin with)!
So we know that L-lysine can help to fight HSV-1 outside of the brain, and we know that HSV-1 may (at least in some cases) be the initiating cause of AD. We also know that L-lysine can cross the blood-brain barrier. The next logical question is, do we have any evidence that L-lysine helps to prevent or combat AD?
Not directly, but yes, there is some evidence. It’s important to keep in mind that it’s not necessarily the absolute level of L-lysine that’s important with respect to HSV-1 activation, but rather its relative proportion to arginine. When looking at populations with low rates of AD, you see that their diets are high in L-lysine relative to arginine—the most well-known example being the Mediterranean diet. Furthermore, people who eat a lot of fish tend to have lower risk of AD, which could be due to the omega-3 fatty acids, but it’s also true that fish have high levels of L-lysine. Rubey (2010) notes that while the Ballabgarh community in northern India has the lowest rate of AD (4.7 per 1,000 people) and eat a dairy-rich diet (high in L-lysine), the Sudanese and Japanese have a similar lifestyle except for the increased consumption of tofu (high arginine) among the elderly people in those populations. Interestingly, there is also a higher rate of cognitive impairment among those two populations.
Purely as a hypothesis, Rubey (2010) also suggests that in western populations, as people get older, they tend to eat fewer lysine-rich foods and shift more to lower protein diets. They also tend to eat less in general, and since L-lysine can only be obtained from your diet and arginine can be synthesize by the human body, eating less in general could result in a shift in L-lysine/arginine ratios in a direction that would favor the growth of HSV-1. Thus, theoretically and given that HSV-1 is present in the brains of up to 90% of elderly people, as people begin to shift to a lower L-lysine rich diet, conditions would begin to support the activation and growth of HSV-1, leading to Alzheimer’s Disease.
There’s a nice, clear story there, but we were unable to find any studies directly supporting this hypothesis (we also didn’t find any that don’t support it). Since L-lysine is a supplement that you can easily buy over the counter, drug companies have no interest in spending lots of money on trials to test its efficacy against AD, so we likely won’t find any direct evidence for it any time soon. Since there is a very low risk of negative effects from taking L-lysine, you could just blindly take it and hope for the best. But if you wanted to make sure you weren’t wasting your money, you could track your cognitive health with a Brain Gauge and find out for yourself if L-lysine has a positive effect on you.
Step-By-Step Guide to Testing the Effects of L-Lysine on Your Brain Health
Whether or not you’re currently taking L-lysine, use your Brain Gauge to get a baseline score. Try to keep other parts of your life as consistent as possible through the next steps (diet, exercise, sleep, other supplements/medications, etc).
If you ARE currently taking L-lysine, stop taking it for at least 1-2 weeks. Retest with your Brain Gauge and note any significant changes. For Alzheimer’s Disease specifically, we would – theoretically - expect to see a high Sequential Amplitude Discrimination score relative to your Simultaneous Amplitude Discrimination score.
If you are NOT currently taking L-lysine, start taking it for at least 1-2 weeks. Retest with your Brain Gauge and note any significant changes. For Alzheimer’s Disease specifically, we would – theoretically - expect to see a high Sequential Amplitude Discrimination score relative to your Simultaneous Amplitude Discrimination score.
If you noted better scores with L-lysine in your system, great! Keep taking it. If not, you could:
a. Keep the same dosage for another 1-2+ weeks (we’re just guessing with the timeline for how long it will take to see effects).
b. Up your dosage for 1-2 weeks and retest.
c. Change brands of L-lysine. Some brands are more absorbable and/or effective than others, and there’s no way to know which brand is best without testing!
If you DO see a positive effect, feel free to play around with your dosage and different brands to see what optimizes your personal brain health. Having the tools to be your own detective allows you to make sure you aren’t wasting money on excessive doses and make sure that you’re not wasting money on a brand or low dose that isn’t doing you any good.
Let us know what you find out!
Given the hypothesized mechanism for the effect of L-lysine on brain health, we would expect to see more of an effect if 1) you have an active case of HSV-1 and/or 2) you have an arginine-rich diet prior to starting L-lysine.
Regardless if it affects Alzheimer’s Disease or not, there are other known benefits of L-lysine, including helping with anxiety/depression and migraines (which you could also track with your Brain Gauge), plus having positive effects on peripheral HSV-1 infections/flare ups, osteoporosis, hair loss, shingles, cancer, cardiovascular disease, and collagen formation (Singh et al. 2011). As long as you aren’t taking ridiculously high doses (>15-40 grams/day), there’s very low risk that you’ll do any harm giving it a try!
Ball MJ. Limbic predilection in Alzheimer dementia: is reactivated herpesvirus involved? Canadian Journal of Neurological Sciences. 1982 Aug;9(3):303-6.
Meenu Singh et al., Medicinal uses of L-lysine: Past and future. Int. J. Res. Pharm. Sci., 2(4), 2011, 637-642.
Rubey RN. Could lysine supplementation prevent Alzheimer’s dementia? A novel hypothesis. Neuropsychiatric disease and treatment. 2010;6:707.
Also, check out this article about Lysine on People's Pharmacy: