Alzheimer’s disease and the ketogenic diet

When it comes to Alzheimer’s Disease, we’d all love to hear about a cure.  Better yet, we’d love to hear about fool-proof prevention.  Diet and nutrition are certainly on the radar screen for prevention research, but at the moment we have mostly speculation.  The mechanisms of Alzheimer’s disease aren’t even clear.  Are the infamous plaques and tangles in the brain the root cause of symptoms or an effect of some other process?

Plenty of specific foods, herbs, diets and nutrients have been proposed to cure Alzheimer’s.  Nothing has really panned out.  But one unusual diet is still on the radar screen as a possible intervention: the ketogenic diet.

As a long-time nutrition professional, I’m inclined to look for good evidence, or at least a plausible argument, when a diet is promoted for some disease state.  So I’ve been a bit suspicious about claims that the ketogenic diet might be an Alzheimer’s intervention.  But I found a pretty interesting review recently that has me rethinking the issue.

What is a Ketogenic Diet

The ketogenic diet has been around for 100+ years, first used to treat epilepsy and other seizure disorders, particularly in children.  The official diet is at least 70% fat, although there are variations.  Protein is moderate, and carbohydrates are extremely low.  As in maybe 4% of calories.  This pushes metabolism into ketosis.  Insulin levels fall because carbohydrates are in short supply.  You still need an energy source for cells, so the liver ramps up metabolism fatty acids to ketone bodies, which are used for energy when glucose is low.  A person in ketosis has a very high level of ketone bodies in the blood, which are flushed out in urine.  One strange side effect: a person in ketosis can smell like nail polish remover, because acetone (a component of nail polish remover) is a ketone.

Why would this help a person with Alzheimer’s disease?  One hallmark of the characteristically impaired brain function is inability of cells to utilize glucose for energy.  Normally the brain uses up a large proportion of your daily glucose supply.  Brain cells are always active and need a lot of energy.  But when they can’t use their preferred fuel — glucose — ketones are a viable substitute.  The ketogenic diet could bypass the cells need for glucose.  Brain cell function could be improved and cognitive ability restored.  Or at least not allowed to deteriorate further.

Some rodent studies have shown improved brain function with ketogenic diets.  Human studies have been very small.  The subjects weren’t always on strict ketogenic diets, and many of the subjects had mild cognitive impairment rather than Alzheimer’s disease.  Still, some studies showed improvements in brain blood flow and memory.  However, the study diets did not help the subjects with a specific genetic risk factor — the APOE e4 gene — for late-onset Alzheimer’s.

Practical considerations

While a ketogenic might be helpful in theory, putting it into practice is a different matter.  In the best of circumstances, it’s really hard to implement.  Eating a diet that’s 70% fat means a steady daily menu of:

  • butter
  • oil
  • sour cream
  • cream
  • cheese
  • avocado
  • coconut fat
  • bacon
  • eggs

Even nuts and nut butters must be limited because they contain carbohydrates.  High fat meats, eggs and cheese must also be restricted because protein intake should not be too high.  As for carbohydrate foods, forget about it.  Watery vegetables like lettuce or spinach can be permitted.  You need to become very familiar with the carbohydrate content of all other vegetables, from celery to green pepper to onion and broccoli.  Fruit is out.  Legumes are out. Grain-based foods are out.  Sweets are out.

The problem of feeding this diet to a person with Alzheimer’s disease should be obvious.  Day after day of nothing but fatty foods can get old really fast.  There isn’t much variety at all.  The diet ends up being low fiber and not particularly conducive to a healthy gut microbe population (gut microbes prefer undigested carbohydrates).  The prohibition on sweets is another problem, as taste preferences for people with dementia might lean towards sweet flavors.

From a nutritional standpoint, the diet ends up being seriously unbalanced.  All the nutrients concentrated in plant foods are limited: potassium, magnesium, B-vitamins, C, A, and so forth.  Calcium intake is negligible.  Caregivers night say “So what, as long as it works, just take a vitamin supplement.”  That can work for some nutrients, not all.  Plus swallowing a pill might be a problem for someone with dementia.

I suspect the research is going to take this in the direction of prepared ketogenic drinks that are fortified with nutrients, artificially sweetened and flavored, and pumped up with fat.  In fact, some of the studies did use special high ketone beverages.  Special forms of fat — medium chain triglycerides — can promote ketosis because they are metabolized quickly to ketones.  One food particularly high in these MCTs is coconut fat.

What to do

Let’s be clear: I am not promoting a ketogenic diet for Alzheimer’s disease at the moment, because the evidence that humans are helped is not convincing.  As more research is reported, I’ll certainly be paying attention.

Even if evidence does emerge, I strongly recommend that anyone who wants to try this diet needs professional guidance, preferably from a registered dietitian nutritionist who is well-versed in the complexities of the ketogenic diet, as well as monitoring by your physician.  Buying a book or following a website that promotes ketogenic diets is not the way to go, especially not if you’re dealing with a serious problem like Alzheimer’s disease.

No doubt, if a ketogenic diet shows any benefit, food and pharmaceutical companies will jump into the market for fortified ketogenic beverages to make implementation of the diet easier.

The National Institute on Aging has an abundance of up-to-date information on all aspects of Alzheimer’s disease.