Tag Archives: microbiome

Seven Diets for Seven Health Objectives?

I want to maintain a healthy blood glucose level. I think I will go on a glucose-control diet such as the one described in The New Glucose Revolution by Jennie Brand-Miller.

Then again, perhaps maintaining a healthy level of alkalinity in my body would be more benefical. I think I will instead go on an alkalinizing diet such as the one described in The Alkaline Diet Plan by Connie Jeon.

Then again, I’ve been hearing a lot about the importance of maintaining a healthy balance of bacteria in my digestive tract. I think I will instead go on a diet for gut health such as the one described in The Microbiome Diet by Raphael Kellman.

Then again, I understand that inflammation is the underlying cause of most chronic diseases. I think I will instead go on an anti-inflammation diet such as the one described in Anti Inflammatory Diet by Victoria Lane.

Then again, what’s a little inflammation compared to the Big C? I think I will instead go on a cancer-prevention diet such as the one described in The Cancer Prevention Diet by Michio Kushi.

Then again, heart disease kills more people than cancer does. I think I will instead go on a heart-health diet such as the one described in Prevent and Reverse Heart Disease by Caldwell Esselstyn.

Then again, what I really want more than anything is to stay young as long as possible. I think I will instead go on an anti-aging diet such as the one described in The Longevity Diet by Brian Delaney.

It’s just too bad that by eating to maximize my lifespan I will have to forsake eating to maintain a healthy blood glucose level, maintain a healthy pH balance in my body, maintain a healthy microbiome, minimize inflammation, minimize my cancer risk, and prevent heart disease.

Or do I? On closer inspection it appears that the authors of all of the above-mentioned books recommend eating lots of vegetables and not a lot of sweets and other junk foods. Indeed, I’m tempted to conclude that just one broadly defined healthy diet will allow me to achieve all of my health objectives! (Agnostic healthy eating, anyone?)

Okay, I’ve removed my tongue from my cheek. The point of the forgoing exercise, as you may have guessed, was to highlight the absurdity of eating for single, specific objectives. The body is an integrated whole. A person has only one diet, and it affects every dimension of health simultaneously. What’s more, precisely because the body is an integrated whole, any food type that enhances one dimension of health is likely to enhance others and is unlikely to have a negative impact on any.

Take whole grains, for example. Consumption of whole grains has been shown to favorably impact gut health and to reduce insulin resistance and systemic inflammation as well as the risk for several cancer types and heart disease. Vegetables and fruits likewise boost all dimensions of human health while nuts and seeds have a wide range of healthful effects and no negative effects. Fish too has a handful of beneficial health effects and (mercury contamination not withstanding) no negative effects. So whichever dimension of overall health is most important to you, you should eat whole grains, vegetables, fruit, nuts and seeds, and probably fish as well.

By the same token, any food type that harms one dimension of health is likely to harm others and is unlikely to have a positive impact on any. This category includes soft drinks, processed meats, refined grains and fried foods. These foods should have a small place in the diet and may be eliminated entirely with no ill effects.

The only food type that is really a mixed bag in terms of its health effects is dairy, which has been shown to slightly increase the risk for certain cancers while slashing the risk for heart disease and diabetes and having no effect one way or the other on longevity. Yogurt specifically prevents weight gain and enhances gut health. If all you care about is minimizing your cancer risk, don’t eat dairy. If you’re more concerned about preventing diabetes, keep your milk and cereal.

The best stand-in for overall health, in my view, is longevity. Since dairy neither extends nor shortens life, it’s fair to label its overall effect on health as neutral. Health isn’t the only reason we eat, though, is it? Cheese is delicious. I include dairy in my diet because of the following calculation: neutral health effect + yummy = eat it!

Does The World Need Any More Diets?

Recently I came across a new book called The Microbiome Diet. It is based on the idea that the colonies of bacteria in our guts are “the secret to healthy weight loss and to feeling healthy, energized, optimistic, and at the top of [our] game.” Author Raphael Kellman prescribes a three-phase plan that entails including prebiotic and probiotic “superfoods” such as yogurt, sauerkraut, garlic, and tomatoes in every meal.

Like most inventors of new diets, Kellman argues that his diet is needed because existing diets are based on bad information and consequently don’t work. He writes, “I believe that this book will challenge everything you know about the causes of obesity—and about the kind of diet that can successfully overcome it.”

It’s easy to laugh at Kellman’s suggestion that his diet is the only true solution to the problem of diet-related health problems. Only a few hundred people in the entire world are currently following it and it’s unlikely that more than a few thousand ever will. The notion that the only diet that’s truly good enough for humans would come along for the first time in 2014 and then pass into oblivion having made barely a ripple seems far fetched. But what about some of the other new diets, the ones that have caught on in a big way, such as the Paleo diet and the gluten-free diet and the high-fat version of the low-carb diet? The creators of each of these diets has also argued that his is needed because no previously existing diet was good enough to yield optimal health. Is any of these diets really needed? No.

What allows the creators of such diets to convince many people that a new way of eating is needed is the fact that the incidence of diet-related chronic diseases is higher than it’s ever been. This is clear proof, they say, that existing diets don’t work. Except it isn’t. For if all currently existing diets were ineffective in producing good health, then everyone would be unhealthy. But while most American adults are fat and doomed to die from heart disease, diabetes, or another disease affected by diet (Alzheimer’s, some cancers), in absolute numbers there are lots of healthy people. Indeed, virtually everyone who actually makes an honest effort to eat healthy by any definition and sustains this effort throughout life is rewarded with robust health. The people who end up fat and saddled with chronic disease are the majority that doesn’t even try to eat healthy.

If we look at the small sliver of the population that sustains its efforts to eat healthy, we find that many existing diets work perfectly well. People who start and stay on sensible versions of vegetarian, Mediterranean, low-carb, low-fat, clean-eating, locavorian, agnostic, and other diets are typically hale and hearty. The problem is not, as the inventors of new diets assert, that there are no good options. The problem is that only a tiny fraction of us takes advantage of the many good options available to us.

Here’s another way to look at it: In 1950, virtually no one was following anything we would recognize as a microbiome diet or a gluten-free diet or a Paleo diet or a high-fat/low-carb (HFLC) diet because A) these diets hadn’t been invented yet and B) they are not culturally normal, so it was unlikely that some random weirdo would eat by the rules of any of them accidentally. Thus, to argue that any of these new diets is needed because no previously existing diet was good enough is essentially to argue that no one living in 1950 was healthy.

Of course, advocates of the Paleo diet argue that their way of eating is not new at all but a reversion to “the original human diet,” and some proponents of the HFLC diet do the same. This argument represents a complete inversion of the truth. Paleo dieters eat the same modern foods that everyone else eats, all of which are only distantly related to the foods eaten by Paleolithic humans. The only difference between the way the average Paleo dieter eats and the way his next door neighbor eats is that the Paleo dieter eschews some foods, such as dairy, that his neighbor eats. This combination of modern foods and selective exclusions is fundamentally novel. When Loren Cordain published The Paleo Diet in 2002, the eating program unveiled therein was the world’s newest diet. If it resembled primitive diets more than other modern diets did, it was only on the most superficial level.

In any case, a more important way in which Paleo diet doctrine stretches credulity is the same way that most other new diets do. According to Paleo doctrine, humans stopped eating right at the dawn of the agricultural revolution some 12,000 years ago. Therefore, to argue that the Paleo diet is needed because no post-Paleolithic diet was good enough to support optimal health is essentially to argue that there have been no healthy humans for the past 12 millennia.

Let me be clear: I’m not suggesting that all new diets are bad. I think most of them are good. Humans can thrive on a wide range of diets, so it’s not hard to come up with a novel diet that respects the few nutritional laws that can’t be broken without repercussions for health. But no new diets are needed. The current epidemic of diet-related diseases will not be solved by the discovery of the first and only diet that really works. Good-enough diets have always been available. Until scientists invent a pill that makes people crave broccoli and gag at the sight of french fries, each of us is on his own to solve the problem individually by selecting one of the many good-enough diets and sticking with it.

Never Try Anything New

This post consists of three observations that may or may not be related to one another.


The Paleo diet is built on the premise that all animal species, humans included, are rigidly dependent on the foods that have been in their diet for the greatest amount of time. The genome of each species is like a lock that only one key will open, and that key is the specific food or set of foods that the species has evolved to depend on. Any other foods are like non-fitting keys that not only lack the ability to open the lock but destroy the lock when one tries to jam them in anyway.

In other words, animals are not very adaptable dietetically.

It was on the basis of this belief that Loren Cordain asserted in his book The Paleo Diet that the “333 generations [that] have come and gone” since the dawn of the agricultural revolution have offered “scant evolutionary experience” for the human body to adapt to “new” foods such as cow’s milk, and therefore these foods must be killing us.


The quino checkerspot is a species of butterfly that is native to Mexico and California. Since time immemorial it has eaten only one food, the dwarf plantain. Unfortunately, global warming has created climatic conditions in its native habitat that are too warm and dry for the plant to survive in. In the 1990s, biologists began to warn that when the dwarf plantain went extinct, the butterfly that was completely dependent upon it would disappear with it.

But then a funny thing happened. The two surviving colonies of checkerspots spontaneously migrated from their natural, sea-level habitat to a new habit at higher elevation. When biologists discovered this relocation they also discovered that the checkerspot had chosen a completely new food source—a flowering plant that has little in common with the dwarf plantain. Far from ruining the health of the species, this sudden and total transformation of the species’ diet has caused its population numbers to rebound dramatically.


Last year, Lawrence David and colleagues at Duke University conducted an experiment that was designed to study the effects of radical changes in diet on the microbiome in human subjects. The term “microbiome” refers to the large and diverse populations of bacteria that live in the human gut, and without which we would be incapable of properly digesting food.

The Duke researchers recruited 10 healthy volunteers (six men and four women between the ages of 21 and 32) and placed them sequentially on two different diets for five consecutive days. One diet consisted entirely of plant foods (grains, legumes, fruits, and vegetables), while the other diet consisted entirely of animal foods (meat, cheese, and eggs). As you would expect, the nutritional compositions of the two diets were divergent in the extreme. For example, on the carnivorous diet, subjects got 70 percent of their daily calories from fat and consumed zero fiber, whereas on the herbivorous diet, subjects got only 22 percent of their calories from fat and fiber intake increased nearly threefold from baseline levels.

After just three days on each diet, significant changes were seen in the composition and functioning of the microbiome in all subjects. On the carnivorous diet, subjects exhibited a marked increase in the presence and activity of bacteria that thrive in a bile-rich environment, which makes sense, because the gut produces more bile when digesting animal foods. In contrast, on the herbivorous diet, the subjects exhibited a large increase in the presence and activity of bacteria that metabolize polysaccharides from plants.

The researchers even noted changes in gene expression within certain strains of bacteria in response to the disparate diets. So not only had the human subjects rapidly adapted to changes in diet through their gut flora, but the flora themselves had adapted epigenetically.

In three days.