Category Archives: Gratitude - Page 5

How to Recognize and Fix a Brain Infection

Posted by on July 20, 2011 195 comments

I thought I’d pull up an interesting tale from the comments. It is a great illustration of what we’re trying to accomplish on this blog.

Thomas first commented here on December 31:

I just got your book from a relative for Christmas (I told them to buy me it!) and am reading through it now. Very interesting, although some of it is beyond a simple layman like me.

The part of this blog post that starts “Thus common symptoms of a bacterial infection of the brain are those of cognitive hypoglycemia and serotonin deficiency” and continues for several paragraphs describes precisely the mysterious changes I have experience over the last decade of life (I am now 33), with the one variation being that I suffer extreme fatigue rather than insomnia or restlessness. Every other sympton, including the odd mental state you mention, is a perfect match, and I experience them all to a marked degree….

I have been diagnosed with general anxiety but never depression. I do not feel sad ever, just irritable and anhedonia-ac, if I may coin a word. Anti-depressants, and I’ve tried a bunch, do absolutely nothing for me.

Brain infections are widespread – I wouldn’t be surprised if 20% of the adult population has a brain infection of mild severity – but they are hardly ever diagnosed or treated.

Fortunately, there are some symptoms that are almost universally generated by brain infections, so it’s not necessarily that difficult to diagnose them. But I think no one knows the symptoms. Infections are generally allowed to progress for decades.

One of my crucial steps forward was when I recognized that I had the cognitive symptoms of hypoglycemia when my blood sugar was normal. I could relieve the symptoms if my blood sugar became highly elevated. Thinking about why that might be led me toward the idea of bacterial infections.

Thomas went on to describe the origin of his symptoms:

I began to decline after suffering the second subdural hematoma of my life at age 20 when I was in Italy, followed by a 5 year binge on alcohol.

This was another clue. Traumatic brain injuries, such as hematomas, often initiate brain infections, because they breach the blood-brain barrier. Alcohol is also a risk factor, as I pointed out in my reply to Thomas:

Alcohol abuse depresses bacterial immunity and would be a risk factor for a brain infection: http://www.ncbi.nlm.nih.gov/pubmed/16413723, http://www.ncbi.nlm.nih.gov/pubmed/20161709. Subdural hematomas frequently show infections, e.g. http://www.ncbi.nlm.nih.gov/pubmed/20430901.

We next heard from Thomas on February 22, when he had been on our diet for 7 weeks and had just tried his first ketogenic fast:

I’ve been doing PHD for about 7 weeks now, and tried a ketogenic fast this past weekend. I ended up going 33 hours with some coconut oil and cream. It was a bit tough having to eat a bunch of oil on an empty stomach, but nothing too bad.

I can’t say there was any improvement cognitively or with anhedonia, but there seemed to me to be a pronounced calming effect after about 24 hours of fasting. I often stutter or stumble over words (again, for about 10 years now), which usually goes away only with two or three alcoholic drinks. But the speech problems stopped almost completely during the fast, which makes me thing that there is some link to anxiety and stuttering.

Positive changes in brain function during ketosis suggest that the brain isn’t functioning normally when it relies on glucose as a fuel. There are several possible causes of this, but one is a bacterial infection. Another clue.

I generally recommend getting on our diet and supplement regimen, and reaching a stable health condition, before starting antibiotics. There are several reasons for this, which I’ll elaborate on later, but briefly:

  • Antibiotics work well on a good diet but may fail on a bad diet.
  • Pathogen die-off toxins can cause significant neurological damage and this toxicity may be substantially increased on a bad diet.
  • There is considerable diagnostic value in being able to clearly discern the reaction to antibiotics. Rarely is it certain that a brain infection is bacterial, or that the antibiotic in question is the correct one. To judge whether the antibiotic is working, it’s important that health be stable and as good as possible.

I therefore recommend being on our diet and supplement regimen for 3-4 months before starting antibiotics.

Thomas seems to have followed this advice, since he has just reported starting antibiotics:

I’ve been on PHD for a few months, and about a month ago went to the low-carb therapeutic ketogenic version of the PHD. After reading some of Paul’s posts, I believe that I might have a brain infection as a result of a head injury from more than a decade ago (Paul, if you recall, my condition has a lot of similarities to the one you once had). I started taking doxycycline a few days ago, and I have already noticed pronounced improvement (whether due to the diet or the antibiotic or both) in controlling the irritability and anxiety that have plagued me for years….

I definitely feel great since making the diet changes. My blood pressure, which has been creeping upwards over the last few years to 135/80 or so, is back down to 110/70. My testosterone is 824, and I am pleased to see that I maintaining my strength in the gym despite being on a ketogenic diet.

Pronounced improvement in the first days of doxycycline is quite possible, because doxy acts as a protein synthesis inhibitor. It essentially blocks bacterial functions and switches them into a state of hibernation. The bacteria are still there, but they are not interfering with brain function as much as before.

This improvement is confirmation that Thomas has a bacterial infection of the brain. If there were no infection, he wouldn’t notice an effect from the antibiotics.

Over a period of months, the doxycycline plus ketogenic dieting should help his innate immune defenses clear the brain of most bacteria. Combination antibiotic protocols may be even more effective.

In a follow-up comment, Thomas mentioned Ben Franklin and the blessing of good health:

Thanks for the response Paul, as well as all your help. If this works, I owe you my first-born child and then some! Ben Franklin (I think it was him) might have been right about health being the greatest blessing. The improvements I’ve seen recently have done more for my well-being than anything in the last decade, and I am profoundly grateful to you for all your excellent advice.

It’s comments like this that make blogging and book writing worthwhile.

It’s probably hard for those who have never had ill health to appreciate how enjoyable it can be for those with chronic diseases to recover good health. I’ve blogged on this before (Of Recovery, Hope, and Happiness, July 13, 2010 – don’t miss Ladybug’s painting).

Thomas, antibiotics and ketogenic dieting will work, I’m pretty sure. May you come to perfect health, and always remain grateful for the many blessings that are yours.

In Memory of Jack Lalanne

Posted by on January 23, 2011 18 comments

Jack Lalanne, the great fitness guru and natural food advocate, is dead at 96. (Hat tip: Jamie Scott.)

He died of pneumonia, just a year after having heart valve surgery. Both conditions are suggestive of Chlamydia pneumoniae infection; perhaps antibiotics could have gotten him to 100.

The Associated Press obituary notes that his youthful diet wasn’t very good:

The son of poor French immigrants, he was born in 1914 and grew up to become a sugar addict, he said.

The turning point occurred one night when he heard a lecture by pioneering nutritionist Paul Bragg, who advocated the benefits of brown rice, whole wheat and a vegetarian diet.

“He got me so enthused,” LaLanne said. “After the lecture I went to his dressing room and spent an hour and a half with him. He said, ‘Jack, you’re a walking garbage can.'”

Lalanne was an advocate of eating whole foods, but may have over-emphasized the carbohydrates. Late in life, his diet consisted mainly of fruit, vegetables, brown rice, and fish. Rather like the Kitavans, but with less coconut oil.

Nevertheless he was a great example of healthy living. He joked at age 92 that he couldn’t die, because it would wreck his image.

Here he demonstrates fingertip push-ups:

Here he explains how to cure “pooped out-itis”:

Thanks, Jack! The fitness classes of heaven just got a little more entertaining.

Old Diets, New Knowledge: For Auld Lang Syne

Posted by on December 31, 2010 79 comments

As I said yesterday, Chris Masterjohn’s review has inspired me to wrap up the year with a look at the big picture. What is the current state of dietary knowledge, and where is it heading? What can we, the blog community, do to help people become healthier?

The State of Dietary Science

For decades it seems the dominant paradigm shaping official dietary recommendations has been the lipid hypothesis, which engendered hostility to dietary fat. But not all fats: in short term animal studies polyunsaturated fats sometimes lowered blood lipids. As a result, industrial seed oils, which are PUFA rich, were encouraged and natural animal and dairy fats, which are rich in saturated fats, were discouraged.

But evidence has piled up that low-carb Paleo diets high in animal foods are beneficial, and that the lipid hypothesis was mistaken about the dietary causes of bad blood lipids. It looks like the old paradigm is finally dying a well-deserved death.

But what would science be without a scapegoat, a witch for burning? Modern science needs villains, and if fat no longer serves another macronutrient will have to fill in. Many in the low-carb Paleo blogosphere took note of this comment by Dr. Walter Willett in the Dec. 20 Los Angeles Times story “A Reversal on Carbs”:

“Fat is not the problem,” says Dr. Walter Willett, chairman of the department of nutrition at the Harvard School of Public Health. “If Americans could eliminate sugary beverages, potatoes, white bread, pasta, white rice and sugary snacks, we would wipe out almost all the problems we have with weight and diabetes and other metabolic diseases.”

Of course this comment lumps safe starches like potatoes and rice with toxic carb sources like sugar and wheat. The scientists continue to overlook the overwhelming important issue of food toxins, and focus on the minor issue of macronutrient toxicity.

I was not quite sure how significant this story was until I remembered that the reason Chris Voigt started his all-potato diet was to protest the US government’s move to ban potatoes from school lunches and the WIC welfare program:

[T]he Institute of Medicine, the health arm of the National Academy of Sciences, recommended that the U.S. Department of Agriculture stop participants of the federal Women, Infants and Children program, known as WIC, from buying potatoes with federal dollars. The institute also called for the USDA-backed school lunch program to limit use of potatoes.

Under an interim rule, the USDA agreed to bar WIC participants from buying potatoes with their federal dollars. Potatoes are the only vegetable not allowed. Next year, the agency will roll out a final rule …

From a scientific perspective it’s puzzling that potatoes, one of the healthiest starch sources, would be singled out. I think this is yet more evidence that IoM and USDA dietary guidelines serve political rather than health goals, and that the strongest lobbying come from within the government itself. Potatoes are an important US crop, but they do not receive government subsidies. The major subsidized crops, wheat, corn, and soybeans, always seem to be the most highly recommended foods in IoM and USDA analyses. News reports suggest that a reason for the potato ban is the desire to get kids eating more whole grains.

Many Paleo bloggers took the new criticism of carbs as a positive sign. I’m not so sure it represents progress.

Prediction for 2011: Politics, not science, will continue to determine official dietary guidelines.

Popular Paleo Diet Books

If Dr. Willett is serious about eliminating starches and sugars, then his recommended diet will presumably look like the Cordain – Eades – Sisson – Wolf – de Vany low-carb Paleo diet: the recommended plant foods must be fruits and vegetables.

I think this illustrates the power that popular diet books have over scientists and doctors. Paleo diet books have been out for over 10 years now, and millions of people have experienced improved health on these diets. Powerful scientists are starting to surrender to this evidence. Peer review cliques can restrain the progress of science, but not so thoroughly that scientists trail more than a decade behind the general public!

This year saw Robb Wolf and Art de Vany come out with their Paleo books. I collected some diet books for Christmas, and have been perusing them. I am afraid I don’t see much progress from the books of Cordain and Eades a decade ago.

Robb Wolf’s book devotes 32 pages to a “Thirty-Day Meal Plan.” There isn’t a safe starch in the whole month!

I have a few objections:

These Diets Aren’t Paleo Diets: They are really hybrid diets pairing the animal foods of a savannah hunter with the plant foods of chimpanzees and mountain gorillas. But for at least 3 million years ancestral humans have flourished mainly in open woodland habitats near rivers, lakes, and seashores. The available plant foods were mainly the pith and underground storage organs of starch-containing plants. Archaeological evidence confirms that starches have been, with animal foods, the primary calorie sources of ancestral humans for millions of years.

These Diets Aren’t Tasty. Menus like “tuna and cabbage salad,” “chicken apple hash,” “turkey over spinach,” “pork and roasted veggie salad,” “slow-cooked rosemary veggies and meat,” “flank steak, bacon and greens,” “lamb sausage with artichokes,” “chicken and cauliflower,” “tip steak and steamed vegetables,” and “rotisserie chicken, steamed broccoli, side salad” (all taken from Robb’s meal plan) – in short, “lean meat with vegetables” – have never excited me. Such meals assist weight loss, I’m sure, but for most people such an overly restrictive diet unnecessarily removes some of the savor from life.

These Aren’t the Optimal Diets for Human Health: This is the really important issue. Now I am a fan of all of these writers: their diets are big improvements over the Standard American Diet, and they have improved the lives of millions. But their diets are not optimal for longevity or immune defense due to excessive protein and, in some cases, insufficient glucose.

Fortunately it appears that popular Paleo diets may soon evolve to include more starches. In October 2010 Mark Sisson, a bellwether, gave a partial endorsement to the potato:

Potatoes should be limited, or even outright eliminated, for this (large) subset of the population. For the lean and active, however, I don’t think a few red potatoes with dinner are anything to worry about.

A few potatoes – if they are red, and if you are an athlete. Grudging, perhaps, but a big step forward. Since the Harvard Department of Nutrition follows Mark Sisson after 10 years, we can expect potatoes to get off the government’s proscribed list by 2020.

Prediction for 2011: Paleo will become ever more popular. But it will flourish even more if “safe starches” are recognized as genuinely Paleo foods, and lean meats and protein are de-emphasized.

Food Toxins: Weston A Price Lives!

In his review, Chris called our discussion of food toxins “incredibly important.” As he points out, this very important but very complex topic could easily warrant a book (or several) in its own right:

I believe a more complete discussion of food toxicity would include the methods that humans have developed to detoxify these foods, variation in susceptibility to food toxins, the role of nutrition in preventing food intolerances, and a number of other food toxins that occur in foods …

I agree.

In framing the subject of nutrition and food toxicity, I think our “economic” analysis makes an important contribution. In this analysis, increasing doses of a nutrient provide first declining marginal benefits, then inconsequential effects throughout a “plateau range,” and finally increasing marginal toxicity.

A slight complexity is that some nutrients are complements for one another, so that (for instance) omega-6 and omega-3 fats or vitamins A and D need to be in balance.

I found that this method of analysis makes sense out of the many seeming paradoxes and contradictions in the literature. A nutrient can be “good” or “bad” depending on whether it is present in deficiency or in excess in the diet.

If this approach is correct, then the key to health is providing adequate amounts of nutrients and avoiding toxins. This way of thinking would require a big conceptual change on the part of many dietary scientists. The concepts of nutritional context and food toxicity would become unifying concepts in nutrition.

This way of thinking holds the potential to integrate distinct strands of dietary thought. An important line of dietary research studies traditional diets and their methods of food preparation. Weston A. Price and the Weston A. Price Foundation are exemplars of this approach. Stephan Guyenet of WholeHealthSource is a blogger who writes with great respect for traditional diets.

The congruence of Stephan’s approach to diet and ours is apparent in the fact that he is the most cited blogger in our book – mentioned 23 times.

Traditional cultures tended to eat a diversity of “safe” (i.e. low-toxicity) starches, and also had elaborate food preparation methods that tended to de-toxify foods. Soaking, sprouting, fermenting, and long cooking can often make toxic foods into safe foods, as Chris notes in his review.

Traditional cultures probably ate more authentic “Paleo” diets than the popular Paleo diets!  The diet of Kitava, for instance, has probably changed little in the last 40,000 years. We know that early “Out of Africa” settlers to that area around 45,000 BC were already clearing forests in order to plant yams; and were notable boaters and fishermen. Fish, coconuts, and yams remain the staples of the Kitavan diet.

There is no reason why the Paleo and traditional food communities should not reach a mutually pleasing synthesis:

  • The Paleo community should accept low-toxicity starchy plants as a healthy part of the human diet; recognize that Paleo cultures were willing to eat any food that was nourishing and low in toxins; and recognize traditional food preparation methods as genuine Paleolithic technologies for food de-toxification that enabled a broadening of the diet.
  • The traditional foods community should recognize that Neolithic foods like wheat are among the most toxic foods, and that in practical life it is not always feasible to detoxify highly toxic foods, so that it a “Paleo” style diet will most often be most healthful for most people.

One of the most exciting aspects of the current blogosphere is the emergence of bloggers who link these two communities and scientists. Stephan and Chris are two scientist-bloggers who are helping to synthesize the best threads in contemporary dietary thought.

Prediction for 2011: The dichotomy between low-carbers and traditional dieters will continue to narrow. More people will happily identify themselves as Paleo dieters and fans of traditional food cultures. In particular, increasing numbers of young scientists and doctors will be in our corner.

Integrating Medicine and Diet

The part of our book which may attract the least attention in the short run, but which we hope will have the most long-term impact, is Step Four. This part of the book stresses pathogens as the cause of most diseases, and diet as the essential therapy for chronic infectious diseases.

In his review, Chris states:

Rather than considering sanitation, hygiene, or vaccines to be the most important tools in the fight against infectious disease, the Jaminets provide a refreshing integration of the fields of immunology and nutrition. They discuss eleven dietary and lifestyle strategies one can enlist in this fight …

We’ll be discussing additional ways to strengthen immunity and heal disease in the New Year. Using diet to modulate immunity is really one of the most overlooked pathways to good health, and we have only begun to scratch the surface here.

Most doctors are unaware of the prevalence of chronic infections. New chronic pathogens are rapidly being discovered and linked to diseases. Just this year, a new human gamma retrovirus was linked to chronic fatigue, and several viruses were linked to cancers. Evidence continues to grow linking both viral and bacterial infections to neurological disorders.

Doctors are even less aware of the powerful influence of diet and dietary practices like fasting upon immune function. Patients have the ability to modulate their diet to optimize immune function and direct it specifically against the type of pathogen – intracellular or extracellular – that causes their disease.

In a recent comment, gunthergatherer introduced me to an e-book by Ron Mignery suggesting alternate-day protein elimination (a “protein cycling diet”) as an autophagy-promoting practice that should help prevent neurological disorders. This is a variation of our protein restriction, fasting, and ketogenic dieting techniques, all of which are designed to promote autophagy. Autophagy is the key intracellular immune mechanism that protects against bacterial and viral infections.

It is good to see that other people are developing the same ideas we are. Hopefully these ideas can spread beyond a few scientist-dieters into general practice.

Prediction for 2011: Evidence will continue to pile up linking bacteria, viruses, protozoa, and fungi to chronic disease. New pathogens will be discovered to cause disease in humans. But diet and nutrition will continue to be overlooked as potential therapeutic steps. Meanwhile, bacterial resistance to antibiotics will continue to outpace the development of new antibiotics. Concern by doctors, scientists, and patients will continue to largely go unheeded by the FDA and funding agencies.

Conclusion

It’s been an exciting year for us:  we published our book and began this blog. In the new year, we hope to delve more deeply into the issues discussed in the book, and explore more thoroughly how dietary and nutritional practices can help heal disease. We are excited to see if our ideas will be as beneficial for others as they have been for us.

Of course, if we didn’t have a delightful community of readers, commenters, and fellow bloggers, this would neither be fun nor productive. Therefore, we thank you all very much, and wish you a very happy and healthy new year!

Reflections on Our Book Inspired by Chris Masterjohn, I

Posted by on December 30, 2010 58 comments

Chris Masterjohn has put up a detailed review of our book. He calls my wife and I “awesome,” the book “excellent,” and awards “two thumbs up.” Thanks Chris!

Chris’s review led me to reflect a bit on our book, and I thought it might be appropriate to close the blogging year with a couple of posts about it. Specifically, I will:

  1. Clarify our argument for optimal macronutrient ratios. Chris spends a substantial part of his review discussing the issue of carbs, and I think readers may be interested in my perspective on the issues he raises.
  2. Look at the “big picture”. What is the state of dietary science, and where does it need to go? How close are bloggers and scientists to integrating the various perspectives and reaching the truth? What does our book in particular contribute to both popular and scientific debates?

Today I’ll discuss the carb issue.

Macronutrient Ratios and Carbohydrate Intake

Step One of our book is about macronutrient ratios. The key goal of Step One is to help readers understand how much of each macronutrient they need to avoid deficiencies and what levels will produce toxicity conditions.

For some macronutrients this is easy, because the evidence is fairly clear:

  • Protein. Roughly 5% of energy as protein is sufficient to avert a deficiency, and the evidence of toxicity is also fairly clear: protein over 40% of energy can be fatal, and there are less severe indications of toxicity at about 30% for adults, 20% for pregnant women, and 9% for infants.
  • Polyunsaturated fats. About 0.5% of energy will avert deficiencies of both omega-6 and omega-3 fats, and there are subtle indications of toxicity above about 4% of energy, with the indications becoming obvious above 10%-15% of energy.
  • Saturated and monounsaturated fats. These are benign at all intake levels: non-toxic in high doses, and impossible to become deficient in (except during starvation) because the body will manufacture them from carbohydrate or protein.

But determining the optimal intake range of carbohydrates is difficult, because unlike the other macronutrients there is no data that lacks confounding factors.

The main problem is that the main sources of carbohydrates in western diets – grains and sugar – contain food toxins such as gluten and fructose. So any benefits from reducing carbs could be the result of reduced toxin intake, not reduced carbohydrate calories.

We know these plant toxins are important, because populations that obtain carbs from “safe starches,” such as yam-eating Kitavans, rice-eating Chinese and Japanese, and potato-eating Irish have been notably healthy. (See, for instance, our China Study posts, our wheat series, and Stephan’s Kitava and potato posts.)

However, in none of those “safe starch” eating populations do we have good data on how health outcomes vary with a differing mix of carbohydrates vs. saturated and monounsaturated fat.

With data lacking, our prescriptions have to be based largely on biologically-informed theory – theory instructed by, as Chris puts it, “circumstantial evidence.”

The “Eat What We Are” Argument

A good first estimate for carb intake comes from the simple precept that we should “eat what we need.” The body’s glucose utilization level, about 600 calories per day, tells us how much we need. The simple prescription, then, would be to eat about 600 calories, or 30% of energy for a slender person, as carbs. Let’s call this intake a “moderate carb” diet.

Evolutionary Arguments

Another place to look for guidance is evolution: what macronutrient ratios has evolution selected for?  Here we do not place much weight on ancestral Paleolithic diets, which varied substantially from place to place and time to time. Rather, we place more weight on animal diets and the composition of mother’s milk.

Both human and animal breast milk is majority-fat, moderate-carb, low-protein. In milk of all species, the carb percentage closely tracks the infant’s glucose needs.

In animal diets, the macronutrient ratios delivered to the body depend on the design of the digestive tract, which transforms the macronutrient content of food. Digestive tracts are generally good at transforming carbs into fat. As a result, after transformation most animals have carb intakes equal to or below their carb needs. In ruminants and foregut fermenters, the transformation of carbs into fats is virtually complete; in hindgut fermenters, it is only partial.

Many animals achieve so many of their calories from bacterial fermentation of dietary carbs that their diets are actually highly “ketogenic” and nearly zero-carb.

Thus, evolutionary considerations suggest:

  • Optimal human carb intake is probably close to or below our glucose utilization of 600 calories per day.
  • Ketogenic diets with substantial calories from short-chain fats are probably healthy.

I find evolutionary logic convincing. Since healthy creatures will generally have more descendants than unhealthy ones, evolution surely selects for health.

The Argument From Palatability

In addition to being healthy, a diet should be tasty – palatable. People should enjoy it and be pleased to eat it.

This has an influence on macronutrient ratios. Fatty animal foods in general have higher caloric density than carb-rich plant foods. Fruits and berries have 200 calories per pound; potatoes and sweet potatoes 300; taro 600; white rice 1300. In contrast, meat often has about 1000 calories per pound; bacon has about 2400. To eat 30% of calories from carbs, while avoiding toxic foods like grains and sugar, requires eating substantially more plant food than animal food.

But people generally find food most palatable when there is a mix of plant and animal foods. Since carbs come exclusively from plant foods (excepting milk), which have lower caloric density, this means a tasty diet inevitably has more fat than carb calories.

The Argument From Toxicity

As we note in the book, plant foods have more toxins than animal foods. This is because they use toxins to poison animals that might eat them, while animals cannot easily poison predators without also poisoning themselves.

Toxins are found in nearly all plant foods. Peter at Hyperlipid has a post today about berry toxins, pointing out that they have a similar biological effect to a pharamaceutical drug, anacetrapib, that raised the death rate in clinical trials. (I note in the comments that the benefits from poisoning gut pathogens and cancer cells might outweigh the damage from direct toxicity. This is why I eat “Neo-Agutak” – cranberries. )

If it’s desirable to avoid toxins, it’s desirable to keep plant food intake down and animal food intake up. Given the low caloric density of most plant foods, that also implies that carb calories will need to be low on an optimal diet.

Plateau Ranges

As Chris notes, we do not define precise optima for each nutrient, but rather suggest “plateau ranges” that achieve all the benefits and none of the toxic effects.

Based on the above reasoning, for carbohydrates, our estimated plateau range is from 10% of energy on the low end (which we recommend for therapeutic ketogenic diets) to 30% on the high end (a “moderate carb” diet in which all the body’s glucose needs are met from diet).

We do suggest specific values of 20% carbs, 15% protein, and 65% fat. These are mid-range values which casual dieters may wish to aim for; even if they miss by 10% of energy on any macronutrient, they will still be in the plateau range.

What Happens If You Deviate From the Optimum?

But if this logic tells us what the optimal carb intake is, it does not tell us how much harm is done by carb intakes different from the optimum.   

Here I agree with Chris that in healthy people, the damage to health from changes in the carb:fat ratio could be very small, as long as the carb sources do not contain appreciable toxins. The body has a great capacity to convert carbs to fat. So long as that transformational capability remains undamaged, a very high-carb diet may be functionally very little different from an optimal diet.

In metabolically damaged people, however, transformations from one macronutrient to another may be impaired. In this case, the body may have very little flexibility in repairing a suboptimal carb:fat ratio.

I thus agree with Chris’s conclusion:

I thus find it very difficult to believe that humans must maintain their diets within a very narrow range of macronutrient ratios. More likely, the human body is extraordinarily flexible and can tolerate a wide range of carbohydrate and fat intakes.

That said, it may well be the case that in modern folks with damaged metabolism, low-carb is the way to go. Indeed, well controlled studies have clearly shown that low-carbohydrate diets are superior to low-fat diets by a multitude of criteria for people with various markers of the metabolic syndrome (references here, here, and here).

Nothing in the book contradicts this conclusion. As an editorial decision, we chose to describe the “perfect” diet for health without spending space discussing imperfect diets. Given that decision, we didn’t need to address whether a 90% carb diet is only marginally worse, or much worse, than a 30% carb diet.

But that is an appropriate topic for discussion on the blog. I’ve begun a “zero-carb dangers” series; perhaps I should do a “high-carb dangers” series too.

Conclusion

Much research will be needed to disentangle the relative contributions of plant toxins and carbohydrate calories to health.

It looks from early evidence that intake of plant toxins may be much more consequential for health than the overall carbohydrate level. This is good news, since selection of low-toxicity foods and preparation methods that detoxify foods may enable big improvements in human health.

Nevertheless, even if most toxins can be removed, there are reasons to believe that a low- to moderate-carb (10% to 30% of calories as carbs) diet will be optimal for human health. Such a diet seems to work well for nearly everyone, even the metabolically damaged; and it produces a tasty diet that is a pleasure to eat. It therefore seems the most prudent recommendation for diet book authors to make. And we stand by it!