After I dissed saturated fat on Facebook a friend told me to read “The Perfect Health Diet”, which usually doesn’t work. But he also offered me a free copy, which does. If you can’t get a free copy, you can get a lot of the material from their website.
Let’s get the obvious out of the way first. The title, dust jacket, and introduction are all doing their best to make it sound like a sketchy diet fad book. Even its proponents admit it does a very poor job at not sounding like a sketchy diet fad book. I don’t know how much importance to give this. Maybe any diet advice, including very scientifically based and sober advice, inevitably ends up looking like a sketchy fad book because that is the most effective way to market it? Let’s just raise the red flag count to “one” and move on.
The best word for my opinions on the content would be “mixed”.
Let’s start with the good. It clearly tries to be science-based. It mostly succeeds. It is evolutionarily informed without being silly about it. It ties a lot of research together into a consistent and conclusive whole.
The overall diet it recommends is…pretty good, actually. Sort of similar to the paleo diet, with its emphasis on unprocessed whole meats and vegetables, and an acceptance bordering on fetish for saturated fat. But it adds the concept of a “safe starch” – where the classic paleo diet has a zero tolerance policy toward carbohydrates, the Perfect Health Diet allows certain carbs like rice, potatoes, and lots of weird things like “taro” and “sago”.
I really like this change. Hunter gatherers do eat certain roots and tubers, so it’s not like an evolutionary perspective has to exclude them entirely. And the Japanese remain some of the healthiest people in the world while eating rice by the bucketload, so anyone who tells you that rice is bad for you has got something like a hundred million contrary data points to overcome. Pre-contact Polynesians were also exceptionally healthy, so all the weird Polynesian starches they recommend have my seal of approval as well.
This makes their diet much easier than normal paleo diets. With a moderate amount of work, you can find a lot of the breadstuffs you like made with rice or potato or something rather than wheat – my local Asian food store has rice noodles that can almost pass for spaghetti to my unsophisticated palate. And since I have been trained not to feel full without some carbs in me, having a small plate of rice with a meal really helps.
I am slightly skeptical about admitting potatoes to the same pantheon as rice and Weird Polynesian Starches. This comes from my four years studying medicine in Ireland. The traditional Irish diet is beef, lamb, butter, cabbage, and potato, which is about as Perfect Health Diet compliant as it’s possible to get (yeah, okay, they do eat bread and drink beer, but other than that). The Irish can be very insistent on sticking to just these couple of things. I remember working at a rural GP office and staying at the home of an elderly Irish couple. I made a trip into town and brought back some spaghetti to make for dinner, and my hosts were impressed that I was making them “exotic foreign foods”. By which they meant spaghetti. This was 2010.
Anyway, despite this rigid diet elderly Irish people seemed pretty unhealthy and cardiovascular-disease-ridden, maybe not much better than the US. If we’re sticking Polynesians and Japanese on one side, and Americans on the other, the Irish are over with us. I don’t know if the Perfect Health people want to blame all of that on their bread and alcohol and whatever ungodly oils they fry stuff in, but I am going to view potatoes with suspicion until this gets cleared up.
The other thing about the book I really liked was their discussion of “toxins”. Normally whenever any diet book discusses “toxins” I throw it aside with great force, because they mean “mysterious evil spirits in foods I don’t like which can be banished only with juice cleanses.” Perfect Health Diet, despite using the same language, singles out very specific chemicals and cites all the reasons which each chemical can be expected to be harmful.
The part that stuck with me most here was their section on omega-6 fats, which might be literally the Devil. I find their speculation on omega-6s and obesity intriguing, not to mention the connection to crime I have already blogged about. Stephan Guyenet seems to take this seriously as well, which is always a good sign. And it makes evolutionary-historical sense that this random stuff we’ve been adding to foods in massive quantities over the past couple of decades and not before is screwing us up.
Also wheat. So, so much wheat. I haven’t had time to investigate this much so far, but a lot of smart people seem very worried about wheat and corn and all those other grains, and if one tenth of the darts they throw at them stick, we should probably start looking for a new staple food for Western civilization.
So much for the good. Let’s move on to the bad.
This book has a very consistent pattern of making a strong claim, citing one study that supports their claim, and failing to mention that there have been many more much larger studies since then that have come to the opposite conclusion.
For example, they mentioned every single study to say breathlessly excited things about Vitamin D for the past fifty years, but failed to mention that all of them have since been disconfirmed by larger and more careful trials.
And it’s not just Vitamin D. Vitamin K prevents prostate cancer! Vitamin K prevents liver cancer! Vitamin K reduces all kinds of cancer by 75%! Vitamin K heals cancer in people who already have the disease! A recommendation: take lots of Vitamin K!
But look at how the American Cancer Society describes these same trials:
A large European epidemiologic study published in 2008 found higher risk of prostate cancer in men with low intake of some forms of vitamin K. But people who take in plenty of vitamin K usually get it from fruits and vegetables. This means that people who get lots of vitamin K from foods are more likely to take in many other vitamins and phytochemicals that can affect cancer risk. In some cases, vitamin K may be given credit for benefits that are actually due to other compounds that appear in the same foods. So studies like this, which only observe large groups of people, may not be very useful for looking at the effects of vitamin K intake.
A small clinical trial from Japan suggested that vitamin K lowers the risk of developing liver cancer among women with cirrhosis due to hepatitis C. A later study also seemed to show some effect, but it was not statistically significant. Further study is needed.
There have been some studies examining whether menadione (vitamin K3) can help overcome cancer cells’ resistance to certain types of chemotherapy drugs. Results in lab animals and cell cultures are mixed, but there is no evidence available of significant effects in humans yet.
A small Phase I clinical trial in California tested different doses of intravenous vitamin K3 in people with advanced cancer. The patients did not improve. In that study, several patients also had allergic reactions, especially at higher doses.
Look. I know alternative medicine is hard to do. It’s also useful. Sometimes they come up with genuinely interesting stuff the mainstream has missed. So I’m not demanding that you not speculate about Vitamin K just because the mainstream medical community has interpreted the results as unimpressive. Go ahead and try to find reasons why the earlier successful trials were more believable than the later more pessimistic trials. But at least mention that everyone else disagrees with you about this. Don’t present it as some well-established thing which the mainstream community is just completely ignoring.
We repeat this exact same frickin’ pattern with just about every vitamin and mineral ever discovered. Selenium prevents gastric cancer! Selenium reduces tumor incidence! A randomized controlled trial of selenium in China decreased liver cancer! A trial of selenium in America decreased skin cancer! Selenium improves immune function! Selenium decreases all-cause mortality by a quarter! Selenium cuts cardiovascular mortality in half! Selenium cures all diseases! Selenium will make you rich and famous! Women will want to date you! Men will want to be you! You will live in a beautiful house on the beach, with a huge yacht made entirely of selenium! You will sail it over seas of liquid selenium, to selenium islands where selenium-based life-forms play haunting music beautiful beyond anything you have ever imagined upon their selenium flutes. If you take enough selenium you will never die, yet if by chance you should, you will go to Selenium Heaven, which is to regular Heaven what a supernova is to a firefly.
Meanwhile, look at any respectable medical source like Cochrane Review, and the actual list of effects that they find for selenium is exactly zero. The process is the same as always. Some preliminary exciting studies come out. So we do much bigger, more rigorous studies and the effects go away. I did a really thorough evaluation of the selenium literature for my Quantified Health Prize entry and although I was totally happy to disagree with expert advice in several areas, in the case of selenium I found that the experts were exactly right and it is useless. Perfect Health Diet doesn’t even mention the expert consensus or rigorous studies here.
This leads to this weird pattern where Perfect Health Diet manages to explain about 1500% of human mortality. That is, if you add up all of their claims (“Vitamin Q decreases mortality by 50%!” “Vitamin R decreases mortality by 75%!”) then although I haven’t exactly done the calculations my guess is they would add up to around 1500%. This isn’t quite mathematically impossible – if there are fifteen vitamins, any single one of them prevents cancer completely, and you can just choose which one you want – then added together they would decrease cancer mortality by 1500%. But even though it’s not mathematically impossible, it doesn’t seem right to me and it seems much more likely that they use hugely inflated claims than that fifteen different interventions all cut mortality even more than any of the things we know cut mortality like exercise or quitting smoking.
I’ll skip over the T3/T4 thyroid thing and a few others that will be more of the same, and just spare a second to complain about folic acid: they say supplementing pregnancies with folic acid causes autism. This is not only not proven, but there’s much stronger evidence for the opposite: multiple good studies show folic acid supplemention decreases autism risk by as much as 40%. Perfect Health Diet’s only source for the opposite claim was a correlational study in, of all places, the Journal of Medical Hypotheses, which specifically exists to signal-boost claims that don’t really have any support but need further investigation.
Now, to be fair to PHD, they did briefly mention this counterexample. But their scare study was in bold and exaggerated, and the existence of a counterexample was in parentheses and had the word “slightly” appended to the front even though it was not slight at all.
So. Alternative medicine people? Please listen very closely. STOP SAYING THAT VITAL CHILDRENS’ HEALTH INTERVENTIONS CAUSE AUTISM. THIS. NEVER. HELPS.
Overall I thought their entire section on vitamin and mineral supplementation was a disaster area. This is a little worrying because I know more about vitamins and minerals than I do about macronutrients and diet in general, and the Gell-Mann Amnesia Effect argues that if the parts you know something about are bad, you should assume the parts you don’t know enough to criticize are as well.
I will, however, give praise where praise is due. PHD gets that multivitamins aren’t a great idea and does not recommend them. It gets that calcium is not a great idea and doesn’t recommend it either. And they have praise for iodine and lithium, which are the two minerals I went out on a limb to recommend in my QHP entry and which I really do think deserve more attention than they’re getting.
In conclusion, PHD is not a terrible book and you could do much worse as far as diet books go. It is written by smart people who are familiar with at least some of the literature. It is a good idea-generation source to learn about things you might not have otherwise known (did you know there is some evidence a chronic bacterial infection can be one cause of Alzheimers Disease?) and the diet it recommends will probably not kill you and in fact probably be good for you. If their stuff about wheat and omega-6 and the like pans out, and I would not be surprised if it does, it might be really good for you. I don’t have any complaints there.
(actually, I tried the diet they recommended for about two weeks, just to see what would happen, and I lost seven pounds without really trying. This is a sufficiently large number of pounds that I find this result implausible and am hesitant to pronounce a “This is what happens when you follow Perfect Health Diet”. But still, nice.)
But I also cannot wholeheartedly recommend it, especially for epistemically-minded people who want something correct as opposed to something full of nice diet advice. It has a lot of shoddy research and presents extremely controversial positions as if they are settled science. There are very few mistakes that will kill anyone (they even couched their folic acid advice with an incongruous yet welcome “but you should still take a little folic acid during pregnancy”) but a lot of mistakes that will leave you very confused or have you taking very silly amounts of vitamins.
This book might be suitable for someone who wants to try a paleo-inspired diet for purely practical reasons, but who needs some encouragement and inspiration through a discussion of the science behind it. It might also be good for someone who already knows a lot about health from a mainstream point of view, is sufficiently skeptical to catch the mistakes, and wants to see what sorts of stuff the paleo diet and alternative-medicine-which-is-smarter-and-more-sciency-than-homeopathy people are about so they can grab the useful insights and discard the rest.
I was originally sent this book because I dissed saturated fat, so I should tie up my review there – especially since it makes a good metaphor for the book in general. Perfect Health Diet gives a lot of good evolutionary reasons why saturated fat might be good for you, and reflects the growing consensus that yeah, we kind of went overboard turning it into demon-food and should take a step back from there – something most people don’t realize and that this book could be very helpful in teaching.
But then it goes on to say that the old story that saturated fats led to heart disease has been debunked, citing as the only discussion for this claim a link to a systematic review that did in fact find saturated fats not to correlate with heart disease. What the book doesn’t mention is that this study was funded by the National Dairy Council, or that nine out of eleven other systematic reviews that have investigated the issue did find a saturated fat/heart disease link, or that Cochrane Review, which is the gold standard for systematic reviews of medical evidence, concluded that on balance there is good evidence for a saturated fat-heart disease link. All they do is cite the increasingly-lonely one that found the conclusions they wanted, declare that to be the state of the evidence, and move on.
So that is PHD in a nutshell. Interesting points, broadly reasonable dietary advice, and total denial of the existence of any evidence that doesn’t support their claims.