Thursday, February 20, 2014

Killjoy vs. Freak Flag

I read a recent story by Julia Llewellyn Smith about John Yudkin, an early proponent of the theory that sugar (not fat) is likely to be the main culprit behind many modern diseases. It contained the following paragraph:

"One of the problems with the anti-sugar message — then and now — is how depressing it is. The substance is so much part of our culture, that to be told buying children an ice cream may be tantamount to poisoning them, is most unwelcome. But Yudkin, who grew up in dire poverty in east London and went on to win a scholarship to Cambridge, was no killjoy. “He didn’t ban sugar from his house, and certainly didn’t deprive his grandchildren of ice cream or cake,” recalls his granddaughter, Ruth, a psychotherapist. “He was hugely fun-loving and would never have wanted to be deprived of a pleasure, partly, perhaps, because he grew up in poverty and had worked so hard to escape that level of deprivation.”"

While I am glad that such stories are gaining prominence, I object to the idea that saying no to ice cream, or keeping a sugar-free household makes one a killjoy.

If it were shown that the link between routine sugar consumption and heart attacks or Alzheimer's or breast cancer was, for example, even a fraction as strong as that between smoking and lung cancer, would you feel that turning down a piece of cake, or not keeping ice cream in the house, indicated insufficient desire for and approval of pleasure? Or contrary-wise, if you went to live in a place where children were normally given a cigarette after supper, would you just let it go in the name of good fun? Such a strong link has yet to be shown, but the body of evidence of such links has increased.

I contrast this idea with an essay by Kurt Harris a few years ago, containing this passage:

"When you go to the birthday party for your neighbor’s kid, and you eat the birthday cake, what message does that send?

You show up looking trim and fit. You are pleased if people ask you how you lost weight. After eating this way for a few years, though, you are perhaps most comfortable if no one says anything at all.

You are weary of the reactions -the incredulity, the mockery, the eye-rolling. Pushing 50, you’ve tried explaining how a diet high in animal fats and low in grains works to keep you slim, but you’ve learned that the segue to explaining why you are not just cultivating an attractive corpse due to all that arterycloggingsaturatedfat that you live on is tedious and it gets you nowhere.

So, when the rectangular slab of Hy-Vee or Piggly-Wiggly birthday cake – frosted 3/8” thick with a stratum of oily granular sugar running through the middle to boot – is proferred, you say “thank you”, flash a smile that only a trained psychologist would question, and accept it, holding the flimsy paper plate and plastic fork with both hands to keep it from tumbling onto the ground.

You repair to some corner of the party where you can nibble at the cake, maybe spill a few crumbs, and eventually hide the paper plate, now soggy with vegetable oil absorbed from the corpus of the cake.

Who are the agents of acculturation here?"


"If you are a vector for cultural change, which way is the arrow pointing?

Wear your Real Food Uniform.

Active Duty.

Fly your freak-flag high.

Say no to the cake."

Ruth may not have been deprived of sugar in her grandfather's presence, but perhaps she was deprived of something after all. As Yudkin was the author of a book entitled “Pure, White and Deadly”, I am left wondering at the power of acculturation to affect our choices.

Friday, February 14, 2014

Response to Mark Sisson's assertion that vegetables are necessary for health

Mark Sisson is the author of The Primal Blueprint, and the blog Mark's Daily Apple. His blog is a great reference, and I like his work. However, I take exception to the article he posted this week entitled Do You Really Need to Eat Vegetables to Be Healthy?

Although he admits at the end that you probably don't need them, this admission has much less prominence than the section near the top where he says

"Yes. Yes, you do. Maybe not a huge amount, necessarily. But you do need some."

Then he goes on to make some arguments for eating vegetables that I'd like to address.

  1. Modern Hunter-Gatherer diets: First he argues that three of the four known modern hunter-gatherers that are purported to be carnivorous (Inuit, Masai, and Sami — leaving out Plains Indians) weren't actually. I don't think that's really settled, but more importantly it doesn't matter. Even if it were true that all modern primarily carnivorous societies ate some plants, that doesn't and couldn't prove we need them.

  2. Plants as medicine: A second argument that is weaved throughout the post is that plants have medicinal compounds, and therefore should be eaten. But this doesn't make sense. This is an argument for growing plants and extracting compounds so that we can isolate and concentrate medicine into useful portions, while removing the toxins that accompany the source. It's no argument for taking daily minute doses of medicine along with a bunch of other random stuff that grew with it. I've addressed that more fully in the post Biochemical Warfare

  3. Missing nutrients: Another argument is about getting some particular nutrients. It is argued that modern meat may be depleted of some minerals and vitamins that are dependent on the diet of the animal. That is, there are wild plants that are part of the diet of wild animals, that they use to make vitamins that we then eat, and modern meat may be inadequate. This may well be true, but insofar as it is, it does not make a convincing argument for eating those plants ourselves, along with whatever other matter they contain, any more than it argues for taking supplements. Even if modern meat is insufficient, that is no argument for eating vegetables. Moreover, a similar argument is sometimes made about plant vitamin and mineral content due to soil depletion, so eating plants may not even solve it.

    (I'm ignoring the part of that section that suggests we only need plants if we refuse to eat offal or reserve the cooking water, since they support the ability to get those nutrients from meat.)

  4. Feeding gut bacteria: Finally, the argument is made that we should eat fermentable fiber to feed our gut bacteria. Although there is much interesting research into the role of gut bacteria in health, it is far from conclusive what the best health practice is with respect to them.

    As a researcher aptly pointed out in an editorial last year:

    "This considerable increase in the number of [publications devoted to the study of digestive microbiota] has generated assumptions and speculations on the role of digestive microbiota in human and animal health are likely far beyond our current knowledge." — Didier Raoult. Digestive microbiota and its influence on health: Facts and myths. Microbial Pathogenesis. 2013 Aug-Sep;61-62:A1. doi: 10.1016/j.micpath.2013.05.008. Epub 2013 May 27.

In sum, I respectfully disagree with Mark Sisson's statement that the question "Do You Really Need to Eat Vegetables to Be Healthy" can be answered definitively, let alone with a "yes".

I am more inclined to agree with the points he makes along the way: that if you do not eat vegetables, then you should consider eating offal, drinking broth, eating wild game, or taking supplements. In fact, I think those are worth consideration even if you do eat vegetables.

Thursday, February 13, 2014

Red Light, Green Light: responses to cortisol levels in keto vs. longevity research

How a scientist interprets outcomes often depends on whether she thinks the outcome should be good or bad.

Cortisol levels make a good example.

In the context of low carb, ketogenic diets, the finding of slightly higher cortisol levels have been interpreted as a warning sign. In a recent post on our blog, Zooko and I attempt to explain why the “red light” that Boston Children's Hospital gave low carb diets is not justified.

Boston Children's Hospital graphic (with our markup in black). Click for the original.

It is interesting to note that while cortisol sends up red flags for ketogenic diets, which mainstream medicine actively disapproves of, it sends up green flags in another context: longevity research.

Time and again I have come across glib statements in longevity papers saying that the beneficial, health-enhancing and lifespan-increasing effects of caloric restriction probably come in part from the moderately increased cortisol that is consistently seen in calorie restricted animals. The intuitiveness of the beneficial effects of cortisol is usually based on cortisol's known anti-inflammatory action.

Here are just a few such quotes:

  • "The mechanisms responsible for calorie restriction–mediated beneficial effects on primary aging observed in rodents probably involve the metabolic adaptations to restriction itself, including... a modest increase in levels of circulating cortisol, which result in a reduction in systemic inflammation." — Aging, adiposity, and calorie restriction. Fontana L, Klein S. JAMA. 2007 Mar 7;297(9):986-94.

  • "Even short-term DR can attenuate inflammation and affect metabolic and DNA repair pathways. Mechanisms by which DR suppresses peripheral inflammation include the elevation of glucocorticoids, lowering of glucose and activation of PPARs. Although the effects of DR are less understood in the brain, common pathways are emerging that link many normal aging inflammatory processes with age related diseases such as AD, cancer, diabetes and cardiovascular disease." — Anti-inflammatory mechanisms of dietary restriction in slowing aging processes. Morgan TE, Wong AM, Finch CE. Interdiscip Top Gerontol. 2007;35:83-97.

  • "Glucocorticoids are yet another class of hormones that may contribute to the anticarcinogenic action of DR [101, 102]. Total and/or free glucocorticoid levels are increased by DR [103–105]. Glucocorticoids suppress cellular proliferation and enhance apoptosis in a number of cell types, including osteoblasts, lymphocytes and keratinocytes (for reviews, see Weinstein [106], Herold et al. [107] and Budunova et al. [108]). In humans, glucocorticoids are effectively used for treating lymphoid neoplasms [109]. Importantly, adrenalectomy abolishes the protective effect of DR on skin and pulmonary carcinogenesis, while glucocorticoid replacement restores this protection [110–112]. — Can short-term dietary restriction and fasting have a long-term anticarcinogenic effect? Klebanov S. Interdiscip Top Gerontol. 2007;35:176-92.

  • Another mechanism by which CR may selectively exert it’s anti-inflammatory effects is via enhanced endogenous corticosteroid production (Sabatino et al. 1991). Chronic CR potentiates the diurnal elevation of plasma corticosterone. CR mice and rats have “moderately” but significantly higher daily mean plasma free corticosterone concentration than mice fed “ad libitum” throughout their lifespan...

    It is well known that the hypothalamic–pituitary–adrenal axis and glucocorticoids in particular are essential in limiting and resolving the inflammatory process (Sapolsky et al. 2000). Glucocorticoids have pleiotropic inhibitory effects on the immune system and inflammatory gene expression (Rhen and Cidlowski 2005). In addition, treatment with pharmacological doses of exogenous glucocorticoids has been used to block many inflammatory and autoimmune diseases, including rheumatoid arthritis, systemic lupus erythematosus, Graves’ disease, thyroiditis, glomerulonephritis, multiple sclerosis, and psoriasis." — Neuroendocrine Factors in the Regulation of Inflammation: Excessive Adiposity and Calorie Restriction Luigi Fontana, Exp Gerontol. 2009; 44(1-2): 41–45.

I particularly like that last one, because of the use of the word “enhanced”, which connotes that the thing that has increased is surely a Good Thing.

Now of course, the longevity researchers can't pick up on a significant difference between the animals that lived longer and those that didn't and say: Well, the diet might be good for some things, but this difference warrants caution. They can't do that because the end outcome is definitive. It's true that there is a significant school of thought that says that longevity is a result of hormesis. The hormetic explanation amounts to “what doesn't kill you makes you stronger.” That way a researcher gets to say that phenomenon X is bad for you, and that things that are bad for you improve your health. It is a way out of a paradox, as expressed nicely here:

"One well-known, exemplified response to stress is the hormonal increase in adrenal corticosterone levels in plasma during aging, where increases in these levels appear to be proportional to the degree of stress. Aged animals appear to have a diminished ability to attenuate the increase, causing the aged to have continually elevated plasma levels of corticosterones. These authors suggested that increased levels of corticosterone in aged rats result in hippocampal neuronal cell death, that is, the stage of exhaustion. However, this scenario in the glucocorticoid cascade hypothesis is obviously not applicable in the case of the CR paradigm, because CR results in an increased life span in spite of chronically elevated diurnal levels of serum corticosterone. This apparent contradiction makes the interrelation of glucocorticoid and aging far more complex than one might want to narrowly define it and needs other mechanistic explanations like stress resistance to resolve the disparity in responses." — Stress resistance by caloric restriction for longevity. Yu BP, Chung HY. Ann N Y Acad Sci. 2001 Apr;928:39-47. (my emphasis)

As Carol Loffelmann recently said on twitter: Scientists who discover paradoxes should examine their initial assumptions.

So supposing we have a study showing that a group that looks healthier than the other groups in essentially every measure also has higher levels of cortisol. We can reason, as Ebbeling et al. do, that since higher cortisol is associated with bad health outcomes, the ketogenic diet may be dangerous, despite the other measures. Or we can reason, as the longevity researchers do (and as Zooko and I did), that since the group is healthier, higher cortisol must be exerting or reflecting a healthy process, and this may present a paradox that we as researchers have to resolve.

Allow me one further point:

The findings of higher cortisol in calorie restricted animals is itself a body of literature of relevance here. Anyone finding that their intervention moderately elevates cortisol can and should now say: Higher cortisol levels are found in animals whose lifespans have been increased experimentally by dietary intervention, and so this finding in our intervention could be indicative of a longevity-inducing effect.