Category: nutrition

Fish and Pregnancy Danger

Seth Roberts5 Comments

An article in the latest issue of the American Journal of Epidemiology reports a correlation between fish consumption and worse pregnancy outcomes. It was done in Denmark. Mothers who had eaten fish four or more times per month during their pregnancy had babies that were less healthy on several measures of fetal growth than mothers who had not eaten fish.

The differences were small; they required a sample of about 40,000 women to detect. However, they are convincing partly because this effect was found for only fatty-fish consumption. For lean fish, the results were quite different. Organic pollutants accumulate in fat; mercury accumulates in protein, so these results are more likely due to organic pollutants than to mercury.

A reason to get one’s omega-3 from flaxseed oil rather than lots of fish or fish oil.

Earlier post about a study that found beneficial effects of pregnant women eating fish.

Reference: Is High Consumption of Fatty Fish during Pregnancy a Risk Factor for Fetal Growth Retardation? A Study of 44,824 Danish Pregnant Women. Th. I. Halldorsson, HM Meltzer, I Thorsdottir, V Knudsen, and SF Olsen. Am. J. Epidemiol. 2007 166: 687-696.

Vitamins, minerals, and mood

Seth Roberts2 Comments

… is the title of a just-published article in Psychological Bulletin. From the abstract:

Since the 1920s, there have been many studies on individual vitamins (especially B vitamins and Vitamins C, D, and E), minerals (calcium, chromium, iron, magnesium, zinc, and selenium), and vitamin-like compounds (choline). Recent investigations with multi-ingredient formulas are especially promising. However, without a reasonable conceptual framework for understanding mechanisms by which micronutrients might influence mood, the published literature is too readily dismissed. Consequently, 4 explanatory models are presented, suggesting that mood symptoms may be expressions of inborn errors of metabolism, manifestations of deficient methylation reactions, alterations of gene expression by nutrient deficiency, and/or long-latency deficiency diseases.

I am eager to see the data. The whole brain is the same stuff. If something affects mood, it should also affect reaction time, which is much easier to measure.

Reference: Psychological Bulletin. 2007 Sep Vol 133(5) 747-760

Nutritional Psychology: A Gaping Hole Where a Field Should Be

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Yesterday I attended the annual convention of the American Psychological Association (APA) in San Francisco. I was also measuring (again) the time course of omega-3 effects. The exhibits hall was full of books. I picked up three introductory psychology texts to see what they said about nutrition. None of their indexes listed nutrition; apparently they said nothing about it. None of the hundreds of books I saw was about nutrition — that is, about how to nourish the brain. Yet the APA is mainly about mental health.

It’s not just APA. At Berkeley, I’ve attended dozens of talks in the Nutrition Department. I have never seen another psych professor or grad student at any of them. Nor have I seen a nutrition professor at any Psychology Department talk. Both disciplines have Annual Review series. In last seven years, there hasn’t been a single article in the Nutrition series about behavior or cognition (aside from eating) nor a single article in the Psychology series about nutrition (aside from an article about weight control).

Sometimes interdisciplinary is hard. Cognitive science has tried to unite computer scientists with linguists and philosophers and psychologists. That’s hard because computer scientists are engineers, not scientists, and philosophers are neither. But nutrition and psychology are both experimental sciences. Nutrition is an independent variable (food), psychology a dependent variable (behavior). They naturally go together, especially if you are concerned with mental health.

Now and then someone will study how Disorder X responds to Nutritional Treatment Y — how depression responds to omega-3, for example. Better than nothing, absolutely, but not the best approach. By the time something is broken it is likely to be (a) a mess and therefore hard to measure and (b) hard to put back together. If you want to learn how a car works, should you study a car that works or a car that doesn’t work? The answer isn’t obvious, at least to cognitive psychologists, because for half a century they mainly studied how memory, perception, etc., failed. In the 1960s, Saul Sternberg taught the rest of the profession a better approach — namely, study a car that works. Sternberg made popular the kinds of experiments usually done today: reaction time experiments with easy problems that subjects almost always get right. My omega-3 research has illustrated the truth of Sternberg’s general point. I found much clearer effects of flaxseed oil on easy tasks (easy arithmetic, an easy memory task) than on a difficult task (digit span). A better way to learn how food affects our brains will be to study the effect of food on healthy brains. Such experiments will be much much easier than studying people who are depressed, children with ADD, schizophrenics, autistic children, drug addicts, and so on. I’m sure that the conclusions from healthy brains will generalize to malfunctioning brains, just as all cars — working or broken — work the same way.

Something is Better Than Nothing (part 2)

Seth Roberts1 Comment

In a recent post I said that scientists are often much too dismissive. They are “evidence snobs,” Alex Tabarrok might say. A letter in the current issue of the American Journal of Clinical Nutrition criticizes a important example of just such dismissiveness:

In conclusion, whereas we agree that policy decisions should be evidence-based and not hasty, we do not agree that the evidence base [used to make those decisions] should be constrained to one type of study [long-term randomized controlled trials]—in particular, not to a study design that is inherently limited. Do we really want to wait perhaps decades for results of long-term RCTs, which almost certainly will not provide definitive evidence, while ignoring other relevant evidence involving shorter-term endpoints? An example is provided in the panel’s own summary statement (2). In lauding RCTs as the “gold standard for evidence-based decision making,” the panel proudly points to the fact that, even though folate was well known to decrease the risk of neural tube defects in animal studies, policy recommendations for folate supplementation to prevent neural tube defects were delayed while authorities waited some years for confirmation from RCTs. One can only wonder how many infants were born with neural tube defects while authorities waited.

“Proudly,” huh? Inclusion of that word shows how pissed the authors of the letter are — and rightly so. One author is Bruce Ames, a neighbor of mine, for whom I have great respect; another is Walter Willett, the Harvard epidemiologist. In 1998, Willett wrote a smart article challenging the popular belief that a low-fat diet is a good way to lose weight.

Here is part of the reply from the authors of the report that Ames et al. criticized:

It is important to note that our panel was not charged with asking whether vitamins and minerals play a role in human disease –a topic that occupies much of the letter by Ames et al, and for which observational evidence is indeed central — but, as a State-of-the Science Panel, was charged to reflect on the state of the available evidence for a treatment recommendation on the use of vitamins and minerals in the general population. For treatment decisions, the RCT is the established standard. No better proof of this principle can be found than in the RCTs reviewed in our report, which showed serious harm from vitamin ingestion in certain circumstances.

A less-than-reassuring answer. A commentator on my earlier post thought I should address the strongest arguments on the other side. I had trouble thinking of any. It’s hard to argue that less evidence is better. You can see that those who wrote this paragraph — some of the most prominent nutrition scientists in the country — were equally baffled.

I will revise my “common mistakes” article to mention the Ames et al. letter.

Omega-3: I Can See For Myself

Seth Roberts11 Comments

“The flax seed oil scam” by a herbalist named Henriette says bad things about flaxseed oil. One is about (lack of) conversion of ALA (the short-chain omega-3 in flaxseed oil) to EPA and DHA (the long-chain omega-3s found in fish oil and presumably active in the brain):

The scam is in flax seed oil folks trying to maintain that we can convert ALA into EPA and DHA in anything like relevant amounts.

We can’t. We convert at most 10 %, but usually less than half that.

Which is “fairly common knowledge among nutritionists,” says Henriette. She quotes the abstracts of two scientific papers to support this point. The other criticism is that flaxseed oil goes bad quickly:

I dislike flax seed oil for another reason as well: it oxidizes (goes rancid) pretty much the minute it’s pressed, and unless it’s been refrigerated ALL the way from press to consumer, it’s ALWAYS rancid.

After I read this, I realized I was in an unusual position. When it comes to flaxseed oil, I don’t have to take anyone’s word for it. I have been able to measure the benefits by myself on myself. Apparently the conversion ratio, whatever it is, is high enough; and the suppliers of my flaxseed oil (I have used Spectrum Organic, Barlean’s, and the Whole Foods house brand) have solved the oxidation problem.

With almost every other nutrient, my knowledge is far less certain. Sure, I need some Vitamin C, but how much is best? Too much may cause cancer. I’ll probably never know the best amount for the average person, much less the best amount for myself.

Irritability and Coca-Cola

Seth Roberts9 Comments

The following is from a friend of mine. He is in the middle of a self-experiment to measure the effect of various forms of Coca-Cola (regular, diet, diet w/o caffeine) on his mood.

TODAY’S EVENT

Today ~20 oz of coca cola (w/ caffeine and w/ sugar) dramatically eliminated (in about a minute) a very real, strong feeling of irritability.

BACKGROUND

I am on day 17/30 of the experiment and I am still blinded to the results of the first 16 days. I do know that none of my previous mood experiences in the past 16 days were like the one today.

I had a significant bought of irritability (6/10) today. This irritability has been brewing last 48 hours but was palpable all morning after I woke up this AM. This irritability was the REAL DEAL that I have been seeking the past few weeks – my family was well aware of my irritability yesterday and this AM. Since this irritability was so palpable, I decided to break my experimental protocol and drink a known real coke. Quite remarkably, within a minute or so of consuming the whole coke (~20 oz – large) my irritability was gone (really gone). [He drank the coke in 2 or 3 minutes. The effect lasted about an hour.] Be clear, this was not some psychological maybe I feel this maybe I don’t, this was real psychiatric, can’t miss it, need some drugs, psychotropic bad/irritable feeling.

The past 16 days of this experiment has made me very familiar with hunger, bad moods, hunger irritability, assessing my feelings around hunger, assessing feelings around soda pop, assessing feelings around a good meal. Therefore, today I was well prepared to focus on the minute to minute dynamics around drinking this coke – the coke abruptly ended hours of feeling irritable (no better word to describe the mood than irritable).

RESULTS

-1) Now that I am half way through the experiment, I think I can break the blind by identifying the three different types of coke. I can taste the clean sweetness of real coke immediately, I can feel caffeine in my body from the diet coke in about 5 minutes.

0) I am currently blinded to the results of the experiment I am doing. However, I do have some anecdotal impressions that presumed diet w/o caffeine causes no mood affect, diet w/ caf does affect mood, coke w/ caffeine and w/ sugar does affect mood. My anecdotal impression is that these effects are mild to modest.

1) Today was the first time I felt psychiatric grade irritability confounded by hunger irritability. Today unblinded Coke abruptly eliminated the bad feelings associated with this irritability.

2) I have been rating my mood with full meals 20-40 minutes after my soda pop drink and my impression is that real satiation does have some positive mood effects.

DISCUSSION

The big target is understanding how 20 oz of sugar and caffeine totally eliminates the strong and persistent feeling of psychiatric grade irritability confounded by hunger irritability. Designing an experiment to go for this issue is challenged by the infrequentness of this psychiatric grade irritability.

Coke eliminating irritability appears to produce happiness by eliminating the presence of bad irritability feelings. In this setting, Coke did not produce any positive feelings, Coke simply eliminated some strong bad feelings. Coke is not producing a good mood, it removed a bad one. (There may have been some “psychological” grade good mood, but this was so tentative and hard to assess that I am happy saying Coke produced no positive affect. The removal of the psychiatric irritable mood was clear and absolute).

In contrast to the absence of irritability caused by coke (and no good mood effects), I think the satiation I have experienced these past 16 days from the big healthy meals following my soda pop does has some positive feelings associated with it. Satiation presumably feels good not just because of elimination of hunger, there seems to be some warm glow from eating a large, well-balanced, fatty, carbo, vegetable, sweet meal.

There appear to be different kinds of irritability. More than six hours without food brings on a form of irritability, but this hunger irritability appears to be different from “mood” irritability. Mood irritability lasts for days while hunger irritability lasts for hours. Hunger irritability produced in the setting of no mood irritability is not that profound. Hunger irritability on top of mood irritability appears to be the REAL DEAL of irritability. It is this REAL DEAL of irritability which today (and typically) creates the setting such that a large caffeine/sugar soft drink eliminates the persistent palpable bad feelings associated with REAL DEAL irritability.

I understand why it would be nice if the subject is blinded. However, I am not sure the subject needs to be blinded. I think one still gets meaningful results even if placebo/nocebo effects are folded into the results.

CONCLUSION

A couple of days of irritability compounded by hunger produces a strong form of irritability which was dramatically relieved by a large glass of caffeine/sugar coke today (unblinded N = 1 in experiment). Strategies for further behavioral characterization of this phenomenon are needed. A physiological hypothesis is needed. A future design for FMRI measurements of this quick irritability response to caffeine/sugar will be fun to design.

In the final analysis, I guess it is worth finishing the current experiment – even though I think I can determine the identity of each drink. Good data from an inadequate experimental design will be helpful in creating a better experimental design.

About the author: John Keltner has a Ph.D. in Physics from UC Berkeley and an M.D. from Harvard. He is a research fellow at the University of Oxford. Given these results, I asked John if he was addicted to caffeine. He told me no, going without caffeine did not make him more irritable.

Memorial University Continues to Destroy Its Reputation

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A paper by Saul Sternberg and me questioned a 2001 Nutrition paper by Ranjit Chandra, a nutrition professor at Memorial University of Newfoundland. We were not the first to question Chandra’s published work. Many years earlier, a nurse named Marilyn Harvey, who worked for Chandra, complained to Memorial that Chandra could not have done the research he claimed to have done. It is now obvious that Harvey was right. A panel convened by Memorial, however, found that she was wrong — more precisely,

The university said it did conduct an investigation of Chandra’s research, but based on what it knew at the time, “properly determined there was insufficient evidence to sustain the complaint against Dr. Chandra.”

Harvey claimed that certain data didn’t exist. The Memorial panel was unable to figure out if this was right or wrong!

Harvey showed a lot of courage. She put herself at considerable risk by challenging Chandra, who was the best-known professor at Memorial. By doing a travesty of an investigation, Memorial University failed to protect her. And now Memorial University is defending what they did! Such a defense is a second travesty.

As the person responsible, the President of Memorial, Axel Meisen, continues to demonstrate his cluelessness. When the truth about Chandra became evident, he said, “I don’t think one can conclude that everything Dr. Chandra did is under suspicion.”

More about Chandra.

A Stanford Nutrition Professor’s Explanation of SLD

Seth Roberts2 Comments

A Palo Alto resident found SLD so effective (lost 10 pounds in 1.5 months) that he told others about it. “Everyone I speak to about the diet laughs at me or just shakes their head,” he wrote. (Which is good.) A tenant of his, a Stanford medical student, asked his nutrition professor how such a crazy diet could possibly work. The professor, Dr. Clyde Wilson, replied:

Fats and sugars reduce hunger when consumed in moderate amounts. Fructose stimulates less of an insulin response than glucose, putting you at less risk of subsequent hunger. Flavored foods result in a greater caloric consumption. Unflavored fructose and olive oil would therefore reduce hunger during a subsequent meal. Any small healthy snack will provide the same result. A small healthy snack would be, for example, a whole grain cracker with some peanut butter and half an apple.

The interesting thing about SLD is not that the oil or sugar water reduces hunger — most food does that — but that it causes easy weight loss. This is what needs explaining. Why does X calories of sugar water cause you to reduce future consumption by more than X calories? This paragraph doesn’t explain this.

Since fructose, sucrose, and unflavored oils all have the same effect, it cannot be due to a special property of fructose.

As for the prediction that a small healthy snack will have the same effect, that has not been my experience. I’m pretty sure that weight loss would not be such a big problem if one could lose substantial weight (such as 10 pounds in 1.5 months) by eating as many small healthy snacks as you want.

Does the Type of Fat in Your Diet Affect Your Brain?

Seth Roberts8 Comments

Here’s how a Ph.D. student at UC San Francisco doing research on neural stem cells answered that question:

If dietary fat affected the brain in a significant way, we would know about it. It would have been discovered. Which isn’t to say it doesn’t affect it in a trivial way. Not just an acute action — like if you drink a small amount of alcohol or the effect of a sugar high. I mean the long-term functioning.

Why?

Because a lot of people would have tested it. Fat gets a lot of money. It’s a crowded area of research. People try to exploit it. It’s an area with a lot of public interest. It’s very popular to study anything related to fat. Also anything related to the brain. People are worried that they will lose their mind as they age. If there was something significant found it would have been a big story all over the New York Times.

She was very sure of this, it seemed to me.

My main posts about omega-3.

Selenium, the Anti-Mercury

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I’ve been worried about the mercury in tuna. I didn’t know that selenium protects against mercury damage. See this paper, for example — see Table 1. Moreover, the same fish that contain mercury contain protective amounts of selenium. “It appears that selenium levels in fish are high enough to give protection against mercury toxicity,” concluded a review article. These important facts were missing from all discussions of the dangers of mercury in fish that I had seen, such as this one.

I already take selenium supplements because selenium protects against cancer. An especially convincing bit of evidence for this effect is a map of United States county-by-county colorectal cancer rates. There is a sharp separation of high- and low-rate areas along the Ohio and Mississippi Rivers. Attempts to explain the difference eventually decided it was due to selenium in the soil of the low-rate areas.