Category: nutrition

Tucker Max on Paleo: “I Started Feeling So Much Better”

Seth Roberts2 Comments

In this interview, Tucker Max talks about eating paleo.

Once I started doing this, I started feeling so much better. My brain felt like it worked better. Everything about me improved. So I kinda went down the rabbit hole, and I started reading up on diet and nutrition from alternate sources. Art De Vany, Robb Wolf, and Loren Cordain, they didn’t invent it but they kinda popularized the concept of paleo eating. I realized that if you’re just a normal person, and you have the normal ideas about diet and nutrition, everything you know is wrong.

If you ask me, Tucker’s enthusiasm/support for paleo is huge. Max Planck said progress happens funeral by funeral. I say it happens keg party by keg party — college students, more than anyone else, have open minds. A friend told me that when she was a freshman in college, her sociology professor criticized the textbook. Whoa! she thought. Textbooks can be criticized!? She had thought they were beyond criticism. As far as I can tell, American college students respect Tucker more than they respect anyone else. (My Tsinghua students may favor Nassim Taleb.) For example, this recent tweet: “ TuckerMax is my idol. and he’s on this paleodiet…so i think im going to do it too.” I found no tweets about the dietary influence of Michelle Obama (“ coolest First Lady ever“).

In spite of what the interview was shortened to say, Tucker got the idea of eating flaxseed oil from this blog, especially Tyler Cowen’s experience. He wrote to me about it at the time. I posted his comments about dental health (here and here) and sports injuries (here, here and here) under the name Anonymous.

I am pleased to announce that Tucker will be talking at the upcoming Ancestral Health Symposium at UCLA. The title of his talk is::

From Cave to Cage: Mixed Martial Arts in Ancestral Health

Sorry Tucker Max fans, symposium tickets are sold out. But after the conference you will be able to see the talk on the website.

Tucker’s latest book is Assholes Finish First.


Danger of Low-Carb Diet: Not Enough Vitamin C

Seth Roberts37 Comments

I eat a low-carb diet for reasons that have nothing to do with weight loss: To keep my blood sugar down. I am sure high blood sugar is bad. A few months ago, I noticed that my lips were chapped, which was unusual. I suspected it was due to lack of Vitamin C. About two months before that, I had stopped doing two things that I usually did: taking a multi-vitamin pill (which had Vitamin C) and eating fruit. I don’t know if the Vitamin C in the pill is absorbed but I’m sure the Vitamin C in fruit is. I started eating kumquats — the skins of four kumquats/day. (One kumquat contains about 15% of the recommended daily allowance of Vitamin C). My lips returned to normal.

Paul Jaminet, author of Perfect Health Diet, had a similar experience, which I knew nothing about when I noticed my chapped lips. While eating “a lot of vegetables but no starches and hardly any fruit,” he developed outright scurvy, including wounds that wouldn’t heal. This happened while he was taking a multi-vitamin pill with 90 mg Vitamin C (my four kumquats contain only 35 mg Vitamin C). “Four grams a day of vitamin C for two months cured all the scurvy symptoms,” he found.

Why do we like sweet foods? The usual answer (so that we will eat more calories) is nonsense (except for children). The striking thing about our liking for sweetness is that it disappears when we are really hungry, which is the opposite of what the calorie-seeking explanation predicts. Desserts are served at the end of a meal because they taste much better then. But our liking for sweetness (when we’re not hungry) is so strong and obvious it must mean something important. I think it is pushing us to eat more fruit so that we will get enough Vitamin C. Fruits are much sweeter than other food groups and they are much higher in Vitamin C. We don’t like sweet things when we are hungry because a high-fruit diet is terrible (it is low in omega-3, other necessary fats, several minerals, and microbes, for example). But a small amount of fruit may be a big help. Paul and my experiences suggest it may be hard to get enough Vitamin C in other ways.

More Paul has a different idea about why we like sweetness.

Meat-Only Diet: Crave Carbs. Meat + Egg: No Craving

Seth Roberts5 Comments

Joseph Buchignani, a businessman in Shenzhen, has suffered from irritable bowel syndrome (IBS) since he was a teenager. He is now in his 20s. By trial and error, he discovered that a meat-only diet eliminated his IBS. However, it also caused craving for carbs. Because carbs caused IBS, he couldn’t simply eat carbs. He tried many ways of getting rid of the craving for carbs: eating more animal fat, eating less animal fat, eating oil, eating lard, and eating different kinds of animals and cuts of meat. He varied how he cooked the meat, eating especially fresh meat, and eating fresh whole fish. All of these attempts failed. He did not try taking a multivitamin pill.

Finally he tried adding egg to the meat. That eliminated his craving for carbs. It made his diet much more sustainable.

This is fascinating for four reasons.

1. Sure, some cravings reflect nutrient deficiencies. (Not all cravings: An alcoholic craves alcohol.) But in the cases I know about, there is an obvious or semi-obvious connection between the craving and the deficiency. For example, people who chew too much ice (pagophagia) crave ice to chew. They are iron-deficient. Eating iron eliminates the pagophagia. Long ago, a craving to eat something crunchy would have led you to eat bones. Bone marrow is high in iron. So the craving makes sense. In contrast, there is no obvious or semi-obvious connection between carbs and eggs.

2. It suggests that a paleo diet is a good place to start looking for the ideal diet. Paleo ideas suggest a high-meat diet. But no matter how long you study what Stone-Age people ate, you will not figure out that eggs will eliminate carb cravings.

3. Like many people, especially those doing paleo, I eat mostly meat and vegetables (a conventional low-carb diet). Unlike most low-carbers, I also eat lots of fermented foods. I don’t crave carbs, perhaps because of the lactose in yogurt or the sucrose in kombucha. It hadn’t occurred to me to start eating eggs regularly but Joseph’s discovery suggests I should try it.

4. Joseph’s personal science led him to discover something highly useful and completely non-obvious.

Different Effects of Omega-3 and Omega-6 on Heart Disease

Seth Roberts5 Comments

You have probably read hundreds of recommendations to eat more polyunsaturated fatty acids (PUFAs), which in practice means omega-6 and omega-3. If you shop at Whole Foods, you may see Udo’s Blend, a blend of PUFAs which includes both omega-3 and omega-6, as if someone isn’t getting enough omega-6. It is unquestionable that omega-3 is beneficial but there is plenty of evidence that omega-6 is harmful, starting with the Israeli Paradox. Why are they lumped together?

A just-published paper in the British Journal of Nutrition makes several new points about the relation of PUFAs and heart disease. Its main point is a new look at experiments in which one group was given more PUFAs than another group. Those experiments — there are only about eight — can be divided into two groups: (a) experiments in which the treated group was given both omega-3 and omega-6 and (b) experiments in which the treated group was given only omega-6. The two groups of experiments seem to have different results. In the “both” experiments the treated group seems to benefit; in the “only omega-6″ experiments, the treated group seems to be worse off. Suggesting that omega-3 and omega-6 have different effects on heart disease. They have been lumped together because experiments have lumped them together (varied both at the same time).
Experiments that try to measure the effect of PUFAs usually say they are replacing saturated fats. More PUFAs, less butter. The paper points out that studies of the effect of PUFAs have at least sometimes confounded reduction in saturated fats with reduction in trans fats. Benefits of the change may be due to the reduction in trans fats, not the reduction in saturate fats.

The paper also makes several good points about the Finnish study, a classic in the fat/heart disease literature. Supposedly the Finnish study showed that PUFAs (replacing saturated fats) reduce heart disease. It had hundreds of subjects but they were not randomized separately. The subjects were divided by hospital. Everyone in one hospital got one diet, everyone in a second hospital got a different diet. This meant it was easy for there to be confoundings (i.e., the treatment wasn’t the only difference between the groups). Indeed, there were big differences in consumption of a certain dangerous medication and margarine between hospitals. (Margarine is high in trans fats.)

Perhaps the first author, Christopher Ramsden, who works at NIH, is responsible for the high quality of this paper.
Thanks to Susan Allport.

Food For Thought

Seth Roberts6 Comments

A perfectly good Economist article about food and brain function includes the following:

Many studies suggest that diets which are rich in trans- and saturated fatty acids, such as those containing a lot of deep-fried foods and butter, have bad effects on cognition. Rodents put on such diets show declines in cognitive performance within weeks.

Whereas I found butter improved my cognitive performance within a day. And pork fat improved my sleep within a day. On the other hand, I wouldn’t be surprised if foods deep-fried in plant oils, such as corn oil, are bad for the brain.

Dangers of Supplements

Seth Roberts2 Comments

Via Robin Hanson I found this study of the effects of antioxidant supplements. It studied five (e.g., Vitamins A and C). Overall they were slightly harmful, except selenium.

This isn’t intuitive — why should they differ? — but fits well with previous work:

1. Evidence for benefits of selenium is overwhelming. You can look at a county-by-county map of US cancer rates and see a sharp drop along a certain line in the northeast. The line separates different geology. There is much more selenium in the soil on the low-cancer side of the line. Yet another case where correlation is powerful evidence for causation. An experiment with selenium supplementation found a reduction in cancer.

2. Several years ago, two experiments found Vitamin A supplements increased lung cancer. (Another study.) Later experiments cast doubt on Vitamins C and E. As one of Robin’s readers put it: “two of which were previously well known to be bad for you.”

Given this previous research, which is far more persuasive than the current study, the interesting contribution of the new study is methodological: will a meta-analysis of epidemiological studies reach the right conclusions? Will the signal outweigh the many sources of bias and error? In fact, it did. Again suggesting that severe critics of epidemiology, such as John Ioannidis, go too far.

Dairy Consumption and Health

Seth Roberts6 Comments

Two studies of the effect of dairy consumption on health have recently appeared. Both suggest it is healthy. One of them– a prospective study where about 1500 people were followed for 16 years — found no association of dairy intake with overall mortality but did find a protective effect of full-fat dairy against heart disease. The study considered lots of possibilities and the authors write ” it is important to take into account the large number of comparisons considered in this study and thus we cannot rule out the possibility that the protective association between full-fat dairy intake and cardiovascular mortality was due to chance.”

I mentioned this study earlier. It gains more credence because of the other study, which is a meta-analysis. The second study found protective effects of dairy products on several outcomes, including overall mortality:

Meta-analyses suggest a reduction in risk in the subjects with the highest dairy consumption relative to those with the lowest intake: 0.87 (0.77, 0.98) for all-cause deaths, 0.92 (0.80, 0.99) for ischaemic heart disease, 0.79 (0.68, 0.91) for stroke and 0.85 (0.75, 0.96) for incident diabetes.

This is good news for me since I eat yogurt and butter every day.

Thanks to Peter Spero.

Assorted Links

Seth Roberts4 Comments

Thanks to Dave Lull and Anne Weiss.

Avocado Raises Blood Sugar

Seth Roberts17 Comments

Tim Lundeen writes:

We [Tim and his partner, Alexandra] first noticed that eating avocados raised our blood glucose when we were on a low-protein/low-fat/high-fruit nutrition plan. After 1/4 avocado each, we would both have fasting glucose of 95-99 instead of 80-85, with the effect lasting for about 4 days. It was quite repeatable, so we stopped eating avocados. We speculated at the time that it was due to the omega-6 content of the avocado fat.

We just tried avocado again with more typical nutrition, with about 25% protein, 25% fat, 50% carbohydrate with very low fructose, thinking that because we were eating more fat the effect might not be so pronounced, but saw the same elevated fasting blood glucose as before.

After some more research, we found out it is because avocados contain a sugar called mannoheptulose, which causes temporary dysregulation of blood sugar.

Mannoheptulose was first isolated in 1917. Mannoheptulose has been proven to be present in many foods, but is found most abundantly in the avocado (La Forge 1916-1917). In 1957, the first research was published in the Archives of Biochemistry and Biophysics (Volume 69, page 592), suggesting that avocado extract blocked normal insulin secretion. In 1963, it was demonstrated that avocado extract blocks glucose-stimulated release of insulin (Nature, Volume 197, page 1264). By 1967, low doses of avocado extract were found to inhibit both pancreatic secretion and synthesis of insulin without eliciting measurable hyperglycemia (high blood sugar) (Nature, Volume 214, page 276). This finding was significant because it demonstrated that a controlled dose of avocado extract could suppress pancreatic production of insulin without inducing a diabetic state. [https://www.health-marketplace.com/p-Obesity-3.htm]The problem with this is that your cells don’t absorb nutrition because insulin is reduced, so we have strong cravings for food, feel extra hungry all the time, and have been eating about 50% more calories to feel full. The net effect is not a good feeling…

This makes sense. And it is methodologically interesting. Spending zero research dollars, Tim and Alexandra learned something important about blood sugar control that the rest of the world seems not to know. (Except perhaps the researchers who did the avocado extract research.) None of the research articles they mention make clear the practical significance of the effect. To say that avocado extract does X doesn’t tell you how much avocado you need to get the effect.

When I google “avocado” and “blood sugar” (together), the first page of links all claim, at least at first glance, that avocado lowers blood sugar. But that’s just the internet. (Although Google is supposed to put the most reliable links at the top.) Then I went to the most authoritative possible source on what we should eat: the American Journal of Clinical Nutrition. I found only three articles that mention avocados in their title or abstract. None was about this effect. I also looked in Eat Drink and Be Healthy by Walter Willett and the Harvard School of Public Health. Nothing about this effect of avocado.

Assorted Links

Seth Roberts2 Comments