Category Archives: Nutrients - Page 6

Around the Web; and Why Is Aspirin Toxic to Cats?

Posted by on April 9, 2011 31 comments

[1] Interesting posts this week: Melissa McEwen assures us: Robb Wolf is not Satan. Kurt Harris’s reader Tara makes the most persuasive case I’ve seen for grass-fed meat through pictures. Emily Deans compares eating disorders to addictions.

[2] Kurt Harris re-re-brands: Paleonu became PaNu became Paleo 2.0 becomes Archevore.com, archevore being a neologism for “one who eats of the essentials.”

Well, it’s more euphonious than “EM2vore,” for “one who eats of the evolutionary metabolic milieu.” A more descriptive name might have been “nontoxivore,” since Kurt’s primary theme is avoidance of “neolithic agents of disease – wheat, excess fructose and excess linoleic acid.”

It will be interesting to see where he’s taking this. Are Archevorean essentials the same as PaNu?

[3] Posts of the week: Chris Masterjohn posts always deserve special notice. On Tuesday he continued his important series investigating whether wheat causes leaky gut, which will trigger a few edits in the next edition of our book. I was asked about this last Saturday and said:

There’s no question that gluten causes problems in non-celiacs – that’s the main result of the Fasano paper Chris cites, and also of papers cited by Andrew Badenoch in a post I linked today. It’s just that leaky gut does not appear to be one of those problems.

It certainly doesn’t mean that wheat is safe to eat.

I may add that pathogens and other food toxins – even perhaps other wheat toxins besides gluten – can cause a leaky gut, providing a way for wheat toxins to enter the body. Moreover, some wheat toxins don’t even need a leaky gut to enter the body. As we discuss in the book (p 134), wheat germ agglutinin can cross barriers via transcytosis, enabling them to enter the body even if the intestinal barrier is intact. Finally, wheat toxins can damage the gut without entering the body at all. So there are many pathways through which wheat toxicity can matter.

Chris had another outstanding post on Friday, about fatty liver disease.

[4] Rosacea is an infection of the skin and vessels: That’s why it can be transmitted through facial skin grafts.

Source: Kanitakis J. Transmission of Rosacea from the Graft in Facial Allotransplantation. Am J Transplant. 2011 Mar 28. [Epub ahead of print] http://pmid.us/21443678.

[5] Special offer: The folks at Emerald Forest Xylitol noticed that we recommend their product and would like to give a special offer to PerfectHealthDiet.com readers. Use the coupon code FIRST to get 10% off all products at www.emeraldforestxylitol.com.

Also, Matt Willer of Emerald Forest Xylitol is looking for recipes that include Xylitol for use in his newsletter. If you have a recipe, send it to matt@xylitolusa.com.

[6] Animal photos: If you saw a grizzly charging straight toward you, would you stop to take this photo?

Photographer Alex Wypyszinski did in Yellowstone. The grizzly was chasing an injured bison, and the pair went right past him:

For the full story, see Grizzly versus Bison: the rest of the story (Drew Trafton, 10/29/10, KRTV, Great Falls, Montana). Hat tip Orrin Judd.

[7] Don’t hate the sun: From Britain comes the sad story of a 21-year-old who “hated the sun” and died of skin cancer at 21.

Dr. John Briffa has a summary of the relevant science.

[8] I couldn’t disagree more: Mike the Mad Biologist and Newt Gingrich are dead wrong in their prescription for research funding. We don’t need more concentrated funding, we need more distributed, decentralized funding that is patient-driven, not top-scientist driven.

Discovering cures can be cheap – if you’re looking in the right place. If you’re looking in the wrong direction, the cost of a cure may be infinite.

[9] I hate when that happens:

(Via Stephen Wangen)

[10] Are choline supplements toxic?: At the very beginning of the book (p 3) we state that “the perfect diet should … deliver … no excess nutrients for pathogens.”

Later in the book we give examples of nutrients that, in excess, primarily benefit pathogens: niacin (the primary vitamin for bacteria), iron (critical for metabolism of most pathogens, and a component of bacterial biofilms), and calcium (a component of bacterial biofilms). These are on our list of micronutrients we recommend not supplementing (beyond a multivitamin).

Two readers, Leonardo and Patricia (thank you both!), emailed us about a ScienceDaily article suggesting that choline, one of the micronutrients we most frequently recommend, should be added to this list:

When fed to mice, lecithin and choline were converted to a heart disease-forming product by the intestinal microbes, which promoted fatty plaque deposits to form within arteries (atherosclerosis); in humans, higher blood levels of choline and the heart disease forming microorganism products are strongly associated with increased cardiovascular disease risk.

The story didn’t have enough information, so I downloaded the paper. The paper notes that choline is metabolized by gut bacteria to a gas with a fishy odor called TMA, which is then oxidized in the liver to a compound called TMAO:

Briefly, initial catabolism of choline and other trimethylamine-containing species (for example, betaine) by intestinal microbes forms the gas trimethylamine (TMA), which is efficiently absorbed and rapidly metabolized by at least one member of the hepatic flavin monooxygenase (FMO) family of enzymes, FMO3, to form trimethylamine N-oxide (TMAO).

They showed that (a) feeding phosphatidylcholine from egg yolk to mice led to increased blood levels of TMAO and that (b) in a separate study, people with atherosclerosis have elevated blood levels of TMAO, choline, and trimethylglycine.

Supplementing choline at 10 times normal levels to Apoe-knockout mice led to increased TMAO but not choline in blood:

Atherosclerosis-prone mice (C57BL/6J Apoe-/-) at time of weaning were placed on either normal chow diet (contains 0.08–0.09% total choline, wt/wt) or normal chow diet supplemented with intermediate (0.5%) or high amounts of additional choline (1.0%) or TMAO (0.12%)….

Analysis of plasma levels of choline and TMAO in each of the dietary arms showed nominal changes in plasma levels of choline, but significant increases of TMAO in mice receiving either choline or TMAO supplementation (Supplementary Fig. 10).

Serum TMAO levels were correlated with atherosclerotic plaque size and with macrophages turning into foam cells:

[A]ll dietary groups of mice revealed a significant positive correlation between plasma levels of TMAO and atherosclerotic plaque size (Fig. 3e and Supplementary Fig. 9b).

TMA (a gas with a fish odor) has to be converted in the liver to the toxic TMAO in order to produce these bigger atherosclerotic lesions. This conversion happened mainly in mice with low HDL:

Interestingly, a highly significant negative correlation with plasma high-density lipoprotein (HDL) cholesterol levels was noted in both male and female mice (Fig. 4b and Supplementary Fig. 12, middle row).

So if you’re an Apoe(-/-) mouse and eat ten times normal choline, if you have high HDL your arteries are safe but you smell fishy; if you have low HDL you smell fine but your arteries get injured.

What does this tell us about choline supplementation?

For humans with working ApoE alleles, I doubt we can infer anything yet.

For Apoe(-/-) mice fed ten times normal choline, I would suggest shooting for low HDL while dating, then high HDL after marriage.

Reference: Wang Z et al. Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease. Nature, 2011; 472 (7341): 57 DOI: 10.1038/nature09922

[11] One-upping the standing desk: Jamie Scott has a walking desk:

[12] Why is aspirin toxic to cats?: In the book we mention that plant foods always contain toxins, but animal foods don’t – because in poisoning us, animals would poison themselves. As we point out in the book, Bruce Ames and Lois Gold estimate that over 99% of the toxins humans ingest come from plant foods – not industrial or environmental toxins.

One of the main functions of the liver is detoxification. A healthy liver enables us to consume plant foods.

But what happens to the livers of animals that never eat plant foods? If they and their descendants avoid plant foods for millions of years, how would their livers evolve?

The answer is in a fascinating piece by Ed Yong at Discover blogs: “Why Is Aspirin Toxic to Cats?”. The puzzle:

[C]ats are extremely sensitive to aspirin, and even a single extra-strength pill can trigger a fatal overdose.

Some scientists have been investigating this puzzle since the early 1990s. It turns out that all 18 of 18 species of cat studied, including housecats, cheetahs, servals, and tigers, have crippling mutations in a gene involved in liver detoxification. The same gene is also lost in other hypercarnivores, including the brown hyena and the northern elephant seal.

Mr. Yong explains:

Like many other “detoxifying” proteins, UGT1A6 evolved to help animals cope with the thousands of dangerous chemicals in the plants they eat….

But if an animal’s menu consists largely of meat, it has little use for these anti-plant defences. The genes are dispensable…. [T]he ancestral cats gradually built up mutations that disabled their UGT1A6 gene. Evolution is merciless that way – it works on a “use it or lose it” basis.

So – millions of years of hypercarnivory will disable the liver’s ability to metabolize toxins.

Pet owners, be kind to your cats: Don’t feed them plants!

And a new zero-carb danger: After ten thousand generations, your descendants may be unable to take aspirin.

Reference: Shrestha B et al. Evolution of a Major Drug Metabolizing Enzyme Defect in the Domestic Cat and Other Felidae: Phylogenetic Timing and the Role of Hypercarnivory. PLoS One. 2011 Mar 28;6(3):e18046. http://pmid.us/21464924.

[13] Not the weekly video: Best mobile phone commercial I’ve seen:

[14] Weekly video: I grew up near the University of Connecticut campus and have been a fan of their men’s basketball team since the late 1970’s. What Jim Calhoun has done there, building a minor program to national prominence and three championships, is one of the great accomplishment in coaching history. And this year’s team was a minor miracle: with unheralded and under-recruited freshmen playing half the minutes, they won a national championship.

Every year CBS makes a video montage of the tournament. Here it is, One Shining Moment:

Why Did We Evolve a Taste for Sweetness?

Posted by on March 24, 2011 83 comments

After I did my post on Seth Roberts’s new therapies for circadian rhythm disorders, Seth learned of my experience with scurvy and blogged about a similar experience of his own.

Seth made the important point that food cravings are driven by nutritional deficiencies – a point I heartily agree with, which is why it’s so important for those seeking to lose weight to be well nourished – and asked, “Why do we like sweet foods?” His suggested answer was that the taste for sweetness encouraged Paleo man “to eat more fruit so that we will get enough Vitamin C.”

This led to a fascinating contribution from Tomas in the comment thread:

I have read several books on the Traditional Chinese Medicine and they attributed that increased craving for sweets is in fact signaling some serious nutritious deficiencies. They said that it’s in fact meat or starches or other nutritionally dense foods that will soothe the craving, but sweets are more readily available. The taste of meat is in fact sweet as well.

In my experience this seems (the TCM view) to be true. I always have been very skinny, but eating enormous amounts of sweets. After I switched to a proper, paleo-like diet, the situation changed in many aspects and I no longer have such strong cravings and slowly I am gaining some weight.

Shou-Ching and I have great respect for the empirical claims of Traditional Chinese Medicine, and so I found this a fascinating idea. Is our modern taste for sweets actually derived from a taste that evolved to encourage meat eating?

Human tastes

It is generally agreed that animals evolved the sense of taste to detect nutrients and toxins:

Taste helps animals to decide whether a food is beneficial for them and should be consumed or whether it is dangerous for them and should be rejected. Probably, taste evolved to insure animals choose food appropriate for body needs. [1]

The five basic human tastes are sweet, salty, sour, bitter, and umami. Each taste detects either a nutrient class we need or toxins we should avoid:

  • Sweet – carbohydrate.
  • Salty – electrolytes.
  • Sour – acids.
  • Bitter – toxins.
  • Umami – glutamate and nucleotides.

Electrolytes are essential to life, and toxins best avoided, so the evolution of salty and bitter tastes is easy to understand. The umami taste is mainly a sensor for natural (healthy) protein. The sour taste is interesting, in that it is attractive in small doses but aversive in large. Seth argues that low-dose sourness is desirable because it leads us to seek out fermented foods, which supply probiotic bacteria and their fermentation products such as vitamin K2. If so, it is natural that strong sourness, indicating high bacterial populations, would be aversive.

But what of the sweet taste? Is it really a sensor for carbohydrates? If so it does a rather poor job. The healthiest carbohydrate source – starch, which is fructose-free – hardly activates this taste, while fructose, a toxin, activates it in spades. If this taste evolved to be a carbohydrate sensor, it should have made us aversive to the carbohydrates it detects, as the bitter taste makes us avoid toxins. But sweet tastes are attractive!

Sweetness activators

It turns out that the sweetness receptors are complex; many things activate them, and they appear to serve multiple functions.

Wikipedia (“Sweetness”) notes:

A great diversity of chemical compounds, such as aldehydes and ketones, are sweet.

Some of the amino acids are mildly sweet: alanine, glycine, and serine are the sweetest. Some other amino acids are perceived as both sweet and bitter.

The sweetness of some amino acids would seem to support Tomas’s assertions that sweetness detect meat: perhaps it is detecting amino acids. But this seems a bit odd: there is another taste, umami, that detects protein. Would we really need two taste receptors for protein? And lean meats don’t taste sweet.

A possible clue is that the sweet tasting amino acids are hydrophobic, while hydrophilic (or polar) amino acids are not sweet.

Proteins that are hydrophobic end up lodging in cell membranes alongside lipids; proteins that are hydrophilic dissolve in water and reside apart from the fat. Glutamate and nucleotides, which are detected by the umami taste, are hydrophilic and water-soluble.

So maybe the umami taste detects proteins that aren’t associated with fat, while the sweet taste detects proteins that are associated with fat.

Indeed, a leading theories of sweetness holds that compounds must be hydrophobic, or fat-associated, in order to invoke the sweetness taste:

B-X theory proposed by Lemont Kier in 1972. While previous researchers had noted that among some groups of compounds, there seemed to be a correlation between hydrophobicity and sweetness, this theory formalized these observations by proposing that to be sweet, a compound must have a third binding site (labeled X) that could interact with a hydrophobic site on the sweetness receptor via London dispersion forces. Wikipedia (“Sweetness”)

The sweet taste seems to work in collaboration with the bitter taste to regulate toxin avoidance. Wikipedia (“Sweetness”) again:

Sweetness appears to have the highest taste recognition threshold, being detectable at around 1 part in 200 of sucrose in solution. By comparison, bitterness appears to have the lowest detection threshold, at about 1 part in 2 million for quinine in solution.[4] In the natural settings that human primate ancestors evolved in, sweetness intensity should indicate energy density, while bitterness tends to indicate toxicity[5][6][7] The high sweetness detection threshold and low bitterness detection threshold would have predisposed our primate ancestors to seek out sweet-tasting (and energy-dense) foods and avoid bitter-tasting foods. Even amongst leaf-eating primates, there is a tendency to prefer immature leaves, which tend to be higher in protein and lower in fibre and poisons than mature leaves.[8]

This makes some sense: we need a certain number of calories per day, and since “the dose makes the poison,” what determines the toxicity of the diet as a whole is not the amount of toxins in a food, but the ratio of toxins to calories. In an evolutionary setting, our ancestors needed to eat foods with a low toxin-to-calorie ratio in order to minimize daily toxin intake.

So if sweetness is an “energy density” detector, it should be especially strongly activated by fatty foods. If it detects fat-associated compounds, then it would do so.

Why not detect fats directly? In natural foods, fats are bound in triglycerides or phospholipids which are chemically inert. So they won’t bond to taste receptors. Free fatty acids will, but these are not present in fresh foods and would probably indicate some kind of degradation of the food. In fact there seems to be a taste receptor for free fatty acids, CD36 [2], but this may be an aversive sensor for decayed food.

Interestingly, color also affects sweetness:

The color of food can affect sweetness perception. Adding more red color to a drink increases its sweetness with darker colored solutions being rated 2–10% higher than lighter ones even though it had 1% less sucrose concentration.[26] Wikipedia (“Sweetness”)

So red meats are sweetest. Richard Nikoley would approve.

Summary and A Puzzle

A plausible inference would be:

1.      The sweet taste evolved primarily to encourage the eating of fatty, energy-dense meats; and of essential fat-associated micronutrients such as choline and inositol.

2.      The sweetness of fruit may result from plants having evolved a way to hijack the sweetness receptors, and animal food preferences, for their own purposes.

This still leaves a few puzzles. Why, Seth asks, do we tend to neglect sweet tastes when we are hungry, but after dinner is done crave sweet desserts?

Here’s something to consider. Fats are a special macronutrient. We have unlimited storage space for fats, in our adipose tissue, but very limited storage space for other calories. Once we’re full, of course we should lose our appetite for calories we cannot store. But for fats, why not get a little extra in case food is scarce in days to come? There’s always room for a little more fat.

Implications for Binge Eaters

Correct me if I’m wrong, but when people go on an eating binge, they go for sweets.

Presumably, they have a craving for the sweet taste – which, evolutionarily, may be a craving for fatty meats and fat-associated micronutrients.

But if they’ve imbibed the anti-fat propaganda of recent decades and are afraid to eat fat, binge eaters must follow their taste buds to sugars – which unfortunately fail to satisfy any of the micronutrient deficiencies the sweet craving is designed to redress.

Perhaps, then, a good fatty steak, preferably accompanied by some liver and cream sauce, would be the best cure for binge eating. It would satisfy the craving, but also satisfy the underlying nutritional need that generated the craving.

Implications for Weight Loss

If, as I believe, the key to weight loss and curing obesity is eliminating appetite, then it’s important to eliminate any deficiencies of fat-associated micronutrients. Micronutrient deficiencies trigger food cravings, and deficiencies of fat-associated micronutrients will trigger a craving for sweets.

In the modern world, we know how a craving for sweets is likely to be satisfied – by eating sugary, nutrient-poor foods. Unfortunately these foods do not contain the fat-associated nutrients (such as choline) whose deficiency is probably driving the craving. So the craving persists unabated no matter how many sugars are eaten.

Persistent food cravings despite an excess of caloric intake is probably a necessary (though not sufficient) condition for obesity to develop. Unsatisfied cravings probably make weight loss extremely difficult.

What of Vitamin C?

Vitamin C – ascorbic acid – is an acid so it directly activates the sour taste.

So perhaps the sour taste evolved to help us get vitamin C. This would actually complement Seth’s idea that the sour taste encourages us to eat fermented foods. Fermented foods are high in vitamin C.

I had a fairly severe case of scurvy and don’t recall being attracted to sweet flavors. Instead, I was ravenously hungry. My appetite generally, not craving for any particular taste, was promoted. If anything, I was less attracted to sweet tastes. So I think it’s plausible that vitamin C deficiencies may lead to a general appetite upregulation, or to cravings for sour foods, rather than a craving for sweets.

Conclusion

Our evolved taste receptors can tell us a lot about what our bodies need. Food cravings are a pretty good sign of an unsatisfied nutrient deficiency.

But sometimes, it’s less than obvious what a craving signifies. Our modern food environment is so different from the Paleolithic: We have many industrially produced foods designed to fool our Paleolithic taste buds into eating nutritionally unsatisfying calories.

Humans evolved, not in the forests where fruit was available, but in open woodlands where tubers and other tasteless starch sources were abundant but fruit rare. In this context, our cravings for sweet foods may have been directing us to eat animal fats.

It may be that the cravings for sweets often experienced by binge eaters and the obese are really a craving for animal fats. If you feel drawn to sugar, perhaps you should ask yourself: Steak or salmon?

References

[1] Bachmanov AA, Beauchamp GK. Taste receptor genes. Annu Rev Nutr. 2007;27:389-414. http://pmid.us/17444812.

[2] Laugerette F et al. CD36 involvement in orosensory detection of dietary lipids, spontaneous fat preference, and digestive secretions. J Clin Invest. 2005 Nov;115(11):3177-84. http://pmid.us/16276419.

Iodine, the Thyroid, and Radiation Protection

Posted by on March 17, 2011 86 comments

We have friends in Japan, living both north and south of the damaged reactors, and Shou-Ching asked me to do a post about how to protect against radiation.

The Concern

The radioactive substances released by the Chernobyl nuclear power plant meltdown are represented in this chart:

(Source. If you’re wondering what the other radioactive elements are, or why radioactive iodine is a byproduct of uranium fission, a possible place to start is Wikipedia, “Fission products by element” ).

Note first of all that the chart presents percentages of radioactive substances, not amounts. The amounts are highest on the first day and then decline rapidly. The great danger comes in the first few days.

During these dangerous first days, iodine-131 is, along with tellurium-132 and its decay product iodine-132, the dominant source of radioactivity. These radioactive iodine species account for over 50% of the radiation.

Not only its abundance, but also its effectiveness at causing biological damage make iodine far and away the greatest danger. Iodine radiation is highly effective at causing cellular damage:

Due to its mode of beta decay, iodine-131 is notable for causing mutation and death in cells which it penetrates, and other cells up to several millimeters away. [Source: Wikipedia, Iodine-131]

Worse, iodine is an important biological molecule that gets concentrated in the thyroid. So the dose of radiation becomes very high in the thyroid, and this leads to DNA damage producing a high risk for thyroid cancer.

Thyroid cancer is “the only unequivocal radiological effect of the Chernobyl accident on human health.” [1] Since Chernobyl released a great deal more radiation than the Japanese reactor meltdowns are likely to do, it’s likely that this will be the case in Japan also.

The rate of thyroid cancer after Chernobyl was higher the younger the age at time of exposure. Children and infants are at greatest risk:

It is now well documented that children and adolescents exposed to radioiodines from Chernobyl fallout have a sizeable dose-related increase in thyroid cancer, with the risk greatest in those youngest at exposure and with a suggestion that deficiency in stable iodine may increase the risk. [2]

The last point is crucial – iodine deficiency increases the risk.

Iodine deficiency and radiation risk

In iodine deficiency, the thyroid gland has difficulty generating enough thyroid hormone. T4 thyroid hormone, manufactured in the thyroid and so named because it has 4 iodine atoms, is 65.4% iodine by weight, so iodine is the key ingredient in thyroid hormone.

To compensate for an iodine deficiency, the body does two things:

  • The thyroid gland grows, so that it can more aggressively scan the blood for iodine. An enlarged thyroid is called a goiter.
  • The pituitary gland issues thyroid stimulating hormone (TSH), which induces the thyroid to aggressively scavenge iodine from the blood and turn it into thyroid hormone.

So in iodine deficiency the thyroid is aggressively scavenging all available iodine. This means that when a large dose of iodine-131 or iodine-132 arrives during radiation fallout, these radioactive iodine atoms are quickly picked up by the thyroid. There, they release their radiation and damage the thyroid.

On the other hand, in thyroid replete persons, the thyroid has all the iodine it needs and takes up little iodine from the blood. In this case, iodine that enters the body is distributed throughout the body, or excreted. Doses in any single cell are much lower. The danger to the thyroid is not much greater than that to other organs – which, the Chernobyl experience tells us, is not detectable to epidemiology. (There is even a theory that low-level radiation may be beneficial through hormesis.)

How can the thyroid be made replete with iodine?

The best way, which we recommend in our book, is to supplement with iodine and gradually build up the dose over a four to six month period. Start below 1 mg/day, take that for a month, then double the dose. After a month, double the dose again. Continue doubling until you reach your desired maintenance dose; we recommend at least 3 mg/day (a quarter Iodoral tablet), with 12.5 mg/day a reasonable dose. Some people taking as much as 50 mg/day.

At 12.5 mg/day, it can take a year or more to become replete with iodine in all tissues and to fully drive out other halogens, such as bromine, from the body. This has great benefits for immune function. So, it is best to get started!

Risks of high-dose iodine supplementation

If a person’s thyroid gland is adapted for iodine scarcity and the person takes a large dose of (non-radioactive) iodine, the likely course of events is:

1.      Hyperthyroidism. The thyroid, aggressively scavenging for iodine to repair a deficiency of thyroid hormone, scoops up all the iodine and makes a large amount of thyroid hormone. The person develops symptoms of hyperthyroidism (too much thyroid hormone): anxiety, intolerance of heat, muscle aches, hyperactivity, irritability, hypoglycemia, elevated body temperature, palpitations, hair loss, difficulty sleeping.

2.      Wolff-Chaikoff effect. As thyroid hormone levels become too high, the body induces mechanisms for suppressing thyroid hormone production. Simply reducing TSH output is not effective to suppress thyroid hormone production if a very large iodine influx is received. Fortunately there is another mechanism for suppressing thyroid hormone formation, mediated by iodine itself: the formation of iodine-rich proteins (iodopeptides) in the thyroid that inhibt synthesis of the thyroid peroxidase (TPO) enzyme. Normally, this mechanism operates for a few days and wears off, restoring normal thyroid function. [3]

3.      Reactive hypothyroidism? Usually, everything will normally return to normal after a few days. But sometimes in previously iodine-deficient adults and more commonly in newborns and fetuses and some diseased persons, after very high doses of iodine the Wolff-Chaikoff effect can persist. In this case the early hyperthyroidism is followed by a period of hypothyroidism (too little thyroid hormone). This “hypothyroidism is transient and thyroid function returns to normal in 2 to 3 weeks after iodide withdrawal, but transient T4 replacement therapy may be required in some patients.” [3]

4.      Risk for lasting hypothyroidism. People who develop a reactive hypothyroidism following a large dose of iodine are at high risk for later development of persistent hypothyroidism. [3]

So most people will experience transient hyperthyroid symptoms for a few days and then do fine. Some will develop a reactive hypothyroidism lasting a few weeks and then be OK, save for an elevated risk of hypothyroidism later which may or may not be due to the reactive episode.

Advice of the authorities to fallout victims

The advice from public health authorities is a compromise between the protective effects of high-dose iodine and the risk of messing up the thyroid.

A US Center for Disease Control (CDC) fact sheet explains the recommendations. A single large dose of iodine offers protection for about 24 hours. Recommended intakes are:

  • Adults should take 130 mg/day while exposure persists.
  • Children older than 3 and smaller than adults should take 65 mg/day while exposure persists.
  • Infants and toddlers aged 1 month to 3 years should take 32 mg/day.
  • Newborns should take 16 mg/day.

Our advice

The CDC dosage advice strikes us as very reasonable.

If you are not currently exposed to fallout, but think you may be exposed in the near future, you should consider beginning with small doses of iodine now – say, 3 mg/day. If that does not produce any symptoms, then try 6 mg/day; if it does, back off to half that dose. This will begin the adaptation process for your thyroid gland and help minimize hyperthyroid or hypothyroid reactions if you do have to take high doses.

Also, obtain your iodine tablets in advance. If fallout does occur, it may be hard to find iodine pills. NukePills.com says they are out of stock and have a large order backlog. I saw a story the other day that a 14-dose packet of potassium iodide was being sold at one site for $200, up from the normal $10 list price.

We recommend Iodoral 12.5 mg tablets. This is a good size for supplemental use; to reduce it to a 3 mg dose, cut the tablet in quarters with a razor blade. If fallout arrives, you can use ten Iodoral tablets to get a 125 mg adult dose.

For doses below 3 mg, smaller iodine tablets or liquid iodine solutions may be best; you can dilute liquid solutions to your desired dose. Some brands were recommended by readers in comments on our Supplement Recommendations page.

Conclusion

Outside of Japan, the risk is minimal, and even in Japan those who are replete with iodine are unlikely to develop thyroid cancer from exposure. After Chernobyl, thyroid cancer rates were high in Russia, the Ukraine, and Belarus which did not distribute iodine, but low in Poland which did. Fortunately, Japan has one of the highest iodine intakes in the world thanks to its high seaweed consumption. With that preparation plus proactive distribution of iodine tablets, we can expect and hope that the health effects of the reactor meltdowns will be minimal.

References

[1] Thomas GA et al. Integrating Research on Thyroid Cancer after Chernobyl-The Chernobyl Tissue Bank. Clin Oncol (R Coll Radiol). 2011 Feb 22. [Epub ahead of print] http://pmid.us/21345659.

[2] Cardis E, Hatch M. The Chernobyl Accident-An Epidemiological Perspective. Clin Oncol (R Coll Radiol). 2011 Mar 9. [Epub ahead of print] http://pmid.us/21396807.

[3] Markou K et al. Iodine-Induced hypothyroidism. Thyroid. 2001 May;11(5):501-10. http://pmid.us/11396709.

Protein for Athletes

Posted by on March 15, 2011 103 comments

How much protein should athletes consume?

Bodybuilders have long known that consuming extra protein makes it easier to add muscle. Yet low protein dieting can enhance immunity against viruses and bacteria, and extends lifespan in animals.

The Perfect Health Diet, because we’re positive toward saturated fats and starches, will often lead to lower protein consumption than other Paleo diets that restrict fatty or starchy foods. So it’s natural that some athletes and bodybuilders have asked how to optimize protein intake.

Robert recently asked about this, but let’s look specifically at the case of Advocatus Avocado:

I believe my performance improved (albeit marginally–the differences aren’t large) when I allowed my protein/carb/fat ratios to remain consistent despite my high caloric intake, which is ~3,600 calories/day. In other words, I had a sense of better performance when I lowered my fat% to around 65 and allowed around 200g/day of protein (I work out 2-3x a week for an hour).

At 3,600 calories per day, 65% fat is 2340 calories; 200 g protein is 800 calories; that leaves 460 calories carbs. How do these compare with Perfect Health Diet recommendations for athletes?

Nitrogen Balance, Exhaustion of Benefits, and Toxicity

There are a few magic numbers for protein intake that we want to be aware of:

  • Nitrogen balance. Nitrogen comes into the body in dietary protein and leaves the body in urine as ammonia, urea, and uric acid after proteins are metabolized. So when a person is in nitrogen balance, the amount of dietary protein matches the amount of metabolized protein, and the protein content of the body is unchanged. Very likely, the muscle content is unchanged too.
  • Exhaustion of benefits. We want to find the “plateau region” for nutrients. Athletes want to know: at what level of protein intake does protein no longer help build muscle?
  • Toxicity. At what level of protein intake does protein begin to damage health?

Luckily Ned Kock of the superb Health Correlator blog has done much of the work for us in his post “How much protein does one need to be in nitrogen balance?.”

He presents this chart, from a book on Exercise Physiology [1]:

There’s a great deal of variability across persons. Some people are in nitrogen balance at protein intake of 0.9 g/kg/day; others need as much as 1.5 g/kg/day. At 1.2 g/kg/day, half the sample was in nitrogen balance.

Various factors influence the interpretation of this data:

  • The sample was of endurance athletes. Endurance exercise increases protein needs, so most people would reach nitrogen balance at lower protein intakes. Resistance exercise doesn’t require as much protein: Experienced bodybuilders are typically in nitrogen balance at 1.2 g/kg/day. [2]
  • Most of the sample probably ate a high-carb diet. Glucose needs were met from dietary carbohydrates. Low-carb dieters would need additional protein for glucose manufacture.
  • As Ned states, in caloric deficit, protein needs are increased; in caloric surplus, protein needs are decreased. If you’re restricting calories for weight loss, expect to need a bit more protein to avoid muscle loss.
  • Supplementing leucine “increased protein synthesis and decreased protein breakdown” [2], thus leading to nitrogen balance at lower protein intakes.
  • The point of nitrogen balance is dynamic: if everyone in the sample ate 0.9 g/kg/day, then they’d eventually get into nitrogen balance at 0.9 g/kg/day. The body adjusts to conserve muscle at given food availability.

The average person needs much less protein to be in nitrogen balance. The US RDA for protein, 0.8 g/kg/day, was set so that 97.5% of Americans would be in nitrogen balance. [2] But just to be conservative, and because we’re developing advice for athletes, let’s consider 1.5 g/kg/day as the protein intake that brings our athletes into nitrogen balance.

What about the protein intake that exhausts benefits?  At what intake is muscle synthesis no longer promoted?

Ned, citing a review paper [2], offers the following answer: “[P]rotein intake beyond 25 percent of what is necessary to achieve a nitrogen balance of zero would have no effect on muscle gain.”

On my reading it’s not so easy to infer a clear answer, but let’s go with this. If so, then muscle gains would be exhausted at 1.25*1.5 = 1.875 g/kg/day even for the most strenuous athletes.

What about toxicity?

We deal with this in our book (p 25). At a protein intake of 230 g/day (920 calories), the body’s ability to convert ammonia to urea is saturated. [3] This means the nitrogen from every additional gram of protein lingers in the body as ammonia, a toxin.

Clearly marginal dietary protein is toxic, via ammonia poisoning, at this intake level. A reasonable estimate for where toxicity begins is between 150 to 200 g/day.

Putting it together: A prescription for athletes

Let’s say our athlete is an 80 kg man. Then maximum muscle gain will be achieved at a protein intake of 1.875*80 = 150 g/day. Toxicity will begin somewhere between 150 to 200 g/day. So the “plateau region” where all the benefits, and none of the toxicity, are achieved is between 150 g/day and some protein intake not much above 150 g/day.

The plateau region is quite narrow! What this tells us is that athletes should consume about 150 g/day protein.

This assumes a high-carb diet, so that no protein is needed for gluconeogenesis. The body utilizes about 600 calories/day of glucose, plus another 100 calories per hour of intense training.

With carb intakes below 600 calories/day, additional dietary protein would be needed, because protein would be consumed nearly 1-for-1 with the missing carbs.

So we can summarize these results as follows:

  • On a high-carb diet (>600 calories/day), 600 protein calories/day maximizes muscle gain.
  • On a low-carb diet (<600 calories/day), 1200 carb+protein calories/day maximizes muscle gain.

Looking back at Advocatus Avocado’s personal experience, he eats a low-carb diet with 460 carb calories per day. We predict therefore that he would need 740 protein calories a day to maximize his muscle gain (plus up to another 100 calories per hour of training, to replace lost glycogen).

Advocatus says he needs 800 protein calories/day to maximize muscle gain. Close enough for blog work!

At these protein intake levels, Advocatus is probably experiencing mild ammonia toxicity. He might slightly improve his health by eating a few more carbs, and cutting his protein intake a bit.

He might also find that leucine supplementation would reduce his protein needs a bit.

Overall, however, I think his experiences are consistent with our framework for understanding nutritional needs. Those who are content with maintaining an ordinary person’s muscle mass can get by with relatively low protein intakes of 0.8 g/kg/day or less. But muscle-building athletes need high protein intakes, around 1.9 g/kg/day, to maximize the rate of muscle gain. If they eat low-carb, they may need even more protein. Such high protein intakes are likely to exceed the threshold of toxicity.

References

[1] Brooks, G.A., Fahey, T.D., & Baldwin, K.M. (2005). Exercise physiology: Human bioenergetics and its applications. Boston, MA: McGraw-Hill.

[2] Wilson, J., & Wilson, G.J. (2006). Contemporary issues in protein requirements and consumption for resistance trained athletes. Journal of the International Society of Sports Nutrition, 3(1), 7-27.

[3] Rudman D et al. Maximal rates of excretion and synthesis of urea in normal and cirrhotic subjects. J Clin Invest. 1973 Sep;52(9):2241-9. http://pmid.us/4727456.