Nuts by numbers: Should you eat them, and how much?

Nuts are generally seen as good sources of protein and magnesium. The latter plays a number of roles in the human body, and is considered critical for bone health. Nuts are also believed to be good sources of vitamin E. While there is a lot of debate about vitamin E’s role in health, it is considered by many to be a powerful antioxidant. Other than in nuts, vitamin E is not easily found in foods other than seeds and seed oils.

Some of the foods that we call nuts are actually seeds; others are legumes. For simplification, in this post I am calling nuts those foods that are generally protected by shells (some harder than others). This protective layer is what makes most people call them nuts.

Let us see how different nuts stack up against each other in terms of key nutrients. The quantities listed below are per 1 oz (28 g), and are based on data from Nutritiondata.com. All are raw. Roasting tends to reduce the vitamin content of nuts, often by half, and has little effect on the mineral content. Protein and fat content are also reduced, but not as much as the vitamin content.

These two figures show the protein, fat, and carbohydrate content of nuts (on the left); and the omega-6 and omega-3 fat content (on the right).

When we talk about nuts, walnuts are frequently presented in a very positive light. The reason normally given is that walnuts have a high omega-3 content; the plant form of omega-3, alpha-linolenic acid (ALA). That is true. But look at the large amount of omega-6 in walnuts. The difference between the omega-6 and omega-3 content in walnuts is about 8 g! And this is in only 1 oz of walnuts. That is 8 g of possibly pro-inflammatory omega-6 fats to be “neutralized”. It would take many fish oil softgels to achieve that.

Walnuts should be eaten in moderation. Most studies looking at the health effects of nuts, including walnuts, show positive results in short-term interventions. But they usually involve moderate consumption, often of 1 oz per day. Eat several ounces of walnuts every day, and you are entering industrial see oil territory in terms of omega-6 fats consumption. Maybe other nutrients in walnuts have protective effects, but still, this looks like dangerous territory; “diseases of civilization” territory.

A side note. Focusing too much on the omega-6 to omega-3 ratio of individual foods can be quite misleading. The reason is that a food with a very small amount of omega-6 (e.g., 50 mg) but close to zero omega-3 will have a very high ratio. (Any number divided by zero yields infinity.) Yet, that food will contribute little omega-6 to a person’s diet. It is the ratio at the end of the day that matters, when all foods that have been eaten are considered.

The figures below show the magnesium content of nuts (on the left); and the vitamin E content (on the right).

Let us say that you are looking for the best combination of protein, magnesium, and vitamin E. And you also want to limit your intake of omega-6 fats, which is a very wise thing to do. Then what is the best choice? It looks like it is almonds. And even they should be eaten in small amounts, as 1 oz has more than 3 g of omega-6 fats.

Macadamia nuts don’t have much omega-6; their fats are mostly monounsaturated, which are very good. Their protein to fat ratio is very low, and they don’t have much magnesium or vitamin E. Coconuts (i.e., their meat) have mostly medium-chain saturated fats, which are also very good. Coconuts have little protein, magnesium, and vitamin E. If you want to increase your intake of healthy fats, both macadamia nuts and coconuts are good choices, with macadamia nuts providing about 3 times more fat.

There are many other dietary sources of magnesium around. In fact, magnesium is found in many foods. Examples are, in approximate descending order of content: salmon, spinach, sardine, cod, halibut, banana, white potato, sweet potato, beef, chicken, pork, liver, and cabbage. This is by no means a comprehensive list.

As for vitamin E, it likes to hide in seeds. While it may be a powerful antioxidant, I wonder whether Mother Nature really had it “in mind” as she tinkered with our DNA for the last few million years.

Potato Diet Interpretation

If you read my post on December 16th, you know that Chris Voigt saw remarkable fat loss and improvements in health markers as a result of two months of eating almost nothing but potatoes. This has left many people scratching their heads, because potatoes are not generally viewed as a healthy food. This is partially due to the fact that potatoes are very rich in carbohydrate, which also happens to be a quickly digested type, resulting in a high glycemic index. The glycemic index refers to the degree to which a particular food increases blood glucose when it's eaten, and I've questioned the relevance of this concept to health outcomes in the past (1, 2, 3). I think Mr. Voigt's results once again argue against the importance of the glycemic index as a diet-health concept.

It's often pointed out that potatoes are low in vitamins and minerals compared to vegetables on a per-calorie basis, but I think it's a misleading comparison because potatoes are much more calorie-dense than most vegetables. Potatoes compare favorably to other starchy staples such as bread, rice and taro.

Over the course of two months, Mr. Voigt lost 21 pounds. No one knows exactly how much of that weight came out of fat and how much out of lean mass, but the fact that he reported a decrease in waist and neck circumference indicates that most of it probably came out of fat. Previous long-term potato feeding experiments have indicated that it's possible to maintain an athletic muscle mass on the amount of protein in whole potatoes alone (4). So yes, Mr. Voigt lost fat on a very high-carbohydrate diet (75-80% carbohydrate, up to 440g per day).

On to the most interesting question: why did he lose fat? Losing fat requires that energy leaving the body exceed energy entering the body. But of course, that's obvious but it doesn't get us anywhere. In the first three weeks of his diet, Mr. Voigt estimates that he was only eating 1,600 calories per day. Aha! That's why he lost weight! Well, yes. But let's look into this more deeply. Mr. Voigt was not deliberately restricting his calorie intake at all, and he did not intend this as a weight loss diet. In my interview, I asked him if he was hungry during the diet. He said that he was not hungry, and that he ate to appetite during this period, realizing only after three weeks that he was not eating nearly enough calories to maintain his weight*. I also asked him how his energy level was, and he said repeatedly that it was very good, perhaps even better than usual. Those were not idle questions.

Calorie restriction causes a predictable physiological response in humans that includes hunger and decreased energy. It's the starvation response, and it's powerful in both lean and overweight people, as anyone knows who has tried to lose fat by decreasing calorie intake alone. The fact that he didn't experience hunger or fatigue implies that his body did not think it was starving. Why would that be?

I believe Mr. Voigt's diet lowered his fat mass 'setpoint'. In other words, for whatever reason, the diet made his body 'want' to be leaner that it already was. His body began releasing stored fat that it considered excess, and therefore he had to eat less food to complete his energy needs. You see this same phenomenon very clearly in rodent feeding studies. Changes in diet composition/quality can cause dramatic shifts in the fat mass setpoint (5, 6). Mr. Voigt's appetite would eventually have returned to normal once he had stabilized at a lower body fat mass, just as rodents do.

Rodent studies have made it clear that diet composition has a massive effect on the level of fat mass that the body will 'defend' against changes in calorie intake (5, 6). Human studies have shown similar effects from changes in diet composition/quality. For example, in controlled diet trials, low-carbohydrate dieters spontaneously reduce their calorie intake quite significantly and lose body fat, without being asked to restrict calories (7). In Dr. Staffan Lindeberg's Paleolithic diet trials, participants lost a remarkable amount of fat, yet a recent publication from his group shows that the satiety (fullness) level of the Paleolithic group was not different from a non-Paleolithic comparison group despite a considerably lower calorie intake over 12 weeks (8, 9). I'll discuss this important new paper soon. Together, this suggests that diet composition/quality can have a dominant impact on the fat mass setpoint.

One possibility is that cutting the wheat, sugar, most vegetable oil and other processed food out of Mr. Voigt's diet was responsible for the fat loss.  Many people find, for example, that they lose fat simply by eliminating wheat from their diet.

Another possibility that I've been exploring recently is that changes in palatability (pleasantness of flavor) influence the fat mass setpoint. There is evidence in rodents that it does, although it's not entirely consistent. For example, rats will become massively obese if you provide them with chocolate flavored Ensure (a meal replacement drink), but not with vanilla or strawberry Ensure (10). They will defend their elevated fat mass against calorie restriction (i.e. they show a physiological starvation response when you try to bring them down to a lower weight by feeding them less chocolate Ensure) while they're eating chocolate Ensure, but as soon as you put them back on unpurified rodent pellets, they will lose fat and defend the lower fat mass. Giving them food in liquid or paste form often causes obesity, while the same food in solid pellet form will not. Eating nothing but potatoes is obviously a diet with a low overall palatability.

So I think that both a change in diet composition/quality and a decrease in palatability probably contributed to a decrease in Mr. Voigt's fat mass setpoint, which allowed him to lose fat mass without triggering a starvation response (hunger, fatigue).

The rest of his improvements in health markers were partially due to the fat loss, including his decreased fasting glucose, decreased triglycerides, and presumably increased insulin sensitivity. They may also have been partially due to a lack of industrial food and increased intake of certain micronutrients such as magnesium.

One of the most striking changes was in his calculated LDL cholesterol ("bad" cholesterol), which decreased by 41%, putting him in a range that's more typical of healthy non-industrial cultures including hunter-gatherers. Yet hunter-gatherers didn't eat nothing but potatoes, often didn't eat much starch, and in some cases had a high intake of fat and saturated fat, so what gives? It's possible that a reduced saturated fat intake had an impact on his LDL, given the relatively short timescale of the diet. But I think there's something mysterious about this setpoint mechanism that has a much broader impact on metabolism than is generally appreciated. For example, calorie restriction in humans has a massive impact on LDL, much larger than the impact of saturated fat (11). And in any case, the latter appears to be a short-term phenomenon (12). It's just beginning to be appreciated that energy balance control systems in the brain influence cholesterol metabolism.

Mr. Voigt's digestion appeared to be just fine on his potato diet, even though he generally ate the skins. This makes me even more skeptical of the idea that potato glycoalkaloids in common potato varieties are a health concern, especially if you were to eliminate most of the glycoalkaloids by peeling.

I asked Mr. Voigt about what foods he was craving during the diet to get an idea of whether he was experiencing any major deficiencies. The fact that Mr. Voigt did not mention craving meat or other high-protein foods reinforces the fact that potatoes are a reasonable source of complete protein. The only thing he craved was crunchy/juicy food, which I'm not sure how to interpret.

He also stopped snoring during the diet, and began again immediately upon resuming his normal diet, perhaps indicating that his potato diet reduced airway inflammation. This could be due to avoiding food allergies and irritants (wheat anyone?) and also fat loss.

Overall, a very informative experiment! Enjoy your potatoes.


*Until the last 5.5 weeks, when he deliberately stuffed himself beyond his appetite because his rapid weight loss worried him. Yet, even with deliberate overfeeding up to his estimated calorie requirement of 2,200 calories per day, he continued to lose weight. He probably was not quite reaching his calorie goal, or his requirement is higher than he thought.

Trouble With RSS Feed?

I've received several comments that my blog posts are no longer showing up in peoples' RSS feeds. I've gone into my settings, and the blog is still set to full feed mode, so I don't know why that would be. I'm trying to understand if the problem is widespread or only affects a few people. Please let me know in the comments section if new posts (since the potatoes and human health series) are not showing up in your reader. Also, please let me know if new posts are showing up. Thanks!

Interview with Chris Voigt of 20 Potatoes a Day

Introduction

Chris Voigt is the executive director of the Washington State Potato Commission, which supports and promotes the Washington state potato industry (1). On October 1st, Mr. Voigt began a two month, potato-only diet to raise awareness about the health properties of potatoes. It was partially in response to the recent decision by the federal WIC (Women, Infants and Children) low-income assistance program to remove potatoes from the list of vegetables it will pay for. Mr. Voigt's potato diet has been a media sensation, leading to widespread coverage in several countries. He maintains a website and blog called 20 Potatoes a Day.


Diet Facts

For 60 days, Mr Voigt's diet consisted of nothing but potatoes and a small amount of cooking oil (canola and olive), with no added nutritional supplements. Based on what he has told me, I estimate that 10-15% of his calories came from fat, 10% from protein and 75-80% from high-glycemic carbohydrate. His calorie intake ranged from 1,600 kcal (first 3 weeks) to 2,200 kcal (remaining 5.5 weeks) per day. Prior to the diet, he estimated that his calorie requirement was 2,200 kcal, so he attempted to stay as close to that as possible.

Health Markers

Mr. Voigt has posted the results of physical examinations, including bloodwork, from the beginning, middle and end of the diet. The change he experienced during that time is nothing short of remarkable. He shed 21 pounds, his fasting glucose decreased by 10 mg/dL (104 to 94 mg/dL), his serum triglycerides dropped by nearly 50%, his HDL cholesterol increased slightly, and his calculated LDL cholesterol dropped by a stunning 41% (142 to 84 mg/dL). The changes in his HDL, triglycerides and fasting glucose are consistent with improved insulin sensitivity (2, 3), and are not consistent with a shift of LDL particle size to the dangerous "small, dense" variety (4).

Interview

What was your diet like prior to the potato diet?

My best estimate is that it was probably a little better than the average US citizen only because of a high rate of produce consumption. I generally would eat about 10 servings of fruits and vegetables a day. But I ate everything else too. I would eat a wide range of food, a little bit of everything, including foods that aren’t considered “healthy”.

You essentially ate nothing but potatoes, fat and flavorings for two months. Can you give us an idea of how much fat you were eating? What kind of fat was it?

I averaged about 2 tablespoons of cooking oil a day over the span of the 60 days. Canola oil was used for frying and olive oil was used for roasting.

How was your digestion?

Potatoes are pretty easy on the digestive system. I actually got a lot of emails from people who suffer from severe digestive disorders and literally, potatoes are the only thing they can eat. My 60 days of potatoes was nothing compared to some folks with these digestive disorders. I was getting a lot of fiber so things were pretty regular, but not too regular :)

You lost 21 pounds during your two months of eating only potatoes. Do you have a sense of whether it came out of fat, muscle or both? For example, did your pants become looser?

Pants definitely became looser. I also noticed it in my neck size for shirts. I’m assuming most all of it was due to fat loss.

Do you think you were able to meet your calorie goal of 2,200 calories per day? Were you hungry during the diet?

I was not meeting the goal of 2,200 calories a day during the first 3 weeks of the diet. During the first three weeks of the diet I only ate until I was full. I didn’t realize that potatoes would give me such a high sense of fullness after each meal. So for those first 3 weeks, I was only consuming about 1,600 calories a day. After the third week I had lost 12 pounds and realized that I needed to change strategy. I then began to eat more potatoes despite the sense of fullness I was experiencing. So for the remaining 5 ½ weeks I was very diligent about eating the 2,200 calories. I continued to lose weight but at a slower place. I lost an additional 9 pounds over the course of those remaining 5 1/2 weeks. At the start of my diet I estimated, via a couple different on line calorie calculators, that I burn about 2,200 calories a day. Since I continued to lose weight, I’m assuming I actually burn closer to 2,800 calories a day. Something that may have also played a role in continued weight loss was the amount of resistant starch I was getting from potatoes. I ate a lot of cooked potatoes that had been refrigerated. These are generally higher in resistant starch. If I were to do the diet again, I would like to set up an experiment to gauge the effect of resistant starch.

What foods did you crave the most?

I craved mostly foods that had a “juicy crunch”, like an apple, or cucumbers, or carrots, or celery. I never acquired a taste for raw potatoes so virtually all the potatoes I consumed were cooked. No matter how you cook your potatoes, you always get that same soft cooked texture. I craved foods with a crisper texture.

How was your energy level?

My energy level was very good the entire time of the diet. I really didn’t notice a change in energy at the start of the diet so I assumed that the potato diet didn’t have a positive or negative effect on my energy level. It wasn’t until I finished the diet and started to consume other foods that I noticed my energy level has seemed to drop a bit.

How did you feel overall? Were there any unexpected effects of the diet?

I felt really good on the diet. I had lots of energy, slept good at night, and seemed to avoid the cold viruses that circulated at home and work.

The only unusual thing that occurred is what my wife told me. I’m a habitual snorer. The day I started eating only potatoes, my snoring stopped. It restarted the day I started to include other foods in my diet. I’m assuming it was just some weird coincidence but that’s what she tells me.

My doctor and I expected my cholesterol to drop but not at the level we saw. I’ve had borderline high cholesterol for the past decade. I started the diet at 214 and saw it drop to 147 at the end of 60 days. We anticipated a drop of maybe 10-25 points. It was a huge surprise to see a 67 point drop.

Your fasting glucose went from 104 mg/dL, which I consider high, to 94 mg/dL, which is on the high side for someone eating a high-carbohydrate diet, but within the clinically normal range. Do you have a family history of diabetes?

No history of diabetes. My parents are in their early eighties and their parents lived to their 70’s and 80’s with no history of type one or two diabetes.

Reading your blog posts, it seemed like you were having a hard time with the diet at first, but after a while you complained less and even seemed to enjoy it at times. Did you get used to it?

I would say that week 2 and 3 were probably the hardest. The first week was easy probably because of the novelty of the diet. Then reality set in for week 2 and 3. After that, I found my groove and it got easier. During the work week was easy but weekends, particularly Sunday’s, were the hardest. During the work week I did most of my eating at my desk so I wasn’t around a lot of other people eating or surrounded by other foods. Weekends were more difficult because I was around other people every meal and always had other foods in front of me at home.

What kinds of potatoes did you eat?

I literally ate every kind of potato I could get my hands on. I ate yellow skin/yellow flesh potatoes, red skin/white flesh, red skin/red flesh, purple skin/white flesh, purple skin/purple flesh, russet potatoes with white flesh, russet potatoes with yellow flesh, white potatoes, yellow potatoes with white flesh, purple fingerlings, yellow fingerlings, red fingerlings and numerous experimental varieties.

Did you peel them or eat the skin?

I ate the skin at least 90% of the time if not more. There is a myth that all the nutrition in a potato is in the skin or right under the skin. That’s not true, there are nutrients spread throughout the potato but most of the fiber is located in the skin.

What variety of potato is your favorite?

It really depended on the cooking method. For frying, I preferred russet potatoes. For baking, I preferred red potatoes. For mashed, I preferred yellow potatoes. For roasting, a toss-up between russets and reds.

How long did it take you after the diet ended to eat another potato?

As strange as it sounds, potatoes were my first two meals after my diet ended. I was saving my first non-potato meal for a special event that was planned at the local Head Start facility. The beef, dairy, apple, and potato producers put together a nice dinner event and nutrition workshop for all the kids and their parents at the Head Start center in Moses Lake. I still eat potatoes pretty regularly, but most of the time now I’m eating them with more than just seasonings.

Are there any other facts about potatoes you think Whole Health Source readers might find interesting?

Just a reminder that I’m not encouraging anyone to follow in my footsteps and eat just potatoes. This diet is not intended to be the next “fad” diet but was simply a bold statement to remind people that there is a tremendous amount of nutrition in a potato. There is no one food product that can meet all of your nutritional needs. I fully support a well balanced healthy diet, which potatoes can be a part of.

In 2008, the United Nations declared it to be the “Year of the Potato”. This was done to bring attention to the fact that the potato is one of the most efficient crops for developing nations to grow, as a way of delivery a high level of nutrition to growing populations, with fewer needed resources than other traditional crops. In the summer of 2010, China approved new government policies that positioned the potato as the key crop to feed its growing population. The Chinese government formed a partnership with the International Potato Center in Peru to help them facilitate this new emphasis on the potato.

Thanks Chris, for doing your experiment and taking the time to share these details with us!

In the next post, I'll give my interpretation of all this.

Maknig to mayn tipos? Myabe ur teh boz

Undoubtedly one of the big differences between life today and in our Paleolithic past is the level of stress that modern humans face on a daily basis. Much stress happens at work, which is very different from what our Paleolithic ancestors would call work. Modern office work, in particular, would probably be seen as a form of slavery by our Paleolithic ancestors.

Some recent research suggests that organizational power distance is a big factor in work-related stress. Power distance is essentially the degree to which bosses and subordinates accept wide differences in organizational power between them (Hofstede, 2001).

(Source: talentedapps.wordpress.com)

I have been studying the topic of information overload for a while. It is a fascinating topic. People who experience it have the impression that they have more information to process than they can handle. They also experience significant stress as a result of it, and both the quality of their work and their productivity goes down.

Recently some colleagues and I conducted a study that included employees from companies in New Zealand, Spain, and the USA (Kock, Del Aguila-Obra & Padilla-Meléndez, 2009). These are countries whose organizations typically display significant differences in power distance. We found something unexpected. Information overload was much more strongly associated with power distance than with the actual amount of information employees had to process on a daily basis.

While looking for explanations to this paradoxical finding, I recalled an interview I gave way back in 2001 to the Philadelphia Inquirer, commenting on research by Dr. David A. Owens. His research uncovered an interesting phenomenon. The higher up in the organizational pecking order one was, the less the person was concerned about typos on emails to subordinates.

There is also some cool research by Carlson & Davis (1998) suggesting that bosses tend to pick the communication media that are the most convenient for them, and don’t care much about convenience for the subordinates. One example would be calling a subordinate on the phone to assign a task, and then demanding a detailed follow-up report by email.

As a side note, writing a reasonably sized email takes a lot longer than conveying the same ideas over the phone or face-to-face (Kock, 2005). To be more precise, it takes about 10 times longer when the word count is over 250 and the ideas being conveyed are somewhat complex. For very short messages, a written medium like email is fairly convenient, and the amount of time to convey ideas may be even shorter than by using the phone or doing it face-to-face.

So a picture started to emerge. Bosses choose the communication media that are convenient for them when dealing with subordinates. If the media are written, they don’t care about typos at all. The subordinates use the media that are imposed on them, and if the media are written they certainly don’t want something with typos coming from them to reach their bosses. It would make them look bad.

The final result is this. Subordinates experience significant information overload, particularly in high power distance organizations. They also experience significant stress. Work quality and productivity goes down, and they get even more stressed. They get fat, or sickly thin. Their health deteriorates. Eventually they get fired, which doesn’t help a bit.

What should you do, if you are not the boss? Here are some suggestions:

- Try to tactfully avoid letting communication media being imposed on you all the time by your boss (and others). Explicitly state, in a polite way, the media that would be most convenient for you in various circusmtances, both as a receiver and sender. Generally, media that support oral speech are better for discussing complex ideas. Written media are better for short exchanges. Want an evolutionary reason for that? As you wish: Kock (2004).

- Discuss the ideas in this post with your boss; assuming that the person cares. Perhaps there is something that can be done to reduce power distance, for example. Making the work environment more democratic seems to help in some cases.

- And ... dot’n wrory soo mach aobut tipos ... which could be extrapolated to: don’t sweat the small stuff. Most bosses really care about results, and will gladly take an email with some typos telling them that a new customer signed a contract. They will not be as happy with an email telling them the opposite, no matter how well written it is.

Otherwise, your organizational demise may come sooner than you think.

References

Carlson, P.J., & Davis, G.B. (1998). An investigation of media selection among directors and managers: From "self" to "other" orientation. MIS Quarterly, 22(3), 335-362.

Hofstede, G. (2001). Culture’s consequences: Comparing values, behaviors, institutions, and organizations across nations. Thousand Oaks, CA: Sage.

Kock, N. (2004). The psychobiological model: Towards a new theory of computer-mediated communication based on Darwinian evolution. Organization Science, 15(3), 327-348.

Kock, N. (2005). Business process improvement through e-collaboration: Knowledge sharing through the use of virtual groups. Hershey, PA: Idea Group Publishing.

Kock, N., Del Aguila-Obra, A.R., & Padilla-Meléndez, A. (2009). The information overload paradox: A structural equation modeling analysis of data from New Zealand, Spain and the U.S.A. Journal of Global Information Management, 17(3), 1-17.

What is a reasonable vitamin D level?

The figure and table below are from Vieth (1999); one of the most widely cited articles on vitamin D. The figure shows the gradual increase in blood concentrations of 25-Hydroxyvitamin, or 25(OH)D, following the start of daily vitamin D3 supplementation of 10,000 IU/day. The table shows the average levels for people living and/or working in sun-rich environments; vitamin D3 is produced by the skin based on sun exposure.

25(OH)D is also referred to as calcidiol. It is a pre-hormone that is produced by the liver based on vitamin D3. To convert from nmol/L to ng/mL, divide by 2.496. The figure suggests that levels start to plateau at around 1 month after the beginning of supplementation, reaching a point of saturation after 2-3 months. Without supplementation or sunlight exposure, levels should go down at a comparable rate. The maximum average level shown on the table is 163 nmol/L (65 ng/mL), and refers to a sample of lifeguards.

From the figure we can infer that people on average will plateau at approximately 130 nmol/L, after months of 10,000 IU/d supplementation. That is 52 ng/mL. Assuming a normal distribution with a standard deviation of about 20 percent of the range of average levels, we can expect about 68 percent of those taking that level of supplementation to be in the 42 to 63 ng/mL range.

This might be the range most of us should expect to be in at an intake of 10,000 IU/d. This is the equivalent to the body’s own natural production through sun exposure.

Approximately 32 percent of the population can be expected to be outside this range. A person who is two standard deviations (SDs) above the mean (i.e., average) would be at around 73 ng/mL. Three SDs above the mean would be 83 ng/mL. Two SDs below the mean would be 31 ng/mL.

There are other factors that may affect levels. For example, being overweight tends to reduce them. Excess cortisol production, from stress, may also reduce them.

Supplementing beyond 10,000 IU/d to reach levels much higher than those in the range of 42 to 63 ng/mL may not be optimal. Interestingly, one cannot overdose through sun exposure, and the idea that people do not produce vitamin D3 after 40 years of age is a myth.

One would be taking in about 14,000 IU/d of vitamin D3 by combining sun exposure with a supplemental dose of 4,000 IU/d. Clear signs of toxicity may not occur until one reaches 50,000 IU/d. Still, one may develop other complications, such as kidney stones, at levels significantly above 10,000 IU/d.

See this post by Chris Masterjohn, which makes a different argument, but with somewhat similar conclusions. Chris points out that there is a point of saturation above which the liver is unable to properly hydroxylate vitamin D3 to produce 25(OH)D.

How likely it is that a person will develop complications like kidney stones at levels above 10,000 IU/d, and what the danger threshold level could be, are hard to guess. Kidney stone incidence is a sensitive measure of possible problems; but it is, by itself, an unreliable measure. The reason is that it is caused by factors that are correlated with high levels of vitamin D, where those levels may not be the problem.

There is some evidence that kidney stones are associated with living in sunny regions. This is not, in my view, due to high levels of vitamin D3 production from sunlight. Kidney stones are also associated with chronic dehydration, and populations living in sunny regions may be at a higher than average risk of chronic dehydration. This is particularly true for sunny regions that are also very hot and/or dry.

Reference

Vieth, R. (1999). Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. American Journal of Clinical Nutrition, 69(5), 842-856.

Dr. Mellanby's Tooth Decay Reversal Diet

I have a lot of admiration for Drs. Edward and May Mellanby. A husband-and-wife team, they discovered vitamin D, and determined that rickets is caused by poor calcium (or phosphorus) status, typically due to vitamin D deficiency. They believed that an ideal diet is omnivorous, based on whole foods, and offers an adequate supply of fat-soluble vitamins and easily absorbed minerals. They also felt that grain intake should be modest, as their research showed that unsoaked whole grains antagonize the effect of vitamins D and A.

Not only did the Mellanbys discover vitamin D and end the rickets epidemic that was devastating Western cities at the time, they also discovered a cure for early-stage tooth decay that has been gathering dust in medical libraries throughout the world since 1924.

It was in that year that Dr. May Mellanby published a summary of the results of the Mellanby tooth decay reversal studies in the British Medical Journal, titled "Remarks on the Influence of a Cereal-free Diet Rich in Vitamin D and Calcium on Dental Caries in Children". Last year, I had to specially request this article from the basement of the University of Washington medical library (1). Thanks to the magic of the internet, the full version of the paper is now freely available online (2).

You don't need my help to read the study, but in this post I offer a little background, a summary and my interpretation.

In previous studies, the Mellanbys used dogs to define the dietary factors that influence tooth development and repair. They identified three, which together made the difference between excellent and poor dental health (from Nutrition and Disease):

1. The diet's mineral content, particularly calcium and phosphorus
2. The diet's fat-soluble vitamin content, chiefly vitamin D
3. The diet's content of inhibitors of mineral absorption, primarily phytic acid

Once they had defined these factors, they set about testing their hypotheses in humans. They performed eight trials, each one in children in an institutionalized setting where diet could be completely controlled. The number of cavities in each child's mouth was noted at the beginning and end of the period. I'll only discuss the three most informative, and only the most successful in detail. First, the results:

I'll start with diet 1. Children on this diet ate the typical fare, plus extra oatmeal. Oatmeal is typically eaten as an unsoaked whole grain (and soaking it isn't very effective in any case), and so it is high in phytic acid, which effectively inhibits the absorption of a number of minerals including calcium. These children formed 5.8 cavities each and healed virtually none-- not good!

Diet number 2 was similar to diet 1, except there was no extra oatmeal and the children received a large supplemental dose of vitamin D. Over 28 weeks, only 1 cavity per child developed or worsened, while 3.9 healed. Thus, simply adding vitamin D to a reasonable diet allowed most of their cavities to heal.

Diet number 3 was the most effective. This was a grain-free diet plus supplemental vitamin D. Over 26 weeks, children in this group saw an average of only 0.4 cavities form or worsen, while 4.7 healed. The Mellanbys considered that they had essentially found a cure for this disorder in its early stages.

What exactly was this diet? Here's how it was described in the paper (note: cereals = grains):

...instead of cereals- for example, bread, oatmeal, rice, and tapioca- an increased allowance of potatoes and other vegetables, milk, fat, meat, and eggs was given. The total sugar, jam, and syrup intake was the same as before. Vitamin D was present in abundance in either cod-liver oil or irradiated ergosterol, and in egg yolk, butter, milk, etc. The diet of these children was thus rich in those factors, especially vitamin D and calcium, which experimental evidence has shown to assist calcification, and was devoid of those factors- namely, cereals- which interfere with the process.

Carbohydrate intake was reduced by almost half. Bread and oatmeal were replaced by potatoes, milk, meat, fish, eggs, butter and vegetables. The diet is reminiscent of what Dr. Weston Price used to reverse tooth decay in his dental clinic in Cleveland, although Price's diet did include rolls made from freshly ground whole wheat. Price also identified the fat-soluble vitamin K2 MK-4 as another important factor in tooth decay reversal, which would have been abundant in Mellanby's studies due to the dairy. The Mellanbys and Price were contemporaries and had parallel and complementary findings. The Mellanbys did not understand the role of vitamin K2 in mineral metabolism, and Price did not seem to appreciate the role of phytic acid from unsoaked whole grains in preventing mineral absorption.

Here are two sample meals provided in Dr. Mellanby's paper. I believe the word "dinner" refers to the noon meal, and "supper" refers to the evening meal:

Breakfast- Omelette, cocoa, with milk.
Lunch- Milk.
Dinner- Potatoes, steamed minced meat, carrots, stewed fruit, milk.
Tea- Fresh fruit salad, cocoa made with milk.
Supper- Fish and potatoes fried in dripping, milk.

Breakfast- Scrambled egg, milk, fresh salad.
Dinner- Irish stew, potatoes, cabbage, stewed fruit, milk.
Tea- Minced meat warmed with bovril, green salad, milk.
Supper- Thick potato soup made with milk.

In addition, children received vitamin D daily. Here's Dr. Mellanby's summary of their findings:

The tests do not indicate that in order to prevent dental caries children must live on a cereal-free diet, but in association with the results of the other investigations on animals and children they do indicate that the amount of cereal eaten should be reduced, particularly during infancy and in the earlier years of life, and should be replaced by an increased consumption of milk, eggs, butter, potatoes, and other vegetables. They also indicate that a sufficiency of vitamin D and calcium should be given from birth, and before birth, by supplying a suitable diet to the pregnant mother. The teeth of the children would be well formed and more resistant to dental caries instead of being hypoplastic and badly calcified, as were those in this investigation.

If I could add something to this program, I would recommend daily tooth brushing and flossing, avoiding sugar, and rinsing the mouth with water after each meal.

This diet is capable of reversing early stage tooth decay. It will not reverse advanced decay, which requires professional dental treatment as soon as possible. It is not a substitute for dental care in general, and if you try using diet to reverse your own tooth decay, please do it under the supervision of a dentist. And while you're there, tell her about Edward and May Mellanby!

Preventing Tooth Decay
Reversing Tooth Decay
Images of Tooth Decay Healing due to an Improved Diet
Dental Anecdotes