Wednesday, 22 December 2010

A Gluten-free January

Are You Gluten Sensitive?

Many people are totally unaware of the fact that they react poorly to gluten. Because they've been eating wheat, barley and/or rye products every day for virtually their entire lives, they don't know what their bodies feel like without gluten. In susceptible people, eating gluten is linked to a dizzying array of health problems that stem from an immune reaction to gliadins and other proteins in gluten (1). Are you a susceptible person? How do you know?

The gold standard way to detect a gluten sensitivity is to do a gluten "challenge" after a period of avoidance and see how you feel. People who react poorly to gluten may feel better after a period of avoidance. After a gluten challenge, symptoms can range from digestive upset, to skin symptoms, to fatigue or irritability within minutes to days of the gluten challenge.

With 2011 approaching, why not make your new year's resolution to go gluten-free for a month? A man named Matt Lentzner e-mailed me this week to ask if I would help with his (non-commercial) project, "A Gluten-free January". I said I'd be delighted. Although I don't typically eat much gluten, this January I'm going 100% gluten-free. Are you on board? Read on.

A Message from Matt Lentzner

Hi There.

My name is Matt Lentzner. I'm just some guy who lifts weights on his patio and tries to eat healthy. That's not important, but I have an idea that just might be.

I am trying to get as many people as possible to go gluten-free for one month - this January 2011.

I've considered this whole ancestral diet thing and I've come to a conclusion. If you could only do just one thing to improve your health then not eating gluten would be it. This is not to say that avoiding other nasty things like fructose or industrial vegetable oil is not important. They are, but you'd get the most bang for your buck from not eating gluten.

"Eat No Gluten" is simple and easy to remember. I think that sometimes the rules get so complicated and overwhelming and people just give up on it. We're keeping it simple here. Even at this simplified level I see that it's difficult for a lot of folks. I think people, Americans especially, tend not to pay much attention to what they're eating - what it is, where it came from, etc.

Getting people to get out of their eating ruts and think a little about what goes into their mouths is a valuable exercise. It sets the stage for better choices in the future. I hope that some success with the simple step will encourage people to further improve their diets.

I have a website at If you want to sign up just send an email with your first name, last initial, and town of residence to If you are on Facebook there's a community you can 'Like' called: Gluten Free January. So far I have over 120 people all over the world signed up. If you are already gluten-free then I still want you to sign up - the more the merrier. You can also use this opportunity to spread the word and sign up your family and friends.

Merry Christmas - Looking forward to a gluten-free New Year.


Monday, 20 December 2010

Dairy Fat and Diabetes


Having access to embargoed news from the Annals of Internal Medicine is really fun. I get to report on important studies at the same time as the news media. But this week, I got my hands on a study that I'm not sure will be widely reported (Mozaffarian et al. Trans-palmitoleic Acid, Metabolic Risk Factors, and New-Onset Diabetes in US Adults. Ann Internal Med. 2010). Why? Because it suggests that dairy fat may protect against diabetes.

The lead author is Dr. Dariush Mozaffarian, whose meta-analysis of diet-heart controlled trials I recently criticized (1). I think this is a good opportunity for me to acknowledge that Dr. Mozaffarian and his colleagues have published some brave papers in the past that challenged conventional wisdom. For example, in a 2005 study, they found that postmenopausal women who ate the most saturated fat had the slowest rate of narrowing of their coronary arteries over time (2). It wasn't a popular finding but he has defended it. His colleague Dr. Walter Willett thinks dietary fat is fine (although he favors corn oil), whole eggs can be part of a healthy diet, and there are worse things than eating coconut from time to time. Dr. Willett is also a strong advocate of unrefined foods and home cooking, which I believe are two of the main pillars of healthy eating.

Let's hit the data

Investigators collected two measures of dairy fat intake in 3,736 Americans:
  1. 24 hour dietary recall questionnaires, six times. This records volunteers' food intake at the beginning of the study.
  2. Blood (plasma phospholipid) content of trans-palmitoleate. Dairy fat and red meat fat are virtually the only sources of this fatty acid, so it reflects the intake of these foods. Most of the trans-palmitoleate came from dairy in this study, although red meat was also a significant source.
After adjustment for confounding factors, trans-palmitoleate levels were associated with a smaller waist circumference, higher HDL cholesterol, lower serum triglycerides, lower C-reactive protein, lower fasting insulin and lower calculated insulin resistance. Furthermore, people with the highest trans-palmitoleate levels had 1/3 the risk of developing diabetes over the three years volunteers were followed. Keep in mind, however, that this is an observational study and does not prove that dairy fat prevents diabetes.

Even though certain blood fatty acids partially represent food intake, they can also represent metabolic conditions. For example, people on their way to type II diabetes tend to have more saturated blood lipids, independent of diet (3, 4)*. So it's reassuring to see that dietary trans-palmitoleate intake was closely related to the serum level. The investigators also noted that "greater whole-fat dairy consumption was associated with lower risk for diabetes," which increases my confidence that serum trans-palmitoleate is actually measuring dairy fat intake to some degree. However, in the end, I think the striking association they observed was partially due to dairy fat intake, but mostly due to metabolic factors that had nothing to do with dairy fat**.

Here's a nice quote:
Our findings support potential metabolic benefits of dairy consumption and suggest that trans-palmitoleate may mediate these effects***. They also suggest that efforts to promote exclusive consumption of low-fat and nonfat dairy products, which would lower population exposure to trans-palmitoleate, may be premature until the mediators of the health effects of dairy consumption are better established.
Never thought I'd see the day! Not bad, but I can do better:
Our findings support eating as much butter as possible****. Don't waste your money on low-fat cream, either (half-n-half). We're sorry that public health authorities have spent 30 years telling you to eat low-fat dairy when most studies are actually more consistent with the idea that dairy fat reduces the risk obesity and chronic disease.
What are these studies suggesting that dairy fat may be protective, you ask? That will be the topic of another post, my friends.

*Probably due to uncontrolled de novo lipogenesis because of insulin resistance. Many studies find that serum saturated fatty acids are higher in those with metabolic dysfunction, independent of diet. They sometimes interpret that as showing that people are lying about their diet, rather than that serum saturated fatty acids don't reflect diet very well. For example, in one study I cited, investigators found no relationship between dietary saturated fat and diabetes risk, but they did find a relationship between serum saturated fatty acids and diabetes risk (5). They then proceeded to refer to the serum measurements as "objective measurements" that can tease apart "important associations with diabetes incidence that may be missed when assessed by [food questionnaires]." They go on to say that serum fatty acids are "useful as biomarkers for fatty acid intake," which is true for some fatty acids but not remotely for most of the saturated ones, according to their own study. Basically, they try to insinuate that dietary saturated fat is the culprit, and the only reason they couldn't measure that association directly is that people who went on to develop diabetes inaccurately reported their diets! A more likely explanation is that elevated serum saturated fatty acids are simply a marker of insulin resistance (and thus uncontrolled de novo lipogenesis), and had nothing to do with diet.

**Why do I say that? Because mathematically adjusting for dairy and meat fat intake did not substantially weaken the association between phospholipid trans-palmitoleate and reduced diabetes risk (Table 4). In other words, if you believe their math, dairy/meat fat intake only accounted for a small part of the protective association. That implies that healthy people maintain a higher serum phospholipid trans-palmitoleate level than unhealthy people, even if both groups eat the same amount of trans-palmitoleate. If they hadn't mentioned that full-fat dairy fat intake was directly associated with a lower risk of diabetes, I would not find the study very interesting because I'd have my doubts that it was relevant to diet.

***I find it highly doubtful that trans-palmitoleate entirely mediates the positive health outcomes associated with dairy fat intake. I think it's more likely to simply be a marker of milk fat, which contains a number of potentially protective substances such as CLA, vitamin K2, butyric acid, and the natural trans fats including trans-palmitoleate. In addition, dairy fat is low in omega-6 polyunsaturated fat. I find it unlikely that their fancy math was able to tease those factors apart, because those substances all travel together in dairy fat. trans-palmitoleate pills are not going to replace butter.

****That's a joke. I think butter can be part of healthy diet, but that doesn't mean gorging on it is a good idea. This study does not prove that dairy fat prevents diabetes, it simply suggests that it may.

Sunday, 19 December 2010

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 as Gary Taubes would say, 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. I think that's likely to have contributed. 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.

Saturday, 18 December 2010

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!

Thursday, 16 December 2010

Interview with Chris Voigt of 20 Potatoes a Day


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).


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.