This blog is about the intersection between evolutionary biology and food. But also about practical applications, sustainable agriculture, and general tasty things.
While I was doing research on variations in gastric acidity, I came across an interesting paper: Diet, reflux and the development of squamous cell carcinoma of the esophagus in Africa. It's interesting that a lot of conventional dietary advice on digestion is based on studies done in Africa that found that African agrarian cultures eating low-fat high-fiber diets had low rates of common Western digestive issues like hemorrhoids and colon cancer. Unfortunately they forgot to mention that there are a host of similarly bad digestive issues that are MORE common in such cultures, such as sigmoid volvulus and squamous cell carcinoma (SCC) of the esophagus. The latter they have tried to blame on everything from pickled vegetables to malnutrition to alcohol, with none of those hypotheses holding up very well.
A promising villain is linoleic acid, AKA omega-6 fatty acids, well known for their harmful effects in the ancestral health/paleo/primal communities. The epidemic of SCC tracks the widespread adoption of linoleic acid-rich corn as a staple, not just in Africa, but in regions of Europe as well.
I bet you are wondering why Americans don't have SCC. I think there are two factors, one is that higher levels of fat in the diet are protective, but I think another is that it's possible that a precursor to it is heartburn, which is widely treated in the US with proton-pump inhibitors. Those have some seriously bad effects, but they might prevent some types of cancer. I think it's better to remove the cause, but if you are going to continue to eat garbage, a PPI might save your life.
Linoleic acid may be causing heartburn by increasing levels of prostaglandin E2 (PGE2). In animal models, high levels of linoleic acid, particularly in combination with low levels of other fatty acids, lead to elevated PGE2. Other micronutrient deficiencies, such as riboflavin deficiency, might make it worse. PGE2 then inhibits gastric acid production and reduces the tone of reduces of the pyloric and lower esophageal sphincters, causing heartburn. If you thought heartburn was a Western disease, consider that 60% of people in Transkei, South Africa suffer from it. Untreated heartburn exposes the esophagus to damage from the acid, in the long-term this can lead to the development of abnormal cancerous cells. Trypsin can possibly squelch the growth of such cells, but the paper notes that the South African diet is also rich in vegetables that are trypsin inhibitors, such as beans and pumpkin. They also eat the very very bad for you vegetable known as Black Nightshade, which is a pepsin inhibitor. And a lot of people smoke. A bad combination leading to a cancer epidemic.
Since I have gotten rid of my GERD, I've wondered and wondered how I did it. I started eating a high-fat nutrient-dense diet, which was low in grains and free of vegetable oils, but not completely gluten or grain free. So that ruled out a gluten allergy as a major culprit. Wheat tracks as a cause of SCC too, but rather than an allergy as work, it seems like a complex inflammatory process is at play. We need to look at omega-6 as one of the true causes of GERD. It's also a possible connection between omega-6 and skin issues via the gut-brain-skin axis.
I'm dedicating this week to Soybean Oil, an ingredient I think all rational people should be able to rally against. Despite massive amounts of scientific evidence that large amounts of omega-6 oils are bad for anyone, this ingredient remains common in our food supply.
This year I was VERY VERY disapointed to find that Chipotle uses it in almost all their ingredients besides their pork. I don't know why I never knew this, I guess it was an instance of "maybe if I don't look at the ingredients I don't be upset."
Chipotle is one of the rare fast food outlets that tries to source meat decently and the salad bowl has been a favorite of mine for a long time.
This week I'm going to devote a blog post a day on why we shouldn't use this ingredient. This will culminate in a paleo flashmob of sorts at the Chipotle Test Kitchen in NYC. If you are in New York, please join us!
I've mentioned Susan Allport's book The Queen of Fats on this blog when taking about fatty acids because it's a fairly good simple primer on the subject. So today via Seth's Blog I found that she abandoned her omega-3/omega-6 balanced diet to do a "Super Size Me" article for O Magazine. They didn't pick it up because the changes she saw were subtle but important...and women's magazines just care about weight. You can read the draft here.
Most medical organizations, as I’ve said, wouldn’t see anything harmful in this change, but a large number of scientists believe that our reliance on cheap, high omega-6 vegetable oils is the underlying cause of many of our health problems. Both omega-3s and omega-6s are essential: we can’t make them ourselves and must consume them in our diet. But a balance between them creates tissues with just the right amount of speed and activity, inflammation and blood flow. Ever since vegetable oil consumption began to skyrocket in the 1950s (replacing butter and lard) so has the incidence of inflammatory diseases, such as heart disease, and metabolic diseases, such as obesity and diabetes.
It's interesting because she mentions she usually consumes canola oil, which is a cheap oil fairly low in omega-6 that has become fairly ubiquitous in restaurants and on ingredient lists of processed foods. Canola oil is not popular in the paleo community because it's so highly refined and probably contains excess polyunsaturated fatty acids, but compared to soybean oil, it's an angel. Considering the low price of canola and how much healthier it is, it's kind of unconscionable that companies like Annie's are still using soybean.
So what effects did the high omega-6 diet experiment produce? Thickening of belly fat, upset stomach, shortness of breath... and get this... a drop in metabolic rate. The conventional wisdom is that people who struggle with health problems related to weight eat more, but there is more and more evidence that what you eat is more important than how much you eat. Her arteries also became stiffer.
Something striking is that a main omega-6 source in her experiment seemed to be peanut butter, a food commonly thought of as healthy. Unfortunately, this is a food I crave often.
It would be interesting to do a third experience where Allport reduces total polyunsaturated fatty acids and increases saturated fats. But for those not interested in paleo, it's at least worth eliminating corn/soy oils and getting some DHA(seafood or supplements).
When I started out on paleo, I used to buy a container of almond butter every couple of days. Some of you might be thinking that it's a lot of omega-6, others might be thinking...what's the big deal? I think at the beginning of your paleo diet you shouldn't worry about omega-6 from whole foods like nuts. You will probably see great improvements, as I did, even on a diet dominated by nuts. I don't want to turn people off from paleo by making these foods seem problematic, but as time passes there might be issues you are still having and it make be worth going closer and closer to the diet of the Stone Age.
I think it's worth mentioning the economic concept of diminishing marginal returns here. The idea is that inputs initially contribute a great deal to production, but eventually the return per individual added unit decreases. It can be a useful analogy in dietary philosophy as well. I'm betting that the very basic first steps towards an evolutionarily appropriate diet are going to be the most significant for us- the removal of soda, candy bars, whole wheat bread, pasta, and other food that's mostly just bad. Beyond that we might get diminishing returns. I personally have cleared up a few minor problems by reducing my intake of omega-6 fatty acids from even whole foods, but they certainly aren't as significant as the ones I got from not eating vegetable shortening and high fructose corn syrup. We all have to look at how close we can get to our ancestor's food and how much is worth it, which can be very individual and can seem nitpicky and obsessive.
But people in the Stone Age didn't have to worry about these things because they simply weren't exposed to them. Nuts were a seasonal food, olive oil didn't exist, and humans simply didn't encounter avocados until we migrated to South America. Even if they are pastured, domestic hogs and poultry require significant amounts of legume and grain rations, so they are going to have very different fatty acid profiles anything our ancestors encountered. One of my friends who processes poultry told me the sad story of a farmer who tried to do pastured chicken without grain/legume rations and they were miserably sickly and thin. Domestic poultry isn't built for surviving on that diet.
I'm not saying that these foods are bad, but if you are on a paleo diet and you are still having some nagging problems, it might be worth limiting them.
This is the diet I've moved to personally. Nuts are there, but I'm no longer eating bags of them. I'm also through with my "lets eat every type of salted/cured pork for every meal" stage. A "basic" paleo diet took care of most of my problems, like GERD, but I still had some lingering IBS issues. Minimizing these foods that are on the borderline made a big difference, but it required trial and error. I've met people who can eat as much bacon as they want, but no tomatoes. When I eliminated nightshades...nothing happened that I could discern and I missed the taste. It just wasn't worth it.
I do think that just because we know saturated fat isn't the worst thing in the entire world means that we should eat as much as we want.
This interview with Cordain points out that while the Inuit were healthier than many modern Americans on an almost all-meat diet, there is evidence they had arterial plaque and lower bone density. I also think Kurt Harris has been a great voice of reason from the other side and his recommendation of mostly animals that eat grass has worked well for me. Probably because I am already thin, I have had good results with a "medium" saturated fat, low omega-6, and medium-carb diet. I don't need to count any calories or do any micromanaging if I eat mostly seafood, coconut, vegetables and things that ate grass...and treat the rest as dessert and flavoring.
What has been your experience?
Edit: Just want to clarify that I don't think saturated fat is bad. I certainly get more than any mainstream recommendation and get much of my calories from it, but I think there is an upper limit to how much is optimal.
I meet them all the time- people who tell me that they would never try the paleo diet because their diet makes them feel awesome. Maybe they don't realize that a face covered with acne and a spare tire around their waist aren't exactly markers of feeling awesome.
I thought of that when reading this NYT article about Alicia Silverstone where she eats a meal presumably loaded with inflammatory omega-6 fatty acids
She settled on nachos and onion rings to start, and mulled beer selections with two girlfriends who had seen her show that night. This was no dive bar that the trio had chosen for a post-performance meal; it was Candle 79, a cozy Upper East Side restaurant that specializes in organic and vegan cuisine. The nachos came slathered in refried pinto beans, tofu sour cream and chili-grilled seitan, a wheat-based meat substitute.
If you are at a vegan restaurant, be sure to avoid fried things. Unless Candle 79 is bucking the trend, they are using canola, safflower, and soy oils, which are rich in omega-6, which to boot is also sensitive to eat. Alicia's fried food was probably loaded with rancid inflammatory fats. I was sad when I realized my favorite veggie-friendly restaurant, Souen, uses such oils to fry in. I LOVED their fried oysters, but I can't order them again.
But she claims she feels awesome
The karma of turning vegan is amazing. And then to get this sudden weight loss, and my skin is glowing and my nails are strong and my eyes are white — it was wonderful.
But if you google Alicia Silverstone and acne, you can find pictures of her without makeup showing off her not-exactly glowing skin. It's not a surprise: gluten and rancid omega-6s are a nasty combination. It's not veganism that's the real problem here though, it's the idea that veganism is THE PERFECT diet and as long as you don't touch those nasty animal products you are AOK. The truth is that acne is usually caused by things like gluten, sugar, and omega-6 oils. It's hard to avoid these as a vegan...or anyone who eats one, but worth it for everyone!
Last year I had some issues with acne. I realized it was because of my "cheat meal" at the Swedish pub, which was a burger with mayo. The burger bun and the oil in the mayo=bad news for my skin. I have delicate skin and what I eat really does show up, for some lucky people it doesn't, but maybe they aren't so lucky because they don't get that visual indicator. Either way, so many women I know accept acne as normal! If you are 25 and still have acne, that's the sign of a problem.
I was reading this excellent interview with an ex-vegan this morning and she also talks about her "veganism as perfect diet" blinders:
Did you feel better or worse as a vegan?
I felt better for the first four months and then progressively worse for the next seven years.
But did you tell people you felt better?
While I was vegan I worked as a manager in a health food store. I always told myself and others that I felt much better as a vegan (deep down I knew I didn’t). I think I was actually trying to convince myself that I felt better. “I’m thinner, so I MUST feel better.”
If you do the paleo diet you have to be conscious of blinders too. If you are having a problem, admit it and look for solutions. It's very much possible to have a diet that causes problems, but is technically paleo.
Non- ruminants are much more subject to passing on the ratio they get in their diets. So the unhealthiest beef has a 6:3 ratio as good or better than pastured free range bug-eating chicken, and fowl fat from industrial operations is like eating vegetable oil.
That's something good to remember. I had a roommate who was a poultry scientist and I learned lots about chicken feed from him. It's nearly impossible to raise modern breeds of chicken...or any chicken for market weights without using lots and lots of grains, seeds, and legumes. Same goes for hogs. I've updated paleo foods in light of this.
While feedlot beef might have gorged on grains at the end of their lives, they spent much of their lives relying on grass. If I am at a restaurant and the choice is between chicken of dubious origin and beef of dubious origin, I pick beef. Lamb is an even better choice.
When I'm dining with friends who could give a damn about local or paleo food, I try to steer them towards Middle Eastern or Indian restaurants that might use Halal meat. There isn't much terribly special about it, except they are likely to serve lamb and the is likely to be from New Zealand (major producer of halal meats) and thus grass fed. Don Wiss pointed this out at in the forums at Eating Paleo in NYC.
Some readers have wondered: what's the big deal about these omega-3 fatty acids you have been talking about? So here is a list of important facts and why you should care about them.
Omega-3 fatty acids and omega-6 fatty acids are essential fatty acids that both have important roles to play. The scientific evidence shows that omega-3 fatty acids play an important role in the health of the heart and the brain as discussed in this post from Mark's Daily Apple on Fats.
The standard American diet is very very high in omega-6 fatty acids primarily from vegetable oils and grains and fairly low in omega-3 fatty acids. Why is this bad? From an evolutionary perspective it's inappropriate- we evolved on a diet with a ratio of omega-6 to omega-3 that was 2:1- 1:1. There is strong evidence excess omega–6 intake prevents the body from utilizing omega-3 and even depletes it from our body.
Of course we can have a brain without adequete omega-3s, but for optimal mental development omega-3s play a huge role. This post at Whole Health Source talks about research showing that deficient children suffered various effects ranging from low verbal intelligence to poor social behavior.
In another post he talks about how omega-3s play a huge role in the risk for heart disease.Omega-6s oils are often considered heart-healthy, but this is based on outdated and misinterpreted research. The unfortunate connsquences of a high-omega 6 diet are evident in the Israeli Paradox: people in Israeli consume tons of "heart healthy" oils like soybean oil, yet have very high rates of heart disease.
Seafood is the primary source of omega-3s that are readily utilized by the body. Flax and some other plant sources have small amounts, but their conversion to the usable form is low, though this can be increased by decreasing intake of omega-6 as I discussed in my post about seeds. The most interesting evidence, which Susan Allport talks about in The Queen of Fats, comes from a study that compared Africans eating no fish compared to Minnesotans eating some fish, but also lots of Western high omega-6 foods. The Africans had more optimal omega-3 levels! Their low omega-6 intake allows them to utilize more of the omega-3s found in plants.
The role of the ratio is controversial. Some believe that as long as your ratio of omega-6 to omega-3 is 10:1-1:1, you are in the clear, but Stephen from Whole Health source presented some good evidence that the total amount of omega-6 is more important. His conclusion is that you should get no more than 4% of our calories from omega-6 fats. The sad fact is that eating lots of fish and fish oil might help with preventing heart disease, but it's like putting a bandaid on a severed arm if omega-6 intake continues to be high. Acculturated Inuit still eat plenty of fish, but that so far hasn't protected them from getting obesity and diabetes from consuming too much omega-6.
The bottom line is that omega-3s are important and too much omega-6 is damaging. Ditch the high-omega 6 oils (safflower, sunflower, soybean, corn, canola) and anything with them (store-bought mayo and sauces unfortunately). All the omega-6s you need can be obtained by consuming nuts and fruit oils like olive oil..though not too much of course! It's also probably wise to consume some seafood or fish oil, but the lower the consumption of omega-6s is, the lower that need is. I personally don't take fish oil anymore because it does have some side effects (burping, bleeding more when cut) that I found unpleasant and it's hard to find a fresh and environmentally friendly source.
I hope Stephen from Whole Health Source writes a book about this someday! The only book I can recommend right now is Susan Allport's The Queen of Fats, which is an interesting primer, though unfortunately it focuses too much on the ratio theory.
This post by Holly Hickman takes issue with the idea that phytic acid in nuts is bad news. I posted very recently about this issue and came to the opposite conclusion. Perhaps it is because my site is oriented towards people eating paleo to help autoimmune conditions. Holly is right that every plant food contains some sort of "don't eat me" chemical. You can be sensitive to many of these...or none of them. There are plenty of people who gobble down Planter's Mixed Nuts without a problem, but I'm not one of them. I can eat a few fresh nuts, but something like almond-flour crackers would make me sick for days. If your gut has problems, it's worth it to examine your intake of plant foods and figure out which ones are making your problems worse.
It's also worth remembering that nuts were seasonal and eaten in small amounts by paleolithic people. When we buy shell nuts we forget how tough they are to crack! Shelled nuts might also be a bad idea because the fats in nuts can go rancid easily. Rancid fats might sound gross, but actually some rancid fats do not have a detectable taste or smell.
That's bad news, because according to Oxidized Fat in the Diet by Jeffrey S. Cohn is a review article summarizing several research studies,
Consumption of lower levels of oxidized fat on repeated occasions may pose a more chronic threat to health, however, particularly because low-level oxidation of meat, milk, poultry and cereal products during storage and processing is virtually unavoidable . More extreme oxidation of fat can also occur when oils are used for cooking.
He mentions that the natural oxidation of cholesterol produces at least 30 different compounds that are biologically active and are particularly prevalent in the milk and egg powders used in processed foods. Compounds such of these are shown in experiments to absorb quite easily into the intestinal wall. In animal studies, oxidized fat led to higher incidence of atherosclerosis. In studies of healthy adults, the consumption of these fats led to impaired arterial function. These effects were not seen following low-fat meals or meals of less oxidized fats.
Comparative Nutritional Value of Diets Containing Rancid Fat, Neutral Fat, and No Fat by Dorothy Whipple is an old one and describes the diet of lab animals. Lab rats fed slightly rancid fats slowly developed horrible symptoms like swelling, hair loss, and neurological degeneration...and eventually died prematurely. Animals fed no fats developed the typical dry-skin symptoms and lived somewhat longer. Animals fed fresh fats were the healthiest and lived the longest. The researcher concluded that in terms of her experimental animals, it was better to feed no fat than oxidized fat, though neither was optimal.
Nuts are probably not the worst source of rancid fats. If you are eating paleo, you are avoiding most of the worst sources like cereals, milk powders, egg powders, and other trash. But I still think it's worth seeking out the best freshest nuts if you are going to eat them. This nut-growing website notes that "Levels of vitamin E are reduced by around 30% after three months of refrigerated storage."....most walnuts aren't even refrigerated. The best chefs contract with growers and buy fresh nuts which they freeze.
I'm definitely thinking of contacting a NY farmer and doing a nut CSA here. Right now there isn't one, which is too bad.
Nuts are delicious...they aren't a grain, they are full of fat, low-carb, they are "paleo" what is there not to love?
In the interview, Rami told me that peanuts are as bad as soybeans when it comes to phytic acid content. He said that nuts are extremely high in phytic acid. He said that he thinks peanut butter that has not been soaked and sprouted is a “garbage food”. Rami told me that seeds are the absolute worst. Even worse than soy or peanuts. Sesame seeds have double or triple the phytic acid that soy has.
Let's look at the data:
How can paleo dieters bash grains and legumes for antinutrients when they are eating just as many in the form of nuts and seeds? It makes me wonder... which is really a better choice: a "paleo" pancake made from almond butter or a traditionally fermented idli? The idli probably has less phytic acid, that's for sure.
Since phytic acid robs the body of minerals, I think I will avoid it best I can. If I think about it carefully, since I am eating expensive meat...when I eat phytic acid it is robbing me of money!
The paleo diet can blind people by forcing them to argue about the history of food rather than its objective properties. But nuts lose either way. The only evidence of large-scale consumption of nuts comes from mesolithic and neolithic societies. They were between agrarian and foragers, as they still consumed wild foods, but they also engaged in activities that boasted nut production. As I was reminded in a recent permaculture workshop I took (you can view the slideshow from it here), agroforestry is still a form of agriculture.
woman will be happy when I spend all day gathering 1000 tiny seeds to make tahini with instead of clubbing a deer
While nuts are well-accepted as paleolithic foods, seeds are little more contentious. Technically nuts ARE seeds, but botanics aside, what we think of as nuts are big enough that gathering a decent amount of calories from them in the wild is feasible. The same can't be said for seeds- most are tiny and it can take a long time to harvest enough to make anything out of. I learned this harvesting pigweed seeds. I was hoping to get enough of this amaranth relative to make porridge with, but I ended up with only enough to garnish a piece of fish.
What about their place in a modern paleo diet? After all, we eat plenty of things that would have been tough to gather. For me, the problem with seeds is that if you eat large amounts of them you will be eating nutrients in ratios and amounts that are not appropriate for us evolutionarily. Furthermore, the polyunsaturated fats in them go rancid easily. While some might find hemp useful, I think it's a bad food, at least in the US because you cannot buy it whole and how long has that hemp powder been sitting on the shelf? Probably long enough to render some of those nice omega-3 fatty acids rotten. Flax is a popular ingredient in "paleo" baked goods, but ground and shoved in the oven, the fats can't be good.
Furthermore, if you eat lots of seeds with the exception of flax, the ratio of omega-6 fatty acids to omega-3 fatty acids is likely to tip towards the latter, which is probably not a good thing.
Several sources of information suggest that human beings evolved on a diet with a ratio of omega-6 to omega-3 essential fatty acids (EFA) of approximately 1 whereas in Western diets the ratio is 15/1-16.7/1. Western diets are deficient in omega-3 fatty acids, and have excessive amounts of omega-6 fatty acids compared with the diet on which human beings evolved and their genetic patterns were established. Excessive amounts of omega-6 polyunsaturated fatty acids (PUFA) and a very high omega-6/omega-3 ratio, as is found in today's Western diets, promote the pathogenesis of many diseases, including cardiovascular disease, cancer, and inflammatory and autoimmune disease
Furthermore, the conversion of any omega-3 from plants in your diet is hampered. The omega-3 fatty acids present in plants, alpha linolenic acid, is not immediately usable in the body. In order to be used, it must be converted to Docosahexaenoic acid. The enzymes that do this conversion are called Holman's enzymes. Unfortunately, they are also responsible for converting omega-6 fatty acids (mostly linoleic acid) to arachidonic acid. Lots of omega-6 means that there is not enough of Holman's enzymes to do the job. This is discussed in Susan Allport's book The Queen of Fats
Data for the US indicate that Americans consume between 11 and 16 grams of linoleic acid per day during the years 1989 and 91 and about 1 to 2 grams of alpha linolenic acid. At that ratio, only about 15 percent of the alpha linolenic acid is converted to DHA and eicosapentaenoic acid. At lower ratios, the conservation rate is much higher. The best conversion occurs at a ratio of 2.3:1
For paleo dieters who eat seafood, this shouldn't be a huge problem, but if not, it can be an issue.
Let's also talk about phytic acid, an anti-nutrient present in many seeds, can reduce mineral absorption. There are a couple of other issues, like some estrogenic compounds in flax.
So that's why, in the Paleo Foods section of the site, I classify seeds as Not Paleo, but give the pros and cons. Some tahini sauce on your kale probably isn't as bad as some whole bran bread, but I would recommend keeping their consumption low. Use them as if you had to gather them yourself.