A year or so ago I posted on the fact that most of the vitamins and other phytonutrients in fruits and vegetables are fat soluble and, therefore, not absorbed when said fruits and vegetables are eaten…unless they are eaten with fat.
The front page of the Personal Journal section of today’s Wall Street Journal has an article (available on through subscription) by the healthy columnist Tara Parker-Pope on this very issue. Whereas I wrote in general terms that most of the flavonoids, carotenoids and other nutrients are fat soluble, Ms. Parker-Pope does me one better and actually gives the ratios of absorption with and without accompanying fat. She relied on reports from several researchers for her accuracy and peppers her article with the expected amount of hand wringing about the dangers of that ol’ devil saturated fat.
She reports on a study of the nutrient absorption from fat-free salsa with and without extra fat.
For the salsa study, 11 test subjects were first given a meal of fat-free salsa and some bread. Another day, the same meal was offered, but this time avocado was added to the salsa, boosting the fat content of the meal to about 37% of calories. In checking blood levels of the test subjects, researchers found that the men and women absorbed an average of 4.4 times as much lycopene and 2.6 times as much beta carotene when the avocado was added to the food.
A study using salad with and without avocado was even more impressive.
The first salad included romaine lettuce, baby spinach, shredded carrots and a no-fat dressing, resulting in a fat content of about 2%. After avocado was added, the fat content jumped to 42%. When the salad was consumed with the avocado, the 11 test subjects absorbed seven times the lutein and nearly 18 times the beta carotene. Lutein is a carotenoid found in many green vegetables and is linked with improved eye and heart health.
Another study done a few years ago at Ohio State University showed that salad dressing with oil brings out the best in a salad when compared to no-fat, low-fat dressings.
When the seven test subjects consumed salads with no-fat dressing, the absorption of carotenoids was negligible. When a reduced-fat dressing was used, the added fat led to a higher absorption of alpha and beta carotene and lycopene. But there was substantially more absorption of the healthful compounds when full-fat dressing was used.
Researchers, who are often taken aback when fat does anything good, were astounded.
Study researchers say they were not only surprised by how much more absorption occurred with the avocado added to the meal, but they were taken aback at how little the body absorbed when no fats were present. “The fact that so little was absorbed when no fat was there was just amazing to me,” says Dr. Clinton.
No matter how much good comes from it, no academic researcher worth his (or her) salt could ever utter a sentence in which fat comes off looking good without shedding caveats like dandruff.
The article ends in a blizzard of ‘don’t overdo the fats’ and ‘choose heart-healthy unsaturated fats’ and watch ‘the overall fat content of the meal’ and all the rest of the idiocy that these folks think they have to say to avoid being accused of recommending fat.
As for me, I’m gonna go have a pile of ribs prepared by my lovely wife along with some slaw and sliced tomatoes. And given the amount of fat I’m going to eat, I suspect I’ll snake every bit of lycopene, carotenoid, and flavonoid out of later two dishes. The majority of the fat I will eat will not be of the heart healthy variety, at least as defined by the nimrods quoted above. In fact, the amount of fat I’ll leave on my napkin will be enough to send them into apoplexy. But, hey, I just went and gave blood yesterday, and my blood pressure was 117/63 and my pulse was 59 after a breakfast of bacon and eggs and about four cups of Cafe Americano. Not bad for an old man on no medications who eats a lot of saturated fat.
Next post will be about the article I’m sure you’ve all heard of by now ‘showing’ that saturated fat–even one meal thereof–causes bad vascular changes. Until then…don’t believe everything you read. Unless it’s on this site, of course.
When I read the article yesterday I looked up and said to myself, “Duh!”
Hi Steve–
Me, too. That’s why I decided to post on it.
Best–
MRE
Primarily referring back to the 7/20/05 column which indicated that the deodorization process for canola oil creates trans fats, does cold pressed canola oil go through the same deodorization process? It apparently does. Unrefined canola oil has a smoke point of 225 F, i.e. barely above boiling and therefore useless for frying and baking.
P.S. I’ve enclosed this from the website http://www.cookingforengineers.com/forums/viewtopic.php?t=216&postdays=0&postorder=asc&start=0
This site seems right up your alley and probably your wife’s with your engineering background and her cooking interests.
It explains the process by which cis unsaturated oils become trans unsaturated oils. Note that this would apply to any high heating of the oil including cooking.
Quote:
Michael, trans fats are made through the process of hydrogenation. While heating an oil past its smoke point will cause it to break down and oxidize, it DOES NOT cause trans fats.
Oh yes it does!
Here’s the chemistry. “trans” and “cis” refer to the shape of otherwise identical molecules. In an unsaturated fat, there are occasional double bonds. This leaves two adjacent carbon atoms with only a single hydrogen attached to each instead of the usual two. This produces a slight push on one side of the chain. Hence the molecule can take either of two shapes: if the hydrogens are on the same side, the chain gets a (double) kink, if they are opposite, there is just a tiny zig-zag and the chain remains pretty well straight.
So we have:
Code:
H H H H H H
| | | | | |
-C-C-C -C-C-C H H
| | \\ | | \\ | |
H H C-H H H C-C-C-
| | | |
H-C-H H H H
|
H-C-H
|
cis trans
The natural form of most fats is the kinked “cis” isomer, the straighter “trans” form is unnatural and harmful. Both forms are stable at room temperature. However, when oil is heated the thermal vibration can wrench the double bond around into the other position. This occurs below the smoke point, so high temperature cooking transforms some of the natural cis fat into the harmful trans variety. It is not entirely negligible – this is one of the reasons they recommend not using cooking oil over and over again.
You don’t have to publish this. I thought you might find the website interesting and the unreferenced explanation of trans fat creation.
Hi Mark–
Thanks for the website info on cooking engineering.
I stand by my comment that heating vegetables oils will NOT convert them from the cis form to the trans form. I get my info on this from Mary Enig, who has probably done more trans fat research than anyone around. She insists that one CANNOT make a trans fat by simply heating an oil. The process requires a catalyst, pressurization and a ready supply of hydrogen.
See:
http://www.westonaprice.org/knowyourfats/howtransform.html
Best–
MRE
‘Fat’ Mike and the milling throng Hola…..i know you’re unlikely to suggest or rec brands but can you point me in the direction of where to find really good quality vits and mins, please ?
My probs have been that as have been in Europe, Africa, Australia, America and now finally Can-Ardour since starting eating this ‘way'(since 96)its diff to find the same brand in each place.
So for N America can anyone suggest what they think are really good quality multivits and antioxidants and magnesium pleasum ?
Email is supachramp@yahoo.com
thanks muchly
OK, I’ve read this posting and last years about canola oil and I have a question. I just got married and received a great deep fryer from Waring Pro, what oil should I use in it? Organic grape seed and peanut oils is tough on the wallet but seem the best choices. Opinion?
Hi David–
If you can find it beef tallow is a great choice. Others would be lard or coconut oil, but those are kind of expensive too. I wouldn’t use grape seen oil, organic or otherwise, because it contains way too much of the polyunsaturated fats that are prone to oxidation.
Best–
MRE
Hi Mike. Great post. Vacationing in Greece right now and eating the local fare.
Perhaps this is why I’m feeling so good? Lots of veggies, fat, fruit, fat, meat, fat and local red wines.
Never felt more anabolic!
Fred
Hi Fred–
Thanks for the kind words about the post. Have fun in Greece and eat some good lamb and a cucumber and tomato salad for me. Don’t forget to have a couple of glasses of that good, prickly local Greek red wine.
Best–
MRE
http://www.madehow.com/Volume-1/Cooking-Oil.html – 23k9
Finally, the oil is deodorized. In this
process, steam is passed over hot oil in a vacuum at between 440 and 485 degrees Fahrenheit
(225 and 250 degrees Celsius), thus allowing the volatile taste and odor components to distill
from the oil. Typically, citric acid at. 01 percent is also added to oil after deodorization to inactivate trace metals that might promote oxidation within the oil and hence shorten its
shelf-life.
Hydrogenation (Volume-2/How Margarine and Butter are made from same website)
2 The oil is then hydrogenated to ensure the correct consistency for margarine production, a
state referred to as “plastic” or semi-solid. In this process, hydrogen gas is added to the oil under pressurized conditions. The hydrogen particles stay with the oil, helping to increase the temperature point at which it will melt and to make the oil less susceptible to contamination
through oxidation.
Color me confused. While not disagreeing with the foremost authority on trans fats, Mary Enig who probably deserves a Nobel Prize for blowing the whistle on trans fats, these scientists produced trans fats without the use of nickel as catalyst, without a source of hydrogen (although it’s possible that steam could be a source) and in a vacuum rather than under pressure. This is not withstanding that ruminants also produce trans fats although in different composition, because man cannot duplicate that process. Thanks for the space and time and also the interesting websites I keep finding.
Hi Mark–
Looks to me like they did use hydrogen (“hydrogen gas is added to the oil under pressurized conditions”) At any rate, what I’m (and Mary Enig) talking about is that you can’t hydrogentate vegetable oils by heating them on a stove or in a deep fryer. There may well be some process food manufacturers use that does result in partial hydrogenation, but nothing that I know of that the average Joe can do to the oil in his own kitchen to convert it to a trans fat.
Best–
MRE
Formation of Modified Fatty Acids and Oxyphytosterols during Refining of Low Erucic Acid Rapeseed Oil
Formation of trans fatty acids and cyclic fatty acid monomers was investigated during refining of low erucic acid rapeseed oil. The first steps of the refining process, that is, degumming, neutralization, and bleaching, hardly modified the fatty acid profile. In contrast, deodorization produced substantial quantities of trans fatty acids (>5% of total fatty acids)
The above was supposed to be the 1st section of comment that I sent. I apologize for the mistake. My point simply was that these researchers had found that the deodorization process had produced trans fatty acids in canola oil. Your point that these conditions cannot be duplicated in the frying pan is accurate. Deodorization occurs under vacuum and at > 400F, at or above the smoke point under normal conditions. As always, thanks for your time and the space to comment and my apologies for the error.
Hi Mark–
I think I posted a while back about the deodorization process creating trans fats in canola oil. It can absolutely occur in that way. That’s why MD and I avoid them now.
Best–
MRE
The whole debate between how good or how bad saturated fats are just reminds me of Einstein’s words:
“If the facts don’t fit theory… change the facts!”
I should know. I set out to follow your Protein Power plan to the letter so I could ‘disprove’ your theory with my facts and point its flaws to you and MD, remember? Seven years later, without having found the flaw, and after ‘changing my facts’, I’m so happy I was wrong. The lipid hypothesis, and in some ‘expert’ minds already the lipid ‘theory’ is long overdue and given the amount of data against it, is just amazing how many serious scientists are still trying to make the facts fit their hypothesis… whatever the cost!
Since I love to read about the geniuses of the past, perhaps what Max Planck said will prove valid regarding the lipid hypothesis:
“A scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die and a new generation grows up that is familiar with it.”
Hi Gabe–
Thanks for the kind words about PP.
The Max Planck quote is, unfortunately, right on the money. But it’s understandable. If I were a researcher who had built my career on the idea that fat is a demon, it would be difficult to write it all off if the facts showed (as they have) that fat is okay. I would spend the rest of my days trying to justify my beliefs.
Best–
MRE
Any rules of thumb on how much fat you should consume with a salad or a piece of fruit?
Hi–
I don’t know of a rule of thumb. I just always try to eat at least a little fat every time I eat fruits and/or vegetables. A little cheese with the fruit, a little butter with the vegetables.
MRE
If this helps the person who asked about a rule of thumb on how much fat to consume, when we discuss the practicalities of Protein Power in the discussion board, I usually say this (Mike, please correct if and where I’m wrong):
“Whatever fat comes with the good choices of protein, plus a little of the good fats in avocados, cheese and butter/good oils used to cook vegetables provides plenty of fat. ‘Plenty’ usually falls into the ‘moderate’ category, thus making the plan carbohydrate-controlled, adequate in protein and moderate in fat”.
Even if the choices of protein are lean (if one of the protein sources is beef), they always come with its nice amount of fat, which not only helps with the absorption of vitamins in vegetables but also with the taste of the meat itself.
It’s common to hear the argument of ‘all that fat…’ but it’s really hard for people to consciously add excessive fat to their diet, unless they choose to start eating butter sticks.
Hi Gabe–
I agree with everything you wrote. But, the commenter asked about a rule of thumb concerning sugar intake, not fat.
Thanks–
MRE
I came across an old comment of Loren Cordain’s in the Paleodiet archives:
***
The carbohydrate content of pre-agricultural diets was generally
lower than the 45-55% of the western diet. Consequently the
post-prandial lipemic excursions, during which LDL molecules are most
prone to oxidation would have been reduced, since the addition of
carbohydrate to a fat rich meal exacerbates this swing (12).
Pre-agricultural eating patterns show that fat and protein were
generally eaten together whereas, carbohydrate meals were eaten
separately. This eating pattern would have reduced post-prandial
lipemic excursions. Additionally, the reduced carbohydrate content of
pre-agricultural diets would have improved the portions of the blood
lipid profile (TG, VLDL, HDL, Lp(a)) which are worsened by high
carbohydrate diets (13).
12. Chen YDI et al. Effect of acute variations in dietary fat and
carbohydrate intake on retinly ester content of intestinally derived
lipoproteins. J Clin Endocrin Metabolism 1992;74:28-32.
13. Reaven GM. Pathophysiology of insulin resistance in human disease.
Physiol Rev 1995 75:473-86.
***
So Cordain says fat and carbs together is a bad idea because of LDL oxidation. But this study says you don’t absorb nutrients in carbs if you eat don’t fat and carbs together. What to do?
Hi Imsovain–
I’ve read all the above papers and I’ve talked about this with Dr. Cordain. Neither of us thinks that the amount of carb contained in a good, whole foods, low-carb diet is enough to oxidize LDL. Go for the colorful fruits and vegetables, use a little good quality oil or butter, and eat up.
Best–
MRE
Mike, I was pretty sure I read how much fat… Indeed:
“Any rules of thumb on how much fat you should consume with a salad or a piece of fruit?”
Unless I misunderstood… Anyway, the good thing is that you get so many comments here and it’s easy to get lost sometimes, isn’t it? I mean, as you saw before, somebody misquoted me on another entry you made. In any case, I’m glad the advice was the correct one and hopefully it will help somebody. Cheers!
Hi Gabe–
You’re right. Sorry. I got the comment that you wrote about ‘how much fat’ confused with another that I had just answered asking the question ‘is there a rule of thumb about how much sugar.’ My apologies.
With all the comments flying so fast and furiously, it’s hard to keep them straight in my head.
Best–
MRE