I was going to blog about this, but vlogging is so much easier, right?
Thursday, December 2, 2010
Diet-Heart Controlled Trials: a New Literature Review
Many controlled studies have measured the cardiovascular effects of replacing animal ("saturated") fats with seed oils (predominantly the omega-6 polyunsaturated fat linoleic acid) in humans. A number of these studies recorded heart attacks and total mortality during the following 1-8 years. Several investigators have done meta-analyses (literature reviews) to try to tease out overall conclusions from these studies.
I'm pleased to point out a new meta-analysis of these controlled trials by Dr. Christopher Ramsden and colleagues (1). This paper finally cleans up the mess that previous meta-analyses have made of the diet-heart literature. One recent paper in particular by Dr. Dariush Mozaffarian and colleagues concluded that overall, the controlled trials show that replacing animal fat with linoleic acid (LA)-rich seed oils reduces heart attack risk (2). I disagreed strongly with their conclusion because I felt their methods were faulty (3).
Dr. Ramsden and colleagues pointed out several fundamental flaws in the review paper by Dr. Mozaffarian and colleagues, as well as in the prevailing interpretation of these studies in the scientific literature in general. These overlap with the concerns that I voiced in my post (4):
What did they find?
The article also contains an excellent discussion of the Finnish mental hospital trial (5, 6) and why it was excluded from the meta-analysis, in which Dr. Ramsden and colleagues point out major design flaws, some of which I was not aware of. For example, trans fat intake was on average 13 times higher in the control groups than in the experimental groups. In addition, one of the control groups received more than twice as much of the antipsychotic drug thioridazine, which is known to be highly toxic to the heart, as any other group. Ouch. I'm glad to see this study finally discussed in an open and honest manner. I discussed my own problems with the Finnish trial in an earlier post (7).
I was also glad to see an open discussion of the Oslo Diet-heart study (8), in which diet changes led to a reduction in heart attack risk over five years. Dr. Mozaffarian and colleagues included it in their analysis as if it were a controlled trial in which animal fat was replaced by seed oils only. In reality, the investigators changed many variables at once, which I had also pointed out in my critique of Dr. Mozaffarian's meta-analysis (9). Here's what Dr. Ramsden and colleagues had to say about it:
One criticism I have of Dr. Ramsden's paper is that they used the Oslo trial in their analysis, despite the major limitation described above. However, they were extremely open about it and discussed the problem in detail. Furthermore, the overall result would have been essentially the same even if they had excluded the Oslo trial from the analysis.
Overall, the paper is an excellent addition to the literature, and I hope it will bring a new level of sophistication to the dialogue on dietary prevention of cardiovascular disease. In the meantime, brace yourselves for an avalanche of criticism from the seed oil brigade.
* Guidelines that determine which studies to include in the analysis. For example, you want to exclude any study that wasn't randomized, because it will not be interpretable from a statistical standpoint. You also want to exclude trials where major variables differ between groups besides the specific variable you're trying to test. The Finnish mental hospital trial fails by both criteria.
I'm pleased to point out a new meta-analysis of these controlled trials by Dr. Christopher Ramsden and colleagues (1). This paper finally cleans up the mess that previous meta-analyses have made of the diet-heart literature. One recent paper in particular by Dr. Dariush Mozaffarian and colleagues concluded that overall, the controlled trials show that replacing animal fat with linoleic acid (LA)-rich seed oils reduces heart attack risk (2). I disagreed strongly with their conclusion because I felt their methods were faulty (3).
Dr. Ramsden and colleagues pointed out several fundamental flaws in the review paper by Dr. Mozaffarian and colleagues, as well as in the prevailing interpretation of these studies in the scientific literature in general. These overlap with the concerns that I voiced in my post (4):
- Omission of unfavorable studies, including the Rose corn oil trial and the Sydney diet-heart trial.
- Inclusion of weak trials with major confounding variables, such as the Finnish mental hospital trial.
- Failure to distinguish between omega-6 and omega-3 fatty acids.
- Failure to acknowledge that seed oils often replaced large quantities of industrial trans fats in addition to animal fat in these trials.
What did they find?
- Interventions that replaced animal and trans fat with seed oils that were rich in LA but low in omega-3 caused a non-significant trend toward increased heart attacks (13% increase) and overall mortality.
- Interventions that replaced animal and trans fat with a combination of LA and omega-3 fats significantly reduced heart attacks (by 22%). The numbers for total mortality followed a similar trend.
...experimental diets replaced common ‘hard’ margarines, industrial shortenings and other sources of [trans fat] in all seven of the [controlled trials] included in the meta-analysis by Mozaffarian et al. The mean estimated [trans fat] content of the seven control diets was 3·0 [% of calories] (range 1·5–9·6 [%]).In other words, it looks like trans fat is probably the issue, not animal fat, but these trials replaced both simultaneously so we can't know for sure. I will note here that trans fat does not generally promote atherosclerosis (thickening and hardening of arteries) in animal models, so if it does truly increase heart attack risk as many studies suggest, it's probably through a mechanism that is independent of atherosclerosis.
...the displacement of [trans fat], rather than the substitution of mixed n-3/n-6 [polyunsaturated fat] for [saturated fat], may account for some or all of the 22% reduction in non-fatal [heart attacks and heart attack] death in our meta-analysis. By contrast, the increased [heart attack] risks from n-6 specific [polyunsaturated fat] diets in our meta-analysis may be underestimated as n-6 [polyunsaturated fat] also replaced substantial quantities of [trans fat] (Table 3). The consistent trends towards increased [heart attack] risk of n-6 specific [polyunsaturated fat] diets may have become significant if the n-6 [polyunsaturated fat] replaced only [saturated fat], instead of a combination of [saturated fat] and [trans fat].
The article also contains an excellent discussion of the Finnish mental hospital trial (5, 6) and why it was excluded from the meta-analysis, in which Dr. Ramsden and colleagues point out major design flaws, some of which I was not aware of. For example, trans fat intake was on average 13 times higher in the control groups than in the experimental groups. In addition, one of the control groups received more than twice as much of the antipsychotic drug thioridazine, which is known to be highly toxic to the heart, as any other group. Ouch. I'm glad to see this study finally discussed in an open and honest manner. I discussed my own problems with the Finnish trial in an earlier post (7).
I was also glad to see an open discussion of the Oslo Diet-heart study (8), in which diet changes led to a reduction in heart attack risk over five years. Dr. Mozaffarian and colleagues included it in their analysis as if it were a controlled trial in which animal fat was replaced by seed oils only. In reality, the investigators changed many variables at once, which I had also pointed out in my critique of Dr. Mozaffarian's meta-analysis (9). Here's what Dr. Ramsden and colleagues had to say about it:
First, experimental dieters were instructed to substitute fish, shellfish and ‘whale beef’ for meats and eggs, and were actually supplied with ‘considerable quantities of Norwegian sardines canned in cod liver oil, which proved to be popular as a bread spread’(32)... Second, the experimental group consumed massive amounts of soybean oil, which provided large quantities of both LA (15·6 en %) and ALA (2·7 en %). ALA consumption was about 4·5 times average US intake(42), or about twelve typical flax oil pills (1 g pill ¼ 560 mg ALA) per d. In addition, the fish and cod liver oil consumption provided Oslo (598N latitude) dieters with 610 IU (15·25 mg) of daily vitamin D3, recently linked to lower blood pressure, plaque stabilisation, and reduced [heart attack risk] (64). Furthermore, experimental dieters were encouraged to eat more nuts, fruits, and vegetables; to limit animal fats; and to restrict their intake of refined grains and sugar.trans fat intake was also reduced substantially by excluding margarine in the experimental group. Other review papers have used this trial as a justification to replace animal fat with seed oils. Hmm... The only reason they get away with this is because the trial was published in 1966 and almost no one today has actually read it.
One criticism I have of Dr. Ramsden's paper is that they used the Oslo trial in their analysis, despite the major limitation described above. However, they were extremely open about it and discussed the problem in detail. Furthermore, the overall result would have been essentially the same even if they had excluded the Oslo trial from the analysis.
Overall, the paper is an excellent addition to the literature, and I hope it will bring a new level of sophistication to the dialogue on dietary prevention of cardiovascular disease. In the meantime, brace yourselves for an avalanche of criticism from the seed oil brigade.
* Guidelines that determine which studies to include in the analysis. For example, you want to exclude any study that wasn't randomized, because it will not be interpretable from a statistical standpoint. You also want to exclude trials where major variables differ between groups besides the specific variable you're trying to test. The Finnish mental hospital trial fails by both criteria.
Can you really Lose Weight with Fruit Pills?
Lose an average of 28 pounds in 10 weeks.
A fruit pill can be a great slimming aid. According to a study in Nutrition Journal, subjects taking a fruit concentrate lost an average of 28 pounds in 10 weeks.
Fruit concentrates, like Nutrilite Concentrated Fruits and Vegetables
, are loaded with phytochemicals that significantly reduce metabolism-slowing inflammation.You would have to eat 10 to 20 servings of produce per day to get the same benefits. And even if you did eat that much fruit, you'd be ingesting so many calories, there would be little room for other foods that make up a well-rounded diet.
Still, keep aiming for five daily servings of real produce. This way, you'll get extra slimming and satiety-providing nutrients that pills lack, such as fiber.
Jenny McCarthy's Slimming Treat
This treat reduces cravings, prolongs satiety and increases energy.
In fact, some women who kicked gluten out of their diet lost up to 5 pounds in just 48 hours.
Before heading to bed, Jenny McCarthy snacks on two gluten-free, casein-free cookies and a cup of tea.Such snacks, like Lucy's Cookies
, available in sugar, cinnamon thin, oatmeal and chocolate chip varieties, can lead to fewer insulin spikes.Snack on this goodies and lose up to 5 pounds in just 48 hours.
Curb Cravings with just a Glance
Curb appetite and boost your spirit just by wearing this color.
Chromo therapists attest that the electromagnetic frequency of the color pink prompts the brain's pineal gland to release serotonin, a neurotransmitter that helps curb appetite and boosts your spirit.So wear a pink sweater or bracelet for a sugar-like high minus the calories and guilt.
Tips to Get the Most Out of Your Walk!
A 30-minute walk can burn 200 calories or more.
New Balance, an athletic apparel manufacturer, has put together a few training tips to make sure you get the most out of your walk:
* While walking, pump your arms to get more power from your hips and tone the upper body.
* Control your hips: Move them as extensions of your thighs.
* Stand tall to allow your waist to swivel with the motion of your hips and legs.
* Try interval walking: Normal pace for five minutes, fast for 30 seconds. Repeat eight times.
* Take short quick steps instead of long strides.
* Use the heel-to-toe roll and push off with the back leg.
* Five by fives: While walking, hold your stomach in for five minutes, release for five.
Wednesday, December 1, 2010
Day 4, new day, new attitude
I got home from work last night at 11:30pm. I sat in my car and cried before I came in the house. I do that when I'm mentally and physically past exhaustion. I cry. I couldn't remember the last time I cried. It's been a while. The last time was probably over work too. Seems like it always is about work.
I left my phone on my desk last night. I woke up at 4:40am, which is when my phone alarm usually goes off. I thought, well, it'll go off any minute so I should just get up and go to the gym. After only three hours of sleep I rolled over and fell back asleep. The next time I look at the clock it was almost 7am. My husband had left for work, and I didn't hear a thing (and he didn't wake me up!).
My first thought was "Oh shit! Dave is going to be furious at me." Dave is a guy that sits on the other side of the wall of my cubicle. He comes in at 5:30am and I don't usually get in until 9am. The last time this happened he had to listen to the alarm for about three hours. He didn't know how to turn it off. He told me he didn't know anything about "these fancy phones". It's just a Blackberry. Nothing special. Poor guy. I felt really bad. I called him this morning and he said it was ringing when he came in but he figured it out. I asked if that meant he'd smashed it against the wall. He said he saw the button to "dismiss".
Long story just to tell you I'm skipping the gym today. I've had five back to back, hour plus workouts in the last five days. My body is tired. I think maybe I need a day off. If it's not raining at noon I'll walk, but it's looking pretty dismal outside right now.
About my new attitude. My last several posts seem to have had a negative tone. I don't like that about myself.
Today I woke up (the second time) feeling great. I read a few really inspiring blogs this morning, Helen and Allan. They both made me realize I need to cut the bullshit and really get on with my weight loss. I mean, I ate M&Ms last night? What the hell was that about? I ate 20 total but I hardly ever eat candy. It's the first time I ate out of the candy bowl at work. Of course it was late and I was starving and I can make up all kinds of stupid excuses. Like I said, I need to cut the bullshit.
It's off to work now. I think if it is raining at noon I'll head down to our little workout room at work. It's really a tiny little room with some exercise bikes and weights and a few other oddball pieces of exercise equipment. It's enough to get in a light 30-minute workout. New day, new attitude and no excuses.
I left my phone on my desk last night. I woke up at 4:40am, which is when my phone alarm usually goes off. I thought, well, it'll go off any minute so I should just get up and go to the gym. After only three hours of sleep I rolled over and fell back asleep. The next time I look at the clock it was almost 7am. My husband had left for work, and I didn't hear a thing (and he didn't wake me up!).
My first thought was "Oh shit! Dave is going to be furious at me." Dave is a guy that sits on the other side of the wall of my cubicle. He comes in at 5:30am and I don't usually get in until 9am. The last time this happened he had to listen to the alarm for about three hours. He didn't know how to turn it off. He told me he didn't know anything about "these fancy phones". It's just a Blackberry. Nothing special. Poor guy. I felt really bad. I called him this morning and he said it was ringing when he came in but he figured it out. I asked if that meant he'd smashed it against the wall. He said he saw the button to "dismiss".
Long story just to tell you I'm skipping the gym today. I've had five back to back, hour plus workouts in the last five days. My body is tired. I think maybe I need a day off. If it's not raining at noon I'll walk, but it's looking pretty dismal outside right now.
About my new attitude. My last several posts seem to have had a negative tone. I don't like that about myself.
Today I woke up (the second time) feeling great. I read a few really inspiring blogs this morning, Helen and Allan. They both made me realize I need to cut the bullshit and really get on with my weight loss. I mean, I ate M&Ms last night? What the hell was that about? I ate 20 total but I hardly ever eat candy. It's the first time I ate out of the candy bowl at work. Of course it was late and I was starving and I can make up all kinds of stupid excuses. Like I said, I need to cut the bullshit.
It's off to work now. I think if it is raining at noon I'll head down to our little workout room at work. It's really a tiny little room with some exercise bikes and weights and a few other oddball pieces of exercise equipment. It's enough to get in a light 30-minute workout. New day, new attitude and no excuses.
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