Minor Thoughts from me to you

Archives for Science (page 1 / 3)

The myth of the eight-hour sleep →

For the past several months, I've had trouble sleeping the entire way through the night. I fall asleep easily and sleep well until sometime between 2–4am. Then I wake up and can't fall back to sleep until about 90 minutes later. I've been thinking there's something wrong with me. There's not. I'm just reverting to medieval sleep patterns.

In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.

His book At Day's Close: Night in Times Past, published four years later, unearths more than 500 references to a segmented sleeping pattern - in diaries, court records, medical books and literature, from Homer's Odyssey to an anthropological account of modern tribes in Nigeria.

Much like the experience of Wehr's subjects, these references describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.

"It's not just the number of references - it is the way they refer to it, as if it was common knowledge," Ekirch says.

During this waking period people were quite active. They often got up, went to the toilet or smoked tobacco and some even visited neighbours. Most people stayed in bed, read, wrote and often prayed. Countless prayer manuals from the late 15th Century offered special prayers for the hours in between sleeps.

And these hours weren't entirely solitary - people often chatted to bed-fellows or had sex.

A doctor's manual from 16th Century France even advised couples that the best time to conceive was not at the end of a long day's labour but "after the first sleep", when "they have more enjoyment" and "do it better".

​And this isn't just a difference between older humans and more modern humans.

In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month.

It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.

My problem — waking up and being unable to fall back to sleep right away ​— even has a name: sleep maintenance insomnia.

Today, most people seem to have adapted quite well to the eight-hour sleep, but Ekirch believes many sleeping problems may have roots in the human body's natural preference for segmented sleep as well as the ubiquity of artificial light.

This could be the root of a condition called sleep maintenance insomnia, where people wake during the night and have trouble getting back to sleep, he suggests.

The condition first appears in literature at the end of the 19th Century, at the same time as accounts of segmented sleep disappear.

"For most of evolution we slept a certain way," says sleep psychologist Gregg Jacobs. "Waking up during the night is part of normal human physiology."

​Maybe I should try sleeping from 8pm–midnight, reading or working on a project from midnight–2am and then sleeping again from 2–6am. It might just be good scientific practice.

80% of Americans Support Mandatory Labels on Food Containing DNA →

Ilya Somin writes at the Foundation for Economic Education:

A survey by the Oklahoma State University Department of Agricultural Economics finds that over 80 percent of Americans support “mandatory labels on foods containing DNA,” about the same number as support mandatory labeling of GMO foods “produced with genetic engineering.” Oklahoma State economist Jayson Lusk has some additional details on the survey.

If the government does impose mandatory labeling on foods containing DNA, perhaps the label might look something like this:

WARNING: This product contains deoxyribonucleic acid (DNA). The Surgeon General has determined that DNA is linked to a variety of diseases in both animals and humans. In some configurations, it is a risk factor for cancer and heart disease. Pregnant women are at very high risk of passing on DNA to their children.

The Oklahoma State survey result is probably an example of the intersection between scientific ignorance and political ignorance, both of which are widespread. The most obvious explanation for the data is that most of these people don’t really understand what DNA is and don’t realize that it is contained in almost all food.

When they read that a strange substance called “DNA” might be included in their food, they might suspect that this is some dangerous chemical inserted by greedy corporations for their own nefarious purposes.

Let me be perfectly clear. Those who want mandatory GMO labels on food are only slightly less foolish than those who want mandatory DNA labels on food. In both cases, the labels are born out of a fear driven by ignorance and superstition.

This entry was tagged. Food Regulation

Walking to Better Health

You may have heard that you should walk at least 10,000 steps per day, for your health. How good is that advice? The software developers at cardiogram have developed an app that tracks your heart rate, using your Apple Watch. They decided to combine the data from the Apple Watch's heart beat sensor with the data from the iPhone's step counter, to see how walking distance affects your resting heart rate.

I'm not sure how scientifically rigorous these results are, but they did come up with some interesting correlations.

Graph of step count versus heart rate

In cardiovascular terms, the drop in heart rate from 1000 steps/day to 2000 steps/day is significant: a full 3 bpm decrease. And as step count increases, resting heart rate steadily drops—until you reach about 5000 steps per day. After that—6000, 7000, even up to 10,000 steps—the curve flattens.

Graph of exercise intensity versus heart rate

Even if you get 10,000 steps per day, if your heart rate doesn’t go over 130 bpm, there’s not much impact on your resting heart rate. In contrast, even 4000 steps / day of high intensity exercise delivers a benefit: about a 4 bpm absolute drop in resting bpm, which doubles to 8 bpm at 10,000 steps / day.

Graph of minutes of high intensity exercise versus heart rate

Even 45 minutes per week of high intensity activity (heart rate >= 150bpm) placed participants in the lowest tier of resting heart rate.

I like this kind of analysis because it's actionable. I've been making some, small, effort to walk each day. I have a goal of 5,000 steps per day. But I've been skeptical of whether or not it actually matters, if it's just a few steps here and there. According to these numbers, it doesn't. I'm just fooling myself.

I can use these numbers to make a new goal. I want to start taking high-intensity walks 2-3 times a week. I've already been monitoring my heart rate. It stays around 90 beats per minute, most days. My initial goal is to lower that to 80 bpm. If that happens, I'll set a new goal.

Virgin Galactic and the Future of Transportation →

Virgin Galactic is working to offer tourist trips to space in the next months to year. But they're looking beyond that too.

"If we can make significant progress on the challenge of reusable space access then I think that opens up all kinds of opportunities in the future," he said. "One of the directions that might open up is high-speed point-to-point travel on Earth -- so that you could go from London to Singapore in an hour or go from London to Los Angeles in a couple of hours.

Regular passenger service to the moon and super fast travel around the globe—this was a staple of the Golden Age SF that I read as a teenager. I hardly know how to process the idea that it might actually come true. If it does, I'll be positively giddy.

The Girl Who Turned to Bone →

Carl Zimmer, writing for The Atlantic.

Peeper’s diagnosis meant that, over her lifetime, she would essentially develop a second skeleton. Within a few years, she would begin to grow new bones that would stretch across her body, some fusing to her original skeleton. Bone by bone, the disease would lock her into stillness. The Mayo doctors didn’t tell Peeper’s parents that. All they did say was that Peeper would not live long.

... “Your muscle isn’t turning to bone,” says Shore. “It’s being replaced by bone.”

Strange disease. Incredible story.

This entry was tagged. Good News Medicine

Starvation hormone markedly extends mouse life span, without need for calorie restriction →

A study by UT Southwestern Medical Center researchers finds that a starvation hormone markedly extends life span in mice without the need for calorie restriction.

"Restricting food intake has been shown to extend lifespan in several different kinds of animals. In our study, we found transgenic mice that produced more of the hormone fibroblast growth factor-21 (FGF21) got the benefits of dieting without having to limit their food intake. Male mice that overproduced the hormone had about a 30 percent increase in average life span and female mice had about a 40 percent increase in average life span," said senior author Dr. Steven Kliewer, professor of molecular biology and pharmacology.

... FGF21 seems to provide its health benefits by increasing insulin sensitivity and blocking the growth hormone/insulin-like growth factor-1 signaling pathway. When too abundant, growth hormone can contribute to insulin resistance, cancer, and other diseases, the researchers said.

FGF21 is a hormone secreted by the liver during fasting that helps the body adapt to starvation. It is one of three growth factors that are considered atypical because they behave like hormones, which are substances created by one part of the body that have effects in other parts, the researchers said.

"Prolonged overproduction of the hormone FGF21 causes mice to live extraordinary long lives without requiring a decrease in food intake. It mimics the health benefits of dieting without having to diet," said co-author Dr. David Mangelsdorf, chairman of pharmacology and a Howard Hughes Medical Institute (HHMI) investigator at UT Southwestern.

There was a slight downside though.

FGF21 overproducers tended to be smaller than wild-type mice and the female mice were infertile. While FGF21 overproducers had significantly lower bone density than wild-type mice, the FGF21-abundant mice exhibited no ill effects from the reduced bone density and remained active into old age without any broken bones, the researchers said.

Here's hoping that this offers some insights for how to manage weight in humans. I'm happy to hear about skinny mice, but I'd be happier to have hope for making it easy for me to stay (become) skinny.

This entry was tagged. Food Weight

An Honest Accounting of the Benefits of Genetically Modified Crops →

Take it away, Matt Ridley.

Generally, technologies are judged on their net benefits, not on the claim that they are harmless: The good effects of, say, the automobile and aspirin outweigh their dangers. Today, arguably, adopting certain new technologies is harder not just because of a policy of precaution but because of a bias in much of the media against reporting the benefits.

So to redress the balance, I thought I'd look up the estimated benefits of genetically modified crops. After 15 years of GM planting, there's ample opportunity—with 17 million farmers on almost 400 million acres in 29 countries on six continents—to count the gains from genetic modification of crop plants. A recent comprehensive report by Graham Brookes and Peter Barfoot for a British firm, PG Economics, gives some rough numbers. (The study was funded by Monsanto, which has major operations in biotech, but the authors say the research was independent of the company and published in two peer-reviewed journals.)

The most obvious benefit is yield increase. In 2010, the report estimates, the world's corn crop was 31 million tons larger and the soybean crop 14 million tons larger than it would have been without the use of biotech crops. The direct effect on farm incomes was an increase of $14 billion, more than half of which went to farmers in developing countries (especially those growing insect-resistant cotton).

In addition, a range of non-pecuniary benefits have been recorded, from savings in fuel, time and machinery to a better health and safety record on the farm (since less pesticide is needed), shorter growing cycles and better quality of product. In India—where the International Service for the Acquisition of Agri-Biotech Applications says 88% of cotton is now genetically modified to resist pests and insecticide use has halved—bee keepers are losing fewer bees.

As this illustrates, the most striking benefits are environmental. The report calculates that a cumulative total of 965 million pounds of pesticide have not been used because of the adoption of GM crops. The biggest impacts are from insect-resistant cotton and herbicide-tolerant maize, both of which need fewer sprayings than their conventional equivalents.

The use of less fuel in farming GM crops results in less carbon-dioxide emission. In addition, herbicide-tolerant GM crops can often be grown with little or no plowing in stubble fields that are sprayed with herbicides. The result is to allow more carbon to remain in the soil, since plowing releases carbon as microbial exhalation. Taken together, Messrs. Brookes and Barfoot estimate, this means that the GM crops grown in 2010 had an effect on carbon-dioxide emissions equivalent to taking 8.6 million cars off the road.

There is a rich irony here. The rapidly growing use of shale gas in the U.S. has also driven down carbon-dioxide emissions by replacing coal in the generation of electricity. U.S. carbon emissions are falling so fast they are now back to levels last seen in the 1990s. So the two technologies most reliably and stridently opposed by the environmental movement—genetic modification and fracking—have been the two technologies that most reliably cut carbon emissions.

Global warming stopped 16 years ago →

The world stopped getting warmer almost 16 years ago, according to new data released last week.

The figures, which have triggered debate among climate scientists, reveal that from the beginning of 1997 until August 2012, there was no discernible rise in aggregate global temperatures.

This means that the ‘plateau’ or ‘pause’ in global warming has now lasted for about the same time as the previous period when temperatures rose, 1980 to 1996. Before that, temperatures had been stable or declining for about 40 years.

Interesting.

Dr. Patrick Moore rips 'Greenpeace's Crime Against Humanity' for opposing Golden Rice →

Very harsh accusations against Greenpeace. Especially coming from Greenpeace's co-founder.

Greenpeace has openly and aggressively spread misinformation about Golden Rice since it was first invented and has continued to do so at every opportunity. They claim that there are better ways to alleviate vitamin A deficiency, such as vitamin pills and “home gardening”. Yet Greenpeace is doing nothing to implement alternative programs for the millions of victims, claiming the cause of vitamin A deficiency is “poverty”. One might ask if purposefully condemning millions of children to blindness and early death perpetuates poverty rather than alleviating it. Academies of Science around the world endorse the use of biotechnology, including genetic modification, to improve the nutrition and productivity of our food crops. There is zero evidence of any possible harm from these improvements.

It is clear by the facts that Greenpeace is guilty of crimes against humanity as defined by the International Criminal Court. They claim that “Golden Rice is a failure” while they are the ones responsible for preventing the cure that is so desperately needed by millions of civilians. The fact that Greenpeace perpetuate lies about Golden Rice while at the same time doing nothing to solve the problem themselves constitutes gross negligence on top of the crime against humanity. Will someone please bring them to justice?

Why the Engine Failure Could be Good News for SpaceX →

SpaceX had an engine failure on Sunday. Rand Simberg thinks that's a good thing.

From an engineering perspective, all of this is good news for two reasons.

First, prior to this flight, the idea that the Falcon 9 could still get to orbit even with an engine out was just a marketing claim. Proving it would have required a demonstration in a test flight. Now that claim has been demonstrated and validated in an operational flight, if accidentally. While SpaceX's competitors and opponents will point to the engine loss as a reason for concern, in reality it should increase confidence in the company’s product. Every rocket provider has problems (United Launch Alliance's Delta IV, one of Falcon’s competitors, had a second-stage engine issue itself just last week), but in this case the design was sufficiently robust to overcome them exactly as the designers intended.

Second, if the engine really had exploded, this would have potential safety implications for a crewed version of SpaceX's Dragon capsule. Consider that the upper stage of the Falcon 9 uses the same Merlin 1C engine as the first stage, except with a few changes such as a larger nozzle for vacuum operations and passive radiative cooling rather than the “regenerative” cooling in the first-stage engines (it pumps fuel through channels in the nozzles to carry away the heat). The biggest difference, though, is that there is only one Merlin engine for the upper stage. So if it fails, the mission fails.

There have now been four flights of the Falcon 9, with ten engines each (nine for the first stage, one for the second). Counting the one engine failure from last night’s launch, that means that the engine has a demonstrated operational reliability of 39 out of 40, or 97.5%. That means that there’s a 2.5% chance that the engine would fail in an upper stage (where it has no backup), and would imply that this is an upper boundary on the reliability of the rocket itself (because other things could go wrong). This is in the typical ballpark of mission reliability for expendable launch vehicles for the past half century.

Interesting.

This entry was tagged. Innovation

How "Policy By Panic" Can Backfire for Environmentalists →

Remember how, in the wake of Hurricane Katrina in 2005, Al Gore (and many others) claimed that we were in store for ever more devastating hurricanes? Since then, hurricane incidence has dropped off the charts; indeed, by one measure, global accumulated cyclone energy has decreased to its lowest levels since the late 1970’s. Exaggerated claims merely fuel public distrust and disengagement.

That is unfortunate, because global warming is a real problem, and we do need to address it. Warming will increase some extremes (it is likely that both droughts and fires will become worse toward the end of the century). But warming will also decrease other extremes, for example, leading to fewer deaths from cold and less water scarcity.

This entry was tagged. Global Warming

Are GMO foods safe? Opponents are skewing the science to scare people. →

I started paying attention to how anti-GMO campaigners have distorted the science on genetically modified foods. You might be surprised at how successful they've been and who has helped them pull it off.

I’ve found that fears are stoked by prominent environmental groups, supposed food-safety watchdogs, and influential food columnists; that dodgy science is laundered by well-respected scholars and propaganda is treated credulously by legendary journalists; and that progressive media outlets, which often decry the scurrilous rhetoric that warps the climate debate, serve up a comparable agitprop when it comes to GMOs.

In short, I’ve learned that the emotionally charged, politicized discourse on GMOs is mired in the kind of fever swamps that have polluted climate science beyond recognition.

Well. The anti-science idiots exist on the left too. Worse, this kind of idiocy kills people, since it keeps people from planting GMO crops, thereby keeping crop yields lower than they have to be, and making food more expensive.

This entry was tagged. Food Poverty

No Pulse: How Doctors Reinvented The Human Heart →

This article was fascinating from beginning to end.

“Rare-earth magnets!” Cohn cried, straining to pull one free. He put it in my hand. It was the size of a pencil eraser, and when I loosened my grip, it shot like a bullet to the file cabinet with a clang. “Extremely powerful.” Cohn has pioneered the use of rare-earth magnets to move catheters into place deep inside the body. He avoids having to cut patients open by threading the magnets, and their tiny loads, up through arteries. He pawed several sheets of paper off the floor and drew diagrams on their unused backs, launching an hour-long discourse on the instruments and procedures he’s built around miniature magnets.

Building a heart that mimics nature's lub-dub may be as comically shortsighted as Leonardo Da Vinci designing a flying machine with flapping wings.On his wall hung four metal serving spoons of the kind you might see on a cafeteria line. One was intact; the other three had intricate slots cut in them. Years ago, Cohn butchered the spoons in his home garage to solve the problem of holding a heart still while operating on it. The standard way, at the time, was to shut off the heart altogether and put the patient on a heart-lung machine. But that was risky. Cohn’s spoons let surgeons hold a heart in place while still giving them access to the parts they needed to slice or stitch. Through the custom-cut slots, the surface of the heart would emerge and hold still for tinkering, even while the rest of the heart thrashed around under the spoon. Cohn refined the idea and sold it to a medical-devices company, which has marketed the tools worldwide.

I love genius/crazy scientists who push forward the state of the art.

This entry was tagged. Good News

The Fat Trap →

I think, as a society, we need to stop looking at weight as a moral issue and look at it more as a medical issue. Some people don't gain weight, no matter what they do. Others can't lose weight (and keep it off) no matter what they do. It appears that biology matters far more than mere willpower.

While researchers have known for decades that the body undergoes various metabolic and hormonal changes while it’s losing weight, the Australian team detected something new. A full year after significant weight loss, these men and women remained in what could be described as a biologically altered state. Their still-plump bodies were acting as if they were starving and were working overtime to regain the pounds they lost. For instance, a gastric hormone called ghrelin, often dubbed the “hunger hormone,” was about 20 percent higher than at the start of the study. Another hormone associated with suppressing hunger, peptide YY, was also abnormally low. Levels of leptin, a hormone that suppresses hunger and increases metabolism, also remained lower than expected. A cocktail of other hormones associated with hunger and metabolism all remained significantly changed compared to pre-dieting levels. It was almost as if weight loss had put their bodies into a unique metabolic state, a sort of post-dieting syndrome that set them apart from people who hadn’t tried to lose weight in the first place.

… Another way that the body seems to fight weight loss is by altering the way the brain responds to food. Rosenbaum and his colleague Joy Hirsch, a neuroscientist also at Columbia, used functional magnetic resonance imaging to track the brain patterns of people before and after weight loss while they looked at objects like grapes, Gummi Bears, chocolate, broccoli, cellphones and yo-yos. After weight loss, when the dieter looked at food, the scans showed a bigger response in the parts of the brain associated with reward and a lower response in the areas associated with control. This suggests that the body, in order to get back to its pre-diet weight, induces cravings by making the person feel more excited about food and giving him or her less willpower to resist a high-calorie treat.

This entry was tagged. Food Healthy Living

What's Wrong With the Teenage Mind? →

I thought this was very interesting. I think the key takeaway is that there's a very good argument for giving your kids true responsibility at early ages.

The crucial new idea is that there are two different neural and psychological systems that interact to turn children into adults. Over the past two centuries, and even more over the past generation, the developmental timing of these two systems has changed. That, in turn, has profoundly changed adolescence and produced new kinds of adolescent woe.

… The first of these systems has to do with emotion and motivation. It is very closely linked to the biological and chemical changes of puberty and involves the areas of the brain that respond to rewards.

… The second crucial system in our brains has to do with control; it channels and harnesses all that seething energy. In particular, the prefrontal cortex reaches out to guide other parts of the brain, including the parts that govern motivation and emotion. This is the system that inhibits impulses and guides decision-making, that encourages long-term planning and delays gratification.

This entry was tagged. Children

Can your genes help create ‘designer’ diets? →

Scientists at the University of Miami are doing an interesting research project. I've wonder about this a lot recently, as I monitor what I eat and how my weight changes (especially compared the reports of others).

“I believe if we look at people at the molecular level we can improve their health,” says Sylvia Daunert, Ph.D., chair of the Department of Biochemistry and Molecular Biology at the UM Medical School. The studies question long-held beliefs about food selection and weight loss. For example, could 1,000 calories of turkey cause more weight gain in some people than 1,000 calories of cashews? If so, could a person lose weight through food selection without cutting total calories?

And could a person’s genes pre-determine whether he or she will benefit from a particular type of exercise – or perhaps be at greater risk of injury from it?

UM researchers are looking into it. “We can’t say this is 100 percent correct,” Daunert says. “This is our hypothesis. This is brand-new science.”

This entry was tagged. Food Research

Drug Slims Down Obese Monkeys by Killing Fat Cells →

In a study that provides provocative support for a new approach to treating obesity, a drug that kills a particular type of fat cell by choking off its blood supply was shown to cause significant weight loss in obese monkeys.

After four weeks of treatment at M.D. Anderson Cancer Center in Houston, obese monkeys given daily injections of the drug, called adipotide, lost an average of 11% of their body weight. They also had substantial reductions in waist circumference and body-mass index and, importantly, striking improvement in the ability to respond to insulin, researchers said. The drug didn't have any effect on weight when given to lean monkeys.

Results of the study, published online Wednesday by the journal Science Translational Medicine, confirmed a 2004 report from the same research team showing marked weight loss in mice treated with the agent.

My first reaction was: "I want to take this drug". My second reaction was "I should invest in this drug. Everyone is going to want to take it."

Sugar, and candy, do not make kids hyper →

In my favorite of these studies, children were divided into two groups. All of them were given a sugar-free beverage to drink. But half the parents were told that their child had just had a drink with sugar. Then, all of the parents were told to grade their children’s behavior. Not surprisingly, the parents of children who thought their children had drunk a ton of sugar rated their children as significantly more hyperactive. This myth is entirely in parents’ heads. We see it because we believe it.

This entry was tagged. Research

A Standing Desk? →

I’ve been considering switching to a standing desk for about a year now. This article from Art of Manliness gives a good overview for why and how.

5 Reasons Why:

  1. To Avoid an Early Grave
  2. To Lose Weight
  3. To Save Your Back
  4. To Increase Your Focus
  5. To Gain a Satisfying Tiredness

High Fat Foods Don’t Appear to Cause High Cholesterol

As I think about losing weight (which I do (think about, that is) from time to time), I’m always interested in what kind of a diet would be most effective. I’m most convinced by what I’ve read about low-carb, high protein, high fat diets. But, inevitably, the first objection I’ll hear is that a diet high in eggs and cheese is a diet that will lead to high cholesterol and heart problems.

Stephen Guyenet recently reviewed the literature. He found that there is very little evidence that diets high in saturated fats give you high cholesterol.

The earliest and perhaps most interesting study I found was published in the British Medical Journal in 1963 and is titled "Diet and Plasma Cholesterol in 99 Bank Men" (4). Investigators asked volunteers to weigh all food consumed at home for 1-2 weeks, and describe in detail all food consumed away from home. Compliance was good. This dietary accounting method was much more thorough than in most observational studies today**. Animal fat intake ranged from 55 to 173 grams per day, and blood cholesterol ranged from 154 to 324 mg/dL, yet there was no relationship whatsoever between the two. I'm looking at a graph of animal fat intake vs. blood cholesterol as I write this, and it looks like someone shot it with a shotgun at 50 yards. They twisted the data every which way, but were never able to squeeze even a hint of an association out of it.

Overall, the literature does not offer much support for the idea that long term saturated fat intake has a significant effect on the concentration of blood cholesterol. If it's a factor at all, it must be rather weak, which is consistent with what has been observed in multiple non-human species (13).

I found another interesting analysis, published last January in the American Journal of Clinical Nutrion. In it, the authors did a meta-analysis of lots of other studies. They also concluded that there is very little relationship between the fat in your diet and the fat (cholestrol) in your blood.

BACKGROUND: A reduction in dietary saturated fat has generally been thought to improve cardiovascular health.

OBJECTIVE: The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies.

DESIGN: Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD.

RESULTS: During 5-23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results.

CONCLUSIONS: A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

This entry was tagged. Foods Research