Hunger

It's resolution time.  A time when many people try to lose weight and get healthy.  Most don't succeed.  They may do well for a month or two, or maybe six, but the vast majority give up and eventually put back on all the weight they may have lost.  Most people believe they fail because they aren't disciplined enough, they are weak and have no will power.  Maybe there is another more obvious reason why these calorie restricted diet plans fail so often.

Maybe they are Hungry!!

Now I'm not talking about hunger that comes from boredom or seeing a pizza commercial.  I'm talking about physiological hunger that comes from metabolic disturbances that leads to unbalanced hormones.  There actually is quite a bit of good science on hunger.  J. Stanton wrote a great series on hunger on his blog at gnolls.org (1).  He also gave a talk on hunger at the Ancestral Health Symposium that you can watch on youtube.  (2).  I will try to summarize a few points from his blog post here.

Why are we hungry?  What is metabolic flexibility?

We assume that people gain weight because they eat too much.  But what if we have the causal relationship mixed up. There is evidence that for at least some people, they eat too much because they are gaining weight. This fact is obvious when we talk about vertical growth.  No one would say that the biggest difference between someone who is 7' tall and someone who is 5'6" is that the tall person ate more and moved less! Do you really believe that they would only be 6' tall if they ate less?  Although it is true that a 7' tall 300 lb person would have to eat more than a 5'6" tall 140 lb person, they don't get taller because they eat more.  They get taller because they are secreting more hormones that promote growth.  As a result they have an increased appetite and they eat more and grow taller.  So if people eat more because hormones are making them grow taller why don't we ever ask if other people eat more because a hormonal imbalance is making them grow wider?

One factor that can contribute to this hormonal imbalance is a loss of metabolic flexibility.  We have two main sources of energy for our bodies, fat and glucose.  Studies have shown that obese people have a broken metabolism and don't burn fat very well (3).

Here are a couple of interesting points from the cited study:

• Normal subjects are burning 30% more calories at rest than the formerly obese.
• Normal subjects are burning 7% carbs and 78% fat at rest, whereas formerly obese subjects are burning 49% carbs and 34% fat at rest

 Our bodies can only store a small amount of glucose, but even a lean person will have at least 50 000 calories of stored body fat.  People who burn higher amounts of glucose will use their stored glucose much faster than a metabolically flexible person who is burning mostly fat.  A few hours after eating, their brains realize they are using up their stored glucose and it starts conserving glucose by lowering blood sugar.  Your brain takes priority because if your brain doesn't have energy you die.  Low blood sugar causes fatigue, brain fog, and a hormonal response that leads to insatiable hunger.  Meanwhile, the metabolically flexible skinny person has been burning mostly fat so they have plenty of stored glucose left.  Their brain is happy and their blood sugar is more stable.  They don't get the hormonal response that increases hunger.  For them it doesn't take much willpower to walk by the vending machine at 11 a.m. since they are not hungry.  For the metabolically damaged obese person who has low blood sugar and large amounts of circulating hunger hormones it takes a HUGE amount of willpower to walk by the vending machine without getting a snack.

 Why are we hungry?  Malnutrition?

 

Another factor that can affect hunger is malnutrition.  We live in a food culture today that provides us with more calories than we need, but does not provide us with the nutrients we need.  Research has shown that nutrient deficiencies can lead to over consumption.

In this study (4) two groups of rats were fed the same diet, but one group was supplemented with 25 vitamins and minerals.  They were then given unlimited access to a sugar water solution as well as their regular food.  .

• The supplemented rats ate 60% less sugar than the rats who weren't supplemented.

So the researchers didn't have to tax sugar, or make the rats feel guilty about being a glutton, all they had to do to reduce sugar consumption was to increase the nutrient density of their diets!!

These two studies looked into the effect of  multivitamins (5).  In one study, both the supplemented and non supplemented groups ate as much as they wanted.  In the other study, both groups were on calorie controlled diets and consumed the same amount of calories.

• In the first study the supplemented group had a lower body weight, lower fat mass and a tendency for greater resting energy expenditure.
• In the second study the weight loss was the same in both groups but the supplemented group reported less hunger.

So what does this all mean?

 

A few take away points that may help you if your New Years Resolution is to lose weight. 

Most of the time people who try to lose weight by eating less and moving more fail (6) .  The biggest reason for this is that eating less and moving more makes you hungry.  You can fight your hunger for a while, but eventually your physiology will win. 

If you have a broken metabolism, then eating less of the same diet that contributed to your broken metabolism will not fix the problem.

Even worse, if you are malnourished, eating less of the same diet will make you even more malnourished!

To increase your chances of being successful you have to change what you eat, not just how much you eat. 

A high fat, low carb diet out performs a low fat diet in virtually every study comparing a low fat calorie restricted diet to a high fat, low carb diet (7).  High fat diets lead to greater weight loss as well as greater improvements in heart disease risk factors!!

A high fat, low carb paleo diet forces your body to become metabolically flexible again.  By restricting your bodies access to glucose you force it to up regulate the metabolic pathways and enzymes needed to burn fat.  You may feel lethargic for a couple weeks during this process, but once you become metabolically flexible and start relying on fat as a fuel instead of glucose you will have increased energy and much lower hunger.

A high fat paleo diet also includes some of the most nutrient dense foods on the planet.  Meat, especially organ meat like liver, eggs, fatty fish and non starchy vegetables are packed with nutrients.  More nutrients will mean less hunger.   After being low carb for a few months you can start adding in some sweet potato, white potato or white rice and see how you react.  Everyone has a different carb tolerence based on activity levels, genetics and metabolic health. 

Testosterone

I am going to be talking to Phil Johnson on AM1150 today about testosterone.  Low T seems to be becoming more common than it used to be.  We have to careful to not mistake common for normal. (1)  A gradual decrease in Testosterone is a normal part of aging, but the low levels that are becoming more common are not normal.

Is Low T really that bad? 

Low Testosterone is associated with lower muscle mass(2), low libido(3),  depression(4), low bone density(5), and even death.(6)

There are two main causes of low T. Primary hypogonadism  is caused by a problem with the testes.  Secondary hypogonadism is caused by imbalances in the bodies hormonal system.  As with most health issues diet, lifestyle and exercise play a huge role in Secondary hypogonadism.

War on Cholesterol strikes again! 

 

It isn't surprising that low vitamin D levels are associated with low testosterone (7) since both vitamin D and Testosterone are made from cholesterol.  Without cholesterol we cannot make any of our steroid hormones, including testosterone.  We have been told to "Go Lower" and try and get our cholesterol as low as possible without realizing that cholesterol is one of the most important molecules in our bodies. (8)   There are 65 year old men with low testosterone trying to lower their cholesterol even though studies have shown that in elderly people, those with the highest cholesterol live the longest!!(9) , (10) , (11)

Saturated fat has also been vilified so many men have switched to a low fat diet.  Research has shown that low fat diets can reduce Testosterone in middle aged men (12).   Saturated and monounsaturated fat intake has been positively associated with testosterone levels (13)

Your Stressing me out!

 

Lifestyle factors are also associated with low T.  Stress can raise cortisol which can lower testosterone.  Cortisol levels can also be altered by disruption of circadian rhythms.  Too much light late at night from TV and computer screens and not enough bright light in the day can disrupt sleep patterns which can affect Testosterone (14).

Lift Heavy Things! 

 

Most men either don't exercise or don't do enough of the type of exercise that supports Testosterone.  Long, steady state, chronic cardio can have the same effect on Cortisol that stress has.  Excessive endurance training can cause testosterone and reproductive dysfunction in men (15). 

Lifting weights has been shown to increase post workout testosterone levels (16).  Sprinting has also been shown to increase testosterone (17).  Instead of spending an hour on the treadmill at the gym a better option might be to do a 4 minute tabata sprint training session (18). 

Good Week for Saturated Fat!!

Saturated fat has had some good press the last couple weeks. 

Dr. Perlmutter was on the Dr. Oz show extolling the benefits of butter. 

BMJ published a review article by British cardiologist Asseem Malholta in which he states that saturated fat and cholesterol are not the major issue causing heart disease. (1)

Catalyst, as news show on the ABC network in Australia aired part 1 of a 2 part series with many doctors and researchers who believe that saturated fat and cholesterol do not cause heart disease. (Part 2 will be on next week) It included a quote from George Mann, a retired professor of biochemistry and medicine at Vanderbilt University who worked on the Framingham heart study:

"One of the Framingham researchers became so dismayed with the results, he wrote a scathing review of the whole diet-heart hypothesis, saying that people had been misled 'by the greatest scientific deception of our times, the notion that animal fat causes heart disease'."

Recent Research

 

A 2010 meta-analysis published in the American Journal of Clinical Nutrition Concluded that:(2)

" 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."

Earlier this year a group examined data from The Sydney Diet Heart Study which was done in the 1970's.  In this study the experimental group decreased the saturated fat in the diet and increased the amount of omega 6 polyunsaturated fat. (polyonsaturated fats are the ones the various health agencies claim are heart healthy) 

 When originally published in in the 70's it did not include any data on Cardiovascular deaths.  I find this rather odd since it was called the Sydney Diet HEART Study.  Since the CVD deaths data was omitted I have seen this study used to support the theory that saturated fat causes heart disease since cholesterol was lowered in the low saturated fat group.

When the data was recovered and analyzed it showed that the group eating more saturated fat had lower  rate of CVD deaths than the group eating more polyunsaturated fats which led to the conclusion:(3)

" Advice to substitute polyunsaturated fats for saturated fats is a key component of worldwide dietary guidelines for coronary heart disease risk reduction. However, clinical benefits of the most abundant polyunsaturated fatty acid, omega 6 linoleic acid, have not been established. In this cohort, substituting dietary linoleic acid in place of saturated fats increased the rates of death from all causes, coronary heart disease, and cardiovascular disease. An updated meta-analysis of linoleic acid intervention trials showed no evidence of cardiovascular benefit. These findings could have important implications for worldwide dietary advice to substitute omega 6 linoleic acid, or polyunsaturated fats in general, for saturated fats."

 
 If all this is true why did all the health organizations start giving our dietary recommendations to cut saturated fat in the first place?

 Some bad science.

In the 1950's a researcher named Ancel Keys presented an observational study comparing the percentage of fat in the diet to death from heart disease in 6 countries shown below.  Thanks to Peter from Hyperlipid for the graphs.
 
 


As you can see Keys graph showed a correlation between fat intake and heart disease, it is almost a perfectly straight line.  There were a few problems with his study.  First it was an observational study so although it can show correlations it cannot provide any information on cause and effect.  I discussed the limitations of observational studies in a previous post.

Keys used 6 countries (Japan, Italy, England and Wales, Australia, Canada and the USA) in his study but there was data for 22 countries available when he did his study.  Using 6 other countries  shows a negative correlation between fat in the diet and deaths from heart disease.




 
  When all 22 countries are plotted on a graph they are all over the place and there isn't much of a correlation.  There are countries like the Netherlands that eat a lot of fat and a low rate of heart disease deaths.  In Finland they eat less fat than the Netherlands yet they have rate of heart disease deaths over 3 times as high.  The red dots below are data added from some hunter gatherer populations that eat a high fat diet and have very low rates of heart disease ( Masai, Inuit, Tokelau and a few others)



 

Politics in the American Heart Association

Keys study was initially met with skepticism.  The American Heart Association (AHA) did not immediately accept the diet heart hypothesis.  They acknowledged the correlation in the study but that did not mean there was any proof that reducing fat in the diet would reduce heart disease deaths.  Clinical trials needed to be done that showed a reduction in dietary fat would lead to lower heart disease deaths before they could give a diet recommendation to the American people.  By 1961 the AHA had changed its position and was now recommending a low fat diet.  Does this mean that the clinical trials had been done that proved a high fat diet caused heart disease?  No, those trials had not been done.  What had changed was that now Keys and a few other like minded people were on the AHA committee that made the decision to support Keys research.

The government will makes things better, right??

In 1968 a Senate Select Committee on Nutrition and Human Needs was formed headed by George McGovern.  Originally its mandate was to eliminate malnutrition but in the 70's they started looking into the link between diet and chronic disease.  At the time there was a controversy in the scientific community as to whether lowering the amount of fat in the diet would lead to improvements in health.  The committee  sided with Keys and the AHA despite protests from other researchers.  When the dissenting researchers told McGovern that there wasn't enough evidence to make these recommendation McGovern replied,

 “we Senators don’t have the luxury that a research scientist does of waiting until every last shred of evidence is in.”  

The following clip is from Tom Naughton's documentary "Fathead":

They were so sure that the theory that saturated fat causes heart disease was right they decided to release the guideline without proof they were correct.  They assumed that once the research was done it would validate the theory. ( You know what they say about assumptions )  For the last 40 years they have done study after study spending billions of dollars but have yet to prove that the theory is correct.  During that time people have been following that advice and we have become fatter and sicker.  Obesity and diabetes rates are skyrocketing.  I am hoping that the recent will convince people that the natural saturated fat we have been eating for thousands, if not millions of years is healthy and that the man made vegetable oils, sugars and refined grains that we have only been eating for about 100 years are the real problems in our diets. 

Re Post: why nutrition science is so bad

I am posting this article again to put it on the front page as I will be talking to Phil on 1150 am about it today.  

When I first started looking into nutritional science, I was shocked at how badly it was done.    To be fair, nutrition science if very difficult.  There are so many lifestyle and nutrition choices that can have a positive or negative influence on health, that it is hard to isolate the effect of any one food or group of foods.  There are two main types of studies; Observational (Epidemiological) studies and Controlled Experiments.  Tom Naughton has a really good video called “Science for smart People”  that explains the difference in an informative and humorous way.

The gold standard of science is the controlled experiment.  In a controlled experiment, you hold all variables constant except for the one variable that you are studying.  For example, if you wanted to study the effect of a fertilizer on growing plants, you would plant two groups of the same seeds.  You would use the same soil, same size pot; put the pots in the same area where the temperature and light exposure are the same, and give them the same amount of water.  You would put fertilizer in one but not the other.  If the plants in the fertilized pot grow faster and larger, then this would support your hypothesis that fertilizer helps plants grow.  

It is very hard to do this in a nutritional study.  The only way to be sure of the quality and quantity of food consumed, would be to lock people in a metabolic ward where food could be controlled.  You would have to weigh and measure all the food served, as well as all the food that wasn’t eaten.  Since most people are interested in being healthy for the rest of their life, and not just for the next 6 months, these studies would have to last 10 to 20 years to be really meaningful.  Not too many people would volunteer to be in a study that would lock them in a metabolic ward for 20 years!  (well, maybe Al Bundy would volunteer).  Even if you could do a study like this, it might not be relevant to the real world.  In a metabolic ward you have to stick to the diet; there is no other food choices.  In the real world, there are food choices on almost every street corner.  People have to be able to stay on a nutritional lifestyle long term for it to be useful. 

Very few controlled studies are done in nutritional science.  Almost all the studies we hear about are observational studies.  In these studies information is gathered on what people eat, usually with food frequency questionnaires.  These people are followed for a number of years and their health outcomes are observed.  Correlations are made between the food people ate and their health outcomes.  These types of studies have many limitations, the biggest being that they cannot provide any information on cause and effect.  Observational studies are useful for coming up with a new hypothesis, but then the hypothesis has to be tested in a Controlled Experiment.  A couple hypothetical studies from Tom Naughton's video might explain why this is.

If we were to do a study of the BMI of marathon runners compared to the BMI of the average person, you might find that running marathons is correlated with a lower BMI.  The conclusion of the study could say that running in marathons was linked, or correlated, or associated with a lower BMI.  They could not say that running in marathons causes you to become lean and have a lower BMI, even though most people hearing about this study would think that running marathons does cause people to have a lower BMI.  It conforms with our preconceived notions about exercise and weight, so we assume that causation is proved by the study.   If we look at another hypothetical study, it will illustrate why this is not the case.  If we did a similar study but used professional basketball players and height, we would find that playing basketball is correlated with being taller than the average person.  Does that mean that playing basketball causes you to grow taller?  If you are 5’6” and want to be 6’ tall, can you play basketball for a few years and expect to  grow?  Of course not!  Playing basketball doesn’t cause you to grow taller; it’s just that if you are tall you are more likely to play professional basketball.  The same logic can be used in the other study: Running marathons might not make you lean, it’s just that lean people are more likely to run marathons.  

When something in a study (A) is correlated with something else (B) it is easy to jump to the false conclusion that A is causing B.  A may or may not be causing B, as there is no way to know just from an observational study.  A may be causing B.  B may be causing A.  A third variable, C may be causing A and B.  This third variable C is what is called a confounding variable.  An example of this is that ice cream sales in Florida are correlated with shark attacks.  Does this mean that eating ice cream causes shark attacks?  Maybe the sharks like the ice cream dripping down your chin so they are more likely to attack.  Of course this is silly.  When it is hot, people eat more ice cream and they also go swimming more, which leads to more shark attacks.    Observational studies are full of confounding variables.  There are two main groups of people that influence the outcomes of nutritional studies.  There are people who are very health conscious and do whatever they can to be healthy, and those that do not care about their health and make food and lifestyle choices that are purely based on giving them pleasure.  People who are health conscious tend to have better health than people who are not health conscious.  They follow the health advice that has been generally given the last 40 years; they smoke less, drink less alcohol, exercise more, take vitamins, eat less calories, eat less sugar, eat less refined processed foods, and eat more vegetables.  Any one of these variables could be contributing to their good health, but from an observational study you can’t tell which one.  You would need a controlled experiment to do that.   

Another problem with observational nutritional studies is that the data collected is not very reliable.  It is usually collected using food frequency questionnaires.  In these studies people are asked to recall what they ate in the last day, month, year, or even four years.  You can find an example of a questionnaire here.  Most people can’t remember what they ate last Tuesday, let alone what they ate three years ago.  People who see themselves as healthy tend to overestimate foods they consider healthy and underestimate foods they consider unhealthy. Who wants to admit that their breakfast consisted of twinkies and oreos?  If the data that the study is based on is not accurate, then how useful is the study?

Some scientists can have such a strong belief in what the outcome of their study will be that they become biased.  Since there are so many confounding variables, you can make the outcome of a study say pretty much whatever you want it to say.  Most studies will try and account for these variables, but it is almost impossible to know exactly how much of a part each one played in someone’s health.  Some researchers will use a third variable to link two items when there is no direct link.  A good example of this is saturated fat, cholesterol and heart disease.  Many studies (such as Dr. Jolliffe's Anti-Coronary Club experiment mentioned here) will claim to show that saturated fat causes heart disease even if the data in their data shows that people who ate more saturated fat had a lower incidence of heart disease.  They do this by saying that saturated fat intake was associated with higher cholesterol, which is claimed to be a marker for heart disease. (Even though it has never been proven that high cholesterol causes heart disease)
 

This is why we get so many mixed messages from the so called “nutrition experts”.  The way Observational studies are reported, it gives the idea that they determine cause and effect when they really only show correlation. In one group of people a certain food may be correlated with high cancer rates, in another group they may be correlated with low cancer rates.  The truth may be that the food has NO impact on cancer rates.  As long as we remember the limitations of the study we won’t get sucked into these false assumptions.  So the next time you hear about the latest study telling you to stay away from a certain food, or that another food is a miracle cure, remember that 99% of these studies don’t actually prove anything.  

It is time to stop funding these types of observational studies.  How many studies do we need that give sensational headlines but do not add to our knowledge.  We have enough hypotheses about health and nutrition.  We need to start doing controlled experiments to find out which hypotheses about diet and nutrition result in healthy outcomes.  With obesity related diseases and health care costs skyrocketing, we need to find these answers now. 

Artificial Eggs??

Saw this article yesterday about artificial eggs.

I got me thinking how they are made.

We have been told eating animal products is bad for the environment.

We have been told recycling is good for the environment.

100 years ago most kitchens had one of the best recycling systems in history....Chickens.

Every day people would throw their kitchen scraps into the back yard to their chickens.

Every morning they would come into the kitchen with a basket of eggs. But then came progress.

Now we put our kitchen scraps out on the street so they can be picked up by a deisel powered truck to be taken to the city compost. 

The compost is then taken by another diesel truck to a large organic farm where it is spread by a diesel powered tractor.

Almost all the plants and animals that once lived on that farm are no longer there, the land was cleared to make way for the farm.

Tractors are used to plant and harvest the plants that are grown.

The plants are taken by another diesel truck to a processing plant that is powered by electricity probably generated from coal or nuclear energy.

The natural plant material is processed by mechanical, chemical or heating  methods until it becomes an egg substitute.

The egg substitute is then put on yet another diesel truck so it can be transported to supermarkets around the country where people living in suburbs put it in their gas powered cars and take it home to feed their family's.

We do all this because we have been told that recycling and eating a plant based diet is good for the environment and eating animal products is bad for the environment.

It never ceases to amaze me how much knowledge we have gained in the last 100 years, and how much wisdom we have lost!

Another reason why sunlight may be better than Vitamin D supplementation

Low levels of vitamin D have been associated with hypertension and increased rates of cardiovascular mortality. (1) Most of this evidence is from observational studies that don't have to power to determine cause and effect.  A 2011 Institute of Medicine Report for intake of calcium and vitamin D concluded "the evidence that vitamin D prevents CVD, diabetes or other cardiometabolic outcomes was inconsistent and inconclusive and did not meet criteria for establishing a cause and effect relationship" (2)

A recent study suggest that it may not be the vitamin D that reduces cardiovascular disease.  (3)  In a Tedx Talk that can be found below Richard Weller discusses the research that Vitamin D status might just be a marker for sunlight exposure.  The sunlight exposure itself may have  cardiovascular benefits, even without increases in vitamin D levels.

The research has found that our skin contains large stores of nitrate, nitrite and several reactive nitrogen oxide species.  When the skin is exposed to UV rays from the sun, these stores are converted to nitric oxide.  They have shown that 30 minutes of sun exposure can increase circulating nitrite, lower blood pressure and increased blood flow.  Nitric oxide is a vasodilator which lowers blood pressure.  Nitrite not only dilates blood vessels but also protects organs against ischaemia/reperfusion (I/R) damage. (4) 

Chris Masterjohn stated at his website Cholesterol-and-Health:

"Endothelial cells produce nitric oxide, a gas that protects LDL from oxidation, increases blood flow, decreases the adhesion of monocytes to the endothelium, and decreases blood clotting. Oxidized LDL impairs the endothelial cell's ability to produce nitric oxide" (5)

Vitamin D may very well have its own benefits when it comes to cardiovascular disease.  While supplementing with D3 may be beneficial at times of the year when we do not get enough sunlight, this study demonstrates that we would be better off getting our vitamin D from the sun.  It is always better to get nutrients from natural sources as much as possible.  Whole foods, as well as sunshine, may have benefits that we have not yet identified.  Supplements can supply some nutrients, but we miss out on all the unknown benefits found in nature.

This study also emphasizes why observational studies should be the starting point in science, not the end point.  If these researchers had just accepted the epidemiology and concluded it must be just the vitamin D protecting against heart disease they would not have made this discovery.  Not only do you risk giving credit or blame where it is not warranted, you miss the opportunity to ask the question, "What else could be causing this effect?"

Cholesterol, Part 1

Are you scared of Cholesterol? 

 

Why do we hear so much about trying to lower our cholesterol levels?  The story told by most doctors and drug companies is that  eating animal products that contain saturated fat and cholesterol clog your arteries and cause heart disease.  Saturated fats are solid at room temperature and will clog up your kitchen sink if you try and pour them down the drain so they will do the same thing in your blood vessels.  ( Even though you blood vessels are 15 C warmer than your kitchen pipes)  The scientists who believed cholesterol caused heart disease knew that analogy was ridiculous.  Their theory was that when there is too much cholesterol in the blood it gets stuck in the arterial wall which leads to the build up of plaque and atherosclerosis.

This Means War!

There is a  group of doctors and scientist who are waging a war on cholesterol.  They are trying to get your cholesterol levels as low as possible.The seem to believe that any amount of cholesterol is dangerous and their views can be summed up in the following quote:  "Eating foods that contain any cholesterol above 0 mg. is unhealthy"   T. Colin Campbell, PhD, author of The China Study

There is another group of "Cholesterol Skeptics" who say that cholesterol has nothing to do with heart disease.  They claim that measuring cholesterol at all is a waste of time.  I was confused so I started looking for the truth.  What I found that was there was some truth to both sides.  High cholesterol does not cause heart disease but the metabolism of cholesterol does play a role in heart disease.  I will expand on the latest theories of heart disease in this blog post series.  I found two websites that had a lot of well referenced material run by two incredibly smart people.   Chris Masterjohn, PhD  at his website "Cholesterol and Health" and Peter Attia, MD at his website "The Eating Academy" 

So what is cholesterol??  Is it really a dangerous substance?

Cholesterol is one of the most important molecules in the human body.  Every cell in your body has the ability to make cholesterol since every cell in your body needs cholesterol.  It is a critical part of cell membranes and is essential to cell membrane permeability.(1)

Cholesterol is needed for brain function.  It is involved in the development of synapses,(2) which enables brain cells to communicate with one another.  It is essential for myelin membrane growth which insulates neurons. (3)  The brain represents 2% of the mass of the  human body but it uses 25% of the cholesterol.  Cholesterol is vital to brain health.

Cholesterol is a precursor to all steroid hormones, which include sex hormones and adrenal hormones.(4)

Cholesterol is a precursor to Vitamin D.(5)

Cholesterol is essential to bile acid production which is used to digest and absorb fats and fat soluble vitamins.(6)

What happens to us if we don't have enough cholesterol?

Smith-Lemli-Opitz Syndrome (SLOS) is a metabolic disorder in which sufferers can not make enough cholesterol to support normal growth and development.  Symptoms of SLOS include mental retardation, poor growth, cleft palate, malformed genitals, extra fingers and toes, heart defects, hearing or sight loss and autism.  The most serious cases (produce almost no cholesterol) are spontaneously aborted during pregnancy or die a few months after birth. (8)


Low Cholesterol levels have also been linked to cancer (9), Depression and suicide (10), stroke (11), Infectious disease (12), autoimmunity (13), inflammation (14), and premature birth (15).

What about high cholesterol.

So we know cholesterol is an essential molecule but is too much cholesterol dangerous. Familial Hypercholesterolemia (FH)  is a genetic defect in which cholesterol levels are extremely high.  People with FH have an increased risk of heart disease.  This would suggest that high cholesterol is involved in heart disease.

But we also know that people with low cholesterol also get heart disease.  If high cholesterol causes heart disease how could you get heart disease if you had low cholesterol.  A 2008 study found that 73% of patients admitted to hospital with coronary heart disease had normal or low cholesterol levels. (16)  

Will eating eggs kill me

Many people do not eat eggs because they are trying to keep their cholesterol low.  Does eating cholesterol raise your cholesterol?  It turns out that cholesterol consumption has no effect on blood cholesterol for 70% of people.  Since about 75% of the cholesterol we need is made by our body if we eat more cholesterol our bodies respond by making and absorbing  less.  There is a slight increase in blood cholesterol in 30 % of people, but their HDL (the so called good cholesterol) goes up as much as their LDL  (so called bad cholesterol) so their cholesterol ratios actually get better.  

Even Ancel Keys, the father of the "lipid hypothesis", knew that eating cholesterol does not cause heart disease.  In 1997 he stated:

“There’s no connection whatsoever between the cholesterol in food and cholesterol in the blood. And we’ve known that all along. Cholesterol in the diet doesn’t matter at all unless you happen to be a chicken or a rabbit.”

Dr. William Castelli, the director of the Framingham Heart Study, stated in a 1992 editorial that:

 "... in Framingham Mass., the more saturated fat one ate, the more cholesterol one ate, the more calories one ate, the lower the person's serum cholesterol ... we found that the people who ate the most cholesterol, ate the most saturated fat, ate the most calories, weighed the least and were the most physically active."


So as you can see cholesterol in not an evil toxin.  It is a vital molecule that is needed for life.  In the next post we will examine how it came to be regarded as a dangerous substance.