So You Think Dietary Fat Causes Heart Disease?

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If you believe in unicorns, myth and mythology, you can continue to believe that fat in the diet causes heart blockages and heart attacks. If, on the other hand, you believe in science and evidence, you might want to question those beliefs. Because the evidence is in, and most people are wrong.

Bad science

So what was the problem to begin with? Americans made huge changes to their diets, the food industry changed its grocery store offerings, and lots of patients received rather severe tongue lashings from their doctors. All for no good reason. How could so many people be so wrong for so long?

Well, the answer is bad science.

Correlation is not causation

Scientists, including doctors, conduct trials to see if a particular theory or hypothesis is correct. Now, there are trials, and there are trials.

We have epidemiological studies, where segments of the population are followed for a number of years, and their health outcomes are noted. Observations are then made to see if those outcomes are correlated with certain habits or risk factors.

So what is the problem?

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Correlation is not causation. If two things are correlated, one does not necessarily cause the other. A rooster’s cry and the rising of the sun are correlated, but the rooster does not cause the sun to rise.

A murky beginning

The whole saga appeared to start in the 1970s. The Seven Countries Study by Ancel Keys revealed a strong correlation between the average amount of saturated fat in the diet, the average blood cholesterol levels, and the 10 year death rates from coronary heart disease (blockages in the heart arteries). Again, the key word is correlation. No cause and effect was proved.

However, what followed was an avalanche of government advice, and change in the food industry offerings. There were other epidemiological studies, but there was a lack of well-designed trials to support this undertaking.

What is a good trial?

Well, the gold standard is the so-called randomized controlled trial, often shortened to RCT. The details of such trials are beyond the scope of this article, but RCTs are better suited to look for a cause and effect relationship.

What were we told?

For over fifty years, we have been sold a bill of goods which was defective. And all of this based on epidemiological studies, of doubtful quality.

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Governments, and scientists, and doctors, told us that saturated fat was bad for us, that fat was bad for us. That consuming too much fat would cause blockages in the heart, leading to heart attacks, and premature death.

We were advised to cut down on fat, so that no more than 30% of our daily calories came from dietary fat. We were also told to limit saturated fat intake to no more than 10% of daily calories.

So what happened next?

Well, our calories come from carbohydrates, protein, and fat. If you eat less fat, you will tend to eat more of the other stuff. And that is what people did when they were asked to cut down on fat. They loaded up on carbohydrates. Not protein. Carbohydrates. In fact, in the late 20th century, the US government advised the public to start eating more carbohydrates, including 6-11 servings of grain products daily.

What next?

fat

Americans have dutifully heeded their government’s warnings about fat. Fat used to provide 40% of daily calories in the past. This has dropped to 30% in the last 30 years. But people have become heavier. Obesity rates have tripled in the last few decades. You don’t need data to know this. Just go to any mall or sports stadium and look around. Alarmingly, the incidence of type 2 diabetes has gone up many-fold.

So what is the problem?

It is clearly not dietary fat.

A meta analysis of prospective studies evaluating the association between saturated fat consumption and cardiovascular disease was published in the American Journal of Clinical Nutrition in January 2010. It analyzed 21 studies, which followed nearly 350,000 people over 5-23 years. It revealed that there was no significant evidence for concluding that saturated fat in the diet is associated with an increased risk of coronary heart disease or stroke.

Fat out, sugar in

Sugar

Sugar

The law of unintended consequences can be seen at work in this entire saga. Governments want less fat in the diet, so industry is urged to offer more low-fat products. But fat makes food taste good. Taking fat out worsens the taste. Thus, industry has been replacing fat with sugar, with results that we are seeing all around us: fatter people, with more diabetes. Also, we are witnessing a plateau in cardiovascular disease, which had been showing a decline for decades. And we may well see an uptick in this disease if things continue the way they are.

So is a calorie a calorie?

Not necessarily.

Food has metabolic consequences. A low-fat diet can lead to biological adaptations, such as increased feelings of hunger, a lower metabolic rate, and other components of a starvation response which tend to oppose weight loss.

Sugary drinks and sweets, as well as simple carbohydrates and starches, tend to increase blood levels of insulin, which is related to many chronic diseases, including diabetes and obesity.

Low-carbohydrate diets and low-glycemic index diets (with foods containing complex carbohydrates) tend to lower the levels of insulin in the blood, thus helping people maintain the weight loss they have achieved. Such diets might be protective against chronic diseases such as diabetes.

More recent studies

The Women’s Health Initiative Dietary Modification Trial revealed that over a mean of 8.1 years, a low-total fat diet did not significantly reduce the risk of heart disease or stroke in postmenopausal women.

The PREDIMED trial was a study of the Mediterranean diet in high risk people who were free from known coronary disease at the beginning of the trial. This study showed a 30% lower risk of having a major cardiovascular event in the higher- fat dietary groups compared with the low- fat control. This risk reduction is similar to that shown in the statin (cholesterol lowering drugs) studies, but at no cost to the health system!

Higher death rates?

A study by DD Wang and associates, published in JAMA Internal Medicine in August 2016, noted that men and women following low-fat/high-carbohydrate diets had higher rates of premature death, not lower.

Lesson learned?

Hardly!

The US government, through its Dietary Guidelines for Americans, 2015-2020, still recommends cutting down on saturated fat. These guidelines also state that a healthy eating pattern includes fat-free or low-fat dairy.

MILK

School lunch programs in the US provide only low-fat milk. No whole milk is provided at all, although they do allow chocolate skim milk with its added sugars. And this is in spite of the Dietary Guidelines calling for a restriction on added sugar.

And the general public, of course, keeps buying low-fat everything. In fact, at most grocery stores, it is hard to find full-fat dairy.

And this is in spite of a study published in the reputable journal Circulation early in 2016 which found that people consuming full-fat dairy had a 50% lower risk of diabetes, compared to those consuming the low-fat variety.

So what to do?

  • Don’t obsess about fat. The link between fat, especially saturated fat, and heart disease is tenuous at best.
  • Trans-fat is still bad for you. This is found in cakes, pies, cookies, biscuits, crackers, and many fried or processed foods.
  • Try to eat whole or minimally processed foods.
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  • Include lots of fruits and vegetables in your diet.
  • Cut down on sweets and sugary drinks, as well as simple carbohydrates.
  • Include whole grains in your diet.
  • Eating an ounce of nuts daily is good for you.
  • Low-fat dairy has no benefits over the full-fat variety, and may well be worse, according to recent data.

And finally

Focus more on the overall dietary pattern.

As Dr. Mozaffarian, a leading researcher, says, “If something has a food label, it’s probably not the best choice. We need to move away from the idea that we can manufacture an artificially healthy diet.”

How to Navigate Safely Through the Fat, Lipid, Omega World

 Confused yet?

Confused yet?

Doctors, scientists, and technical people take morbid delight in using terminology which the general public does not always understand fully. However, they get away with it, because people are loath to question them, not wanting to appear ill-informed. Thus, the media throws around terms like fats, lipids, oils, omega-3 fats, and the like, with abandon. And nobody takes them to task.

Speak clearly, please

Fat, lipid, and oil: These are commonly used terms, and their meaning needs to be crystal clear.

Our diet has three major constituents: protein, fats, and carbohydrates. We need fats to ensure our bodily structure and metabolism.

Fat

fat

This is chemically an ester, which is a compound formed by the combination of an acid with an alcohol. In the case of a fat, the acid is a fatty acid, and the alcohol is glycerol.

So a fat is basically a glyceride. If we have three fatty acid chains combining with glycerol, we have a triglyceride, which is another term which nobody explains, but which you see all the time on your report if you have a “cholesterol blood test.”

What, then, is a lipid?

A lipid is an organic compound having certain characteristics. Before we go further, let us refresh our understanding of organic and inorganic compounds.

Organic, inorganic, what’s the difference!

Chemistry consists mainly of organic and inorganic compounds.

Compounds associated with living beings are organic. They always have carbon atoms as part of their structure, while most inorganic molecules don’t.

Almost all of the organic compounds contain bonds between carbon and hydrogen (C—H). Some, however, do not, like urea.

Some examples of organic compounds are fats, lipids, sugars, proteins, nucleic acids, enzymes, etc.

Examples of inorganic compounds are metals, salts, and other molecules not containing carbon-hydrogen bonds.

Back to lipids

So lipids are organic compounds. They have carbon to hydrogen bonds, and they also have oxygen. The number of hydrogen atoms in a lipid molecule is always more than double the number of oxygen atoms.

The carbon to hydrogen bond in a lipid is a special one, called a nonpolar covalent bond. This means that the carbon and hydrogen atoms share a pair of electrons equally. The importance of this is that the molecule of a lipid is made fat soluble. It will not dissolve in water, though.

Types of lipids

Biologically, we have four important lipids. They are fats, steroids, phospholipids, and waxes.

So fat is a type of lipid.

All fats are lipids, but not all lipids are fats.

Then what is an oil?

Fats are usually solid at room temperature.

 OIL

OIL

A fat which is liquid at room temperature is called an oil.

Oils can have saturated, monounsaturated, and polyunsaturated fatty acids. Being liquid at room temperature, they tend to have more unsaturated fats than saturated ones.

Essential fat?

Yes, fat can be essential, in that the body would not function without a healthy dose of fat.

Alpha linolenic acid

Alpha linolenic acid

However, biochemically, the term “essential fatty acid” is applied to those fats which cannot be made by the body. Therefore, we have to eat them as part of our diets. There are two of them: alfpha-linolenic acid (an omega-3 fat) and linolenic acid (an omega-6 fat).

Other fats needed by us can be made by our bodies using these essential fats and other substances.

Are we saturated yet?

Saturated fat is bad, unsaturated is good: You have heard this refrain most of your life. It is not necessarily true.

But what is a saturated fat anyway?

Saturation

Atoms join with other atoms to make molecules. And molecules are what make up matter.

There are laws which govern this union. If a carbon atom is able to join with all the hydrogen atoms it possibly can, it is called saturated. It is happy. In that case, it combines with other carbon atoms with what is called a single bond, chemically shown as C—C. However, if it cannot combine with all the hydrogen atoms it is capable of, it ends up joining with other carbon atoms using a “double bond.” This is shown as C=C. This makes it unsaturated. The same is true of “triple bonds.”

How do you bond with others?

In a fatty acid molecule, if a carbon atom joins with another carbon atom using a double bond (or triple bond), that fat is called “unsaturated.” Otherwise (with carbon-to-carbon single bonds only) it is “saturated.”

Avocado with monounsaturated fat

Avocado with monounsaturated fat

If in one fatty acid molecule, there is only one double bond between two carbon atoms, that is called a “mono-unsaturated fat.”

The presence of more than one double bond makes the fat a “poly-unsaturated fat.”

What is this omega business?

If you are an adult, you must have heard of omega-3 and omega-6 fatty acids. One is supposed to be good, the other one not so good.

But what are they?

It is all about the ending

The fatty acids chains have two ends: the beginning and the tail. The beginning is the so-called acid end, and the tail is the methyl end. Since we are all in love with the Greeks, we call the beginning the “alpha end” (since alpha is the first letter in the Greek alphabet), and the tail is the “omega end.” Omega, of course, is the last letter of the Greek alphabet. This end is also called the n-end.

Omega-3?

This is a polyunsaturated fat. Which means that the fatty acid chain has more than one double bond (C=C).

The omega part means that you start looking at the tail end (omega end) of the chain. Then look at the third carbon atom from that end. If the first double bond occurs at this location, you are dealing with an omega-3 fatty acid.

Why is this important? Read on.

Omega-6?

Apply the same process as above. If the first double bond is at the 6th carbon atom from the tail end, you have an omega-6 fatty acid. Again, this is a polyunsaturated fat.

What’s the big deal?

Mono-unsaturated fatty acids are felt to be better for your health than poly-unsaturated fats. Among the poly-unsaturated fats, the omega-3s are again supposed to be better than the omega-6s.

In fact, many experts feel that in the ancient era, humans had much more omega-3s in their diets than omega-6s, and that nowadays this ratio has been reversed, leading to several ill-effects on our health.

And what about trans fats?

About this, not much debate exists. These fats are universally condemned as the worst types of fats for our heart health. Many localities in the US have legislated to ban them, or severely cut down on their presence in our food supply.

What’s so “trans” about the fat?

It is basically a chemical arrangement.

There are two types of arrangements of hydrogen atoms in unsaturated fatty acids (which have at least one double bond).

The “cis” type occurs when the two hydrogen atoms are on the same side of the double bond in the chain. “Cis” in Latin means “on this side.”

The “trans” type occurs when the hydrogen atoms are on opposite sides of the double bond (“trans” means “across” in Latin).

Again, what’s the big deal?

The trans configuration in unsaturated fatty acids creates problems. So why was it created? For convenience.

Of course, there are some naturally occurring trans fats also. These are produced in the guts of some animals. Meat and milk from these animals can have small amounts of trans fats.

Then we have artificial trans fats, which are created by the hydrogenation of vegetable oils.

Adding hydrogen to a liquid vegetable oil makes the product more solid, and increases its shelf life.

In some instances, trans fatty acids can alter the taste and texture of food in a manner which consumers like.

Oils containing trans fats are often used by fast-food chains and restaurants around the world, because such oils can be reused several times in commercial fryers to deep-fry food.

Trans fat = Bad fat

The hydrogenation of vegetable oil leads to a product which has serious implications for heart disease.

The trans fats produced in this manner can reduce the amount of “good cholesterol,” or HDL cholesterol, and increase the amount of “bad cholesterol, or LDL, in your blood stream.

Conclusion

  • The terms fats, oils, lipids, trans fats, omega-3, and omega-6 are frequently seen by the public, but not always fully understood. It is important to be clear about what they mean.
  • Fats can be saturated or unsaturated, and their ratio in our diet is important.
  • The ratio of omega-3 and omega-6 fats in our diets is also important.
  • Trans fats are the worst kinds of fats, and should be avoided as far as possible.

Food sources of different fats

We will discuss details of this, and their health implications, in subsequent posts.

Stay tuned!