Can a Genetic DNA Test Provide Real Insight on Your Health?

Written by Dr. Steve Chaney on . Posted in genetic dna testing

None Of Us Are Perfect

Author: Dr. Stephen Chaney

 

genetic dna testMost of us think of genetic diseases as something that is very rare. We have learned about diseases like cystic fibrosis or sickle cell disease in school. Those are examples of diseases caused by a rare mutation. If both chromosomes carry the mutation, you have the disease. If not, you don’t.

Can a genetic dna test give you real insight on your health?

We also know that family history is a strong predictor of genetic predisposition. If you are a guy, and most of the males in your family tree have dropped dead of a heart attack at an early age, you can assume you are genetically predisposed to heart disease. If you are a gal and most of the women in your family tree have developed breast cancer at an early age, you can assume you are genetically predisposed to breast cancer.

However, if none of these apply, we assume we are “normal”. We think we’ll probably live to 120. All this healthy lifestyle “stuff” is nice, but it isn’t a priority. It makes me think of Garrison Keillor’s tales of “Lake Wobegon” where all the children were above normal.

What if that weren’t true? What if none of us were normal? What if all of us are predisposed to some disease, perhaps even multiple diseases, and didn’t know it? Would that change how we thought about making the effort to follow a healthy lifestyle?

None Of Us Are Perfect

humans are not perfectOn one hand, this study (MacArthur et al, Science, 335: 823 – 828, 2012 ) may seem of interest only to geneticists, but its implications are huge. The authors looked at genetic variation among the human genomes sequenced as part of the human genome project. Specifically, they looked for loss of function (LOF) variants – mutations that would either partially or completely prevent the synthesis of a functional protein.

After a very complex genetic analysis they concluded that each of us harbors about ~100 LOF variants (mutations) in our genome.

Some of those mutations were in genes coding for proteins that have no known function. Other mutations coded for proteins whose loss might affect minor things like taste sensation.

Still other mutations were in genes coding for proteins that were redundant because there are other proteins in the cell that can perform the same function (Just as NASA designed the space shuttle with backup systems that could take over if a primary system failed, our bodies are frequently designed with more than one enzyme that can carry out the same function).

And, as you might expect, some of those mutations were in genes associated with known diseases like sickle cell disease or cystic fibrosis – but those mutations were very rare.

However, the authors concluded that each of us harbors about 20 LOF mutations that completely inactivate essential genes and might increase the probability that we will develop certain diseases.

That got me thinking. It validated scientifically something that we have all known instinctively for a long time – none of us are perfect. Or, as my childhood friends might have more cruelly put it: “We’re all defective in one way or another.”

What Does This Mean For You?

Now some of you may be saying: “What does this mean for me?” When you carry this idea through to its ultimate conclusion, the bottom line message is:

1) Nutritional recommendations are based on averages – none of us are average.

2) The identified risk factors for developing diseases are based on averages – none of us are average.

3) Clinical trial results are based on averages – none of us are average.

4) Clinical trials on the benefits and dangers of supplementation are based on averages – none of us are average.

5) Even clinical trials of drug efficacy for treating disease or drug safety are based on averages – none of us are average.

That means lots of the advice you may be getting about your risk of developing disease X, the best way to treat disease X, or the role of supplementation in preventing disease X may be generally true – but it might not be true for you.

So, my advice is not to blindly accept the advice of others about what is right for your body. Learn to listen to your body. Learn what foods work best for you. Learn what exercises just feel right for you. Learn what supplementation does for you.

Don’t ignore your doctor’s recommendations, but don’t be afraid to take on some of the responsibility for your own health. You are a unique individual, and nobody else knows what it is like to be you.

 

What Can a Genetic DNA Test Tell You About Your Health?

no-one is averageYou may be thinking: “If we know all the loss of function (LOF) mutations that cause disease, I should just send my saliva off to one of those companies that promises to give you a genetic DNA test and advise you of all your disease risks.”

Not so fast. It isn’t that simple. Here’s what those genetic testing companies aren’t telling you.

  • Genetic predisposition to most diseases is caused by multiple mutations that each make small contributions to your disease risk. There are only a few LOF mutations that dramatically increase your risk of major diseases like cancer, heart disease, and diabetes. Unless you have one of those rare mutations, you are in the dark about your disease risk.
  • LOF mutations are just the tip of the iceberg. There are many more mutations that affect regulation of metabolic pathways which impact your health. Many of these mutations are poorly defined at present. You might get a perfect score on your genetic testing and still be at risk for some major diseases.
  • The effect of LOF mutations on health outcomes varies from person to person. This is a phenomenon that my geneticist colleagues call “penetrance”. Simply put, the effect of any single mutation is modified by the expression of multiple other genes, which also vary from person to person. Your “score” on a genetic testing analysis may not predict your actual risk of disease.
  • Gene expression is modified by diet, lifestyle, and your environment. I have discussed this in previous articles like “Can Diet Alter Your Genetic Destiny?” and “What Is Epigenetics?”.  In short, genes do not determine your destiny. Your healthy lifestyle may protect you from a genetic predisposition to disease. Your unhealthy lifestyle may doom you to poor health in spite of a perfect score on your genetic testing analysis.

I only recommend genetic testing if you have a strong family history of a major disease and plan on working with a certified genetic counselor who can put the results of the analysis into the proper context.

 

The Bottom Line

 

  • A recent study looked at genetic variation among the human genomes sequenced as part of the human genome project. Specifically, the authors looked for loss of function (LOF) variants – mutations that would either partially or completely prevent the synthesis of a functional protein.
  • After a very sophisticated statistical analysis, the authors concluded that each of us harbors about 20 LOF mutations that completely inactivate essential genes and might increase the probability that we will develop certain diseases.
  • That means none of us are perfect. None of us are “average”. We all have genetic defects that predispose us to certain diseases. The implications are staggering.
  • Nutritional recommendations are based on averages – none of us are average.
  • The identified risk factors for developing diseases are based on averages – none of us are average
  • Clinical trial results are based on averages – none of us are average.
  • Clinical trials on the benefits and dangers of supplementation are based on averages – none of us are average.
  • Even clinical trials of drug efficacy for treating disease or drug safety are based on averages – none of us are average.
  • That means lots of the advice you may be getting about your risk of developing disease X, the best way to treat disease X, or the role of supplementation in preventing disease X may be generally true – but it might not be true for you.
  • So, my advice is not to blindly accept the advice of others about what is right for your body. Learn to listen to your body. Learn what foods work best for you. Learn what exercises just feel right for you. Learn what supplementation does for you.

I am not saying we know everything we need to know about genetic predisposition to disease. I’m not saying that genes determine our destiny. I’m not recommending you send off your saliva for a genetic analysis to determine your risk of developing a major disease. To understand why, read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Should You Avoid Sugar Completely?

Posted October 24, 2017 by Dr. Steve Chaney

Is It The Sugar, Or Is It The Food?

Author: Dr. Stephen Chaney

 

Should we avoid sugar completely?  Almost every expert agrees that Americans should cut down on the amount of sugar we are consuming. However, for some people this has become a “sugar phobia”. They have sworn that “sugar shall never touch their lips”. Not only do they avoid sugar sweetened sodas and junk food, but they also have become avid label readers. They scour the label of every food they see and reject foods they find any form of sugar listed as an ingredient. Is this degree of sugar avoidance justified?

 

Should We Avoid Sugar to Keep it From Killing Us?

 

Let me add some perspective:

  • If you just take studies about the dangers of sugar at face value, sugar does, indeed, look dangerous. Excess sugar consumption is associated with increased risk of obesity, diabetes, and heart disease. However, when you look a little closer, you find that most of these studies have been done by looking at the correlation of each of these conditions with sugar sweetened beverage consumption (sodas and fruit juices).

A few studies have looked at the correlation of obesity and disease with total “added sugar” consumption. However, 71.6% of added sugar in the American diet comes from sugar sweetened beverages and junk food. None of the studies have looked at the sugar from healthy foods like fruits, vegetables, and whole grains. That’s because there is ample evidence that these foods decrease the risk of obesity, diabetes, and heart disease.

  • For example, if apples had a nutrition label, it would list 16 grams of sugar in a medium 80 calorie apple, which corresponds to about 80% of the calories in that apple. The sugar in an apple is about the same proportion of fructose and glucose found in high fructose corn syrup. Apples are not unique. The nutrition label would read about the same on most other fruits. Does that mean you should avoid sugar from all fruits? I think not.

Avoid Sugar or Avoid Certain Foods

 

avoid sugar from junk foodsThe obvious question is: “Why are the same sugars, in about the same amounts, unhealthy in sodas and healthy in fruits?” Let’s go back to those studies I just mentioned—the ones that are often used to vilify sugars. They are all association studies, the association of sugar intake with obesity and various diseases.

The weakness of association studies is the association could be with something else that is tightly correlated with the variable (sugar intake) that you are measuring. Could it be the food that is the problem, not the sugar?

If we look at healthy foods (fruits, vegetables, whole grains) they are chock full of vitamins, minerals, phytonutrients, fiber, and (sometimes) protein. Fiber and protein slow the absorption of sugar into the bloodstream. As a result, blood sugar levels rise slowly and are sustained at relatively low levels for a substantial period of time.

In sodas there is nothing to slow the absorption of blood sugar. You get rapid rise in blood sugar followed by an equally rapid fall. The same is true of junk foods consisting primarily of sugar, refined flour and/or fat.  Avoid sugar from those types of foods.

Another consideration is something called caloric density. Here is a simple analogy. I used to explain the concept of caloric density to medical students in my teaching days. There are about the same number of calories in a 2-ounce candy bar and a pound of apples (around 278 in the 2-ounce candy bar and 237 in a pound of apples). You can eat a 2-ounce candy bar and still be hungry. If you eat a pound of apples you are done for a while. In this example, the 2-ounce candy bar had a high caloric density (a lot of calories in a small package). Perhaps a more familiar terminology would be the candy bar was just empty calories.

Are Sodas and Junk Foods Killing Us?

avoid sugar from candyPutting all that together, you can start to understand why the foods the sugars are in are more important than the sugars themselves. When you consume sugars in the form of sugar sweetened beverages or sugary junk foods, your appetite increases. We don’t know for sure whether it is the intense sweetness of those foods, the rapid increase and fall in blood sugar, or the high caloric density (lots of calories ina small package) that makes us hungrier. It doesn’t matter. We crave more food, and it isn’t usually fruits, vegetables, and complex carbohydrates we crave. It’s more junk. That sets in motion a predictable sequence of events.

  • We overeat. Those excess calories are stored as fat and we become obese. [Note: The low carb enthusiasts will tell you our fat stores come from carbohydrates alone. That is incorrect. All excess calories, whether from protein, fat, or carbohydrate, are stored as fat.]
  • It’s not just the fat you can see (belly fat) that is the problem. Some of that fat builds up in our liver and muscles. This sets up an unfortunate sequence of metabolic events.
  • The fat stores release inflammatory cytokines into our bloodstream. That causes inflammation. Inflammation increases the risk of many diseases including heart disease and cancer.
  • The fat stores also cause our cells to become resistant to insulin. That reduces the ability of our cells to take up glucose, which leads to hyperglycemia and type 2 diabetes. [Note: The low carb enthusiasts will tell you carbohydrates cause type 2 diabetes. That is also incorrect. It is our fat stores that cause insulin resistance and type 2 diabetes. Our fat stores come from all excess calories, not just excess calories from carbohydrates.]
  • Insulin resistance also causes the liver to overproduce cholesterol and triglycerides and pump them into the bloodstream. That increases the risk of heart disease.
  • Sugar sweetened beverages and sugary junk foods also displace healthier foods from our diet. That leads to potential nutrient shortfalls that can increase our risk of many diseases.

However, none of this has to happen. The one thing that every successful diet has in common is the elimination of sodas, junk foods, fast foods and convenience foods. You should avoid sugar from those foods as much as possible. Once you eliminate those from your diet,you significantly enhance your chances of being at a healthy weight and being healthy long term.

 

What About Protein Supplements And Similar Foods?

Of course, the dilemma is what you, as an intrepid label reader, should do about protein supplements, meal replacement bars, or snack bars. They are supposed to be healthy, but the label lists one or more sugars. Even worse, the sugar content is higher than your favorite health guru recommends.  So, should you avoid sugar from supplements and the like?

In this case, a more useful concept is glycemic index, which is a measure of the effect of the food on your blood sugar levels. Healthy foods like apples may have a high sugar content, but they havea low glycemic index.

avoid sugar and consume protein to slow absorbptionThe same is true for the protein supplements and bars you are considering. Rather than looking at the sugar content, you should be looking for the term “low glycemic” on the label. That means there is enough fiber and protein in the food to slow the absorption of sugar into the bloodstream and stabilize your blood sugar levels.

What Does This Mean For You?

Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should work on ways to avoid sugar or reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners. I have warned about the dangers of artificial sweeteners previously.

We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. For example, some Starbucks drinks are mostly sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

So we don’t have to avoid sugar completely, but we should reduce sugar from sugar sweetened beverages and junk food.

 

The Bottom Line

 

We need to keep warnings about the dangers of sugar in perspective:

  • The studies showing that sugar consumption leads to obesity, diabetes, and heart disease have all been done with sodas and junk foods.
  • Many fruits have just as much sugar as a soda. They also contain about the same proportion of fructose and glucose as high fructose corn syrup. Yet we know fruits are good for us.
  • Diets rich in fruits, vegetables and whole grains decrease our risk of obesity, diabetes, and heart disease.
  • That is because the sugar in whole foods is generally present along with fiber and protein, which slows the absorption of sugar and prevents the blood sugar spikes we get with sodas and junk foods.
  • In the case of prepared foods like protein supplements, you should look for “low glycemic” on the label rather than sugar content. Low glycemic means that there is enough fiber and protein in the product to slow the absorption of sugar and prevent blood sugar spikes.
  • Don’t misunderstand me. I am not advocating for unlimited consumption of sugar. We should all work on ways to avoid sugar from junk foods or to reduce the amount of sugar in our diet. On the other hand, we don’t need to become so strict that we and our family need to eat foods that taste like cardboard. We also don’t want to replace natural sugars with artificial sweeteners.
  • We can go a long way towards reducing sugar by just eliminating sodas, other sugar sweetened beverages, junk foods, fast foods, convenience foods, and pastries from our diet. When considering fast foods and convenience foods, we should check the label for hidden sugar. When considering foods that are supposed to be healthy, we should look for the term “low glycemic” on the label.

For more details, read the article above.

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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