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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High Protein Diets and Weight Loss

Posted October 16, 2018 by Dr. Steve Chaney

Do High Protein Diets Reduce Fat And Preserve Muscle?

Author: Dr. Stephen Chaney

Healthy Diet food group, proteins, include meat (chicken or turkAre high protein diets your secret to healthy weight loss? There are lots of diets out there – high fat, low fat, Paleolithic, blood type, exotic juices, magic pills and potions. But recently, high protein diets are getting a lot of press. The word is that they preserve muscle mass and preferentially decrease fat mass.

If high protein diets actually did that, it would be huge because:

  • It’s the fat – not the pounds – that causes most of the health problems.
  • Muscle burns more calories than fat, so preserving muscle mass helps keep your metabolic rate high without dangerous herbs or stimulants – and keeping your metabolic rate high helps prevent both the plateau and yo-yo (weight regain) characteristic of so many diets.
  • When you lose fat and retain muscle you are reshaping your body – and that’s why most people are dieting to begin with.

So let’s look more carefully at the recent study that has been generating all the headlines (Pasiakos et al, The FASEB Journal, 27: 3837-3847, 2013).

The Study Design:

This was a randomized control study with 39 young (21), healthy and fit men and women who were only borderline overweight (BMI = 25). These volunteers were put on a 21 day weight loss program in which calories were reduced by 30% and exercise was increased by 10%. They were divided into 3 groups:

  • One group was assigned a diet containing the RDA for protein (about 14% of calories in this study design).
  • The second group’s diet contained 2X the RDA for protein (28% of calories)
  • The third group’s diet contained 3X the RDA for protein (42% of calories)

In the RDA protein group carbohydrate was 56% of calories, and fat was 30% of calories. In the other two groups the carbohydrate and fat content of the diets was decreased proportionally.

Feet_On_ScaleWhat Did The Study Show?

  • Weight loss (7 pounds in 21 days) was the same on all 3 diets.
  • The high protein (28% and 42%) diets caused almost 2X more fat loss (5 pounds versus 2.8 pounds) than the diet supplying the RDA amount of protein.
  • The high protein (28% and 42%) diets caused 2X less muscle loss (2.1 pounds versus 4.2 pounds) than the diet supplying the RDA amount of protein.
  • In case you didn’t notice, there was no difference in overall results between the 28% (2X the RDA) and 42% (3X the RDA) diets.

Pros And Cons Of The Study:

  • The con is fairly obvious. The participants in this study were all young, healthy and were not seriously overweight. If this were the only study of this type one might seriously question whether the results were applicable to middle aged, overweight coach potatoes. However, there have been several other studies with older, more overweight volunteers that have come to the same conclusion – namely that high protein diets preserve muscle mass and enhance fat loss.
  • The value of this study is that it defines for the first time the upper limit for how much protein is required to preserve muscle mass in a weight loss regimen. 28% of calories is sufficient, and there appear to be no benefit from increasing protein further. I would add the caveat that there are studies suggesting that protein requirements for preserving muscle mass may be greater in adults 50 and older.

The Bottom Line:

1)    Forget the high fat diets, low fat diets, pills and potions. High protein diets (~2X the RDA or 28% of calories) do appear to be the safest, most effective way to preserve muscle mass and enhance fat loss in a weight loss regimen.

2)     That’s not a lot of protein, by the way. The average American consumes almost 2X the RDA for protein on a daily basis. However, it is significantly more protein than the average American consumes when they are trying to lose weight. Salads and carrot sticks are great diet foods, but they don’t contain much protein.

3)     Higher protein intake does not appear to offer any additional benefit – at least in young adults.

4)     Not all high protein diets are created equal. What some people call high protein diets are laden with saturated fats or devoid of carbohydrate. The diet in this study, which is what I recommend, had 43% healthy carbohydrates and 30% healthy fats.

5)    These diets were designed to give 7 pounds of weight loss in 21 days – which is what the experts recommend. There are diets out there promising faster weight loss but they severely restrict calories and/or rely heavily on stimulants, they do not preserve muscle mass, and they often are not safe. In addition they are usually temporary.  I do not recommend them.

6)    This level of protein intake is safe for almost everyone. The major exception would be people with kidney disease, who should always check with their doctor before increasing protein intake. The only other caveat is that protein metabolism creates a lot of nitrogenous waste, so you should drink plenty of water to flush that waste out of your system. But, water is always a good idea.

7)     The high protein diets minimized, but did not completely prevent, muscle loss. Other studies suggest that adding the amino acid leucine to a high protein diet can give 100% retention of muscle mass in a weight loss regimen – but that’s another story for another day.

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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