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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Latest Article

Should We Use Supplements For Cardiovascular Health?

Posted July 10, 2018 by Dr. Steve Chaney

Are You Just Wasting Your Money On Supplements?

Author: Dr. Stephen Chaney

 

supplements for cardiovascular health wast moneyYou’ve seen the headlines. “Recent Study Finds Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.”  You are being told that supplements are of no benefit to you. They are a waste of money. You should follow a healthy diet instead. Is all of this true?

If I were like most bloggers, I would give you a simple yes or no answer that would be only partially correct. Instead, I am going to put the study behind these headlines into perspective. I am going to give you a deeper understanding of supplementation, so you can make better choices for your health.

 Should we use supplements for cardiovascular health?

In today’s article I will give you a brief overview of the subject. Here are the topics I will cover today:

  • Is this fake news?
  • Did the study ask the right questions?
  • Is this a question of “Garbage In – Garbage Out?
  • Reducing Heart Disease Risk. What you need to know.

All these topics are covered in much more detail (with references) in my book “Slaying The Supplement Myths”, which will be published this fall.

 

How Was This Study Done?

supplements for cardiovascular healthThis study (D.J.A. Jenkins et al, Journal of the American College Of Cardiology, 71: 2540-2584, 2018 ) was a meta-analysis. Simply put, that means the authors combined the results of many previous studies into a single database to increase the statistical power of their conclusions. This study included 127 randomized control trials published between 2012 and December 2017. These were all studies that included supplementation and looked at cardiovascular end points, cancer end points or overall mortality.

Before looking at the results, it is instructive to look at the strengths and weaknesses of the study. Rather than giving you my interpretation, let me summarize what the authors said about strengths and weaknesses of their own study.

The strengths are obvious. Randomized control trials are considered the gold standard of evidence-based medicine, but they have their weaknesses. Here is what the authors said about the limitations of their study:

  • “Randomized control trials are of shorter duration, whereas longer duration studies might be required to fully capture chronic disease risk.”
  • “Dose-response data were not usually available [from the randomized control studies included in their analysis]. However, larger studies would allow the effect of dose to be assessed.”

There are some other limitations of this study, which I will point out below.

Is This Fake News?

supplements for cardiovascular health fake newsWhen I talk about “fake news” I am referring to the headlines, not to the study behind the headlines. The headlines were definitive: “Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.” However, when you read the study the reality is quite different:

  • In contrast to the negative headlines, the study reported:
    • Folic acid supplementation decreased stroke risk by 20% and overall heart disease risk by 17%.
    • B complex supplements containing folic acid, B6, and B12 decreased stroke risk by 10%.
    • That’s a big deal, but somehow the headlines forgot to mention it.
  • The supplements that had no significant effect on heart disease risk (multivitamins, vitamin D, calcium, and vitamin C) were ones that would not be expected to lower heart disease risk. There was little evidence from previous studies of decreased risk. Furthermore, there is no plausible mechanism for supposing they might decrease heart disease risk.
  • The study did not include vitamin E or omega-3 supplements, which are the ones most likely to prove effective in decreasing heart disease risk when the studies are done properly (see below).

Did The Study Ask The Right Question?

Most of the studies included in this meta-analysis were asking whether a supplement decreased heart disease risk or mortality for everyone. Simply put, the studies started with a group of generally healthy Americans and asked whether supplementation had a significant effect on disease risk for everyone in that population.

That is the wrong question. We should not expect supplementation to benefit everyone equally. Instead, we should be asking who is most likely to benefit from supplementation and design our clinical studies to test whether those people benefit from supplementation.

supplements for cardiovascular health diagramI have created the graphic on the right as a guide to help answer the question of “Who is most likely to benefit from supplementation?”. Let me summarize each of the points using folic acid as the example.

 

Poor Diet: It only makes sense that those people who are deficient in folate from foods are the most likely to benefit from folic acid supplementation. Think about it for a minute. Would you really expect people who are already getting plenty of folate from their diet to obtain additional benefits from folic acid supplementation?

The NIH estimates that around 20% of US women of childbearing age are deficient in folic acid. For other segments of our population, dietary folate insufficiency ranges from 5-10%. Yet, most studies of folic acid supplementation lump everyone together – even though 80-95% of the US population is already getting enough folate through foods, food fortification, and supplementation. It is no wonder most studies fail to find a beneficial effect of folic acid supplementation.

The authors of the meta-analysis I discussed above said that the beneficial effects of folic acid they saw might have been influenced by a very large Chinese study, because a much higher percentage of Chinese are deficient in folic acid. They went on to say that the Chinese study needed to be repeated in this country.

In fact, the US study has already been done. A large study called “The Heart Outcomes Prevention Evaluation (HOPE)” study reported that folic acid supplementation did not reduce heart disease risk in the whole population. However, when the study focused on the subgroup of subjects who were folate-deficient at the beginning of the study, folic acid supplementation significantly decreased their risk of heart attack and cardiovascular death.  This would seem to suggest using supplements for cardiovascular health is a good idea.

Increased Need: There are many factors that increase the need for certain nutrients. However, for the sake of simplicity, let’s only focus on medications. Medications that interfere with folic acid metabolism include anticonvulsants, metformin (used to treat diabetes), methotrexate and sulfasalazine (used to treat severe inflammation), birth control pills, and some diuretics. Use of these medications is not a concern when the diet is adequate. However, when you combine medication use with a folate-deficient diet, health risks are increased and supplementation with folic acid is more likely to be beneficial.

Genetic Predisposition: The best known genetic defect affecting folic acid metabolism is MTHFR. MTHFR deficiency does not mean you have a specific need for methylfolate. However, it does increase your need for folic acid. Again, this is not a concern when the diet is adequate. However, when you combine MTHFR deficiency with a folate-deficient diet, health risks are increased and supplementation with folic acid is more likely to be beneficial. I cover this topic in great detail in my upcoming book, “Slaying The Supplement Myths”. In the meantime, you might wish to view my video, “The Truth About Methyl Folate.”

Diseases: An underlying disease or predisposition to disease often increases the need for one or more nutrients that help reduce disease risk. The best examples of this are two major studies on the effect of vitamin E on heart disease risk in women. Both studies found no effect of vitamin E on heart disease risk in the whole population. However, one study reported that vitamin E reduced heart disease risk in the subgroup of women who were post-menopausal (when the risk of heart disease skyrockets). The other study found that vitamin E reduced heart attack risk in the subgroup of women who had pre-existing heart disease at the beginning of the study.

Finally, if you look at the diagram closely, you will notice a red circle in the middle. When two or three of these factors overlap, that is the “sweet spot” where supplementation is almost certain to make a difference and it may be a good idea to use supplements for cardiovascular health.

Is This A Question Of “Garbage In, Garbage Out”?

supplements for cardiovascular health garbage in outUnfortunately, most clinical studies focus on the “Does everyone benefit from supplementation question?” rather than the “Who benefits from supplementation?” question.

In addition, most clinical studies of supplementation are based on the drug model. They are studying supplementation with a single vitamin or mineral, as if it were a drug. That’s unfortunate, because vitamins and minerals work together synergistically. What we need are more studies of holistic supplementation approaches.

Until these two things change, most supplement studies are doomed to failure. They are doomed to give negative results. In addition, meta-analyses based on these faulty supplement studies will fall victim to what computer programmers refer to as “Garbage In, Garbage Out”. If the data going into the analysis is faulty, the data coming out of the study will be equally faulty. It won’t be worth the paper it is written on. If you are looking for personal guidance on supplementation, this study falls into that category.

 

Should We Use Supplements For Cardiovascular Health?

 

If you want to know whether supplements decrease heart disease risk for everyone, this meta-analysis is clear. Folic acid may decrease the risk of stroke and heart disease. A B complex supplement may decrease the risk of stroke. All the other supplements they included in their analysis did not decrease heart disease risk, but the analysis did not include vitamin E and/or omega-3s.

However, if you want to know whether supplements decrease heart disease risk for you, this study provides no guidance. It did not ask the right questions.

I would be remiss, however, if I failed to point out that we know healthy diets can decrease heart disease risk. In the words of the authors: “The recent science-based report of the U.S. Dietary Guidelines Advisory Committee, also concerned with [heart disease] risk reduction, recommended 3 dietary patterns: 1) a healthy American diet low in saturated fat, trans fat, and meat, but high in fruits and vegetables; 2) a Mediterranean diet; and 3) a vegetarian diet. These diets, with their accompanying recommendations, continue the move towards more plant-based diets…” I cover the effect of diet on heart disease risk in detail in my book, “Slaying The Food Myths”.

 

The Bottom Line

 

You have probably seen the recent headlines proclaiming: “Vitamin and Mineral Supplements Don’t Lower Heart Disease Risk.” The study behind the headlines was a meta-analysis of 127 randomized control trials looking at the effect of supplementation on heart disease risk and mortality.

  • The headlines qualify as “fake news” because:
    • The study found that folic acid decreased stroke and heart disease risk, and B vitamins decreased stroke risk. Somehow the headlines forgot to mention that.
    • The study found that multivitamins, vitamin D, calcium, and vitamin C had no effect on heart disease risk. These are nutrients that were unlikely to decrease heart disease risk to begin with.
    • The study did not include vitamin E and omega-3s. These are nutrients that are likely to decrease heart disease risk when the studies are done properly.
  • The authors of the study stated that a major weakness of their study was that that randomized control studies included in their analysis were short term, whereas longer duration studies might be required to fully capture chronic disease risk.
  • The study behind the headlines is of little use for you as an individual because it asked the wrong question.
  • Most clinical studies focus on the “Does everyone benefit from supplementation question?” That is the wrong question. Instead we need more clinical studies focused on the “Who benefits from supplementation?” question. I discuss that question in more detail in the article above.
  • In addition, most clinical studies of supplementation are based on the drug model. They are studying supplementation with a single vitamin or mineral, as if it were a drug. That’s unfortunate, because vitamins and minerals work together synergistically. What we need are more studies of holistic supplementation approaches.
  • Until these two things change, most supplement studies are doomed to failure. They are doomed to give negative results. In addition, meta-analyses based on these faulty supplement studies will fall victim to what computer programmers refer to as “Garbage In, Garbage Out”. If the data going into the analysis is faulty, the data coming out of the study will be equally faulty. It won’t be worth the paper it is written on. If you are looking for personal guidance on supplementation, this study falls into that category.
  • If you want to know whether supplements decrease heart disease risk for everyone, this study is clear. Folic acid may decrease the risk of stroke and heart disease. A B-complex supplement may decrease the risk of stroke. All the other supplements they included in their analysis did not decrease heart disease risk, but they did not include vitamin E and/or omega-3s in their analysis.
  • If you want to know whether supplements decrease heart disease risk for you, this study provides no guidance. It did not ask the right questions.
  • However, we do know that healthy, plant-based diets can decrease heart disease risk. I cover heart healthy diets in detail in my book, “Slaying The Food Myths.”

 

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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