Prenatal DHA Supplement

Written by Dr. Steve Chaney on . Posted in DHA and Pregnancy, Prenatal DHA Supplement

Author: Dr. Stephen Chaney

Is taking a prenatal DHA supplement wise for brain health?

There are lots of reasons to think that DHA supplementation may be important for healthy brain development.

  • DHA is a major component of the myelin sheath that coats every neuron in the brain.
  • Just as the plastic coating on copper wire allows it to conduct an electrical current, the myelin sheath allows neurons to conduct nerve impulses from one end of the neuron to the other. In short, the myelin sheath is absolutely essential for brain function.
  • Unlike many of the other components of the myelin sheath, the body cannot make DHA. It must be provided by the diet.
  • Recent studies have suggested that most women in the United States and Canada do not get sufficient amounts of the omega-3s EPA and DHA in their diet.
  • Animal studies show that DHA deficiency during pregnancy interferes with normal brain and eye development.

With all that circumstantial evidence, it would seem obvious that a prenatal DHA supplement would be important for healthy brain development in infants and children.  However, clinical studies have been all over the map.

Some studies have reported that DHA supplementation during pregnancy improves cognition, attention span, behavior or reading skills in both infants and children.  Other studies have shown no effect of DHA supplementation on those parameters.  There is no consensus on this very important question.

Thus, when I saw a recent study titled “Prenatal Supplementation with DHA Improves Attention At 5 Years Of Age: A Randomized Controlled Trial” (U Ramakrishnan et al, American Journal of Clinical Nutrition, doi: 10.3945/ajcn.114.101071, 2016), I decided to Investigate.

 

Does Taking a Prenatal DHA Supplement Improve Attention Span?

healthy brains for kidsIn this study 1094 Mexican women were randomly assigned to receive either 400 mg of DHA or a placebo containing corn and soy oil starting in the second trimester of pregnancy (a time at which myelination and brain development begins) until delivery. Of the women enrolled in the study, 973 of them gave birth to healthy babies.

The investigators were able to follow up with 797 (82%) of those children at age 5 and conducted tests to measure overall cognitive function, behavior, and attention span.

  • There were no differences in overall cognitive development or behavior between the two groups.
  • The children from mothers who supplemented with DHA performed significantly better in tests of attention span. They were much less likely to be distracted by external stimuli than the children from mothers not supplementing with DHA.
  • In short, this study suggested that supplementation with DHA during pregnancy produced children who were less likely to suffer from attention deficit disorders at age 5.

This study had a number of strengths:

  • It was a fairly large study (797 children).
  • Supplementation was with pure DHA rather than with a mixture of EPA, DHA, and other omega-3 fatty acids.
  • The population was from an urban area of Mexico where omega-3 intake is generally low, so it was likely that many of the women were DHA-deficient at the beginning of the study.

However, it also had some glaring weaknesses:

  • The DHA status of the women was not measured either at baseline or after supplementation.
  • The quality of the child’s learning environment was not measured.

In short, the study was neither better or worse than the many other published studies.

 

Why Is There So Much Confusion?

To try and clear up the confusion I have also analyzed many of the other published studies in this field. There were things not to like about every study, but there was no obvious reason why some studies showed a positive effect of DHA supplementation and others failed to see any benefit. This is not unusual for human nutrition clinical studies, but it is frustrating.

However, when you look at the totality of the studies in this field there is one obvious reason why there is so much confusion. There is no uniformity in experimental design. No two studies are alike.

The published studies differ in:

  • The composition of omega-3s. Some studies are done with pure DHA. Others with mixtures of EPA and DHA and with varying ratios of EPA to DHA.
  • The amount of DHA. Studies range from 100 mg/day to 800 mg/day.
  • When the DHA is given. Some studies give the DHA to the pregnant mothers. Others give DHA to infants or to children of various ages.

Even worse, most of the published studies to date have not measured omega-3 status prior to supplementation, nor have they documented an improvement in omega-3 status with supplementation. Obviously, DHA supplementation is most likely to be beneficial for individuals who were DHA-deficient at the beginning of the study.

Until there is some uniformity in experimental design and DHA status is routinely measured, it is likely that the confusion will continue and this important question will remain unanswered.

 

  Should Pregnant Women Take a Prenatal DHA Supplement?

prenatal dha supplementIf we were to assume that most American women were getting enough omega-3s in their diet, and the consequences of DHA deficiency were relatively minor, this would be merely an academic discussion. We could afford to wait years until scientists were able to come to a consensus.

However, neither of those assumptions are true:

  • One recent study reported that the United States and Canada rated last in the world with respect to omega-3 intake.
  • If any of the reported consequences (short attention span, cognitive deficits, and behavioral problems) of DHA-deficiency during pregnancy and childhood are true and they are preventable with DHA supplementation, this information is of vital importance to every woman during her child bearing years.

In short, inadequate DHA intake is so widespread and the possible consequences of DHA deficiency during pregnancy are so important that, in my opinion, a prenatal DHA supplement only makes sense. Pregnant women can’t afford to wait until we are absolutely sure that DHA supplementation is essential.

The only caveat to this recommendation is to make sure that the DHA you are getting is pure. Our oceans are increasingly polluted. Many fish and some fish oil supplements are contaminated with heavy metals and/or PCBs. Only use omega-3 and/or DHA supplements from manufacturers that use very stringent quality controls to assure their products are pure.

 

The Bottom Line

 

  • A recent study has reported that DHA supplementation during pregnancy improves attention span in children at age 5.
  • Unfortunately, there is no consensus in this field. Some studies have come to similar conclusions while others have seen no effect of DHA supplementation during pregnancy.
  • If we were to assume that omega-3 deficiency was rare in this country and the consequences of DHA deficiency during pregnancy were inconsequential, this would be an academic discussion. Pregnant women could wait for scientists to reach consensus before deciding whether or not to supplement with DHA. However, neither of those studies are true.
  • Studies show that most women in the US and Canada do not get adequate omega-3s during pregnancy.
  • If any of the reported consequences of DHA deficiency during pregnancy are true and they are preventable with DHA supplementation, this information is of vital importance to every woman during her pregnancy.
  • In short, inadequate DHA intake is so widespread and the possible consequences of DHA deficiency during pregnancy are so important that, in my opinion, DHA supplementation during pregnancy only makes sense. Pregnant women can’t afford to wait until we are absolutely sure that DHA supplementation is essential.
  • The only caveat to this recommendation is to make sure that the DHA you are getting is pure. Our oceans are increasingly polluted. Many fish and some fish oil supplements are contaminated with heavy metals and/or PCBs. Only use omega-3 and/or DHA supplements from manufacturers that use very stringent quality controls to assure their products are pure.

 

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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A Low Carb Diet and Weight Loss

Posted January 15, 2019 by Dr. Steve Chaney

Do Low-Carb Diets Help Maintain Weight Loss?

Author: Dr. Stephen Chaney

 

low carb dietTraditional diets have been based on counting calories, but are all calories equal? Low-carb enthusiasts have long claimed that diets high in sugar and refined carbs cause obesity. Their hypothesis is based on the fact that high blood sugar levels cause a spike in insulin levels, and insulin promotes fat storage.

The problem is that there has been scant evidence to support that hypothesis. In fact, a recent meta-analysis of 32 published clinical studies (KD Hall and J Guo, Gastroenterology, 152: 1718-1727, 2017 ) concluded that low-fat diets resulted in a higher metabolic rate and greater fat loss than isocaloric low-carbohydrate diets.

However, low-carb enthusiasts persisted. They argued that the studies included in the meta-analysis were too short to adequately measure the metabolic effects of a low-carb diet. Recently, a study has been published in the British Medical Journal (CB Ebbeling et al, BMJ 2018, 363:k4583 ) that appears to vindicate their position.

Are low carb diets best for long term weight loss?

Low-carb enthusiasts claim the study conclusively shows that low-carb diets are best for losing weight and for keeping it off once you have lost it. They are saying that it is time to shift away from counting calories and from promoting low-fat diets and focus on low-carb diets instead if we wish to solve the obesity epidemic. In this article I will focus on three issues:

  • How good was the study?
  • What were its limitations?
  • Are the claims justified?

 

How Was The Study Designed?

low carb diet studyThe investigators started with 234 overweight adults (30% male, 78% white, average age 40, BMI 32) recruited from the campus of Framingham State University in Massachusetts. All participants were put on a diet that restricted calories to 60% of estimated needs for 10 weeks. The diet consisted of 45% of calories from carbohydrate, 30% from fat, and 25% from protein. [So much for the claim that the study showed low-carb diets were more effective for weight loss. The diet used for the weight loss portion of the diet was not low-carb.]

During the initial phase of the study 161 of the participants achieved 10% weight loss. These participants were randomly divided into 3 groups for the weight maintenance phase of the study.

  • The diet composition of the high-carb group was 60% carbohydrate, 20% fat, and 20% protein.
  • The diet composition of the moderate-carb group was 40% carbohydrate, 40% fat, and 20% protein.
  • The diet composition of the low-carb group was 20% carbohydrate, 60% fat, and 20% protein.

Other important characteristics of the study were:

  • The weight maintenance portion of the study lasted 5 months – much longer than any previous study.
  • All meals were designed by dietitians and prepared by a commercial food service. The meals were either served in a cafeteria or packaged to be taken home by the participants.
  • The caloric content of the meals was individually adjusted on a weekly basis so that weight was kept within a ± 4-pound range during the 5-month maintenance phase.
  • Sugar, saturated fat, and sodium were limited and kept relatively constant among the 3 diets.

120 participants made it through the 5-month maintenance phase.

 

Do Low-Carb Diets Help Maintain Weight Loss?

low carb diet maintain weight lossThe results were striking:

  • The low-carb group burned an additional 278 calories/day compared to the high-carb group and 131 calories/day more than the moderate-carbohydrate group.
  • These differences were even higher for those individuals with higher insulin secretion at the beginning of the maintenance phase of the study.
  • These differences lead the authors to hypothesize that low-carb diets might be more effective for weight maintenance than other diets.

 

What Are The Pros And Cons Of This Study?

low carb diet pros and consThis was a very well-done study. In fact, it is the most ambitious and well-controlled study of its kind. However, like any other clinical study, it has its limitations. It also needs to be repeated.

The pros of the study are obvious. It was a long study and the dietary intake of the participants was tightly controlled.

As for cons, here are the three limitations of the study listed by the authors:

#1: Potential Measurement Error: This section of the paper was a highly technical consideration of the method used to measure energy expenditure. Suffice it to say that the method they used to measure calories burned per day may overestimate calories burned in the low-carb group. That, of course, would invalidate the major findings of the study. It is unlikely, but it is why the study needs to be repeated using a different measure of energy expenditure.

#2: Compliance: Although the participants were provided with all their meals, there was no way of being sure they ate them. There was also no way of knowing whether they may have eaten other foods in addition to the food they were provided. Again, this is unlikely, but cannot be eliminated from consideration.

#3: Generalizability: This is simply an acknowledgement that the greatest strength of this study is also its greatest weakness. The authors acknowledged that their study was conducted in such a tightly controlled manner it is difficult to translate their findings to the real world. For example:

  • Sugar and saturated fat were restricted and were at very similar levels in all 3 diets. In the real world, people consuming a high-carb diet are likely to consume more sugar than people in the other diet groups. Similarly, people consuming the low-carb diet are likely to consume more saturated fat than people in the other diet groups.
  • Weight was kept constant in the weight maintenance phase by constantly adjusting caloric intake. Unfortunately, this seldom happens in the real world. Most people gain weight once they go off their diet – and this is just as true with low-carb diets as with other diets.
  • The participants had access to dietitian-designed prepared meals 3 times a day for 5 months. This almost never happens in the real world. The authors said “…these results [their data] must be reconciled with the long-term weight loss trials relying on nutrition education and behavioral counseling that find only a small advantage for low carbohydrate compared with low fat diets according to several recent meta-analyses.” [I would add that in the real world, people do not even have access to nutritional education and behavioral modification.]

 

low carb diet and youWhat Does This Study Mean For You?

  • This study shows that under very tightly controlled conditions (dietitian-prepared meals, sugar and saturated fat limited to healthy levels, calories continually adjusted so that weight remains constant) a low-carb diet burns more calories per day than a moderate-carb or high-carb diet. These findings show that it is theoretically possible to increase your metabolic weight and successfully maintain a healthy weight on a low-carb diet. These are the headlines you probably saw. However, a careful reading of the study provides a much more nuanced viewpoint. For example, the fact that the study conditions were so tightly controlled makes it difficult to translate these findings to the real world.
  • In fact, the authors of the study acknowledged that multiple clinical studies show this almost never happens in the real world. These studies show that most people regain the weight they have lost on low-carb diets. More importantly, the rate of weight regain is virtually identical on low-carb and low-fat diets. Consequently, the authors of the current study concluded “…translation [of their results to the real world] requires exploration in future mechanistic oriented research.” Simply put, the authors are saying that more research is needed to provide a mechanistic explanation for this discrepancy before one can make recommendations that are relevant to weight loss and weight maintenance in the real world.
  • The authors also discussed the results of their study in light of a recent, well-designed 12-month study (CD Gardener et al, JAMA, 319: 667-669, 2018 ) that showed no difference in weight change between a healthy low-fat versus a healthy low-carbohydrate diet. That study also reported that the results were unaffected by insulin secretion at baseline. The authors of the current study noted that “…[in the previous study] participants were instructed to minimize or eliminate refined grains and added sugars and maximize intake of vegetables. Probably for this reason, the reported glycemic load [effect of the diet on blood sugar levels] of the low-fat diet was very low…and similar to [the low-carb diet].” In short, the authors of the current study were acknowledging that diets which focus on healthy, plant-based carbohydrates and eliminate sugar, refined grains, and processed foods may be as effective as low-carb diets for helping maintain a healthy weight.
  • This would also be consistent with previous studies showing that primarily plant-based, low-carb diets are more effective at maintaining a healthy weight and better health outcomes long-term than the typical American version of the low-fat diet, which is high in sugar and refined grains. In contrast, meat-based, low-carb diets are no more effective than the American version of the low-fat diet at preventing weight gain and poor health outcomes. I have covered these studies in detail in my book “Slaying The Food Myths.”

Consequently, the lead author of the most recent study has said: “The findings [of this study] do not impugn whole fruits, beans and other unprocessed carbohydrates. Rather, the study suggests that reducing foods with added sugar, flour, and other refined carbohydrates could help people maintain weight loss….” This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.

The Bottom Line

 

  • A recent study compared the calories burned per day on a low-carb, moderate-carb, and high-carb diet. The study concluded that the low-carb diet burned significantly more calories per day than the other two diets and might be suitable for long-term weight control. If confirmed by subsequent studies, this would be the first real evidence that low-carb diets are superior for maintaining a healthy weight.
  • However, the study has some major limitations. For example, it used a methodology that may overestimate the benefits of a low-carb diet, and it was performed under tightly controlled conditions that can never be duplicated in the real world. As acknowledged by the authors, this study is also contradicted by multiple previous studies. Further studies will be required to confirm the results of this study and show how it can be applied in the real world.
  • In addition, the kind of carbohydrate in the diet is every bit as important as the amount of carbohydrate. The authors acknowledge that the differences seen in their study apply mainly to carbohydrates from sugar, refined grains, and processed foods. They advocate diets with low glycemic load (small effects on blood sugar and insulin levels) and acknowledge this can also be achieved by incorporating low-glycemic load, plant-based carbohydrates into your diet. This is something we all can agree on, but strangely this is not reflected in the headlines you may have seen in the media.
  • Finally, clinical studies report averages, but none of us are average. When you examine the data from the current study, it is evident that some participants burned more calories per hour on the high-carb diet than other participants did on the low carb diet. That reinforces the observation that some people lose weight more effectively on low-carb diets while others lose weight more effectively on low-fat diets. If you are someone who does better on a low-carb diet, the best available evidence suggests you will have better long-term health outcomes on a primarily plant-based, low-carb diet such as the low-carb version of the Mediterranean diet.

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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