Do B Vitamins Slow Cognitive Decline?

Written by Dr. Steve Chaney on . Posted in current health articles, Supplements and Health, Vitamins and Health

The B Vitamin Controversy

Author: Dr. Stephen Chaney

 

cognitive-declineDo B Vitamins slow cognitive decline?  Heart disease, cancer and strokes are all pretty scary. Even if we survive, our quality of life may never be the same. But, we can endure many physical afflictions if our mind stays sharp. For most of us the ultimate irony would be to spend a lifetime taking good care of our body, only to lose our mind.

Last week I told you about a study showing that a holistic approach, which to me includes healthy diet, weight control, exercise, supplementation, socialization and memory training, significantly reduces cognitive decline in the elderly (https://healthtipsfromtheprofessor.com/hope-alzheimers/).

This week I’d like to focus on one aspect of that holistic approach, namely B vitamins. If you are like most people, you are probably confused about the role of B vitamins in preserving mental function. On the one hand you are seeing headlines proclaiming that B vitamins slow cognitive decline as we age. On the other hand you are being told “Don’t waste your money. B vitamins won’t slow cognitive aging.” What are you to believe?

 

Why Might Certain B Vitamins Slow Cognitive Decline?

To help you understand how B vitamins might slow cognitive decline I’m going to need to get a little biochemical. Don’t worry. I’ll be merciful.

#1: The story starts with a byproduct of amino acid metabolism called homocysteine.

Multiple studies have shown that elevated blood levels of homocysteine are associated with cognitive decline and Alzheimer’s. Elevated homocysteine levels are found in 5-10% of the overall population and elevated homocysteine levels double the risk of Alzheimer’s.

In our bodies homocysteine is converted to the amino acid methionine in a reaction involving folic acid and vitamin B12. Homocysteine is converted to the amino acid cysteine in a reaction involving vitamin B6. Thus, elevated homocysteine levels are most frequently associated with deficiencies of these three B vitamins caused by inadequate intake or increased need for those B vitamins.

#2: Many of us are deficient in the B vitamins that lower homocysteine levels.

There are many situations in which inadequate intake or increased need of those vitamins can occur. For example:

Vitamin B12:

vitamin-B12

  • The most frequent cause of B12 deficiency is the age related loss of the ability to absorb vitamin B12 in the upper intestine. This affects 10-30% of people over the age of 50.
  • Chronic use of acid-suppressing medications such as Prilosec, Nexium, Tagamet, Pepcid and Zantac also decreases B12 absorption and increases the risk of B12 deficiency. Millions of Americans use those drugs on a daily basis.
  • Finally, vegetarians can become B12 deficient because most naturally occurring B12 is found in meat and dairy products.
  • Overall, B12 deficiency has been estimated to affect about 40% of people over 60 years of age.

Folic Acid:

  • In the past, many Americans consumed diets that were low in folic acid. However, this has been minimized in recent years by the fortification of grain products with folic acid. Today, the primary concern is with factors that increase the need for folic acid.
  • For example, birth control pills along with some anti-inflammatory and anticonvulsant medications interfere with folic acid metabolism and increase the need for folic acid.
  • In addition, deficiency of the enzyme methylenetetrahydrofolate reductase (MTHFR) substantially increase the amount of folic acid needed to reduce homocysteine levels to normal. About 10% of the US population has this enzyme deficiency.

Vitamin B6:

  • Birth control pills along with some drugs used to treat high blood pressure and asthma interfere with vitamin B6 metabolism and increase the need for vitamin B6.
  • Vitamin B6 is found in reasonable amounts in meat, beans, green leafy vegetables, brown rice and whole grain flour. Unless you are consuming a balanced diet containing all of those foods your intake of B6 may be inadequate. About 25% of Americans have low blood levels of B6.

#3: Multiple studies have shown that supplementation with folic acid, B12 and B6 can lower homocysteine levels.

Based on this information it has been hypothesized that supplementation with folic acid, B12 and B6 would decrease the rate of cognitive decline in people with elevated homocysteine levels. It is a logical hypothesis, but is it correct?

The Evidence That B Vitamins Don’t Slow Cognitive Decline

The recent headlines saying that B vitamins don’t slow cognitive decline came from a meta-analysis that included the results of 11 clinical trials with 22,000 individuals B-vitamins-cognitive-decline(Clarke et al, American Journal of Clinical Nutrition, 100: 657-666, 2014). That sounds pretty impressive! But to properly assess the conclusions of this study you need to understand the strengths and weaknesses of meta-analyses.

  • The strength of a meta-analysis is pretty obvious. By combining the results of many clinical trials and thousands of patients you greatly increase the statistical power of the study.
  • However, the strength of a meta-analysis is only as good as the studies it includes. It’s the old “GIGO” principle (Garbage In, Garbage Out). If the individual studies are poorly designed, the conclusions of the meta-analysis will be misleading.

Unfortunately, many of the studies in this meta-analysis were poorly designed. They fall into two groupings:

Problem #1: Many of the studies included in the meta-analysis were not designed to test the actual hypothesis.

Remember that the original hypothesis was that supplementation with folic acid, B12 and B6 would decrease the rate of cognitive decline in people who were deficient in those B vitamins and had elevated homocysteine levels. Nobody was predicting that B vitamin supplementation would make any difference for people who already had adequate B vitamin levels and low homocysteine levels.

Five of the studies were not designed to look at that hypothesis at all. They were very large studies designed to look at the hypothesis that B vitamins might reduce the risk heart attack and stroke in patients with cardiovascular disease. Some of those patients had elevated homocysteine levels, but many did not.

It’s no wonder they did not show any significant effect of B vitamins on cognitive decline. They weren’t designed for that purpose, but they contributed the vast majority of patients and most of the statistical weight to the conclusions of the meta-analysis.

Problem #2: Some of the studies were too short to draw any meaningful conclusions.

Three of the studies were well designed in that they specifically looked at patient populations with elevated homocysteine levels and documented B vitamin deficiency, but they only lasted for 3 to 6 months. There simply was not a large enough cognitive decline in the control group in such a short time span for one to see a statistically significant effect of B vitamin supplementation.

Do B Vitamins Slow Cognitive Decline?

B-vitamins-slow-cognitive-declineThat leaves three studies from the original meta-analysis, plus another clinical study published after the meta-analysis was complete, that were actually designed to test the hypothesis and were long enough to give meaningful results. Three of those four studies showed a positive effect of B vitamin supplementation on cognitive function.

Study #1: This study was a 3-year study in patients with elevated homocysteine levels, folic acid deficiency and normal B12 levels (Durga et al, The Lancet, 369: 208-216, 2007). They were given 800 ug/day of folic acid or a placebo. Folic acid levels increased 576% and homocysteine levels decreased by 25%. At the end of 3 years the change in memory, information processing speed and sensorimotor speed was significantly better in the folic acid group than the control group.

Study #2: This was a 2-year study in patients with elevated homocysteine levels (McMahon et al, New England Journal of Medicine, 354: 2764-2769, 2006). B vitamin deficiencies were not measured. The patients were given either 1000 ug 5-methyltetrahydrofolate, 500 ug of B12 and 10 mg of B6 or a placebo. Homocysteine levels decreased significantly, but there was no effect of B vitamins on cognitive function in this study.

Study #3: This study was a 2-year study in patients over 70 with mild cognitive decline (Smith et al, PLoS ONE 5(9): e12244. doi:10.1371/journal.pone.0012244, 2010). B vitamin deficiencies were not measured. The patients were given either 800 ug of folic acid, 500 ug of B12 and 20 mg of B6 or placebo. B vitamin supplementation increased folic acid levels by 270% and decreased homocysteine levels by 22%. Brain volume was measured by MRI. Overall, B vitamin supplementation decreased brain shrinkage by 30%. The rate of brain shrinkage in the placebo group and the protective effect of B vitamins were greatest in the patients with elevated homocysteine at entry into the trial.

Study #4: This was an expansion of the previous study (Douaud et al, Proceedings of the National Academy of Sciences, 110: 9523-9528, 2013). In this study the same investigators focused on the regions of the brain most vulnerable to cognitive decline and the Alzheimer’s disease process. They found that B vitamin supplementation reduced brain atrophy in those regions by 7-fold (a whopping 86% decrease in brain shrinkage) over a 2-year period. Once again, the rate of brain shrinkage in the placebo group and the protective effect of B vitamins were greatest in the patients with elevated homocysteine at entry into the trial.

Are B Vitamins Only Effective In People With Elevated Homocysteine Levels?

The published data certainly suggest that B vitamins may reduce cognitive decline in people with elevated homocsteine levels, but what about other people with B vitamin deficiencies? For reasons that are not entirely clear, not everyone with folic acid, B12 and/or B6 deficiencies has elevated homocsyteinine levels.

Other symptoms of folic acid, B12 and B6 deficiency are depression, pronounced fatigue, irritability, peripheral neuropathy (tingling and loss of feeling in extremities), and loss of fine motor coordination. If you have these symptoms and they are caused by B vitamin deficiency, B vitamin supplementation may relieve the symptoms.

B vitamin supplementation may also slow cognitive decline in individuals who are B vitamin deficient and have normal homocysteine levels, but that hypothesis has not been clinically tested.

The Bottom Line

1)     Forget the headlines telling you that B vitamins don’t slow cognitive decline. Also ignore headlines implying that B vitamins will help everyone be an Einstein well into their 90’s. As usual, the truth is somewhere in between.

2)    Supplementation works best for people with inadequate dietary intake and/or increased needs. That is just as true for B vitamins and brain health as it is for other health benefits of supplementation.

3)     Many people with deficiencies of folic acid, B12 and/or B6 have elevated homocysteine levels. If you do have elevated homocysteine levels, the data are pretty convincing that supplementation with folic acid, B12 and B6 may reduce the risk of cognitive decline. Unfortunately, homocysteine is not something that is routinely measured in most physical exams, but perhaps it should be.

4)     Not everyone with folic acid, B12 and/or B6 deficiencies has elevated homocsyteinine levels. Other symptoms of folic acid, B12 and B6 deficiency are depression, pronounced fatigue, irritability, peripheral neuropathy (tingling and loss of feeling in extremities), and loss of fine motor coordination. If you have these symptoms and the symptoms are caused by B vitamin deficiency, B vitamin supplementation might also slow cognitive decline. However, that hypothesis has never been clinically tested.

5)     It has been recognized recently that deficiencies of methylenetetrahydrofolate reductase (MTHFR) interfere with folic acid metabolism and cause elevated homocysteine levels. Contrary to what you may have heard, 5 methyltetrahydrofolate is not essential for reducing homocysteine levels in people with MTHFR deficiency. High levels of folic acid work just as well for most MTHFR-deficient individuals. [It is also interesting to note that the only well designed clinical study that did not find B vitamins to be effective in reducing cognitive decline was the one that substituted 5-methyltetrahydrofolate for folic acid.]

6)     B vitamin deficiency is common in the elderly due to impaired absorption and the use of multiple medications that interfere with B vitamin metabolism and can contribute to many of the symptoms commonly associated with aging. In this population, B vitamin supplementation is cheap and often effective.

7)     B12 deficiency is common in adults 60 and older. High doses of folic acid alone can mask B12 deficiency and lead to irreversible nerve damage. For that reason high doses of folic acid should be paired with high dose B12 and B12 nutritional status should be determined. [Contrary to what you may have heard, 5-methyltetrahydrofolate is just as likely to mask B12 deficiency as is folic acid.]

8)     Finally, assuring an adequate intake of B vitamins is just one component of a holistic approach for maintaining brain function as long as possible. Other important lifestyle components for preserving cognitive function are healthy diet, weight control, exercise, supplementation, socialization and memory training. (https://healthtipsfromtheprofessor.com/hope-alzheimers/).

 

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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Comments (5)

  • Gloria Kelley Gonzalez

    |

    Some great information here.

    Reply

  • crissy handley

    |

    I am one who has absorbtion problems of B complex B12 and COQ10. Recently high homocysteine.. With supplementation of Shaklee Bcomplex (4-6 additional plus Vitalizer) and B12, my cognituve function has increased and depression totally in control. This totally makes
    so much sense!! Thank you!

    Reply

    • Dr. Steve Chaney

      |

      Dear Crissy,

      You are a perfect example of the point that I made in my blog post. It is the people who have a B vitamin deficiency (often caused by things like poor absorption) who are most likely to benefit from B vitamin supplementation.

      Dr. Chaney

      Reply

  • Rose Marie Strauss, R.N.

    |

    I have absorption problems.With one tablet of B6/B12 (Trader Joe,s ) suggested use, I take one tablet under the tongue(sublinquel) as a dietary supplement. I need to have my homo-cysteine checked again.I recently had a lab test.and I did not think to ask them to ad this to my lab test.
    It makes a lot sense.Everybody should be informed of
    this great .articles.

    Reply

    • Dr. Steve Chaney

      |

      Dear Rose Marie,

      Sub-lingual Bs are usually not necessary, but it is a good idea to monitor your homocysteine levels. We don’t know whether homocysteine causes cognitive decline, but it does correlate with cognitive decline.

      Dr. Chaney

      Reply

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Latest Article

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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