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

Can Plant-based Diets Be Unhealthy?

Posted September 10, 2019 by Dr. Steve Chaney

Do Plant-Based Diets Reduce Heart Disease Deaths?

Author: Dr. Stephen Chaney

 

plant-based diets vegetablesPlant-based diets have become the “Golden Boys” of the diet world. They are the diets most often recommended by knowledgeable health and nutrition professionals. I’m not talking about all the “Dr. Strangeloves” who pitch weird diets in books and the internet. I am talking legitimate experts who have spent their life studying the impact of nutrition on our health.

Certainly, there is an overwhelming body of evidence supporting the claim that plant-based diets are healthy. Going on a plant-based diet can help you lower blood pressure, inflammation, cholesterol and triglycerides. People who consume a plant-based diet for a lifetime weigh less and have decreased risk of heart disease, diabetes, and cancer.

But, can a plant-based diet be unhealthy? Some people consider a plant-based diet to simply be the absence of meat and other animal foods. Is just replacing animal foods with plant-based foods enough to make a diet healthy?

Maybe not. After all, sugar and white flour are plant-based food ingredients. Fake meats of all kinds abound in our grocery stores. Some are very wholesome, but others are little more than vegetarian junk food. If you replace animal foods with plant-based sweets, desserts, and junk food, is your diet really healthier?

While the answer to that question seems obvious, very few studies have asked that question. Most studies on the benefits of plant-based diets have compared population groups that eat a strictly plant-based diet (Seventh-Day Adventists, vegans, or vegetarians) with the general public. They have not looked at variations in plant food consumption within the general public. Nor have they compared people who consume healthy and unhealthy plant foods.

This study (H Kim et al, Journal of the American Heart Association, 8:e012865, 2019) was designed to fill that void.

 

How Was The Study Done?

plant-based diets studyThis study used data collected from 12,168 middle aged adults in the ARIC (Atherosclerosis Risk in Communities) study between 1987 and 2016.

The participant’s usual intake of foods and beverages was assessed by trained interviewers using a food frequency questionnaire at the time of entry into the study and again 6 years later.

Participants were asked to indicate the frequency with which they consumed 66 foods and beverages of a defined serving size in the previous year. Visual guides were provided to help participants estimate portion sizes.

The participant’s adherence to a plant-based diet was assessed using four different well-established plant-based diet scores. For the sake of simplicity, I will include 3 of them in this review.

  • The PDI (Plant-Based Diet Index) categorizes foods as either plant foods or animal foods. A high PDI score means that the participant’s diet contains more plant foods than animal foods. A low PDI score means the participant’s diet contains more animal foods than plant foods.
  • The hPDI (healthy plant-based diet index) is based on the PDI but emphasizes “healthy” plant foods. A high hPDI score means that the participant’s diet is high in healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) and low in animal foods.
  • The uPDI (unhealthy plant-based diet index) is based on the PDI but emphasizes “unhealthy” plant foods. A high uPDI score means that the participant’s diet is high in unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) and low in animal foods.

For statistical analysis the scores from the various plant-based diet indices were divided into 5 equal groups. In each case, the group with the highest score consumed the most plant foods and least animal foods. The group with the lowest score consumed the least plant foods and the most animal foods.

The health outcomes measured in this study were heart disease events, heart disease deaths, and all-cause deaths. Again, for the sake of simplicity, I will only include 2 of these outcomes (heart disease deaths and all-cause deaths) in this review. The data on deaths were obtained from state death records and the National Death Index. (Yes, your personal information is available on the web even after you die.)

 

Do Plant-Based Diets Reduce Heart Disease Deaths?

plant-based diets reduce heart deathsThe participants in this study were followed for an average of 25 years.

The investigators looked at heart disease deaths over the 25 years and compared people with the highest intake of plant foods to people with the highest intake of red meat and other animal foods. The results were:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, coffee and tea) had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods (refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts) had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

What Else Did The Study Show?

The investigators made a couple of other interesting observations:

  • The association of the overall diet with heart disease and all-cause deaths was stronger than the association of individual food components. This underscores the importance of looking at the effect of the whole diet on health outcomes rather than the “magic” foods you hear about on Dr. Strangelove’s Health Blog.
  • Diets with the highest amount of healthy plant foods were associated with higher intake of carbohydrates, plant protein, fiber, and micronutrients, including potassium, magnesium, iron, vitamin A, vitamin C, folate, and lower intake of saturated fat and cholesterol.
  • Diets with the highest amount of unhealthy plant foods were associated with higher intake of calories and carbohydrates and lower intake of fiber and micronutrients.

The last two observations may help explain some of the health benefits of plant-based diets.

 

Can Plant-Based Diets Be Unhealthy?

plant-based diets unhealthy cookiesNow, let’s return to the question I asked at the beginning of this article: “Can plant-based diets be unhealthy?” Although some previous studies have suggested that unhealthy plant-based diets might increase the risk of heart disease, this study did not show that.

What this study did show was that an unhealthy plant-based diet was no better for you than a diet containing lots of red meat and other animal foods.

If this were the only conclusion from this study, it might be considered a neutral result. However, this result clearly contrasts with the data from this study and many others showing that both plant-based diets in general and healthy plant-based diets reduce the risk of heart disease deaths and all-cause deaths compared to animal-based diets.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

There is one other subtle message from this study. This study did not compare vegans with the general public. Everyone in the study was the general public. Nobody in the study was consuming a 100% plant-based diet.

For example:

  • The group with the highest intake of plant foods consumed 9 servings per day of plant foods and 3.6 servings per day of animal foods.
  • The group with the lowest intake of plant foods consumed 5.4 servings per day of plant foods and 5.6 servings per day of animal foods.

In other words, you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet.

 

The Bottom Line

A recent study analyzed the effect of consuming plant foods on heart disease deaths and all-cause deaths over a 25-year period.

When the investigators looked at heart disease deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had a 19-32% lower risk of dying from heart disease than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

When the investigators looked at all-cause deaths over the 25 years:

  • People with the highest intake of plant foods and the highest intake of healthy plant foods had an 11-25% lower risk of dying from any cause than people with the highest intake of red meat and other animal foods.
  • People with the highest intake of unhealthy plant foods had the same risk of dying from heart disease as people with the highest intake of red meat and other animal foods.

The main message from this study is clear.

  • Replacing red meat and other animal foods with plant foods can be a healthier choice, but only if they are whole, minimally processed plant foods like whole grains, fruits, vegetables, nuts, legumes, coffee and tea.
  • If the plant foods are refined grains, fruit juices, French fries and chips, sugar sweetened and artificially sweetened beverages, sweets and desserts, all bets are off. You may be just as unhealthy as if you kept eating a diet high in red meat and other animal foods.

A more subtle message from the study is that you don’t need to be a vegan purist to experience health benefits from adding more whole, minimally processed plant foods to your diet. The people in this study were not following some special diet. The only difference was that some of the people in this study ate more plant foods and others more animal foods.

For more details on the study, 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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