Will Plant Proteins Help You Live Longer?

Is A Vegan Diet Healthiest?

Author: Dr. Stephen Chaney

Fountain Of YouthUnless you are Rip Van Winkle and have been asleep for the past 40 years, you have probably heard that whole food, primarily plant-based diets are good for you.

  • They help you control your weight.
  • They reduce inflammation.
  • They reduce your risk of diabetes and heart disease.
  • They even reduce your risk of some cancers.

But do they help you live longer? If we take that question literally, the answer appears to be no. There is no “Fountain Of Youth”. There are no diets that extend our lives significantly.

However, what if you could reduce your risk of premature death? It would be tragic to have your life cut short by a heart attack or some other major disease. What if you could prevent that?

And what if you could live healthier longer? It would be equally tragic to spend your golden years debilitated by chronic diseases like heart disease, diabetes, or dementia. What if you could delay these diseases and live healthier longer?

The study I discuss this week (Y Sun, Journal of the American Heart Association, 10:e015553, 2021) looks at the effect of different dietary protein sources on premature death.

This study, like many others, suggests that primarily plant-based diets are healthier than meat-based diets. But what does this mean for you? Should you go completely meatless? Is a vegan diet healthier than other plant-based diets? I discuss what we know and what we do not know about the vegan diet compared to other plant-based diets.

How Was This Study Done?

Clinical StudyThe data for this study were drawn from the Women’s Health Initiative (WHI). The Women’s Health Initiative was designed to help identify strategies for preventing heart disease and other diseases in postmenopausal women. It enrolled 161,000 postmenopausal women from 40 sites across the US between 1993 and 1998 and followed them through 2017.

This study excluded women who had heart disease or cancer when they entered the WHI study and women who had incomplete data on either their diet or their use of postmenopausal hormone therapy. They were left with 102,521 women, age 50-79 at time of entry, who were followed for 18 years.

Each woman filed out an extensive dietary survey at the beginning of the study. There were 25,976 deaths during the study. The cause of death was determined by reviewing death certificates, medical records, autopsy reports or by linkage to the National Death Index.

The investigators asked whether women who ate more plant proteins were healthier than those who ate primarily meat protein. To answer this question, they correlated protein sources in the diet with all-cause mortality and deaths from various diseases.

The greatest difficulty with this type of study is that people who eat more plant protein tend to have a healthier diet and a healthier lifestyle. That makes it hard to separate out the benefits of eating plant proteins from benefits associated with other aspects of their diet and lifestyle. So, the authors corrected their data for every factor known to influence the risk of heart disease, diabetes, dementia, and premature death.

Specifically, the data were statistically corrected for age, race/ethnicity, socioeconomic status, hormone use, lifestyle (smoking status, physical activity, and alcohol intake), baseline health status (diabetes and/or high blood cholesterol), family history of heart attack/stroke, dietary factors (calorie intake, dietary fiber intake, whole grain consumption, fruit and vegetable consumption, sugar-sweetened beverage consumption, glycemic load (effect of foods in the diet on blood sugar), and percentage of saturated fats, polyunsaturated fats, monounsaturated fats, and trans fats), and weight (BMI).

In short, the authors corrected for every other factor that could influence disease risk and/or premature death. By doing so, they were able to focus on the effect of protein sources on disease risk and/or premature death.

Will Plant Proteins Help You Live Longer?

Plant ProteinsThe investigators divided the study participants into quintiles with respect the kind and amount of protein they consumed.

  • For animal protein, the intake ranged from 4 ounces/day in the lowest quintile to 9 ounces a day in the highest quintile (For comparison, 3 ounces is roughly equivalent to the size of a deck of cards).
  • For plant protein, the intake ranged from 2 ounces/day in the lowest quintile to 3.5 ounces/day in the highest quintile.
  • When you combine plant and animal protein in these women’s diet, plant protein ranged from 18% of total protein intake in the lowest quintile to 48% of total protein intake in the highest quintile.

When women who had the highest intake for plant protein were compared with women who had the lowest intake of plant protein, the women with the highest plant protein intake had:

  • 12% lower risk of premature death from heart disease.
  • 21% lower risk of premature death from dementia.
  • 9% lower risk of premature death from all causes.

There was an inverse relationship between the amount of plant protein in the diet and premature death. Specifically, every 3 ounces of animal protein that was replaced with 3 ounces of plant protein resulted in:

  • 22% lower risk of premature death from heart disease.
  • 19% lower risk of premature death from dementia.
  • 14% lower risk of premature death from all causes.

The Effect Of Individual Animal Proteins On Mortality

Fatty SteakThe authors also looked at the effect of various animal proteins on premature death. For example:

Red Meat: Women with the highest consumption of red meat had:

  • 14% higher risk of premature death from heart disease.
  • 20% higher risk of premature death from dementia.
  • 10% higher risk of premature death from all causes.

Eggs: Women with the highest consumption of eggs had:

  • 24% higher risk of premature death from heart disease.
  • 14% lower risk of premature death from dementia.
  • 14% higher risk of premature death from all causes.

Dairy: Women with the highest consumption of dairy had:

  • 11% higher risk of premature death from heart disease.

The authors concluded, “In this large prospective cohort study, we found that higher plant protein intake and substitution of animal protein with plant protein were associated with lower risk of all-cause mortality, cardiovascular mortality, and dementia mortality…Our findings support the need for consideration of protein sources, in addition to the amount of protein intake, in future dietary guidelines.”

Is A Vegan Diet Healthiest?

Vegetarian DietYears ago, as my brother-in-law was coming out of anesthesia at the end of quadruple bypass surgery, the first question he asked was, “Does this mean I need to eat tofu?” Obviously, nothing terrified him more than the thought of eating tofu the rest of his life. In the same vein, some of you are probably asking, “Does this mean I need to go vegan?”

The good news is that none of the women in this study were consuming a vegan diet. They were consuming a typical American diet with varying amounts of plant and animal protein. The group with the highest plant protein consumption were still getting 52% of their protein from animal sources.

This study shows that even people consuming a typical American diet can become healthier by simply swapping out some of the animal protein in their diet with plant protein.

However, you are probably thinking, “Plant protein is good for us, and a vegan diet is 100% plant protein. Does that mean a vegan diet is healthier than other plant-based diets?

The answer is………”Maybe”

If the linear relationship between plant protein consumption and risk of premature death could be extrapolated all the way to 100% plant protein, the answer would be obvious. Vegan diets would be healthier than other plant-based diets. But that extrapolation is an assumption. It might not be true.

For example, some recent studies suggest that completely eliminating meat, eggs, and dairy from your diet may slightly increase your risk of heart disease and stroke:

  • One recent study found that adding 1.4 ounces of fish/day to a primarily vegetarian diet decreases the risk of stroke by 20%.
  • Another study reported that adding one egg/day to a primarily vegetarian diet decreases the risk of heart disease by 12% and stroke by 10-26%.

These studies need to be confirmed, but they do suggest we need to be cautious about assuming that vegan diets are healthier than other primarily plant-based diets. This is why, when I recommend primarily plant-based diets, I include everything from vegan through semi-vegetarian, Mediterranean, and DASH.

They are all healthy diets. My advice is to choose the one that best fits your lifestyle and food preferences. And focus on whole foods, not processed foods.

The Bottom Line 

A recent study asked whether women who ate more plant proteins were healthier than those who ate primarily meat protein. To answer this question, the investigators correlated protein sources in the diet with all-cause mortality and deaths from various diseases.

When women who had the highest intake for plant protein were compared with women who had the lowest intake of plant protein, the women with the highest plant protein intake had:

  • 12% lower risk of premature death from heart disease.
  • 21% lower risk of premature death from dementia.
  • 9% lower risk of premature death from all causes.

There was an inverse relationship between the amount of plant protein in the diet and premature death. Specifically, every 3 ounces of animal protein that was replaced with 3 ounces of plant protein resulted in:

  • 22% lower risk of premature death from heart disease.
  • 19% lower risk of premature death from dementia.
  • 14% lower risk of premature death from all causes.

[Note: A 3-ounce serving is roughly equivalent to a deck of cards.]

The authors concluded, “In this large prospective cohort study, we found that higher plant protein intake and substitution of animal protein with plant protein were associated with lower risk of all-cause mortality, cardiovascular mortality, and dementia mortality…Our findings support the need for consideration of protein sources, in addition to the amount of protein intake, in future dietary guidelines.”

Years ago, as my brother-in-law was coming out of anesthesia at the end of quadruple bypass surgery, the first question he asked was, “Does this mean I need to eat tofu?” Obviously, nothing terrified him more than the thought of eating tofu the rest of his life. In the same vein, some of you are probably asking, “Does this mean I need to go vegan?”

I discuss the answer to that question in the article above.

For more details and a discussion about the vegan diet versus other primarily plant-based diets 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.

How Much DHA Is Needed To Prevent Alzheimer’s

What Are We Missing?

Cognitive-DeclineWe are an aging population. As such, issues like cognitive decline, dementia, and Alzheimer’s Disease are of increasing concern. After all, what is the good of reaching your “Golden Years” with a healthy body if you lose your mind?

The ability of the omega-3 fatty acids DHA and EPA to reduce the risk of cognitive decline, dementia, and Alzheimer’s Disease is controversial. Some studies say yes. Others say no.

When studies are conflicting most experts simply conclude the treatment is unproven. I am sympathetic to that viewpoint, but I first like to ask the questions: “Why are the studies conflicting? What are we missing?”

I start by evaluating the strengths and weaknesses of the individual studies.

  • If the studies claiming the treatment works are weak, I am content to “join the chorus” and consider the treatment unproven.
  • If the studies claiming the treatment doesn’t work are weak, I am a strong advocate for more well-designed studies before we conclude that the treatment doesn’t work.
  • If both the “pro” and “con” studies are strong, I want to ask, “What are we missing?”

This is the situation with studies asking whether DHA reduces the risk of Alzheimer’s Disease and other forms of cognitive decline as we age.

  • Association studies show that greater intake and higher blood levels of the omega-3 fatty acids EPA and DHA are associated with lower risk of Alzheimer’s Disease.
  • However, most placebo-controlled clinical trials with either DHA alone or DHA + EPA have come up negative. Of course, one can always argue that most of the placebo-controlled clinical trials were too short or too small to show a statistically significant effect. But, my question remains, “What else are we missing?”

One recent study has provided an interesting clue. The authors of the study postulated that B vitamins were required to deliver omega-3 fatty acids to the brain, and their study showed that omega-3 fatty acids were only effective at decreasing the risk of cognitive decline in subjects who also had optimal B vitamin status.

In other words, this study suggested that studies on the effect of omega-3 supplementation and risk of developing Alzheimer’s are doomed to failure if a significant percentage of the subjects have sub-optimal B vitamin status.

The authors of the current study ( IC Arellanes et al, EBioMedicine, doi.org/10.1016/j.ebiom.2020.102883) proposed two additional hypotheses for the negative results of previous clinical trials and designed an experiment to test their hypotheses. Their hypotheses were:

  • Uptake of DHA and EPA by the brain is very inefficient, and previous studies have not used sufficient doses of DHA or DHA plus EPA to see a significant effect on cognitive impairment.
  • The APOE4 gene further decreases the uptake of DHA and EPA by the brain.

Before I describe how the study was done, I should probably provide some context by describing how DHA and EPA reach the brain and the role of the apoE protein in the process. It’s time for my favorite topic: “Biochemistry 101”.

Biochemistry 101: What Does The ApoE Protein Do?

ProfessorIf you have ever tried to mix oil and water, it should come as no surprise to you that fats, including DHA and EPA, and cholesterol are not water soluble. That leaves our bodies with a dilemma. How do they get the fat and cholesterol we eat to pass through our bloodstream and get to our cells, where they are needed?

Our body’s solution is to incorporate the fat and cholesterol into particles called lipoproteins. Lipoprotein particles sequester the fat and cholesterol in their interior and surround them with water soluble phospholipids and proteins. Lipoproteins allow our bodies to transport fat and cholesterol through our bloodstream to the tissues that need them.

The next question, of course, is how the lipoproteins know which cells need the fat and cholesterol. This is where apoproteins like apoE come into play. We can think of the apoE protein as a zip code that directs lipoproteins to cells with an apoE receptor.

Our nervous system contains lots of apoE receptors, and binding of the apoE protein to its receptor is instrumental in the delivery of DHA, EPA, and cholesterol to our nervous system.

DHA and cholesterol are both important for brain health. That is because they are major components of the myelin sheath that wraps around our neurons and protects them. EPA may also be important for brain health because its anti-inflammatory effects are thought to prevent the accumulation of the amyloid plaques that are the hallmark of late-onset Alzheimer’s Disease.

There are three major versions of the APOE gene, APOE2, APOE3, and APOE4. Each of them plays slightly different roles in our body. However, it is the APOE4 version that is of interest to us. About 25% of us have the APOE4 version of the APOE gene and it increases our risk of developing Alzheimer’s Disease by a factor of two.

We do not know why this is, but one hypothesis is that lipoproteins with the apoE4 protein have more difficultly delivering much needed DHA, EPA, and cholesterol to the brain. This is one of the hypotheses that the authors set out to study.

How Was The Study Done?

Clinical StudyThere are two things you should know about this study.

  • This was a pilot study designed to test the author’s hypotheses and allow them to choose the correct dose of DHA to use for a subsequent study designed to test whether high-dose DHA can reduce the risk of developing Alzheimer’s Disease.
  • This was a very small study. That’s because the only way to determine how much DHA and EPA reaches the nervous tissue is to perform a lumbar puncture and obtain cerebrospinal fluid at baseline and again at the end of the study. Lumbar punctures are both painful and a bit risky. They were lucky to find 26 individuals who consented to the lumbar punctures.

This was a double-blind, placebo controlled clinical study.

  • Half the subjects were given 2,152 mg/day of DHA for 6 months, and half were given a daily placebo consisting of corn and soybean oil for 6 months.
  • Because previous studies have suggested that B vitamins were important for DHA and EPA uptake by nervous tissue, all subjects received a B vitamin supplement.
  • Levels of DHA and EPA were measured in both plasma and cerebrospinal fluid at baseline and again at the end of 6 months. Note: The subjects were only supplemented with DHA. The investigators were relying on the body’s ability to convert DHA into EPA.
  • All subjects were screened for APOE4

Other important characteristics of the study subjects were:

  • Average age was 69. They were 80% female.
  • All of them had a close family member who had previously been diagnosed with dementia, but none of them had been diagnosed with cognitive impairment at the time of entry into the study.
  • Around 45% of them had the APOE4 version of the APOE.

In other words, none of them currently had dementia, but most were at high risk of developing dementia.

How Much DHA Is Needed To Prevent Alzheimer’s?

fish and fish oilAfter 6 months of supplementing with over 2,000 mg/day of DHA:

  • DHA levels in the blood had increased by 200%.
  • However, DHA levels in cerebrospinal fluid had increased by only 28%.
  • Moreover, DHA levels in cerebrospinal fluid were 40% lower in subjects who had the APOE4 gene compared to subjects with the APOE2 and APOE3

EPA levels in cerebrospinal fluid averaged about 15-fold lower than DHA levels. When they looked at the effect of DHA supplementation on EPA levels.

  • EPA levels in plasma had increased by 50%.
  • EPA levels in cerebrospinal fluid had increased by 43%.
  • EPA levels in cerebrospinal fluid were 3-fold lower in subjects who had the APOE4 gene compared to subjects with the APOE2 and APOE3

The authors concluded:

“We observed only a modest (28%) increase in cerebrospinal fluid DHA levels with 2152 mg per day of DHA supplementation. This finding has implications for past clinical trials that have used lower doses (e.g. 1 g daily of DHA supplements or less) and were overwhelmingly negative. Using lower doses of omega-3 supplements may have resulted in limited omega-3 brain delivery.”

“Another aspect affecting the response to DHA supplementation is APOE4 status. Subjects with the APOE4 gene showed lower DHA levels and significantly lower EPA levels than subjects with other APOE genes”.

“In summary, our study suggests that higher doses of omega-3 fatty acids (2 or more g of DHA) are needed to ensure adequate brain delivery, particularly in APOE4 carriers…Past low dose (1 g per day or less) omega-3 supplementation trials in dementia prevention may not have provided adequate brain levels to fully evaluate the efficacy of omega-3 supplementation on cognitive outcomes.”

Based on the results from this study the authors are currently testing the effect of B vitamins and high dose DHA supplementation on cerebrospinal fluid fatty acid levels, brain imaging, and cognitive outcomes in a larger ongoing clinical trial.

What Does This Study Mean For You?

Questioning ManThe ability of the omega-3 fatty acids DHA and EPA to reduce the risk of cognitive decline, dementia, and Alzheimer’s Disease is confusing. Studies disagree.

In situations like this, most experts dismiss the hypothesis as “unproven”. However, I like to ask, “What are we missing?”

One recent study provided a clue. It suggested that omega-3s and B vitamins were interdependent. We need both to reduce cognitive decline. However, that might not be the complete answer.

This study gave both DHA and B vitamins to subjects and discovered another interesting clue. The study suggests we may not have been giving subjects enough omega-3s to see a significant effect on cognitive decline.

Let me start by saying this study did not test whether or not DHA supplementation prevents cognitive decline, dementia, and Alzheimer’s Disease. Nor does it tell us how much DHA is needed to prevent Alzheimer’s Disease, other than to show that anything less than 2 g per day is likely to be inadequate. 

However, the study did make two important advances:

#1: It showed just how difficult it is to deliver adequate amounts of DHA and EPA to the brain. This is important because it shows:

  • Most previous studies have not used high enough doses of DHA or DHA plus EPA to evaluate the effect of omega-3 fatty acids on cognitive decline. Those studies were not simply negative. They were doomed to failure. The studies were worthless.
  • That means we should stop saying that the ability of omega-3s to prevent cognitive decline and diseases like Alzheimer’s is unproven. Instead, we should say that hypothesis has not adequately been tested.
  • That also means future studies of the ability of DHA to reduce the risk of cognitive decline, dementia, and/or Alzheimer’s will need to use much higher doses or a better delivery system to get adequate amounts of DHA and EPA into the brain.

#2: It showed that the APOE4 gene significantly decreases the ability of the brain to accumulate DHA and EPA. This has several important implications.

  • Because both DHA and EPA are vital for brain health, this may explain why the APOE4 gene increases the risk of Alzheimer’s Disease.
  • It also means those at highest risk for Alzheimer’s Disease are the ones who are most likely to have difficulties accumulating DHA and EPA in their brain.
  • Once again, it means future studies of the ability of supplemental DHA to reduce the risk of Alzheimer’s Disease will need to use much higher doses of DHA.

The Bottom Line

We are an aging population. As such, issues like cognitive decline, dementia, and Alzheimer’s Disease are of increasing concern. After all, what is the good of reaching your “Golden Years” with a healthy body if you lose your mind?

The ability of the omega-3 fatty acids DHA and EPA to reduce the risk of cognitive decline, dementia, and Alzheimer’s Disease is controversial.

  • Association studies show that greater intake and higher blood levels of the omega-3 fatty acids EPA and DHA are associated with lower risk of Alzheimer’s Disease.
  • However, most placebo-controlled clinical trials with either DHA alone or DHA + EPA have come up negative.

In situations like this, most experts dismiss the hypothesis as “unproven”. However, I like to ask, “What are we missing?”

One recent study provided a clue. It suggested that omega-3s and B vitamins were interdependent. We need optimal amounts of both to reduce dementia. However, that might not be the complete answer.

This study gave both DHA and B vitamins to participants and discovered another interesting clue. The study suggests we may not have been giving subjects enough omega-3s to see a significant effect on cognitive decline.

The authors of the study hypothesized:

  • Uptake of DHA and EPA by the brain is very inefficient, and previous studies have not used sufficient doses of DHA or DHA plus EPA to see a significant effect on cognitive impairment.
  • The APOE4 gene, which is known to increase the risk of Alzheimer’s Disease, further decreases the uptake of DHA and EPA by the brain.

Their study confirmed their hypotheses and made two important advancements:

#1: It showed just how difficult it is to deliver adequate amounts of DHA and EPA to the brain. This is important because it shows:

  • Most previous studies have not used high enough doses of DHA or DHA plus EPA to evaluate the effect of omega-3 fatty acids on cognitive decline. Those studies were not simply negative. They were doomed to failure. The studies were worthless.
  • That means we should stop saying that the ability of omega-3s to prevent cognitive decline and diseases like Alzheimer’s is unproven. Instead, we should say that hypothesis has not adequately been tested.
  • That also means future studies of the ability of DHA to reduce the risk of cognitive decline, dementia, and/or Alzheimer’s will need to use much higher doses or a better delivery system to get adequate amounts of DHA and EPA into the brain.

#2: It showed that the APOE4 gene significantly decreases the ability of the brain to accumulate DHA and EPA. This has several important implications.

  • Because both DHA and EPA are vital for brain health, this may explain why the APOE4 gene increases the risk of Alzheimer’s Disease.
  • It also means those at highest risk for Alzheimer’s Disease are the ones who are most likely to have difficulties accumulating DHA and EPA in their brain.
  • Once again, it means future studies of the ability of supplemental DHA to reduce the risk of Alzheimer’s Disease will need to use much higher doses of DHA.

Based on the results from this study the authors are currently testing the effect of B vitamins and high dose DHA supplementation on DHA and EPA levels in the brain, brain imaging, and cognitive outcomes in a larger ongoing clinical trial.

For more details, read the article above. For a better understanding of the roles of DHA, EPA, and the APOE gene in brain health, you may want to read my “Biochemistry 101” section 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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