protein

Are Vegan Diets Bad For Your Bones?

by

The Secrets To A Healthy Vegan Diet

Author: Dr. Stephen Chaney

Frail ElderlyOsteoporosis is a debilitating and potentially deadly disease associated with aging. It affects 54 million Americans. It can cause debilitating back pain and bone fractures. 50% of women and 25% of men over 50 will break a bone due to osteoporosis. Hip fractures in the elderly due to osteoporosis are often a death sentence.

As I discussed in a previous issue of “Health Tips From The Professor”, a “bone-healthy lifestyle requires 3 essentials – calcium, vitamin D, and weight bearing exercise. If any of these three essentials is presence in inadequate amounts, you can’t build healthy bones. In addition, other nutrients such as protein, magnesium, zinc, vitamin B12, and omega-3 fatty acids may play supporting roles.

Vegan and other plant-based diets are thought to be very healthy. They decrease the risk of heart disease, diabetes, and some cancers. However, vegan diets tend to be low in calcium, vitamin D, zinc, vitamin B12, protein, and omega-3 fatty acids. Could vegan diets be bad for your bones?

A meta-analysis of 9 studies published in 2009 (LT Ho-Pham et al, American Journal of Clinical Nutrition 90: 943-950, 2009) reported that vegans had 4% lower bone density than omnivores, but concluded this difference was “not likely to be clinically relevant”.

However, that study did not actually compare bone fracture rates in vegans and omnivores. So, investigators have followed up with a much larger meta-analysis (I Iguacel et al, Nutrition Reviews 77, 1-18, 2019) comparing both bone density and bone fracture rates in vegans and omnivores.

How Was This Study Done?

Clinical StudyThe investigators searched the literature for all human clinical studies through November 2017 that compared bone densities and frequency of bone fractures of people consuming vegan and/or vegetarian diets with people consuming an omnivore diet.

  • Vegan diets were defined as excluding all animal foods.
  • Vegetarian diets were defined as excluding meat, poultry, fish, seafood, and flesh from any animal but including dairy foods and/or eggs. [Note: The more common name for this kind of diet is lacto-ovo vegetarian, but I will use the author’s nomenclature in this review.]
  • Omnivore diets were defined as including both plant and animal foods from every food group.

The investigators ended up with 20 studies that had a total of 37,134 participants. Of the 20 studies, 9 were conducted in Asia (Taiwan, Vietnam, India, Korea, and Hong-Kong), 6 in North America (the United States and Canada), and 4 were conducted in Europe (Italy, Finland, Slovakia, and the United Kingdom).

Are Vegan Diets Bad For Your Bones?

Here is what the investigators found:

Unhealthy BoneBone density: The clinical studies included 3 different sites for bone density measurements – the lumbar spine, the femoral neck, and the total body. When they compared bone density of vegans and vegetarians with the bone density of omnivores, here is what they found:

Lumbar spine:

    • Vegans and vegetarians combined had a 3.2% lower bone density than omnivores.
    • The effect of diet was stronger for vegans (7% decrease in bone density) than it was for vegetarians (2.3% decrease in bone density).

Femoral neck:

    • Vegans and vegetarians combined had a 3.7% lower bone density than omnivores.
    • The effect of diet was stronger for vegans (5.5% decrease in bone density) than it was for vegetarians (2.5% decrease in bone density).

Whole body:

    • Vegans and vegetarians combined had a 3.2% lower bone density than omnivores.
    • The effect of diet was statistically significant for vegans (5.9% decrease in bone density) but not for vegetarians (3.5% decrease in bone density). [Note: Statistical significance is not determined by how much bone density is decreased. It is determined by the size of the sample and the variations in bone density among individuals in the sample.]

Bone FractureBone Fractures: The decrease in bone density of vegans in this study was similar to that reported in the 2009 study I discussed above. However, rather than simply speculating about the clinical significance of this decrease in bone density, the authors of this study also measured the frequency of fractures in vegans, vegetarians, and omnivores. Here is what they found.

  • Vegans and vegetarians combined had a 32% higher risk of bone fractures than omnivores.
  • The effect of diet on risk of bone fractures was statistically significant for vegans (44% higher risk of bone fracture) but not for vegetarians (25% higher risk of bone fractures).
  • These data suggest the decreased bone density in vegans is clinically significant.

The authors concluded, “The findings of this study suggest that both vegetarian and vegan diets are associated with lower bone density compared with omnivorous diets. The effect of vegan diets on bone density is more pronounced than the effect of vegetarian diets, and vegans have a higher fracture risk than omnivores. Both vegetarian and vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.”

The Secrets To A Healthy Vegan Diet

Emoticon-BadThe answer to this question lies in the last statement in the author’s conclusion, “Both vegetarian and vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.” 

The problem also lies in the difference between what a nutrition expert considers a vegan diet and what the average consumer considers a vegan diet. To the average consumer a vegan diet is simply a diet without any animal foods. What could go wrong with that definition? Let me count the ways.

  1. Sugar and white flour are vegan. A vegan expert thinks of a vegan diet as a whole food diet – primarily fruits, vegetables, whole grains, beans, nuts, and seeds. A vegan novice includes all their favorites – sodas, sweets, and highly processed foods. And that may not leave much room for healthier vegan foods.

2) Big Food, Inc is not your friend. Big Food tells you that you don’t need to give up the taste of animal foods just because you are going vegan. They will just combine sugar, white flour, and a witch’s brew of chemicals to give you foods that taste just like your favorite meats and dairy foods. The problem is these are all highly processed foods. They are not healthy. Some people call them “fake meats” or “fake cheeses”. I call them “fake vegan”.

If you are going vegan, embrace your new diet. Bean burgers may not taste like Big Macs, but they are delicious. If need other delicious vegan recipe ideas, I recommend the website https://forksoverknives.com.

3) A bone healthy vegan diet is possible, but it’s not easy. Let’s go back to the author’s phrase “…vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.” A vegan expert will do the necessary planning. A vegan novice will assume all they need to do is give up animal foods. 

As I said earlier, vegan diets tend to be low in calcium, vitamin D, zinc, vitamin B12, protein, and omega-3 fatty acids. Let’s look at how a vegan expert might plan their diet to get enough of those bone-healthy nutrients.

    • Calcium. The top plant sources of calcium are leafy greens and soy foods at about 100-250 mg (10-25% of the DV) of calcium per serving. Some beans and seeds are moderately good sources of calcium. Soy foods are a particularly good choice because they are a good source of calcium and contain phytoestrogens that stimulate bone formation.

A vegan expert makes sure they get these foods every day and often adds a calcium supplement.

    • Protein. Soy foods, beans, and some whole grains are the best plant sources of protein.soy

It drives me crazy when a vegan novice tells me they were told they can get all the protein they need from broccoli and leafy greens. That is incredibly bad advice.

A vegan expert makes sure they get soy foods, beans, and protein-rich grains every day and often adds a protein supplement.

    • Zinc. There are several plant foods that supply around 20% the DV for zinc including lentils, oatmeal, wild rice, squash and pumpkin seeds, quinoa, and black beans.

A vegan expert makes sure they get these foods every day and often adds a multivitamin supplement containing zinc.

    • Vitamin D and vitamin B12. These are very difficult to get from a vegan diet. Even vegan experts usually rely on supplements to get enough of these important nutrients.

4) Certain vegan foods can even be bad for your bones. I divide these into healthy vegan foods and unhealthy “vegan” foods. 

    • Healthy vegan foods that can be bad for your bones include.
      • Pinto beans, navy beans, and peas because they contain phytates.
      • Raw spinach & swiss chard because they contain oxalates.
      • Both phytates and oxalates bind calcium and interfere with its absorption.
      • These foods can be part of a healthy vegan diet, but a vegan expert consumes them in moderation.
    • Unhealthy “vegan” foods that are bad for your bones include sodas, salt, sugar, and alcohol.
      • The mechanisms are complex, but these foods all tend to dissolve bone.
      • A vegan expert minimizes them in their diet.

5) You need more than diet for healthy bones. At the beginning of this article, I talked about the 3 Weight Trainingessentials for bone formation – calcium, vitamin D, and exercise. You can have the healthiest vegan diet in the world, but if you aren’t getting enough weight bearing exercise, you will have low bone density. Let me close with 3 quick thoughts:

    • None of the studies included in this meta-analysis measured how much exercise the study participants were getting.
    • The individual studies were generally carried out in industrialized countries where many people get insufficient exercise.
    • The DV for calcium in the United States is 1,000-1,200 mg/day for adults. In more agrarian societies dietary calcium intake is around 500 mg/day, and osteoporosis is almost nonexistent. What is the difference? These are people who are outside (vitamin D) doing heavy manual labor (exercise) in their farms and pastures every day.

In summary, a bone healthy vegan lifestyle isn’t easy, but it is possible if you work at it.

The Bottom Line 

A recent meta-analysis asked two important questions about vegan diets.

  1.     Do vegans have lower bone density than omnivores?

2) Is the difference in bone density clinically significant? Are vegans more likely to suffer from bone fractures?

The study found that:

  • Vegans had 5.5%–7% lower bone density than omnivores depending on where the bone density was measured.
  • Vegans were 44% more likely to suffer from bone fractures than omnivores.

The authors of the study concluded, ““The findings of this study suggest that…vegan diets are associated with lower bone density compared with omnivorous diets, and vegans have a higher fracture risk than omnivores…Vegan diets should be appropriate planned to avoid dietary deficiencies associated with bone health.”

In evaluating the results of this study, I took a detailed look at the pros and cons of vegan diets and concluded, “A bone healthy vegan lifestyle isn’t easy, but it is possible if you work at it.”

For more details about study and my recommendations for a bone healthy vegan lifestyle 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.

Does Vitamin D Affect Muscle Strength?

by

Why Is Vitamin D Research So Controversial?

vitamin dMost people lose muscle strength as they age, something called sarcopenia. This is not a trivial matter. Loss of muscle mass:

  • Leads to loss of mobility. It can also make it difficult to do simple things like lifting your grandchild or carrying a bag of groceries.
  • Increases your risk of falling. This often leads to serious fracture which increases your of dying prematurely. In fact, bone fractures increase your risk of dying by 3-fold or more. Even in those who recover their mobility and quality of life may never be the same.
  • Lowers your metabolic rate. This increases your risk of obesity and all the diseases that are associated with obesity.

Loss of muscle strength as we age is preventable. There are several things we can do to preserve muscle strength as we age, but in today’s article I will focus on the effect of vitamin D on muscle strength.

What if something as simple as preventing vitamin D deficiency could improve muscle strength as we age? That idea has been around for a decade or more. But, for reasons I will detail below, it has proven controversial. Let me start by sharing the latest study on vitamin D and muscle strength (N Aspell et al, Clinical Investigations in Ageing, volume 2019:14, pages 1751-1761).

How Was The Study Done?

Clinical StudyThe data for this study came from 4157 adults who were enrolled in the English Longitudinal Study On Aging. Participants in this study were all over the age of 60 and were still living in their own homes. The general characteristics of the study population were:

  • Their average age was 69.8 with 45% male and 55% female.
  • While 76% of the participants rated their health as “good” or above
    • 73% were overweight or obese.
    • 54% had a longstanding disease that limited mobility.
    • 29% were taking multiple medications.

Serum 25-hydroxy vitamin D levels were determined as a measure of vitamin D status.

  • 22% of the participants were vitamin D deficient (<30 nmol/L 25-hydroxy vitamin D).
  • 34% of the participants were vitamin D insufficient (between 30 and 50 nmol/L 25-hydroxy vitamin D).
  • 46% of the participants had adequate vitamin D status (>50 nmol/L 25-hydroxy vitamin D).

Muscle strength was assessed by a handgrip strength test with the dominant hand. Muscle performance was assessed with something called the short physical performance battery (SPPB), consisting of a walking speed test, a repeated chair raise test, and a balance test.

Does Vitamin D Affect Muscle Strength?

When the data on handgrip strength were analyzed:

  • Only 22% of the participants who had adequate vitamin D status had low handgrip strength.
  • 40% of participants who were vitamin D deficient had low handgrip strength. That’s almost a 2-fold difference.
  • Handgrip strength increased linearly with vitamin D status.
    • The relationship between vitamin D status and handgrip strength was highly significant (p<001).
    • The beneficial effect of vitamin D status on handgrip strength plateaued at around 55-69 nmol/L 25-hydroxy vitamin D. In other words, you need adequate vitamin D status to support muscle strength, but higher levels provide no additional benefit.

When the data on muscle performance (the SPPB test) were analyzed:

  • Only 8% of the participants who had adequate vitamin D status scored low on this test.
  • 25% of participants who were vitamin D deficient scored low on this test. That’s a 3-fold difference.
  • Muscle performance also increased linearly with vitamin D status.
    • The relationship between vitamin D status and muscle performance was also highly significant (p<001).
    • The beneficial effect of vitamin D status on muscle performance also plateaued at around 55-69 nmol/L 25-hydroxy vitamin D.

The authors concluded: “Vitamin D deficiency was associated with impaired muscle strength and performance in a large study of community-dwelling older people. It is generally accepted that vitamin D deficiency should be reversed to prevent bone disease. This strategy may also protect skeletal muscle function in aging.”

Why Is Vitamin D Research So Controversial?

ArgumentYou can be forgiven if you are saying to yourself: “I’ve heard this sort of thing before. I see a blog or headline claiming that vitamin D has a certain benefit, but it’s usually followed by later headlines saying those claims are false. Why can’t the experts agree? Is all vitamin D research bogus?”

The relationship between vitamin D status and muscle strength is no different.

  • Most, but not all, studies looking at the association between vitamin D status and muscle strength find that vitamin D status affects muscle strength.
  • However, many randomized, placebo-controlled clinical trials looking at the effect of vitamin D supplementation on muscle strength have come up empty.

A meta-analysis (L Rejnmark, Therapeutic Advances in Chronic Disease, 2: 25-37, 2011) of randomized, placebo-controlled clinical trials of vitamin D supplementation and muscle strength provides insight as to why so many of them come up empty.

The meta-analysis combined data from 16 clinical trials. The conclusions were similar to what other meta-analyses have found:

  • Seven of the studies showed a benefit of vitamin D supplementation on muscle strength. Nine did not.
  • When the data from all 16 studies were combined, there was only a slight beneficial effect of vitamin D supplementation on muscle strength.

However, it was in the discussion that the reason for these discrepancies became apparent. There were three major deficiencies in study design that were responsible for the discrepancies.

1) There was a huge difference in study design.

    • The subjects were of different ages, genders, and ethnicities.
    • The dose of vitamin D supplementation varied.
    • Different measures of muscle strength and performance were used.

Until the scientific and medical community agree on a standardized study design it will be difficult to obtain consistent results.

While this deficiency explains the variation in outcomes from study to study, there are two other deficiencies in Garbage In Garbage Outstudy design that explain why many of the studies failed to find an effect of vitamin D on muscle strength. I call this “Garbage In, Garbage Out”. Simply put, if the study has design flaws, it may be incapable of detecting a positive effect of vitamin D on muscle strength.

2) Many of the studies did not measure vitamin D status of the participants at the beginning of the study.

    • The results of the study described above show that additional vitamin D will be of little benefit for anyone who starts the study with an adequate vitamin D status.
    • In the study above 46% of the participants had adequate vitamin D status. This is typical for the elderly community. When almost 50% of the participants in a study have adequate vitamin D status at the beginning of a study it becomes almost impossible to demonstrate a beneficial effect of vitamin D supplementation on any outcome.

It is essential that future studies of vitamin D supplementation start with participants who have low vitamin D status. Otherwise, you are almost guaranteeing a negative outcome.

3) Most of the studies ignored the fact that vitamin D status is only one of three factors that are essential for muscle strength.

    • In the case of muscle strength, especially in the elderly, the three essentials are vitamin D, protein, and exercise. All three are needed to maintain or increase muscle strength. Simply put, if one is missing, the other two will have little or no effect on muscle strength. Unfortunately, you cannot assume that exercise and protein intake are adequate in older Americans:
      • Many older adults don’t get enough exercise because of physical limitations.

Unfortunately, many clinical studies on the effect of vitamin D supplementation and muscle strength fail to include exercise and adequate protein intake in the study. Such clinical trials are doomed to failure.

Now you know why vitamin D research is so controversial. Until the scientific and medical community get their act together and perform better designed experiments, vitamin D research will continue to be controversial and confusing.

What Does This Mean For You?

Old Man Lifting WeightsLoss of muscle mass as we age is not a trivial matter. As described above, it:

  • Leads to loss of mobility.
  • Increases your risk of falling. This often leads to serious fracture which increase your risk of disability and death.
  • Lowers your metabolic rate, which increases your risk of obesity and obesity-related diseases.

So, what can you do prevent loss of muscle mass as you age? The answer is simple:

1) Aim for 25-30 grams of high-quality protein in each meal.

    • That protein can come from meat, fish, eggs, or legumes.
    • That doesn’t mean you need to consume an 8-ounce steak or a half chicken. 3-4 ounces is plenty.
    • However, it does mean you can’t subsist on green salads and leafy greens alone. They are healthy, but you need to include a good protein source if you are going to meet your protein needs.

2) Aim for 150 minutes of moderate intensity exercise per week.

    • At least half of that exercise should be resistance exercise (lifting weights, for example).
    • If you have physical limitations, consult your doctor and a physical therapist or personal trainer to design resistance exercises you can do.
    • Aim for a variety of resistance exercises. You will only strengthen the muscles you exercise.

3) Aim for an adequate vitamin D status.

    • Start with a multivitamin containing at least 800 IU of vitamin D3.
    • Because there is large variation in the efficiency with which we convert vitamin D to 25-hydroxy vitamin D, you should get your serum 25-hydroxyvitamin D tested on a yearly basis. Your health professional can tell you if you need to take larger amounts of vitamin D3.
    • This study suggests that a serum 25-hydroxy vitamin D level of 55-69 nmol/L is optimal, and higher levels provide no additional benefit. That means there is no need to take mega-doses of vitamin D3 unless directed by your health professional.

The Bottom Line

A recent study looked at the effect of vitamin D status on muscle strength and performance in a healthy population with an average age of 69.

When they looked at handgrip strength:

  • Only 22% of the participants with an adequate vitamin D status had low handgrip strength.
  • 40% of participants who were vitamin D deficient had low handgrip strength. That’s almost a 2-fold difference.
  • Handgrip strength increased linearly with vitamin D status.

When they looked at muscle performance:

  • Only 8% of the participants with an adequate vitamin D status scored low on this test.
  • 25% of participants who were vitamin D deficient scored low on this test. That’s a 3-fold difference.
  • Muscle performance also increased linearly with vitamin D status.

The authors concluded: “Vitamin D deficiency was associated with impaired muscle strength and performance in a large study of community-dwelling older people. It is generally accepted that vitamin D deficiency should be reversed to prevent bone disease. This strategy may also protect skeletal muscle function in aging.”

If we look at the research more broadly, there are three factors that are essential for maintaining muscle mass as we age: exercise, protein, and vitamin D. Therefore, my recommendations are to:

1)  Aim for 25-30 grams of high-quality protein in each meal.

2) Aim for 150 minutes of moderate intensity exercise per week. At least half of that exercise should be resistance exercise.

3) Aim for an adequate vitamin D status (>50 nmol/L of serum 25-hydroxy vitamin D). A good place to start is with a multivitamin providing at least 800 IU of vitamin D3.

For more details on my recommendations and a discussion of why studies on vitamin D supplementation are often confusing, 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.

 

Health Tips From The Professor