Can Milk Be Bad For You?

Written by Dr. Steve Chaney on . Posted in Uncategorized

is milk bad for youGot Milk? Maybe Not

Author: Dr. Stephen Chaney

 

 

You’ve probably seen the ads featuring your favorite celebrities sporting a white mustache and saying “Got milk?” Those ads all suggest that milk is essential for strong bones and a healthy body.

And you are probably aware of dietary recommendations from learned experts saying that you should be consuming at least 2-3 servings of milk every day – more if you’re over 65.

If so, you are probably really confused by the recent headlines saying things like: “Milk Consumption May Increase the Risk of Fractures” and “High Consumption of Milk May Increase Mortality Risk”.

Can milk be bad for you?

Before you pour all your milk down the drain and put Bessie the cow out to pasture, we should examine the study behind the headlines.

Does Milk Actually Increase Fracture Risk?

The study in question (Michaelsson et al, British Medical Journal, 2014; 349; g6015 doi: 10.1136/bmj.g6015) followed 61,433 Swedish women (aged 39-74) for an average of 20.2 years and 45,339 Swedish men (aged 45-79) for an average of 11.2 years. The women filled out two food frequency questionnaires, one at the beginning of the study and another approximately 10 years later. The men filled out one food frequency questionnaire at the beginning of the study.

Mortality and cause of death were obtained from the Swedish Cause of Death Registry. Bone fracture information was obtained from the Swedish National Patient Registry (In countries like Sweden big brother knows everything about you).

The results were pretty dramatic. When they compared women who were drinking three or more glasses of milk per day to women who drank less than one glass of milk a day, the highest level of milk consumption was associated with a:

• 93% increased risk of dying from all causes.
• 90% increased risk of dying from cardiovascular disease.
• 44% increased risk of dying from cancer.
• 16% increased risk of having a bone fracture of any kind.
• 60% increased risk of having a hip fracture.

In contrast, consumption of fermented milk products (cheeses, soured milk and yoghurt) was associated with a decreased risk of mortality and bone fracture in women (a 10-15% decrease in risk for every serving consumed).

What Are The Dangers of Drinking Milk?

The authors speculated that that the increased mortality and fracture risk was due to galactose (a sugar formed from lactose, the primary naturally occurring sugar in unfermented milk). Their argument supporting this hypothesis was four fold:

1) In our intestines lactose is split into two sugars, glucose and galactose.

2) In animal models (primarily mice and rats) lifelong consumption of galactose is associated with shortened lifespan caused by, among other things, oxidative damage and chronic inflammation.

3) There is a rare genetic disease called galactosemia in humans that is caused by the lack of a crucial enzyme required to metabolize galactose. Patients with this disease die at a very early age without treatment. Even with dietary restriction of galactose they experience oxidative damage, inflammation and an increased risk for chronic diseases, including osteoporosis.

4) In a subset of patients enrolled in this study, high milk consumption was associated with an increase in blood markers of oxidative stress and inflammation.

While the results seem clear and the hypothesis seems plausible, we should perhaps look at the limitations of the study before making significant dietary changes.

Limitations of the Study

There are a number of significant limitations to this study.

what are the dangers of drinking milk1) It simply measures associations, not cause and effect.

2) The statistics were not entirely consistent. For example, while consumption of three or more glasses of milk (average = 3.4 glasses/day) was associated with 90% increased risk of mortality and cardiovascular mortality in women, there was only a 15% increase in risk associated with every glass of milk consumed. 15%/glass times 3.4 glasses/day = 51% – not 90%. A little bit of higher math tell us that these numbers don’t quite add up.

3) In men the effects were much smaller to nonexistent. In men high milk consumption was associated with a 10% increased risk in overall mortality and a 16% increased risk cardiovascular mortality, but milk consumption had essentially no effect on cancer mortality, fracture risk or hip fracture risk.

4) The galactose hypothesis is interesting, but far from convincing. Mice and rats don’t necessarily metabolize galactose in the same way as humans. Furthermore, in humans galactosemia is a very rare disease, and there is currently no evidence that dietary galactose poses a problem for people without the genetic defect that causes galactosemia.

5) Most importantly, there have been a number of previous studies examining the effects of milk consumption on both fracture risk and mortality, and those studies have been remarkably inconsistent. Some show increased risk and others show decreased risk. Meta-analyses of all previous clinical studies have shown no significant association between milk consumption and mortality (American Journal of Clinical Nutrition, 93: 158-171, 2011) or hip fracture (Journal of Bone Mineral Research, 26: 833-839, 2011).

While some of the media articles were characterizing this study as ground-breaking and one that should lead to changes in dietary recommendations, the authors were far more cautious in their interpretation of the data. They said: “The results of this study should be interpreted cautiously given the observational design of our study. The findings merit independent replication before they can be used for dietary recommendations.” I agree.

Where Else Can You Find The Nutrients That Milk Provides?

In summary, there is no consistent evidence that milk consumption increases your risk of mortality and bone fractures. However, there is also no consistent evidence that milk consumption decreases your risk of mortality or fracture.

Since milk provides no proven benefit and may pose some risk many of you may be wondering where else you can get the nutrients that milk provides.

Milk is an excellent source of calcium, magnesium, vitamin D, protein and riboflavin. When you carefully evaluate alternative food sources for these nutrients you will quickly discover that your choices are not straight forward. You need to be a knowledgeable consumer and careful label reader. For example:

vitamin-C• Green leafy vegetables are a high in calcium, but many of them also contain oxalate, which chelates the calcium and reduces its bioavailability. In short, green leafy vegetables are a healthy source for some of the calcium we need for healthy bones, but they should not be our primary source because of the relatively low calcium bioavailability.

• Cheeses are an excellent source of calcium, but many cheeses are high in fat and sodium.

• Yoghurts and other fermented milk products are an excellent source of calcium, but many of them are high in added sugars and artificial ingredients, which I do not recommend (see my article “Do Artificial Colors Cause Hyperactivity?” (https://healthtipsfromtheprofessor.com/do-artificial-colors-cause-hyperactivity/).

• Tofu and tempeh provide only 1/3 to ½ the calcium found in milk and provide no vitamin D.

• “Milk substitutes” made from soy, rice or other sources are often high in added sugars and may not provide the same nutrient profile as real milk. You have to read the labels carefully.

• Calcium supplements are an excellent source of calcium, but they have been controversial in recent years (see my article “Does Calcium Increase Heart Attack Risk?” (https://healthtipsfromtheprofessor.com/calcium-supplements-increase-heart-attack-risk/). My take on the controversy is that the latest studies have shown fairly convincingly that calcium supplements do not increase heart attack risk. However, if there is any risk, it is associated with calcium supplements that were not designed properly for incorporation of calcium into bone. My recommendation is to only choose calcium supplements that have been clinically proven to increase bone density.

• Well designed protein supplements can also be a good source of calcium and vitamin D, but many of them contain artificial sweeteners, which I do not recommend (see my articles “Do Diet Sodas Make You Fat?” (https://healthtipsfromtheprofessor.com/do-diet-sodas-make-you-fat/), “Does Sugar Cause Heart Disease?” (https://healthtipsfromtheprofessor.com/does-sugar-cause-heart-disease/), and “Can Soft Drinks Cause Heart Disease?” (https://healthtipsfromtheprofessor.com/soft-drinks-and-heart-disease/).

The Bottom Line:

1) A recent study suggested that high milk consumption (> 3 glasses per day) in women might be associated with a:

• 93% increased risk of dying from all causes.
• 90% increased risk of dying from cardiovascular disease.
• 44% increased risk of dying from cancer.
• 16% increased risk of having a bone fracture of any kind.
• 60% increased risk of having a hip fracture.

2) That study has a number of limitations and is not consistent with previous studies. Even the authors of the study stated: “The results [of this study] should be interpreted cautiously…”

3) Previous studies looking at the association of milk consumption and both fractures and mortality have been inconsistent. Meta-analyses of all previous studies show no significant association between milk consumption and either fractures or mortality.

4) In short, there is no consistent evidence to support the recent headlines suggesting that milk consumption might increase your risk of mortality and bone fractures, but there is also no consistent evidence that milk consumption decreases your risk of mortality or fractures.

5) Since milk provides no proven benefits and might pose some risk, you may be asking where else you can find the nutrients that milk provides. While there are a number of other dietary sources of the calcium needed for strong bones, each of them has potential limitations (for details, see the article above). You have to be a knowledgeable consumer and careful label reader if you are looking for non-milk sources of calcium.

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.

Trackback from your site.

Leave a comment

Recent Videos From Dr. Steve Chaney

READ THE ARTICLE
READ THE ARTICLE

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.

UA-43257393-1