Bone health 101

Why do we need strong bones?

Your bones do a lot more than just give your body structure. They serve as your body’s back-up supply of minerals. Just like muscles act as a back up supply of protein, your bones are loaded with minerals, particularly calcium. A whopping 99% of calcium in the body is stored in the bones.

We need calcium for both our skeletal and heart muscle to function. If calcium is too low in your body, your heart will literally stop beating!

So, to make sure we never run out of calcium, our bodies will pull calcium out of our bones if our dietary intake or absorption is too low. Your body will always prioritize muscle function over bone quality.

If this removal of calcium from your bones continues, then you will end up with a low bone mineral density (BMD). You may have brittle bones, but it’s better than your heart stopping. Poor bone health = poor mineral health.

What determines your bone mineral density (BMD)? 

BMD is a measurement of the density of your bones. The denser your bones are, the more minerals they contain, the stronger your bones are. We learned why calcium status is so important, but there are other factors that play a big role. 

Your childhood years

The biggest factor that determines your BMD as an adult is whether you reach your genetic BMD peak as a child (1). Not reaching this peak as a kid is the most common reason for poor bone health as an adult.

Osteoporosis is often called a childhood disease because the biggest thing that causes it is what you did between ages 8-15. That’s why it’s so important to make sure kids get lots of different types of movement. 

Kids ages 8-15 who do different kinds of activities (multiple sports, lots of jumping and playing, etc…) will have a 10% higher BMD in their 20’s (1). Jumping and landing (plyometrics) seems to provide the most benefit for bone (for kids and adults). 

Age

It’s a common belief that you will inevitably lose BMD with age, but new research suggests that is not the case! This trend of reduced BMD with age is directly explained by the loss of physical activity that naturally occurs as you get older, with the exception of menopause.

Men also see a drop as they enter “andropause” (reduction in testosterone), but it’s not nearly as pronounced as it is in women.

So if you stay active throughout life and into older age and continue to do the types of exercises I’ll mention below, then you shouldn’t see a significant drop in BMD with age.

Exercise and bone remodeling

Bones are very metabolically active – they remodel constantly (break down and rebuild) to keep your bones strong and healthy.

In order to remodel your bones, you need to challenge them through progressive heavy lifting and impact training. If you are just lifting the same amount of weight over and over, this will not stimulate bone growth – you need progressive loading. Exercise that involves lots of jumping (plyometrics) and changing direction are one of the best ways to stimulate bone growth (for kids and adults).

Low impact exercise (walking, jogging, cycling, swimming, pilates, yoga, high-rep/low weight exercises) is great for other reasons, but not for building bone.

Not only will these types of exercises help keep your bones strong, you will also be indirectly reducing your fall risk by building on strength and balance. So it’s doing your bones two favors – building them and keeping them safe!

Osteoporosis and exercise

Osteopenia is a condition where BMD is lower than normal but not low enough to be classified as osteoporosis. Osteoporosis is diagnosed when BMD is significantly low, resulting in weak and fragile bones.

A common belief is that strength training is dangerous for people with osteoporosis, but that has since been disproven.

There is a famous study called the LIFTMORE trial that followed a group of postmenopausal women with known low BMD for 8 months. One group did supervised high intensity resistance/impact exercises (2x/week for 30 minutes) and the other group did low impact exercises. The high intensity group saw a significantly higher improvement in their BMD and strength (along with an improvement in activities of daily living).

So the big takeaways from that trial are:

• It is safe to lift heavy weights if you have osteopenia or osteoporosis, as long it is “performed with mindfulness and correct technique under supervision” (4). Check out the ONERO Academy for more resources.
• Supervised high intensity training improves BMD and strength in women with osteoporosis, therefore reducing fall risk.

Osteoporosis can’t be completely reversed, but intervention can help reduce the progression and your fall risk. If you learn that you have low BMD or osteopenia/osteoporosis, the goal is to maintain that current BMD as you continue to get older. It’s more about preventing further loss.

Why bone health is so important for women

Women see a rapid decline in BMD for about 5-8 years through menopause, mostly due to the reduction in estrogen. Men also see a reduction, but not nearly as drastic.

Estrogen keeps osteoclasts (the molecules that break down your bones) in check. When estrogen drops, those osteoclasts start to break down bone at a much higher rate, leading to rapid and significant bone loss. This is why it’s so important to do safe high-impact/strength training exercises during those years, to prevent some of that loss.

Calcium and vitamin D 

So now you know why calcium is so important for bone health – it is the primary building block of bones and nearly all of the calcium in the body is stored in bones. Bone does contain a lot of other minerals (like magnesium, phosphorus, copper, and zinc), but calcium has the largest impact on bone health.

Vitamin D plays an important role in both health because you need adequate vitamin D levels in order to absorb calcium in the gut. So you could be eating more than enough calcium, but not absorbing that calcium due to vitamin D deficiency.

This one of the reasons why milk and many cereals are fortified with vitamin D – because it will help you absorb all of the calcium in the milk. 

Since it’s difficult to get enough vitamin D through diet, it’s one of the very few supplements I take on a regular basis – this one is my favorite.

How to boost bone health with diet

Let’s get into more detail about the minerals important for bone health. If you have good gut health, adequate vitamin D levels, and you’re eating a well rounded diet rich in leafy green veggies, dairy products (like cheese, yogurt, milk), lean meats, nuts/seeds, and whole grains, then you are more than likely getting and absorbing enough calcium and other minerals.

It’s important to note that while diet is important for strong bones, bone responds more dramatically to exercise intervention (4).

Calcium

If you are eating a well rounded diet, it’s more than likely that you’re getting enough calcium. It’s recommended that we get 800-1000mg per day. The best and most absorbable source of calcium is through dairy products like milk, yogurt, and cheese.

Calcium sources and amounts:

• 1 cup of milk = 300mg
• 1 cup of yogurt = 230mg 
• ¼ cup parmesan = 330mg 
• 4 oz canned sardines = 400mg 
• 4 oz tofu = 400mg 
• 1 cup broccoli = 40mg 
• ¼ cup tahini = 140mg 

Vitamin D

This is one of the few things I like to take a supplement for because it’s hard to get enough through diet and we aren’t always able to get enough sunshine year round. It’s recommended that healthy adults supplement with 600IU and up to 1000IU vitamin D per day, but it’s best to consult your doctor. Some foods that are high in vitamin D include fortified milk and cereals, fatty fish, egg yolks, and cheese.

Vitamin K

This vitamin activates proteins needed for bone formation and mineralization. It can be found mostly in leafy green vegetables. One cup of most leafy green vegetables (kale, collard greens, broccoli, spinach, cabbage) will get you well over what you need.

Magnesium

50-60% of your magnesium is stored in your bones. The best sources are nuts, seeds, beans, whole grains, salmon, milk, yogurt, leafy greens. If you’re eating these on a regular basis (which you are if you follow my menus!), then you’re in good shape.

Zinc

30% of zinc is found in your bones. It’s recommended that women get about 8mg per day. The best sources of zinc include oysters, beef, pumpkin seeds, poultry, pork, lentils, cheese, greek yogurt, and milk. 

Zinc sources and amounts:

• 2 oysters = 60-80mg
• 4 oz beef = 5mg
• ½ cup cooked lentils = 2.5mg
• ¼ cup pumpkin seeds = 2.5mg
• ¼ cup cheese = 1.-1.5mg
• 4 oz dark meat chicken = 1.5mg (white meat has less)

What about supplementation for bone health?

As mentioned before, I like to take this vitamin D/K2 supplement since it’s difficult to get enough vitamin D through food and sunlight.

I’m not a fan of calcium supplements, mostly because it’s easy to get enough through your diet. If you are eating enough calcium, then adding a supplement on top of that doesn’t have an impact on bone health (1). 

Other lifestyle factors that impact bone health (1)

We’ve already talked about the importance of diet, movement, exercise, and strength training when it comes to bone health. Below are a few more factors worth mentioning that can negatively impact bone health.

• Environmental toxins – heavy metals (aluminum, mercury, lead cadmium), chemicals (BPA, phthalates, pesticides), air pollutants. 
• Some diseases:
  • Metabolic disease (diabetes, hypothyroid)
  • Gut health disease (celiac, IBS)
  • Oral health – there is a strong connection between tooth health and whole body bone health.
• Drugs and medications:
  • Alcohol and smoking
  • GERD medications
  • Corticosteroids (prednisone strongly connected with bone mineral loss)
• Chronic stress: cortisol is beneficial to bone in short bursts, like the kind you get from exercise. These short bursts stimulate bone turnover. It becomes a problem when you’re experiencing chronic stress.
  • Cortisol inhibits osteoblasts (the molecules that make new bone), blocks the formation of new osteoblasts, and promotes osteoblast death. It also stimulates osteoclasts (the molecules that break down bone) and blocks calcium absorption.
• Poor sleep: often poor sleep and chronic stress go hand in hand. Studies show that people who get less than 5 hours of sleep have a 63% increased risk of getting osteoporosis compared to those who get more than 7 hours of sleep (1). 
  • Sleep duration is important, but another factor that impacts bone health is your circadian rhythm (sleeping at irregular times, night shifts, etc…). This can impact something called your clock genes, which have a direct influence on bone cells (1).

How do I know if my bones are healthy?

“Bone health is a lifelong proposition. Maximizing peak bone mass before age 30 will create the best ‘bone bank’ from which you can ‘withdraw’ across your life. Staying active throughout adulthood into old age will help retain that bone. For older adults, if there is a history of low trauma fractures in the family, a trip to the doctor for a bone density referral is advised. Menopause is a time of increased bone loss and therefore a good time to have a baseline bone density test (4).”

Most people won’t really know they have low BMD until they have a fragility fracture (4). If your parents or grandparents have or had osteoporosis, you are likely at a higher risk (4). Below are a few testing options, always consult and discuss with your doctor (1).

• FRAX (free) – an online assessment tool. 
• DEXA scan ($100-$300) – this scans your body and spits out a total estimated body score for bone mineral density. The general recommendation is for females over 65 or men over 70 to get one. However, many experts believe it should be done before the age of 40. You can be fit and healthy but still have low BMD. Catching it before menopause can help a lot and give you a baseline. Tells you the total estimated body score for BMD. 
• QCT scan – this scan will diagnose osteoporosis/osteopenia by looking at the actual density of individual bone segments. This what you would get if you really think you have osteopenia or had poor DEXA scan results.

A short summary

I hope you learned some new bone health facts and feel empowered to take some steps to improve your own bone health. To recap, below are the key takeaways from the blog post:

• Bones act as your body’s reserve of calcium. If calcium levels are too low, your body will pull calcium out of your bones.
• Whether you reached your peak BMD in childhood is the biggest determinant of your adult BMD. The natural reduction in movement/activity as you age along with the amount and type of exercise you do also play a big role.
• An exercise regimen that incorporates progressive heavy lifting and impact training is the best way to prevent bone loss as you age.
• Women see a rapid decline in BMD around menopause due to loss of estrogen. Strength training and impact training during these years can help reduce this loss.
• Eat enough calcium to prevent calcium being pulled from bone. It’s not difficult to get enough calcium if you consume dairy products. Dairy products are the best and most absorbable source of calcium in the diet, but can also be found in sardines, tofu, seeds, and leafy greens.
• You need adequate vitamin D levels to absorb calcium in the gut. It’s best to supplement with vitamin D.
• Other important nutrients include magnesium, vitamin K, and zinc. If you’re eating a well rounded diet with plenty of dairy, nuts, seeds, whole grains, and vegetables, then you are more than likely getting enough of these minerals and vitamins (assuming you don’t have absorption issues).
• Other modifiable factors that negatively impact bone health include environmental toxins, certain diseases, drugs/medications (+alcohol and smoking), chronic stress, and poor sleep.

References:

1. Perform with Dr. Andy Galpin podcast: Enhancing Bone Health at Every Age. https://podcasts.apple.com/us/podcast/enhancing-bone-health-at-every-age/id1725022545?i=1000696179975
2. https://www.osteoporosis.foundation/sites/iofbonehealth/files/2024-07/iof_fx_cap_july_2024_s_iuliano_final_online.pdf
3. The Aging Project podcast: Let’s Build Strong Bones with Professor Belinda Beck. https://theagingproject.com/lets-build-strong-bones-with-professor-belinda-beck/
4. https://spinehealth.org/article/bone-health-expert/