Where vegans take the crown

In a more general sense, massive studies of thousands of people agree that vegan diets are associated with a lower risk of cardiovascular disease than omnivorous ones.^2-5 If you’re concerned with your heart health or have trouble controlling your cholesterol levels, consider reducing your animal product intake. Start with one meatless day per week!

Blood sugar levels

While the difference doesn’t appear to be huge in the chart below, vegan InsideTracker users do have significantly lower blood glucose levels than non-vegans. The same pattern has been found in multiple studies (the same goes for hemoglobin A1c, too!).^1,6

This might not seem intuitive at first – glucose is a carbohydrate, and animal products mostly contain fat and protein, so where’s the overlap? Well, the specific type of iron found in animal foods (more on that in a minute) may interrupt glucose metabolism.⁷ So if your glucose or A1c levels are above optimal, consider reducing your red meat intake.

Where meat-eaters have a leg up

Men who follow a vegan diet have significantly high Sex Hormone Binding Globulin (SHBG) than those who eat meat. This relationship holds true for women, too; vegan women have significantly higher levels than their meat-eating ones.

SHBG safely transports sex hormones throughout the bloodstream and regulates their levels within the body. SHBG levels tend to increase in parallel with testosterone levels, given it's responsible for regulating sex hormone levels. Additionally, SHBG prevents sex hormones from being cleared from the bloodstream, acting as a pool of reserved hormones that can be tapped into when levels become low.

Since SHBG binds testosterone, high levels may create a false pretense of low testosterone levels. However, given the information above, SHBG prevents bound testosterone from leaving the body. Testosterone metabolism is complex and levels can be unoptimized for a variety of reasons, however, high SHBG is not the sole culprit.

These patterns do appear to hold true for InsideTracker users – vegans have both lower testosterone and higher SHBG levels than non-vegan users. If you follow a vegan diet but are willing to experiment, try supplementing your diet with animal products and monitor your blood levels of SHBG and testosterone over time for any changes. Otherwise, be sure to monitor your protein intake and ensure you're hitting your daily needs (which depend on things like sex, age, and activity level). Good plant-based sources of protein include tofu, lentils, and pumpkin seeds.

Iron status

People who eat animal products with high concentrations of heme iron (the form of iron found in animal sources), like meat and seafood, have significantly higher levels of hemoglobin and hematocrit than those who exclusively get their iron from plant sources.¹³ This is because heme iron is perfectly structured for our bodies to absorb and use, directly influencing our red blood cell and iron biomarkers. Non-heme iron (the form found in plant sources), on the other hand, is in a more difficult structure for our bodies to absorb. This often results in lower iron stores and levels.

In fact, vegan InsideTracker users have significantly lower levels of ferritin than those who eat animal products regularly. If you’re vegan and your iron markers, particularly ferritin, are low, consume your iron-rich meals with a squeeze of citrus – vitamin C makes non-heme iron more bioavailable. Since ferritin is a marker of long-term iron status, it’s slow to respond to any changes we make in our diet – be sure to re-test at least 3 months after your initial results to track changes over time.

What we've learned

Of course, it must be acknowledged that there are plenty of factors (differences in physical activity, other lifestyle habits, etc.)  that may be inherently different between vegans and non-vegans, and therefore contributing to the differences we see between InsideTracker groups. But when considered alongside the numerous studies with similar findings, it seems the science does in fact add up.

When making decisions about the way you eat, there are countless factors to consider (price, environmental impact, accessibility, etc), of which health is just one. Both herbivores and omnivores can be exceptionally healthy, and you don't necessarily have to compromise on the diet pattern that makes sense for you and your values. But ultimately, understanding how your body responds to your diet at the blood level is the only way to know if your eating habits are promoting good health. 

References:

1. https://pubmed.ncbi.nlm.nih.gov/29960809 
2. https://pubmed.ncbi.nlm.nih.gov/26853923 
3. https://pubmed.ncbi.nlm.nih.gov/23836264 
4. https://pubmed.ncbi.nlm.nih.gov/27479196 
5. https://pubmed.ncbi.nlm.nih.gov/29618018 
6. https://pubmed.ncbi.nlm.nih.gov/25414824 
7. https://pubmed.ncbi.nlm.nih.gov/26494808 
8. https://pubmed.ncbi.nlm.nih.gov/10883675 
9. https://pubmed.ncbi.nlm.nih.gov/2526906 
10. https://pubmed.ncbi.nlm.nih.gov/6944545 
11. https://pubmed.ncbi.nlm.nih.gov/19678968 
12. https://pubmed.ncbi.nlm.nih.gov/20211044 
13. https://pubmed.ncbi.nlm.nih.gov/24592585