11 replies to this topic

[drew_ab]

I'm recently had some extensive blood work done, which was quite thorough.  I was a little surprised to find out that my IGF-1 levels were 283 ug/L.  (range is 98-356ug/L)

 

One of the touted benefits of a vegan, whole food based diet, is that you see a reduction in IGF-1 levels.  I was expecting my levels to be a little lower.  

 

Does anyone have any thoughts? I guess it does fall in the range, so that is good. Has anyone had their levels checked?  The rest of my blood work was remarkably good.

[drew_ab]

Thoughts anyone?

[Brett Black]

Dietary protein has been shown to impact IGF-1. It may be that the lower IGF-1 seen in vegans is actually a result of vegans tending to eat lower protein (and/or lower protein-availability) diets. A vegan diet that was not also lower in protein/protein-availability may thus not result in low IGF-1. So the obvious thing to do would be to lower dietary protein (being careful to avoid going below the RDI/RDA for protein) if one wanted to try to lower IGF-1 (which I'm not actually advocating.)
 
The IGF-1 reference range you posted looks to go surprisingly high to me also. How old are you, and has that reference range been calibrated for your age? IGF-1 tends to drop with age (after puberty) and so attempts at comparing values should probably take age into account. Reference values and measured levels may also vary significantly between different labs and populations: I'm under the impression that the IGF-1 blood test is not that well standardized, which further complicates comparisons.
 
Any particular individual may also have a different response to the same level of IGF-1. Some people may be more sensitive to it, some less. For instance circulating IGFBPs (insulin-like growth factor binding proteins) may alter bioavailability/bioactivity of IGF-1, meaning that the same level of IGF-1 may be considerably more or less active depending on the level of IGFBPs. The IGF-1 receptors may also vary between individuals, leading to variable sensitivity/response.
 
Whilst there are all these (and quite probably more) technicalities, there is also just the fundamental question of if lower IGF-1 is beneficial for human longevity/health in the first place. It doesn't seem to me that this has been shown. There is evidence to support the possibility that IGF-1 could have both positive and negative effects on longevity and age-associated diseases. It may be beneficial for brain, muscle and bone health and maintenance, whilst detrimental for cancer risk for instance.
 
Studies examining the relationship in humans between IGF-1, longevity, centenarians and centenarian offspring have shown some contradictory results. At least one study showed that centenarians actually had higher IGF-1, suggesting it may be at least compatible if not responsible, for longevity in some people.
 
 
Here are some relevant papers on these issues:
 
"Long-term effects of calorie or protein restriction on serum IGF-1 and IGFBP-3 concentration in humans"
http://www.ncbi.nlm....les/PMC2673798/
 

"These findings demonstrate that, unlike in rodents, long-term severe CR does not reduce serum IGF-1 concentration and IGF-1 : IGFBP-3 ratio in humans. In addition, our data provide evidence that protein intake is a key determinant of circulating IGF-1 levels in humans, and suggest that reduced protein intake may become an important component of anticancer and anti-aging dietary interventions."

 
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"Diverse Roles of Growth Hormone and Insulin-Like Growth Factor-1 in Mammalian Aging: Progress and Controversies"
http://www.ncbi.nlm....les/PMC3348498/
 

"Based on the literature, GH and IGF-1 have both beneficial and deleterious effects on specific pathologies that undoubtedly influence life span. Therefore, in many cases, the consequences of GH and IGF-1 deficiency are dependent on the species, background strain, and pathologies that the species or strain is susceptible. Those animals that are at risk for cancer, liver, or kidney disease will likely exhibit a shortened life span in response to elevated levels of GH and IGF-1, and we expect that those animals with reduced risk for these diseases will likely not exhibit increased life span in response to this intervention. Similarly, those species at risk for specific cardiovascular diseases (stroke, myocardial infarction, heart failure, vascular cognitive impairment) may benefit from elevated levels of these hormones. These effects are consistent with the classical actions of GH and IGF-1 being important anabolic agents that stimulate cell growth, proliferation, and tissue repair. Because cardiovascular diseases, metabolic diseases, and cancer are all important health issues in the elderly population, the effects of GH/IGF-1 pathway on human health span and life span are predictably complex."

 
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"Low circulating IGF-I bioactivity is associated with human longevity: Findings in centenarians' offspring"
http://www.impactagi...ull/100484.html
 

"Data on IGF-I system in relation to longevity are still controversial. Bonafè et al. [9] previously found that subjects with at least an A allele of the IGF-I receptor (IGF-IR) gene (G/A, codon 1013) had low levels of free plasma IGF-I and were more represented among long-lived people. In contrast, Paolisso et al. [10] found an increased plasma IGF-I/IGF binding protein 3 (IGFBP-3) molar ratio in healthy centenarians compared to aged subjects. They suggested that this elevated ratio reflected higher IGF-I bioavailability which contributed to the observed improved insulin action in centenarians. An overrepresentation of heterozygous mutations in the IGF-IR gene associated with high serum IGF-I levels and reduced activity of the IGF-IR has been reported in Ashkenazi Jewish centenarians compared to controls [11]. In addition, in humans positive associations between circulating total IGF-I levels and cancer mortality have been found in many studies [12-14], while low total IGF-I levels have been associated with an increased risk for cardiovascular diseases and diabetes [15-22]. On the other hand, Rozing et al. showed that offspring of familial nonagenarians displayed similar IGF-I and IGFBP-3 levels compared to their partners [23].
These conflicting results probably reflect the complexity of the IGF-system."

 
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"Functionally significant insulin-like growth factor I receptor mutations in centenarians"
http://www.pnas.org/...105/9/3438.full
 

"Here, we studied the biochemical, phenotypic, and genetic variations in a cohort of Ashkenazi Jewish centenarians, their offspring, and offspring-matched controls and demonstrated a gender-specific increase in serum IGFI associated with a smaller stature in female offspring of centenarians. Sequence analysis of the IGF1 and IGF1 receptor (IGF1R) genes of female centenarians showed overrepresentation of heterozygous mutations in the IGF1R gene among centenarians relative to controls that are associated with high serum IGFI levels and reduced activity of the IGFIR as measured in transformed lymphocytes."

Edited by Brett Black, 23 October 2015 - 07:15 AM.

[drew_ab]

I have been vegan for over 4.5 years, so I was expecting the results to show lower IGF-1.  Though it looks like high IGF-1 has some benefits, though it sounds like an extremely complex relationship.  It sounds like it's good for the heart and circulation related problems, but not cancer.  I hope all the phytonutrients from vegetables, fruits, seeds, starches, etc, provide some level of protection against cancer.

 

I can't imagine my protein intake to be very high, given that I eat maybe 100calories of animals products per month.  I agree that the ref range looking high seems odd.  It's from a Canadian lab, if that means anything.

 

Thanks for posting the relative papers.  It makes for some interesting thoughts.

[misterE]

IGF-1 is the result of good insulin-sensitivity, given that insulin is needed for the conversion of GH into IGF-1. People who are insulin-resistant or full-blown diabetic have low levels of IGF-1 and high levels of GH.

[drew_ab]

IGF-1 is the result of good insulin-sensitivity, given that insulin is needed for the conversion of GH into IGF-1. People who are insulin-resistant or full-blown diabetic have low levels of IGF-1 and high levels of GH.

 

I think this makes sense. My fasting glucose and HBA1C are superb.  This means I have good insulin sensitivity, right?

[aribadabar]

 My fasting glucose and HBA1C are superb. 

 What is considered superb - sub 5.0 and 0.05, respectively?

[misterE]

This means I have good insulin sensitivity, right?

 

 

Yep. Vegans also have higher IGFBPs, which is like a bank account for IGF-1, whereas you save it up and use it later, increasing the overall total-amount. Same thing with SHBG and sex-hormones.

Edited by misterE, 28 October 2015 - 05:36 AM.

[Brett Black]

I have been vegan for over 4.5 years, so I was expecting the results to show lower IGF-1.  Though it looks like high IGF-1 has some benefits, though it sounds like an extremely complex relationship.  It sounds like it's good for the heart and circulation related problems, but not cancer.  I hope all the phytonutrients from vegetables, fruits, seeds, starches, etc, provide some level of protection against cancer.

If I recall correctly, in one of the Luigi Fontana studies(probably one I linked to in my previous post) with caloric restriction subjects, it took less than a month on a lower protein diet to see substantially lower IGF-1.
 

I can't imagine my protein intake to be very high, given that I eat maybe 100calories of animals products per month.

 

Just having a vegan or low animal protein diet doesn't guarantee a low(er) protein diet. There are plenty of mainstream vegan foods that are protein-rich, like legumes, wheat gluten, soy products etc. It can be very difficult(even for professional nutritionists) to get a good idea of the protein(and other macro and micronutrient) content of the diet without making a detailed food diary and analysis. This would include weighing and logging every single item you eat for perhaps at least a week. If you're interested in doing this one of the best and most common (and free) ways is to use the CRONometer application/software.

Also, if you're on the slimmer side and/or exercise quite a lot, with concomitant increased calorie intake relative to your body weight, this could result in protein(and everything else in your diet) intake being higher relative to your body weight (which might be the more important metric for IGF-1, rather than just absolute protein intake level.)

[drew_ab]

 

 My fasting glucose and HBA1C are superb. 

 What is considered superb - sub 5.0 and 0.05, respectively?

 

 

HBA1C is 4.5 and 4.8 (had it done twice in the past while.

 

Fasting glucose was 4.6 and 4.7 mmol/L (3.3-6.0 range).

[drew_ab]

 

I have been vegan for over 4.5 years, so I was expecting the results to show lower IGF-1.  Though it looks like high IGF-1 has some benefits, though it sounds like an extremely complex relationship.  It sounds like it's good for the heart and circulation related problems, but not cancer.  I hope all the phytonutrients from vegetables, fruits, seeds, starches, etc, provide some level of protection against cancer.

If I recall correctly, in one of the Luigi Fontana studies(probably one I linked to in my previous post) with caloric restriction subjects, it took less than a month on a lower protein diet to see substantially lower IGF-1.
 

I can't imagine my protein intake to be very high, given that I eat maybe 100calories of animals products per month.

 

Just having a vegan or low animal protein diet doesn't guarantee a low(er) protein diet. There are plenty of mainstream vegan foods that are protein-rich, like legumes, wheat gluten, soy products etc. It can be very difficult(even for professional nutritionists) to get a good idea of the protein(and other macro and micronutrient) content of the diet without making a detailed food diary and analysis. This would include weighing and logging every single item you eat for perhaps at least a week. If you're interested in doing this one of the best and most common (and free) ways is to use the CRONometer application/software.

Also, if you're on the slimmer side and/or exercise quite a lot, with concomitant increased calorie intake relative to your body weight, this could result in protein(and everything else in your diet) intake being higher relative to your body weight (which might be the more important metric for IGF-1, rather than just absolute protein intake level.)

 

 

Exact I really only eat whole foods. I generally don't eat tofu, wheat protein, fake meats, etc., since I consider them processed foods. I generally have beans or lentils daily though, which give me a decent amount of protein.  I do also have to eat a little extra to make up for the calories I burn in daily exercise (but i'm not running marathons or bodybuilding or anything crazy).  As a %, I'm about 15% of calories from protein, 99% of which is plant based.

[Leon93]

@drew_ab What is your BMI (range) at the time you calculated it?