The FastDay Forum

[carorees]

As far as I can tell, the IGF-1 story (although that is far from the only factor that influences the cancer risk) is that over-nutrition results in high IGF-1. Of course we assume that if we are overweight we have been getting too much nutrition, but normal weight people who can eat large amounts without putting on weight are also likely to fall into the same category.

The issue with milk is that it naturally promotes growth and hence IGF-1 because that is the function of milk!

Also dairy milk is fortified with vitamins, specifically vitamin D. Vitamin D is difficult to consume as its not in a lot of food.

In fact, UK milk is not fortified with vitamin D and what little there is naturally in milk is contained in the fat, so the levels in skimmed or semi-skimmed milk are virtually nil.

the best sources, according to the NHS, are:
oily fish, such as salmon and sardines
eggs
fortified fat spreads
fortified breakfast cereals
powdered milk

In the US, milk is fortified with vitamin D. There have been articles in the UK news recently about the problem with vitamin D deficiency here and some debate about whether it should be added to milk. Considering milk promotes IGF-1, it would be better if they fortified something else!

I can see that IGF-1 (also sometimes called IGF1 or IGF-I, I think they are all the same thing) is a hot topic, maybe it needs forking into a new thread but as there is already discussion here (especially and very helpfully by carorees), and at the risk of going over some ground that was already covered earlier, I'll continue...

We can all agree about the medical benefits of losing weight, for those of us who are or have been overweight. The 5:2 diet delivers these as do other diets. But the 5:2 diet (and other IF regimes) may offer something more and that 'more' seems connected with this mysterious IGF-1, an endocrine hormone mostly produced by the liver.

There is a positive correlation between IGF-1 levels in the bloodstream and prostate cancer risk, see http://jnci.oxfordjournals.org/content/92/23/1910.abstract?ijkey=3f3ecd08353d260c941a424eca6f3688b52f49b6&keytype2=tf_ipsecsha (2000). There is also a positive correlation between levels of intake of animal fat/animal protein and IGF-1 levels http://jnci.oxfordjournals.org/content/93/8/649.full [2001]. Note that there is no correlation between obesity or high BMI or total protein intake or total energy intake and prostate cancer risk.

The problem is knowing whether IGF-1 level is a merely an indicator of risk or whether there is a causal link. If it is only an indicator then targeting its reduction is at best a distraction and at worst may be damaging.

However more recent research http://www.ncbi.nlm.nih.gov/pubmed/22520978 (2012) says that 'IGF1 and IGF2 can promote cancer growth', so it seems that the idea that IGF-1 is a cause and not just a positive correlative for cancer is now in the research mainstream.

If this is the case, then avoiding raised IGF-1 would seem to be a good thing (for adults), and this is what the 5:2 diet might achieve (see the original Horizon programme, which of course is anecdotal evidence only). I think Dr Michael Mosley is pretty persuaded of the connection because lowering his IGF-1 seems to be one of his key aims in the programme. He achieves it (and it is clearly not just a function of the weight loss which he also achieves).

He also seems quite keen to reduce milk consumption, including on fast days, recommending black tea and coffee. I suspect this is because of the link between milk and raised IGF-1; dairy milk is a particularly strong source of IGF-1 (much more so than most other animal products), and unfortunately soya milk seems to be the same (http://www.breastcancercare.org.uk/community/forums/yes-or-no-soya-milk). There are some alternatives such as coconut-based milk (http://www.kokodairyfree.com/) and rice milk which apparently do not raise IGF-1 - I can't say I have tried them.

Dominic (not a medic...)

[carorees]

The original Horizon programme by Dr Mosley focussed a lot on the importance of lowering IGF-1 (insulin-like growth factor 1), but this was because it is something that can be measured in a blood test. What is more important is how what we eat/don't eat affects activation of the FoxO transcription factor.

This paper from 2008 is a good starting point for trying to understand the role of FOXO in ageing.

The FoxO family of Forkhead transcription factors functions at the interface of tumor suppression, energy metabolism, and organismal longevity. FoxO factors are key downstream targets of insulin, growth factor, nutrient, and oxidative stress stimuli that coordinate a wide-range of cellular outputs. FoxO-dependent cellular responses include gluconeogenesis, neuropeptide secretion, atrophy, autophagy, apoptosis, cell cycle arrest, and stress resistance. This review will discuss the roles of the mammalian FoxO family in a variety of cell-types, from stem cells to mature cells, in the context of the whole organism. Given the overwhelming evidence that the FoxO factors promote longevity in invertebrates, this review will also discuss the potential role of the FoxO factors in the aging of mammalian organisms.

Fellow nerds, enjoy!

PS, while the first part of the paper is impenetrable, later on where the authors discuss FOXO in the context of the whole organism it becomes more understandable!

[carorees]

Just found this study which investigated whether calorie restriction or protein restriction reduces IGF1 in humans. The study found that protein restriction is the key thing:

Reducing protein intake from an average of 1.67 g/kg of body weight per day to 0.95 g/kg of body weight per day for 3 weeks in six volunteers practising CR resulted in a reduction in serum IGF-1 from 194 ng/mL to 152 ng/mL. These findings demonstrate that, unlike in rodents, long-term severe CR [calorie restriction] 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-ageing dietary interventions

Of course, as I have posted before, IGF-1 is not the whole story but it explains the rationale behind Dr M's assertion that we need to keep protein intake low on feed days as well as doing fasting.

[carorees]

And then I found this paper which also points to protein reduction as being the key element in a calorie restricted diet.

Thanks Caroline, fascinating (well, to me anyway).

This study was in 2008. So it may explain why Dr Longo is keen on these (horrendous) 3-day fasts every few months, as these do reduce IGF-1 whereas regular calorie restriction does not.

What we don't know is whether regular intermittent fasting a la 5:2 will reduce IGF-1 in the medium or long term. Even the example of Dr M, which is hardly statistically significant, was only the initial results after his first stint of 5:2, even if the same change could be clinically proven with new 5:2ers, it may be that if you practice 5:2 in the medium term the body adapts and any initial fall in IGF-1 is reversed?

And protein now turns out to be potentially a baddie too! The problem is that we definitely need protein and (as Dr M says in the programme) having too little is 'a very bad idea'. But having too much turns out to be bad too! And we can't store it, so we are left with having to eat very carefully all the time to maintain a perfect protein balance? Is this what the Two-Day Diet is about?

Well I guess we all have to die of something...

This has to be the most confusing part of IF. With protein intake it seems you're dammed if you do and dammed if you don't. I guess there's a happy medium somewhere but adhering to it would be to cumbersome for me, as is calorie counting.

[carorees]

I think it's just another of those things one should be mindful of, you know? So if you've had a meat-fest one day/weekend/week, you can make a point of having some vegetable based meals to compensate. I wouldn't go so far as to count the grams of protein!

Basically the more we use vegetables to fill us up the lower our carb, protein and calorie intake!

But we all know we should be eating lots of veggies!

vegetables are basically water, salad more so.

Any idea whether the source of protein matters? I would think getting protein from seeds and nuts and such would be better for you than red meat, of course, but that may have little to do with IGF-1 specifically.

there seemed to be less bodily response to plant based protein than animal / dairy when I was looking, I guessed that the body recognised the animal based stuff but said "what is this shit" to the plant based stuff

Here is a video from Dr Greger about the different effects of plant and animal protein

Oops, here is the link: http://nutritionfacts.org/video/protein ... roduction/

Thanks, Leanne!

It seems that every time I look, the science seems to point to vegan...

When you take a step back from it all, though, it makes sense that growth-inducing stuff is good for kids and bad for adults. Now that I've finally weaned myself from milk, of all things, I guess everything else should be considered.

Hi FL

• From here:
  
  Dairy foods increase growth hormones: In addition to calories and nutrients to support growth, cow’s milk increases hormones that directly stimulate the growth of the calf. The most powerful of these hormones is called insulin-like growth factor-1 (IGF-1). When cow’s milk is fed to people, IGF-1 levels also increase. Studies funded by the dairy industry show a 10% increase in IGF-1 levels in adolescent girls from one pint daily and the same 10% increase for postmenopausal women from 3 servings per day of nonfat milk or 1% milk. [4,5] This rise in IGF-1 level is an important reason for the “bone-building” effects of cow’s milk.
  
  IGF-1 promotes undesirable growth too—like cancer growth and accelerated aging. IGF-1 is one of the most powerful promoters of cancer growth ever discovered for cancers of the breast, prostate, lung, and colon. [6] Overstimulation of growth by IGF-1 leads to premature aging too—and reducing IGF-1 levels is “anti-aging.” [7]
  
  4) Cadogan J, Eastell R, Jones N, Barker ME. Milk intake and bone mineral acquisition in adolescent girls: randomised, controlled intervention trial. BMJ. 1997 Nov 15;315(7118):1255-60.
  
  5) Heaney RP, McCarron DA, Dawson-Hughes B, Oparil S, Berga SL, Stern JS, Barr SI, Rosen CJ. Dietary changes favorably affect bone remodeling in older adults. J Am Diet Assoc. 1999 Oct;99(10):1228-33.
  
  6) Moschos SJ, Mantzoros CS. The role of the IGF system in cancer: from basic to clinical studies and clinical applications. Oncology. 2002;63(4):317-32.
  
  7) Rincon M, Rudin E, Barzilai N. The insulin/IGF-1 signaling in mammals and its relevance to human longevity. Exp Gerontol. 2005 Nov;40(11):873-7.
  
  
• Another article here says, among other things:
  
  Drinking too much milk may increase your risk of developing certain types of cancer, such as prostate and ovarian, according to the Physicians Committee for Responsible Medicine. Milk contains a hormone called insulin-like growth factor-1 which may help stimulate the growth of cancer cells. According to a 1998 study published in "Science," men with the highest levels of this hormone were four times more likely to develop prostate cancer.
  
  
• And lastly (as this post is already long enough!) another from here:
  
  In conclusion, the research shows that nutrition has an important role in determining serum IGF-1 levels (Yaker et al., 2005). Whether the increase in IGF-1 caused by cow’s milk occurs directly (by IGF-1 crossing the gut wall), or indirectly (as a result of the action of other factors), the research is clear. The consumption of cow’s milk and milk products is linked to increased levels of IGF-1, which in turn are linked to various cancers.