As the issue currently stands, there is no definitive evidence proving vegetarians look younger than omnivores. We can only rely on subjective observation that hasn't undergone any kind of meaningful data correction. If you could hypothetically quantify youthful appearance, the data would need to be corrected for smoking / drinking habits, lifetime UV exposure, genetics, facial products used, facial expressions, and level of affluence.. not to mention, you'd need to account for things other than just meat intake like glycemic index / load, total protein intake, total carbohydrate, total fat, wheat or no wheat, soy or no soy, etc. Such a study would be very difficult to conduct.Ha ha, have you seen any of those older paleo guys lately? They are lookin pretty damn good for their age.
I haven't seen too many examples of this, unless you're talking about bodily appearance. The OP is talking about facial appearance I do believe.
My pointing is that simply picking a handful of paleo bloggers and a handful of vegetarian celebrities and making comparisons about their respective diets based on their appearance is totally worthless for drawing meaningful conclusions. So what if Vin Diesel looks older than David Duchovny, there are so many confounding factors involved that we will never know if the variance can be primarily attributed to diet.
Okay... now that I've made that disclaimer...
If we are just playing hypothetical, I would argue that there is no reason why a Paleo type diet would make someone look younger than any other healthy person. A paelo diet is neutral. Consider that in many indigenous pre-western cultures, age is attributed to superiority (rank) within a group. According to a book I recently finished on the Mek culture (hunter-gatherers) of West Papua, Elders are allowed to work less, lead more, and procreate more. Then there is the current hypothesis that male pattern baldness was selected for in early human history as a way of distinguishing age, or superiority, within a group. Male pattern baldness also seems to be rare in hunter-gatherer cultures (see below link) which indicates their androgen hormones are not elevated (see below discussion on mechanism). My point here is that there isn't much evidence that a meat based, paleolithic diet will keep a person looking young. On the contrary, in paleolithic times, looking older (in the face?) might have been adventageous. At any rate, I don't think people living on the fringe of exitense were at all concerned with preserving a youthful appearance. In fact, I can't image that they even saw their own face very often... Vanity as it exists today was probably completely alien to paleolithic peoples.
As for whether meat is inherently pro-DHT... I would argue that 1.) DHT is not bad within normal parameters. 2.) SHBG probably has more to do with balding and physical aging that DHT, and 3.) unpolluted meat consumed in moderation has never been shown to increase SHBG.
SHBG (or sex hormone binding globulin) is responsible for binding testosterone and preventing its bioavailability and conversion to DHT. It is typically lower in individuals with high DHT. SHBG is also downregulated by insulin. The insulinogenic properties of a diet seem to correlate the most with large changes in SHBG (although proportion of fat, protein, and carbohydrate also play a role).
Since meat is not insulinogenic, there is no reason why it would increase DHT if consumed in reasonable amounts. On the contrary, a vegetarian diet that is low in fat might restrict DHT by not allowing adequate fat for production of the sex hormones. Furthermore, a diet high in isoflavones seems to supress DHT. In my opinion, meat is at best a great suppressor of excess SHBG. At worst it is netural.
Consider the following studies:
www.ncbi.nlm.nih.gov/pubmed/3573976
Testosterone concentrations in seven normal men were consistently higher after ten days on a high carbohydrate diet (468 ± 34 ng/dl, mean ± S.E.) than during a high protein diet (3.71 ± 23 ng/d1, p<0.05) and were accompanied by parallel changes in sex hormone binding globulin (32.5 ± 2.8 nmol/1 vs. 23.4 ± 1.6 nmol/1 respectively, p<0.01).
www.ncbi.nlm.nih.gov/pubmed/10424753
Vegetarians and vegans had lower mean body mass indices (BMI) and lower plasma cholesterol concentrations than meat-eaters, but there were no statistically significant differences between meat-eaters, vegetarians and vegans in pre- or post-menopausal plasma concentrations of oestradiol or SHBG.
But when you replace meat with soy, it favorable changes the sex hormones as opposed to their 'normal' counterparts:
www.ncbi.nlm.nih.gov/pubmed/11103227
SHBG was 3% higher (P = 0.07), whereas the FAI was 7% lower (P = 0.06), after the tofu diet compared with the meat diet.
But the difference in SHBG seems to be small (not statistically significant), and the major area of influence seems to be on levels on the other androgen hormones via isoflavones. This corroborates nicely with data on male pattern baldness in Japan. After the introduction of Western goods, baldness increased substantially despite meat intake remaining relatively the same.
www.ncbi.nlm.nih.gov/pubmed/14527633
Compensatory hyperinsulinemia stemming from peripheral insulin resistance is a well-recognized metabolic disturbance that is at the root cause of diseases and maladies of Syndrome X (hypertension, type 2 diabetes, dyslipidemia, coronary artery disease, obesity, abnormal glucose tolerance). Abnormalities of fibrinolysis and hyperuricemia also appear to be members of the cluster of illnesses comprising Syndrome X. Insulin is a well-established growth-promoting hormone, and recent evidence indicates that hyperinsulinemia causes a shift in a number of endocrine pathways that may favor unregulated tissue growth leading to additional illnesses. Specifically, hyperinsulinemia elevates serum concentrations of free insulin-like growth factor-1 (IGF-1) and androgens, while simultaneously reducing insulin-like growth factor-binding protein 3 (IGFBP-3) and sex hormone-binding globulin (SHBG). Since IGFBP-3 is a ligand for the nuclear retinoid X receptor alpha, insulin-mediated reductions in IGFBP-3 may also influence transcription of anti-proliferative genes normally activated by the body's endogenous retinoids. These endocrine shifts alter cellular proliferation and growth in a variety of tissues, the clinical course of which may promote acne, early menarche, certain epithelial cell carcinomas, increased stature, myopia, cutaneous papillomas (skin tags), acanthosis nigricans, polycystic ovary syndrome (PCOS) and male vertex balding. Consequently, these illnesses and conditions may, in part, have hyperinsulinemia at their root cause and therefore should be classified among the diseases of Syndrome X.
So... I guess what I'm saying is that meat isn't bad, isoflavones skew things benefically (at least where appearence is concerned), superficial observations are worthless, and insulin sensitivity is what the immortalist should be concerned about.
Edited by Skötkonung, 19 December 2010 - 02:48 AM.
