Too Much Protein a Bad Thing?

I love steak…chicken…fish. It all tastes good to me. I want to make sure I get enough protein to maintain and build muscle. But it begs to question, is more really better? I’m not talking about the myth of the dangers of so called high protein diets on your kindeys (if you are not even getting 1g/lb of bodyweight then you have nothing to worry about…which is most people). But now looking at ageing and longevity, I am more concerned about what is the right way to eat? I came across this study on the effects of protein oxidation in relation to ageing factors:

Protein oxidation associated with aging is reduced by dietary restriction of protein or calories

The accumulation of unrepaired oxidative damage products may be a major factor in cellular aging. Both oxidative lesions in DNA and oxidatively damaged proteins have been shown to accumulate during aging. The accumulation of oxidized proteins in Fischer 344 rats was compared for animals consuming protein-restricted and calorically restricted diets–both of which have been shown to extend lifespan. Rats were fed diets restricted in either protein (5% or 10% of the diet as compared with the normal 20% casein), or calories (25% or 40% less than normal), or total diet (40% less than normal). In addition, some of the rats fed a diet providing 5% or 20% protein were irradiated twice weekly (125 rads per exposure; 1 rad = 0.01 Gy). The level of oxidative damage to proteins (protein carbonyls) was determined in rats sacrificed at various times. The oxidative damage to proteins increased with aging and with radiation. Either protein or calorie restriction markedly inhibited the accumulation of oxidatively damaged proteins. Protein restriction reduced the accumulation of oxidatively damaged proteins during the oxidative stress of chronic irradiation.

Any type of excess oxidative damage should be avoided. Ageing and disease could just be viewed as a simple process of where the rate of damage at the cellular level exceeds the ability to repair at the cellular level. So it makes sense to stay healthy and live longer we need to reduce amounts of oxidative damage. The main thing we see in CR studies is the reduction of oxidative damage which may explain the biggest factor in how CR allows you to age slower. But how does that affect protein intake?

Protein oxidation and aging article

The importance of protein oxidation in aging is supported by the observation that levels of oxidized proteins increase with animal age. The age-related accumulation of oxidized proteins may reflect age-related increases in rates of ROS generation, decreases in antioxidant activities, or losses in the capacity to degrade oxidized proteins.

Implication of protein oxidation and diseases article:

In view of these results, the possibility that protein oxidation is implicated in various diseases, viz, arthritis, pulmonary dysfunction, and carcinogenesis deserves consideration.

But oxidation has to happen at some point if we are going to burn anything for fuel right? So what do we want to burn? Well your two top source are carbs and fat. So which is more ideal? For longevity and health you want an efficient fat burning metabolism. Why? Because it will keep you from storing fat, keep your muscle around, and perhaps slow down the overall ageing process because of reduction of factors that increase ageing with higher BF%, namely insulin resistance (and blood insulin levels).

Basal fat oxidation decreases with aging women study

These results support the theory that a decrease in fat oxidation with advancing age in healthy women is associated with a decrease in the fat-free mass and not age per se. Interventions that increase or preserve the quantity of fat-free mass (e.g., exercise training) may enhance fat oxidation and thus lessen the age-associated adiposity in women.

So what is the answer when it comes to anti-ageing and disease prevention?

  • Keep intake of protein moderate (not excessively high % of your diet)
  • Higher fat diets (40%+) will increase nitrogen retention (which is fancy terms for saving muscle from breakdown), therefore lessening protein oxidation (and reducing the amount of protein you would need in your diet)
  • Higher fat diets (vs carbs) increase the full time ability of the body to burn fat (increased fat metabolism)
  • Eat a reduced calorie diet to reduce the amount of oxidative damage through the digestive process

So I know the BIG question people will have is how much protein is too much? Well I don’t want to go by % because that will depend on how many calories are in your diet. If you look at the zone model of 30%, I would say that should be as high as you need to go. If your fat intake is high enough to keep your calorie total up, then you really don’t need a ton of protein to even build muscle. The most I would ever say is up to 1g/lb of bodyweight (assuming your BF is lean, muscle building is your top priority, and keep in mind that is still pretty high…most semi-active people who focus on general fat loss and muscle would need only 0.6-0.8g protein/lb of lean body mass). There are lots of other factors in building muscle too besides protein intake, so make sure to master those (see the Muscle Building 101 post)

So looks like another plug for and IF lifestyle that is based on a reduced calorie, mod/higher fat (healthy fat), moderate protein and low/mod carbs mainly from fruits and vegetables.

photo by taminator

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