We measure a persons nitrogen balance to assess protein metabolism. A negative nitrogenbalance indicates that protein requirements are not being met by our diet and proteinis being scavenged from healthy tissue to maintain essential body functions. A negativenitrogen balance will impair training gains in muscle mass and strength.

Protein molecules are built from amino acids. The protein in our diet is broken down in the smallintestine into its component amino acids which are absorbed throughthe intestinal lining cells and then transported to cells throughout the bodywhere they are then available to rebuild and repair cellular proteins. There isno protein storage capacity beyond the protein that is an integral part of cellsthroughout the body. This means cell repair requires either amino acidsfrom protein eaten that day or from amino acids scavenged from cell protein breakdownelsewhere in the body. Any excess dietary protein - beyond that needed for cell repair -is converted into carbohydrates (gluconeogenesis) or fat.

HOW MUCH PROTEIN DO YOU REALLY NEED?

The average adults (not a participant in a regular program of resistance oraerobic training) needs 0.8 - 0.9 grams of protein per kilogram of body weight(or 0.4 grams per pound of body weight) per day. That equates to 46 grams of proteina day for women and 56 grams for men.

Those on a regular resistance training program as well as endurance athletesrequire more than the average individual. Training induced micro trauma repair asthe growth of muscle tissue are assumed to be the reason for the higher requirement.

A 2018 meta analysis of 49 studies on a total of 1800 weightlifters, who lifted at least twice a week for atleast six weeks found that doubling the recommended Dietary Allowance (RDA) of proteinincreased strength gains by nine percent and added about a pound of muscle, with noobvious benefit from additional dietary protein (supplements or meat/plant based).

The average 70 kg (154 pound) recreational cyclist needs 80 to 100 grams of protein per day. And for those at the elite level, the requirement may be as high as 120 grams. As active athletes consume more Calories/day than a normally activeindividual, a balanced diet (without supplements) should meet these needs. Even in extreme endurance activities such as the Tour De France, estimated protein needs of 1.5 gms protein/kg body wt/day were easily met by a normal (or "unsupplemented") diet that met total daily Caloric needs.

A literature review fails to support the need (or benefit) of protein supplementsfor athletes on on a balanced daily diet (a normal distribution of protein/carbohydrates/fats).In fact it has been suggested that too much protein may DECREASE overall performance as the appetite suppressing effects of a high protein diet decreased carbohydrate intake (and pre event muscle glycogen stores).

There may other health risks from eating too much protein.

• One study with protein intakes of over 2.5 grams per kg of body weight per day suggested an increased risk of urea (a byproduct of protein metabolism) overload with dehydration atthese supra-maximal levels.
• Another longer term study documented an increased the risk of kidney stones and bone loss. A studyof 10 volunteers on a high protein/low carbohydrate diet for two weeks documented arise of 90% in blood uric acid levels (uric acid is a major cause of kidney stones)and a 25% drop in urinary levels of citrate (which inhibits kidney stone formation).
• And very high protein diets have been reported to increase the risk for diabetes and cancer.

• If you are training, you will get maximum muscle-building and strength benefit withincreasing protein intake up to 0.7 grams protein per pound of body weight per day.
• More protein from food (meat or plants) or supplements will not add a trainingbenefit and actually may add long term health risks.
• There is no difference between protein from meat, plants, or supplements.
• Everyone loses muscle size and strength with aging. You cannot prevent muscle losswith more protein alone, but only by doing resistance exercises regularly.

SOURCES OF PROTEIN

• Lean beef, skinless chicken, and fish will provide about 7 grams of protein per ounce (quick online reference.
• Beans will provide 6 grams per 1/2 cooked cup.
• Rice (and other cereal grains) about 3 grams per 1/2 cup serving.
• A cup of milk or yogurt supplies 8 grams of protein.
• And if you are a vegetarian, soy (tofu) has 2.5 grams protein per ounce of tofu (10 grams protein per half cup or 4 ounces)

INCREASING PROTEIN NEEDS WITH AGING.

And it is probably too low for older adultswho are less efficient in their protein digestion and absorption. It has been speculated thattoo little dietary protein and as a result being relatively relative protein deficient, may be an aggravating factor in the loss of muscle mass that accompanies aging.

Taking both aging and activity level into account,an international panel of experts recommended protein intakes of 1.0 - 1.2 g/kg/day for all adults 65 years or older, with even higher intakes for those who are more physically active.

So for all of us who are riding regularly, and often competitively - even if just with friendson the weekend, it is important to keep an eye on the protein content of our diets.

I have never been a fan of the over response with the paleo diets as the red meat comes along with a lot of undesirable fats. So if you want to err on the side of caution, there are plenty ofnon meat sources of protein to add to your diet.

PROTEIN AND ATHLETIC PERFORMANCE

• THE IMPACT OF GLUTEN RESTRICTION ON ATHLETIC PERFORMANCE.

  A significant percentage of athletes eat a gluten (a grain protein) free diet - feeling ithelps performance. In this studyfrom Australia ~40% of the athlete group are on a gluten restricted diet.This is twice the rate of the general public ~20%.

  The incidence of clinically proven gluten intolerance (celiac disease) withdocumented inflammation of the small intestine is about 1% in the general population.A critical review of gluten intolerancesuggested that non-celiac gluten sensitivity (NCGS - no inflammation of the bowelon endoscopic biopsy) could be as frequent as 10%. Are athletes, who arepushing their bodies to the max, more sensitive to even minimal symptoms of NCGS?Is this another example of a placebo effect? Or athletes "just buying insurance",eliminating any factor which might impact their performance. What is the data?

  This studylooked at the short term (2 week) impact of a gluten free diet on cycling performanceor GI symptoms (which are common in elite athletes). A quote from the NYTsummarizes the findings. "Cycling performance had proven to be essentiallyidentical after a week in which a rider ate zero gluten or large amounts of gluten.Inflammatory markers likewise were indistinguishable. For their part, the riders'daily reports about the states of their digestive tracts and moods likewiseshowed little variation whether a rider was eating gluten or not. Over all, Ms.Lis said, 'we did not find a beneficial or negative effect of a gluten-free dietfor athletes who had no clinical necessity for the diet.' "

  Points to be taken away?

  1. This was a short term study. 2 weeks of gluten restriction. If you have true celiac disease,this is too short a time for gastrointestinal tract inflammation to resolve completely.
  2. This was a small study group. 13 participants. If 6 - 10% of the population have NCGS, it is likely only 1 of the study group might have suffered from that entity. And as the results are group results, a benefit might have been masked.
  3. But the most important finding, I think, is that a gluten free diet did NOT impairperformance. So if you think you have NCGS, there is no clear downside to limiting your gluten intake.

• PROTEIN AND POST RIDE RECOVERY

  Although it has been speculated that protein aids in post ride muscle glycogen replacement, lessening the odds of chronic glycogen depletion on multiday riding, a comprehensive analysis of the topic in 2018 concluded that it was the Caloric content of the post recovery drink that was important, not whether or not it contained protein. That "....energy intake per se and not macronutrient composition during recovery influence repeated exercise capacity."

  More on the topic of post ride recovery and muscle glycogen replacement at Post Ride Recovery and Your Training Program

• VEGETARIANS

  A growing number of cyclists are moving toward meatless meals or a completely meat free nutritional program. Not only are vegetarians healthier, with lower rates of chronic diseases such as heart disease, obesity, and colon cancer, but the fact that their diets are high in carbohydrates means they are constantly "carob loaded".

  Vegetarians as a group do not appear to be at excessive risk for protein deficiencyand in turn diminished athletic performance.But it is possible that in select individualswith rigorously self-limited selections ofwhat they choose to eat, may be at some risk. The following is a specific example.

  This is a summary from a presentation at the American College ofSports Medicine 2018 Annual Meeting as reported in an article in Medscape online. It suggests thatvegetarians may be at performance risk from a lack of choline (an amino acid - a protein building block)in their diet. (Eggs were the source of choline in this study.)

  A few direct quotes from the article.

  • "Choline plays an essential role in cell membrane integrity, lipid transport, and methylation. It is a precursor to acetylcholine, the neurotransmitter in motor neurons that mediates muscle contraction."
  • "the study supplemented the diets of 37 people, 50 to 69 years of age, with differentamounts of choline. The 13 people assigned to the low group received 0.7 mg of choline perkilogram of lean dietary mass, the 11 people assigned to the medium group received 2.8 mg/kg,and the 13 people assigned to the high group received 7.5 mg/kg."
  • "Three times a week, the participants performed eight exercises in three sets ofeight to 12 repetitions at 70% of 1 maximum repetition."
  • "After 12 weeks of diet and exercise .... the researchers measured participantstrength as a composite of 1 maximum repetition bench press and 1 maximum leg extension.On average, composite strength was lower in the low (choline) group than in the medium andhigh groups (29.4% vs 46.8% vs 47.4%). The difference between the low and medium groupswas significant (P = .034)."

  Their conclusion: "It is hard to get adequate amounts of choline from plant foods,although it is present in, for example, soy beans."

  A couple of my thoughts on this article:

  1. The risk of low choline consumption would be highest in those avoiding animal fat and cholesterol as part of a healthier diet.
  2. Choline deficiency is an even higher risk for vegans, who are avoiding all animal products.
  3. There was no difference between the middle and high supplementation groups so "...more is not better". You just need a threshold amount.
  4. They felt there was minimal potential for CV harm from the cholesterol in the eggs at the supplement levels studied, so an easy way to supplement your diet might be to add a couple eggs a week to your diet plan.
  5. Finally, this was about development of muscle strength, not endurance. So it is unclear how it might impact aerobic performance and endurance athletes.

  There are a few tips to remember if you are considering a move to less meat.

  • Vegans, who eat no animal products whatsoever including dairy, need to be certain they get enough
    • vitamin B12 (from supplements and fortified foods such as cereal, bread, pasta, and brewer's yeast)
    • iron (from beans, kale, dried fruit, and collard greens). Don't use supplements unless recommended by your physician because of the potential toxicity of too much iron.
    • calcium (dark leafy vegetables, broccoli, citrus fruits)
    • choline
  • Eat "balanced" protein (because of the mix of amino acids, non meat protein foods need to be eaten in combinations - same meal or in consecutive meals - to have the right balance of amino acid building blocks to allow the body to use them to build and repair tissue).
    • pinto beans and rice
    • grains (rice, bread, cereal) and legumes (peas or beans)
    • consider adding a couple eggs a week to assure you are getting enough choline

  • Eat a bit more than if you were eating meat as a protein source. For example a 3 ounce piece of meat contains about 21 grams of protein and is can be substituted with a cup of cooked grain and a cup of cooked beans.

WHY VEGETARIANS HAVE LESS HEART DISEASE.

Although both may be contributing factors, more and more evidence is pointing to two proteinsfound in all red meat - carnitine and the cell sugar-protein molecule Neu5Ac - as the root causeof severe blood vessel disease.

Carnitine is a muscle protein. After digestion, carnitine absorbed and processed in theliver into trimethylamine (TMA) which is in turn modified by colon bacteria (our microbiome)into trimethyl n-oxide (TMAO).

In lab experiments, TMAO is directly toxic to blood vessel lining cells. The injured cellsabsorb fats from the circulation which results in the formation of blood vessel plaques,and in the presence of high blood fat and cholesterol levels, the process is accelerated.

A clinical parallel has been identified in studies on patients seen in hospital ERs for chestdiscomfort. Those with the highest blood levels of TMAO (compared to the lowest) are six timesas likely to die within the following month and twice as likely to die within seven years.

Vegetarians as a group have the lowest average blood levels of TMAO. Interestingly, whengiven a single dose of carnitine (a piece of steak) their blood TMAO levels barely budge.The reason? A person's microbiome responds to their diet. Expose the colon bacteria tomore of a specific food and those that thrive on it multiply. Being exposed to only smallamounts of carnitine in a no-meat diet, there are very few carnitine metabolizing bacteriaavailable to process that occasional steak. This suggests that an occasional meat containingmeal should be less harmful to your blood vessels than when it is part of your daily diet.

The second meat protein is Neu5Gc, a cell surface protein found on all non human mammalian cells(but not chicken or fish). Eons ago a genetic mutation in humans led to its modification toa similar molecule (Neu5Ac). As this new protein provided some protection against malaria,it became the dominant form.

Our immune system recognizes invading germs by their cell surface proteins. When it detectsproteins that are different from our own, antibodies to kill the invading germs are produced.

With this change in our cell sugar-protein, the immune system now sees all non human mammal meatas "different", the immune system revs up, and antibodies are formed. The result is that thosewho regularly eat beef (a mammal meat) have blood markers reflecting a state of chronic inflammation.

A side effect of the overactive immune system is collateral damage to cells throughout the body.In the blood vessels this means more atherosclerosis with an increased risk of heart attacksand strokes, and in other cells the damage increases the risk of cancer.

Supportive evidence once again comes from the laboratory where mice, geneticallyaltered with the human gene mutation and placed on a meat diet have twice the heartattack risk of genetically unmodified mice on a similar diet.

These two harmful effects of a mammal meat diet are moderated to a degree by smallmolecules produced from the metabolism of fiber by our microbiome. But with most red meatcontaining diets being lower in fruits,vegetables and whole grains, this protection isweakened. The effect is observed in those on a strict paleo diet (high red meat and nowhole grain) who have much higher blood TMAO levels than those who eat even a smallamount of whole grain.

What does this body of work suggest as far as healthy diet changes?

• First, cut red meat intake and decrease exposure to the toxic effects of TMAO.In one large study, there was a 10% (one in ten) decrease in heart disease deaths inthose who cut their red meat intake to an average of half a serving per day!Alternatives to be considered are poultry, fish, nuts, legumes, low-fat dairy, and whole grains.

• Second is to take advantage of the protective effects of fiber. The benefits ofadditional servings of fruits and vegetables have been shown to increase up to 10 servings per day.

• Finally, it is never too late to make a change. Health professionals who began eatingmore whole grains, fruits, vegetables, and fish were able to significantly lower their risk fordeath in as few as 8 years.

HIGH PROTEIN DIETS

What is the balance of protein/carbohydrates/fats in an "average" diet? For the average active individual,not those participating in endurance sports, on a Calorically balanced diet, not trying to lose weight, we find that Carbohydrates make up 45-65 percent of daily Calories, Fat 20-35 percent of Calories, andProtein 10-35 percent.

The current controversy on healthy eating is over the appropriate balance of total Carbohydrates versus total Fat in that average diet. There is solid evidence that IF you are not eating extracarbohydrate Calories to support special athletic energy needs, you may be healthier ifyou change that balance towards fewer carbohydrate Calories (neared lower range of 40 or 45 % of the daily total)with more Calories from dietary fat (nearer 35 or 40%). In a Calorically balanced diet,protein remains between 10 - 30%.

What about higher protein diets?

The Zone Diet

A couple references:

• Dr. Sear's Website
• Specifics on the Zone diet

The term diet can be used in two ways. It can refer to

• a low caloric, negative calorie balance eating program - a weight loss program
• an approach to eating that emphasizes a preferred ratio of P/C/F Calories - a lifestyle eating program

Used to lose weight, evidence suggests that the Zone diet's emphasis on high protein and fat may have anadvantage over other weight loss programs, not the result of the original conjecture that it facilitated fat metabolism as much as from a blunting of appetite which translated into the intake of fewer Caloriesper day than the comparison diets.

After analyzing the dietary intake of the groups, the research team realized those on the high protein diet had eaten less food. This accounted for the greater weight loss. There were several possible explanations for this reduction in food intake. Protein has a higher satiating (pronounced effect than carbohydrate. In other words, you feel less hungry when consuming a diet high in protein. And a high protein intake seems able to suppress the following days energy intake to a greater extent than carbohydrate.

For an athlete on any weight loss program, there is a significantrisk of riding in a metabolic state similar to that experienced with being "bonked" (when your glycogen isdepleted and no external glucose has being taken in). Dr. Sear's feels that it is this lack of glycogenthat forces the body to "burn" extra fat assisting with weight loss. Riding bonked is just part ofwhat one should expect - on the Zone or any other weight loss diet.

If you are not trying to lose weight, keeping the exact Zone ratio is alleged to provide the health benefitfrom a decrease in total body inflammation and an increase in a sense of "well being". Theseclaims have yet to be proven in long term observations.

How about a Calorically neutral Zone diet and the athlete? Where Calories eatenare adequate to replace those expended each day?

Although the Zone Diet claims to improve performance, a study on athletes following the diet lostendurance. Why is that the case? The problem is in the rigid P/C/F ratio of 40/30/30.

If you want to maintain your weight (not gain weight) your daily Caloric expenditure andintake have to be in balance. Applying the Zone ratio to supply these Calories, an endurance athletes will noteat enough carbohydrate Calories (at 30% of the total daily Calories eaten) to meet their higher levelexercise needs. With fat metabolism being less effective than carbohydrate metabolism tosupport high level (>50 - 60% VO2max) activity, you bonk or run out of gas.

This is demonstrated in this study "The acute1-week effects of the Zone diet on body composition, blood lipid levels, and performance in recreationalendurance athletes." Limiting daily carbohydrate Calories available (by sticking to the correct Zone ratio) led to slowlyprogressive glycogen depletion.

The bottom line - To lose weight, using the Zone ratio with a negative daily caloric balance works. But on a calorically adequate daily diet it is unrealistic to expect that athletes will experience significant improvements in performance. The recommendations for both carbohydrate and Caloric intakes are not sufficient to meet the energy requirements of a regular daily training program. Go high protein/low carbohydrate and you'll be chronically bonked.

The Paleo diet

The paleo diet is the ultimate high protein approach to making diet choices.

It is based on the unproven assumption that our ancestors ate a high meat diet andthus our metabolism is optimized for protein. But the data is not there to supportthat assumption.

First we have the facts from many population studies that demonstrate a strongcorrelation of health status with dietary intake - specifically thenegative impacts of a high meat diet versus the positive benefits of being avegetarian.

PROTEIN SUPPLEMENTS TO A NORMAL DIET

Here is an excerpt of his review:

BACKGROUND. Protein and amino acids are among the most common nutritional supplements taken by athletes. This review evaluates the rationale and potential effects on athletic performance of protein, purported anabolic amino acids, branched-chain amino acids, glutamine, creatine, and hydroxymethylbutyrate (HMB). LITERATURE. Two books, 61 research articles, 10 published abstracts, and 19 review articles or book chapters. FINDINGS. Dietary supplementation of protein beyond that necessary to maintain nitrogen balance does not provide additional benefits for athletes. Ingesting carbohydrate with protein prior to or following exercise may reduce catabolism, promote glycogen re-synthesis, or promote a more anabolic hormonal environment. Whether employing these strategies during training enhances performance is not yet clear. There is some evidence from clinical studies that certain amino acids (e.g., arginine, histidine, lysine, methionine, ornithine, and phenylalanine) have anabolic effects by stimulating the release of growth hormone, insulin, and/or glucocorticoids, but there is little evidence that supplementation of these amino acids enhances athletic performance. Branched-chain amino acids (leucine, isoleucine, and valine) and glutamine may be involved in exercise-induced central fatigue and immune suppression, but their ergogenic value as supplements is equivocal at present. Most studies indicate that creatine supplementation may be an effective and safe way to enhance performance in intermittent high-intensity exercise and to enhance adaptations to training. Supplementation with hydroxymethylbutyrate appears to reduce catabolism and increase gains in strength and fat-free mass in untrained individuals initiating training; as yet, limited data are available to decide how it affects training adaptations in athletes. CONCLUSIONS. Of the nutrients reviewed, creatine appears to have the greatest ergogenic potential for athletes involved in intense training. FURTHER RESEARCH. All supplements reviewed here need more evaluation for safety and effects on athletic performance.

Potential risks of excessive dietary protein or protein supplements include:

• skimping on the carbohydrates needed for muscle glycogen repletion (risking the development of chronic fatigue)
• dehydration
• potential kidney damage over time
• and excessive bone loss (as protein increases urinary calcium loss).

What about protein in combination with carbohydrates in energy and post recovery drinks?It had been suggested at one time that protein/cho mixtures were more effective than CHOalone in repleted or supplementing muscle glycogen stores. The final word, in my mind,is a review of 26 studies,published in 2014. The conclusion: "When carbohydrate is delivered at optimal rates duringor after endurance exercise, protein supplements appear to have no direct endurance performanceenhancing effect. " And in addition, they expanded that conclusion to include supplements whileriding as well as in the post ride recovery period: "...when carbohydrate supplementation wasdelivered at optimal rates during or after exercise, protein supplements provided no furtherergogenic effect, regardless of the performance metric used."

Theoretically, in intense exercise, protein post ride may help jump start the muscle repair process.But this is theory and I am unaware of any studies that support this idea. The one reasonprotein might be considered in a supplement or recovery drink in conjunction with CHOwould be to improve taste and in that way optimize supplement use (maximizing Calories replaced)both during and after a ride. This could be especially important for those riders who do not toleratevery sweet sugary drinks.

SOME PROTEIN IS "SAFER" THAN OTHERS - TMAO AND ATHEROSCLEROSIS

The results of numerous studies and investigations points to Trimethylamine N-Oxide (TMAO)as the real culprit.

There is proof of cause and effect. In an experimental mouse model, raising blood TMAOlevels by dietary manipulation increased blood vessel disease in the absence of anychanges in the cholesterol or fat content.

Numerous clinical studies of heart disease (chest pain in the ER, progression of knownatherosclerotic heart disease) show a direct correlation between increasing blood levelsof TMAO and cardiovascular disease.

Carnitine, a protein found in red meat and to a much lesser degree in chicken and fish, is thesource of TMAO. Any dietary carnitine not digested and absorbed in the small bowel passes intothe colon where bacteria (our microbiome) metabolize it to an intermediate molecule,TMA. TMA is in then absorbed and modified further in the liver to TMAO.

There is a similar pathway for the production of TMAO from lecithin, a protein found inegg yolks.

Solid evidence supports diet as the major determinant of blood TMAO levels. Arecent study documented that a diet low in red meat and eggs lowered TMAO levelsindependent of the amount of cholesterol or saturated fats in those diets.

TMAO production can be reduced with oral antibiotics (which alter the makeup of themicrobiome) or by decreasing the dietary intake of carnitine. Vegans as a group havethe lowest blood TMAO levels (and the lowest rate of cardiovascular diseases) whilethose on a regular red meat diet the highest. just replacing red meat with chickenwill lower the amount of TMAO excreted in the urine by two thirds.

What does this suggest for your diet?

1. Saturated fats, found in butter, cheese, red meat and other animal-based foods,do play a role in the development of cardiovascular disease, but there riskhas been overstated.
2. Your decision on the source of the third component of the daily diet, protein, hasconsiderable impact on your health. We know that vegetarians have the lowest levels ofblood vessel disease, and your goal should be a move toward a meat free diet. But thatdoes not mean you have to move to a full vegetable protein oriented diet. You can cutyour risks by adding one or two meat free dinners a week.Or decrease red meat portion sizes. And now we know that your choice of animal proteinshould focus on substituting chicken or fish for red meat as much as possible.

THE BOTTOM LINE