Is TMAO from Fish, Meat and Eggs Harmful?

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In another confusing nutrition story that should be titled “is there anything left for us to eat?” recent research threw a curveball. Fish, a staple of the Mediterranean diet, as well as meat and eggs may be doing more harm than good thanks to a compound called trimethylamine-N-oxide (TMAO). TMAO is found in fish and produced in the body after eating meat and eggs. TMAO is linked to greater risk for heart attack, stroke and death; yet the research isn’t crystal clear. Is it time to give up fish meat and eggs or ignore the recent media headlines?

This post will cover:

  • TMAO: More than a Gut Reaction—What gives us higher TMAO levels?
  • TMAO and health?
  • The bottom line

TMAO: More than a Gut Reaction

Blood levels of TMAO are ~ 50 times higher after eating fish compared to eggs or beef. The human body absorbs intact TMAO like the kind found in fish, easily. However, the human body’s production of TMAO, after eating foods containing the essential nutrient choline (found in eggs and meat) and the compound l-carnitine (found in meat and pork and in much smaller quantities in chicken breast and dairy products), depends on the makeup of bacteria in your gut, kidney functioning and genetics.

In one study, regular meat eaters produced more TMAO than a vegetarian did after eating steak (which contains ~ 180 mg of l-carnitine). After wiping out their gut bacteria with antibiotics, the carnivores didn’t produce any TMAO after consuming 250 mg l-carnitine. The makeup of gut bacteria in the habitual meat eaters was presumably responsible for greater TMAO production compared to the vegetarian, yet this was a small study and we don’t know anything else about the participants’ diet. Was it the meat that altered gut bacteria or something else in their diet? After all, a steady diet of red meat may mean double cheeseburgers on white bread with regular servings of French fries and soda on the side. This isn’t exactly the diet you want for promoting good bacteria in your gut.

Another study found blood levels of TMAO were greater in those with a less diverse makeup of microbes and greater amounts of a less healthy type of bacteria (firmicutes), compared to one that is healthy (bacteroidetes). A diet higher in saturated fat will promote this environment.

While bacteria seem to influence TMAO production from l-carnitine, l-carnitine also influences the makeup of gut bacteria. A study in mice found those with their gut bacteria wiped out thanks to antibiotics produced a different makeup of bacteria in the gut after consuming l-carnitine while also doubling the risk of plaque buildup in their arteries.

Higher TMAO levels come from:

  • Eating fish
  • Less diverse array of gut bacteria and increased levels of bad versus good bacteria
  • Consuming l-carnitine (mouse study)

TMAO and Health

A few human studies found higher blood levels of TMAO were associated with greater risk for heart disease. However, all research isn’t pointing in the same direction. One study in over 300 patients found blood TMAO levels were not associated with heart attack or heart disease over the course of eight years, following the initial test for TMAO. However, TMAO levels were higher in those with diabetes, patients with metabolic syndrome and those with declining kidney functioning. Another study examined over 800 people between the age of 33 and 55 and found blood TMAO levels were not associated with clogged arteries, insulin resistance (this comes before type 2 diabetes) and inflammatory markers or negative changes in blood lipids suggesting TMAO levels might not contribute significantly to the progression of clogged arteries. However, this study shows TMAO levels were significantly lower than in previous research, showing an association between TMAO and heart disease.

TMAO is considered a risk factor for cardiovascular disease. In those with type 2 diabetes, higher TMAO levels are associated with greater risk for death, heart attack, heart failure and unstable angina (chest pain). Also, higher levels of circulating TMAO are associated with higher risk of death in those with chronic kidney disease and greater risk of certain cancers. Yet, there are several confounding factors. Fish is the primary culprit for higher acute circulating TMAO levels, yet fish-based diets are associated with reduced risk for heart disease. Also, levels of TMAO are dependent upon disease state and the makeup of gut bacteria. Therefore, at this time it isn’t entirely clear which came first – does TMAO cause disease or does TMAO increase due to disease?

The Bottom Line

The story on TMAO isn’t crystal clear, so there’s no reason to avoid fish, meat and eggs in an effort to decrease TMAO levels. All three of these foods are good sources of several nutrients important for health. Though processed red meats are linked to higher risk of colorectal and stomach cancers, when cooked appropriately (lower, moist heat for example) red meat can fit into a healthy diet and deliver important nutrients including iron, zinc and vitamin B12. Eggs are an economical source of protein and contain many nutrients and compounds that contribute to health including two antioxidants important for eyesight.

Though there is no reason to completely avoid these foods, you can alter your diet to help diversify gut bacteria and also increase the amount of good versus bad bacteria. Probiotic rich foods such as yogurt and kefir with live and active cultures, miso soup, tempeh and other fermented foods contain good bacteria. Fiber-rich plant foods (fruits, vegetables, legumes) are important food sources for bacteria to thrive in your body.

Disclosure: this post was sponsored by USFRA. All views are my own and backed by research.

References
Koeth RA, Wang Z, Levison BS et al. Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med 2013 Apr 7.

Cho CE, Caudill MA. Trimethylamine-N-Oxide: Friend, Foe, or Simply Caught in the Cross-Fire? Trends Endocrinol Metab 2016 Nov 4. [Epub ahead of print]

Cho CE, Taesuwan S, Malsheva OV, Bender E, Tulchinsky NF, Yan J, Sutter JL, Caudill MA. Trimethylamine-N-oxide (TMAO) response to animal source foods varies among healthy young men and is influenced by their gut microbiota composition: A randomized controlled trial. Mol Nutr Food Res 2016 Jul 5.

Carnitine. Health Professional Fact Sheet, NIH. https://ods.od.nih.gov/factsheets/Carnitine-HealthProfessional/

Mueller DM, Allenspach M, Othman A, Saely CH, Muendlein A, Vonbank A, Drexel H, von Eckardstein A. Plasma levels of trimethylamine-N-oxide are confounded by impaired kidney function and poor metabolic control.Atherosclerosis 2015;243(2):638-44.

Meyer KA, Benton TZ, Bennett BJ, Jacobs DR Jr., Lloyd-Jones DM, Gross MD, Carr JJ, Gordon-Larsen P, Zeisel SH. Microbiota-Dependent Metabolite Trimethylamine N-Oxide and Coronary Artery Calcium in the Coronary Artery Risk Development in Young Adults Study (CARDIA). J Am Heart Assoc. 2016 Oct 21;5(10). pii: e003970.

How Much Protein Can Your Body Use from One Meal?

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Steak is a high protein meal

How much protein can your body digest and use at a time? If you you eat the right amount of protein at every meal you’ll supposedly hit the sweet spot – maximum muscle growth and satiety (fullness) without wasting food or money. General guidelines based on short term trials and one cross-sectional study suggest adults need regular meals including 25 – 45 grams of protein per meal to maintain or build muscle mass and maximum strength (1, 2, 3). However, it is possible that more protein per meal may be beneficial in some instances while the per meal amount might not matter very much in others. Your body can and will digest all of the protein you eat in a sitting (it might take a while) and it doesn’t just discard any excess that isn’t used to build structures in the body.

In this article I’ll cover:

  1. Why should we focus on a “per meal” dose of protein?
  2. What happens to “leftover” protein;
  3. What influences protein requirements;
  4. How you can estimate your protein needs.

Does the Amount of Protein Per Meal Matter?

In a really cool study conducted by well-known protein scientists, the minimum amount of protein per meal found to maximally spike muscle growth was 0.11 grams per lb. of body weight in younger adults and 0.18 grams per lb. of body weight in older adults (over 71 years of age) (2). Older adults need more protein due to a decline in muscle response to protein intake that occurs with age. In addition to a minimum, there is an upper limit of protein intake; anything beyond this threshold dose will not be used to build muscle. For example, one study examined 4 ounces of beef containing 30 grams of protein compared to 12 ounces of beef containing 90 grams of protein. The larger serving did not lead to a greater increase in acute muscle protein synthesis compared to the 4 ounce serving (4). So now we know we need some protein, but not 90 grams in one sitting. However, we still don’t know what the minimum upper limit is, beyond which higher intakes do not lead to increases in muscle mass or muscle functioning over time (5).

More evidence for a per meal dose came from a short-term study that found an even pattern of high quality protein at each meal (30 grams per meal; 1.2 g/kg for the day) as opposed to a skewed pattern (10 grams at breakfast, 15 g lunch and 65 g at dinner; 1.2 g/kg for the day) may be best for maximally stimulating muscle building in young adults (1).

Despite the evidence in favor of an even distribution of protein intake throughout the day, a short-term study in older, resistance trained adults given 2x the RDA – 0.68 grams of protein per lb. bodyweight (1.5 grams per kg) per day in an uneven or even pattern (see chart at the end of this article) or the RDA of 0.36 grams of protein per lb. bodyweight (0.8 grams per kg) per day again in an uneven or even pattern found the pattern of intake didn’t matter. Consuming 2x the RDA, regardless of whether it was consumed in an uneven or even pattern, led to a significantly greater increase in muscle protein synthesis compared to consuming 1x the RDA. The pattern of protein intake didn’t matter, possibly due to age-related decline in muscle response to protein intake,  greater total daily protein intake or some other factor (6).

What Happens to Excess Protein Intake?

There is no long-term storage site for amino acids, the building blocks of protein. After eating a thick juicy steak, creamy bowl of split pea soup or sizzling soy fajitas, your body digests the protein and absorbs the amino acids, using them to build new structures, including muscle. When excess protein is consumed, more than the body needs at that point in time, the rest is used for energy or  converted to body fat. The nitrogen (from amino acids) is combined with other compounds to form urea, a harmless waste product, which is processed by the kidneys and excreted in the urine.

What Influences Protein Requirements?

Though 90 grams in one sitting may be more than necessary for muscle, science has yet to figure out the exact threshold beyond which there is no benefit for muscle. This is a complicated question as there are many factors that influence a person’s daily protein needs as well as how much protein a person may need at each meal. These include but are not limited to: age, training status, total daily calorie intake (if dieting total protein needs are higher), overall amount of protein consumed each day; the type (anti-nutrients?), quality and leucine (or EAA) content of the protein consumed at each meal, other nutrients consumed at meal time, training program, lean body mass, health status and goals.

How Much Protein Do You Need at Each Meal?

Given the research to date, does a per meal does matter?

If you are dieting, yes.

If you don’t get at least 0.55 grams protein per lb. body weight (1.2 grams per kg), yes.

If you eat plenty of protein every day and a decent amount at regular meals throughout the day, it might not matter that much, or at all.

For now, stick to the general guideline of at least 25 grams per meal (the amount of an average female’s palm worth of chicken, turkey, red meat, fish). You may need more, per meal, to maximize muscle growth and repair  if:

  • You are older (relative term since we don’t know exactly what age qualifies as “older). Aim for 1.0 – 1.5 grams of protein per day (7) and regular meals with a good amount of protein per meal. If you have chronic kidney disease, follow the advice of your RD and MD.
  • You eat primarily vegetarian proteins.

Many factors influence a person’s nutrition needs. If you want to maintain or gain muscle mass and strength, concentrate on your total daily protein intake (at least 0.55 grams of protein per lb. of bodyweight; 1.2 grams per kg) followed by how much you consume at each meal. There is no one-size-fits-all ideal protein intake per meal and the body doesn’t just “waste” protein that isn’t used for muscle building. For now, research suggests 25 to 45 grams per meal is a good general guideline. More may be better for muscle. Less may be necessary if you have chronic kidney disease.

Table: Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults (select data and average leucine intake calculated)

Amount Pattern Meal Protein (grams) Protein as a % of total calories Average leucine intake per meal (calculated)
1x RDA Uneven Breakfast 11.1 8 0.89
Lunch 14.9 8 0.89
Dinner 47.8 12 3.56
Total 73.7 10 4.45
Even Breakfast 22.3 15 1.63
Lunch 21.5 9 1.63
Dinner 22.0 9 0.81
Total 65.8 11 4.07
2x RDA Uneven Breakfast 18.1 15 0.80
Lunch 24.3 12 1.60
Dinner 78.4 22 4.79
Total 120.8 19 7.99
Even Breakfast 38.0 25 2.98
Lunch 36.5 17 2.98
Dinner 37.9 18 2.23
Total 112.4 19 8.2

References

1 Mamerow MM, Mettler JA, English KL, Casperson SL, Arentson-Lantz E, Sheffield-Moore M, Layman DK, Paddon-Jones D. Dietary protein distribution positively influences 24-h muscle protein synthesis in healthy adults. J Nutr. 2014 Jun;144(6):876-80.

2 Moore DR, Churchward-Venne TA, Witard O, Breen L, Burd NA, Tipton KD, Phillips SM. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J Gerontol A Biol Sci Med Sci 2015;70(1):57-62.

3 Loenneke JP, Loprinzi PD, Murphy CH, Phillips SM et al. Per meal dose and frequency of protein consumption is associated with lean mass and muscle performance. Clin Nutr 2016 Apr 7.

4 Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects.J Am Diet Assoc 2009;109(9):1582-6.

5 Deutz NE, Wolfe RR. Is there a maximal anabolic response to protein intake with a meal? Clin Nutr 2013;32(2):309-313.

6 Kim IY, Schutzler S, Schrader A, et al. Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults. Am J Physiol Endocrinol Metab 2015;308(1):E21-8.

7 Paddon-Jones D, Campbell WW, Jacques PF, Kritchevsky SB1, Moore LL, Rodriguez NR, van Loon LJ. Protein and healthy aging. Am J Clin Nutr 2015 Apr 29.

 

 

How Your Body Image Affects Your Weight & Health

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Today I’m going on a slight rant about something that has been on my mind for a while – body image. And because the majority of my clients (all but 1) are male athletes, I don’t run into the overt self-degrading body comments as often as many of my dietitian colleagues who work with women. However, I’ve run into a number of women lately who either put their bodies down, avoid social situations or the beach / pool / bathing suits because they feel “fat”, obsessively cover up their bodies, obsessively diet or exercise (or both) or engage in other self-depreciating comments and related behaviors stemming from how they feel about their body. And I always walk away thinking “one day she is going to look back and think ‘damn I looked good’ and regret wasting so much time and energy hating a body that helped her cross finish lines, hike mountains, pick up small children, build a beautiful garden and do so much more.”

And though I won’t get into the psychology behind body image and self worth or how to improve your body image (you can read more about that in this article), I do want to talk about how this affects a person’s overall health and sense of well-being. First and foremost, the people around you might not notice the subtle behaviors and words you speak (unless you have dietitian or psychologist friends) but your kids will (children, grandchildren, children you teach or coach). Anyone who has spent 5 minutes with a child knows they pick up everything. Now, let’s say you are that female who won’t wear shorts in the summer because you hate the way your legs look. Your little girl will stop wearing shorts and at some point think her legs look bad too. Or maybe you are the grandma who won’t wear a bathing suit to the beach because you can’t fit into the one you wore last year. Your grandkids will wonder why you aren’t going in the water with them. And finally, if you are a coach of young girls, an entire team will learn about how they should be viewing their bodies from what you think of yours.

In addition to affecting the people around you, I’ve noticed that women who don’t love the bodies they live in spend entirely too much time thinking about food and exercise. And by cutting out certain foods, going on cleanses or popular diets or drastically slashing their food intake, they are cutting out a number of nutrients necessary for good health. And the effects might not be obvious at first, but over time they will catch up to you. Cut calories and it will be difficult to get a number of vitamins, minerals and protein in your diet (And when you fall short on protein you will start losing muscle mass. Over time less muscle means you burn a few less calories each day and you won’t be able to exercise as hard in the gym so you burn fewer calories while working out. Both of these make it challenging to keep weight off over time. Plus less muscle means activities of daily living like gardening, picking up kids, or lifting groceries may be tough). Switch to a vegetarian diet and you better really plan on incorporating protein since you will need more total protein to keep and build muscle. Drop dairy and your bones, teeth and nails will suffer over time (yes you can eat kale, spinach and other leafy greens but you will need at least 10 cups of raw leafy greens a day if this is your only source of calcium). I’ve seen women in their 20s with osteopenia (low bone mass, this often comes before the brittle bone disease osteoporosis). And this is just the tip of the iceberg. But, here’s the most important point: your body image affects what you eat (more than just total calories) and don’t eat. And over time I’m going to make a stretch here and say (from observation) that body image-induced changes in diet affect your intake of vitamins and minerals and over time, consistent vitamin and mineral shortages will affect how your body functions and could impair several aspects of health. So, if you feel like you fall into this category of women or men who loathe your body, make the commitment right now to work on this. I promise you that you are wasting time as well as mental and physical energy. Plus, the changes you are making in an effort to keep weight off may be doing more harm than good.