Health Matters: Health hazards of a carnivorous diet

Conway McLean, DPM, Journal columnist

The average American family sits down for dinner to find food on the table. As a generalization, they will be ingesting protein, fats, and carbohydrates. But in what form and flavor is an important question. We know the food we eat is tremendously important to our health and well-being, so a critical concern is what is being put on the plates of that typical family?

Everyone knows protein is a vital part of our diet. About one fifth of the human body is made up of protein, which makes up the primary building blocks of your body. Protein is necessary to produce muscles, tendons, organs and skin. These complex molecules are also required by the body to manufacture enzymes, hormones, neurotransmitters and others, all of which serve critical functions.

Early on, it was thought protein was always the same, regardless of the source. But our understanding of nutrition has grown considerably, although there remains much to learn. Apparently, proteins vary greatly in their quality and health benefits. And the news for that average family isn’t good: red meat carries health hazards, yet most Americans don’t consider it a meal if red meat isn’t the primary component.

As to how much meat one needs to eat, there remains some controversy. The recommended daily allowance, the oft quoted RDA, has caused great confusion, and not just for the lay public but professionals as well. Estimates place the best levels at about twice that of RDA, which is a meager 0.36 grams of protein per pound of body weight. For the average man who works behind a desk, meaning they are minimally active, this amounts to about 56 grams per day, and 46 grams for the average sedentary woman.

But the message being disseminated to the public has shifted away from recommending specific percentages of proteins, fats, and carbs. Instead, the emphasis is on the importance of eating healthier, protein-rich foods rather than concentrating on specific amounts of protein. The right amount is going to depend on your age, sex, and activity level. Other factors include amount of muscle mass, physical body type, health status, even current medical conditions.

Although many aren’t aware, vegetables provide protein. How else do herbivores survive, animals that eat only vegetable matter? They have muscles, bones and skin, all requiring protein to repair and rebuild. Vegetarians don’t eat meat, and these individuals are generally very healthy. This leads to an important question: is it healthier to eat no meat, or just certain kinds of meat?

When a meal is eaten, the protein contained in your food is broken down into its component amino acids, the building blocks for proteins. To form a protein, amino acids are linked together like beads on a string. But some of the amino acids needed to build our proteins can’t be produced by the human body and must be obtained through dietary means.

These are referred to as the essential amino acids, required for health, and necessary to ingest through nutritive sources. Often mentioned by devotee’s of a carnivorous diet is that animal proteins tend to contain a good balance of all the amino acids that we need, while many plant proteins are low or devoid of some of the essential amino acids.

Unfortunate for many, it has become increasingly clear that some sources of protein carry substantial health risks. Numerous studies have revealed this association with red meat and certain significant health conditions. Beef, lamb, pork, and venison, all have been linked with various cancers, heart disease, stroke and early death. Those with higher beef consumption have a greater tendency to develop certain cancers, especially colon. Another study found that eating red meat on a regular basis may shorten your lifespan. There appears to be even greater dangers with processed meats, having a strong association with heart failure and death.

Another well-documented hazard of processed meats is the consumption of nitrates. These substances occur naturally, and are found in many vegetables, providing health benefits. But artificially manufactured nitrates are used to preserve and color meat products and these carry substantial health risks. Nitrates are altered in the gut into nitrites, which are known to be cancer causing. (Notice there was no use of the word ‘may’ since this association is conclusive.) Meats using higher, more dangerous quantities of nitrates include such stellar examples of fine cuisine as hot dogs, bacon and especially ham.

Naturally, proteins in the diet convey multiple health benefits. As mentioned, when there is damage to any tissue, be it a chronic skin wound or an overworked muscle, repair of the structure is needed. Protein is a requirement for this process. Interestingly, an enhanced intake of white meat like poultry or fish has been found to be negatively associated with some types of cancers, meaning higher consumption seems to reduce one’s risk of these diseases.

A critical part of this discussion is the difficulty in studying human nutrition over time. Our research is primarily observational. We ask a study participant about their diet, or maybe they keep a log of what they eat each day, but from this information we can draw only limited conclusions. We aren’t controlling the foods of those being studied over some years. In a prospective study, everything consumed by all the participants would be controlled, measured, calculated, pre-determined. And this kind of research only carries validity if performed over many months or years. As you might imagine, this kind of research is extraordinarily difficult to do.

The consensus has changed concerning the source of the protein, whether animal or plant is better, and how much it matters. Apparently, quality may be more important than quantity health-wise, depending on the source and type of protein. Vegetarians tend to be healthy people, but perhaps it’s because they are more knowledgeable about the importance of physical activity and balanced nutrition. They also need to know how to obtain the essential amino acids since they aren’t ingesting complete proteins.

Most Americans eat enough protein to prevent deficiency. But that is not enough for optimal health. The best evidence, the latest studies, all support a diet that is low in processed meat, high in colorful vegetables, rich in plant protein, with some animal sources such as grass-fed meat, fish, poultry, and eggs. The specific health effects of fat and carbs remain somewhat controversial, but almost everyone agrees that (good) protein is vital. Eat smart and learn about nutrition. This can be life-saving information if it can lead you to an improved diet.

Editor’s note: Dr. Conway McLean is a physician practicing foot and ankle medicine in the Upper Peninsula. Dr. McLean’s practice, Superior Foot and Ankle Centers, has offices in Marquette and Escanaba, and now the Keweenaw following the recent addition of an office in L’Anse. McLean has lectured internationally, and written dozens of articles on wound care, surgery, and diabetic foot medicine. He is board certified in surgery, wound care, and lower extremity biomechanics.


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