For decades governments and health organisations have informed the general public that animal protein (meat and dairy) is required every day as part of a healthy diet. Fast forward and the global chronic disease epidemics in the western world—obesity, type 2 diabetes, cardiovascular disease, and some forms of cancer—are startling examples of how problematic animal protein can be to the human body.
But what is it in animal meat and dairy that causes insulin resistance and can block insulin from letting glucose into our muscle cells? What elements exist that can cause the proliferation and metastasis of cancer? How does animal protein create metabolic inflammation?
Modern diets are largely heat-processed and as a result contain high levels of Advanced Glycation End-Products (AGEs). AGEs are naturally present in uncooked animal-derived foods, and cooking results in the formation of new AGEs within these foods. In particular, grilling, broiling, roasting, searing, and frying propagate and accelerate new AGE formation.
AGEs are sugars joined to proteins and are found in high numbers in cooked animal meat. AGEs are known to contribute to increased inflammation and oxidation, which are linked to the epidemics of diabetes and cardiovascular disease. In contrast, carbohydrate-rich foods such as vegetables, fruits, whole grains contain relatively few AGEs, even after cooking.
Heterocyclic Amines (HCAs) are chemicals that are caused by the heating of amino acids in animal meat and fish. The more well done the animal meat/fish is cooked, the more HCAs are present.
HCAs are recognised by the USDA as carcinogenic, which is concerning as there are no health warnings on meat packaging. Epidemiological studies show associations between intakes of Heterocyclic Amines and cancers of the colon, rectum, breast, prostate, pancreas, lung, stomach, and esophagus.
N-Nitroso Compounds were known almost 40 years ago to be present in food treated with sodium nitrite (salted, cured, processed meats like bacon, prosciutto, etc). Consumption of these meat leads to production of the carcinogenic chemical, N-Nitroso Compounds, which is strongly associated with colon cancer. While fruit, vegetable and plant extracts inhibit NOC formation by destroying nitrosating agents and exert a protective effect against various epithelial cancers.
There are two types of dietary iron; heme iron which is found in animal meat, and non-heme iron which is found in plant-based foods and supplements.
The heme iron found in animal meat is highly oxidising and can form free radicals. This has been strongly associated with affecting the pancreas, which is responsible for the production of insulin and glucagon to regulate blood sugar. Studies have found that high heme iron intake and increased body iron stores are significantly associated with a greater risk of type 2 diabetes, while non-heme iron and supplemental iron intakes are not significantly associated.
A sugar called Neu5Gc is naturally produced in the bodies of most mammals, but is not produced by humans because of a mutation that occurred after our last common ancestor with great apes.
As Neu5Gc is not produced by humans, the human body views red animal meat as a foreign invader and triggers an immune response to the foreign sugar. This produces antibodies that then spark inflammation, which is a powerful force in cancer development where it aids and abets tumour growth. Tumours hijack inflammation and use it to accelerate the progression towards full-blown cancer. Neu5Gc has never been reported in plants or microbes, while it is common in milk products and enriched in red animal meat.
IGF-1 is a natural human growth hormone produced primarily by the liver and promotes cell growth and division, which is instrumental in normal growth during childhood. Humans have specific times when we need to grow, like as a baby or during puberty. Importantly, human cells don’t get larger, they just get more numerous.
Once the human body is grown up, we no longer need extra cells other than what’s required as normal divide-and-conquer cell regeneration (out with the old, in with the new). IGF-1 levels are up during childhood and as you grow up, they start to come back down again. Human adults shouldn’t be making more cells than what we’re able to put out to pasture. Our cells understand when to tip the scale towards dividing because of a key signal from the hypothalamus. Though, if these levels remain too high in adulthood, IGF-1 can promote abnormal growth—the proliferation, spread (metastasis) and invasion of cancer. Simply put, IGF-1 is a growth hormone that helps things grow. It helps the transformation normal cells into cancer cells in the first place, then helps them survive, proliferate, self-renew, grow, migrate, invade, stabilise into new tumours, and even helps supply the blood supply to a new tumour.
Large studies show that animal protein intake is associated with higher levels of IGF-1—animal protein actually stimulates IGF-1, where as plant protein decreases IGF-1 levels. Other studies show that people with the highest levels of IGF-1 had a two-and-a-half times greater risk of colorectal cancer, while IGF-1 increases the invasive potential of breast cancer cells. Epidemiological evidence show that the risk of cancers of the colon, pancreas, endometrium, breast and prostate are related to circulating levels of Insulin-like Growth Factor #1.
Intake of acid
Certain levels of acidosis in the human body are natural because many of the body’s normal processes produce acid waste by-products. As a result, our body has a constant requirement to balance out pH levels so that acidosis does not occur (a normal pH range is 7.4). However, metabolic acidosis occurs when the body has too much acid, or when the kidneys are not removing enough acid from the body, which causes a low pH in our blood and tissues.
If unchecked, metabolic acidosis leads to acidemia where pH in the blood is too low due to increased production of hydrogen ions by the body, or the inability of the body to form bicarbonate in the kidneys. The consequences can be serious including coma and death.
Sulphur is an acidic element and animal protein is high in sulphur-containing amino acids. The two primary sulphur-containing amino acids are methionine (essential) and cysteine (non-essential). Due to the prevalence of sulphur-containing amino acids in animal protein, it creates an acid load to the human body, which needs to be buffered. Acidosis can be seriously problematic if it is recurring—that is, if we continually load acidic foods each day onto our already natural process to balance our pH levels, chronic acidosis can occur. Chronic metabolic acidosis has been implicated in inflammation and disease and can lead to a condition called pathogenic metabolic acidosis, which causes degeneration of the kidneys.
Methionine and leucine are two of nine essential amino acids, which cannot be synthesised by humans and must be provided by our diet. The nine essential amino acids make up a complete protein. High protein diets are praised due to a complete amino acid profile; however, excess amino acids may contribute to ageing and cancer.
Methionine is necessary for cancer to live and restricting methionine may be an important part of treating cancer. While plant-based foods (such as legumes) contain methionine, they tend to be lower in methionine than animal proteins—this is not a negative thing.
Mechanistic Target of Rapamycin (mTOR) is an protein enzyme that regulates cell growth, proliferation, motility and survival. Leucine stimulates mTOR, which has been shown to cause cells to age. Limiting consumption of leucine and methionine may limit ageing. Studies show that dietary methionine reduction increases both mean and maximal lifespan, which indicates that many people consume too much protein, despite popularised attitudes that high protein is the be all and end all of the human diet.
Amino acids methionine and leucine are present whether it’s grass-fed organic meat or not.
The bottom line
is that the world has built a health halo around animal protein. It’s become an institution where people flat out deny or avoid research that provokes the question on whether we should actually be consuming it in the first place. Tradition, culture, and the normativity eating meat and dairy are strong forces that create a seemingly impenetrable belief system that we must eat animal protein, that it is the only valid source of nutrients, and that any associated actions to the use of animals are absolute and justified.
As we can see here, the scientific facts do not support this view whatsoever.
Dea is passionate about pursuing gentle, pure living in all its forms. She’s a veg and fruit foodie, who loves to explore the healing properties of plant-based foods and then fully indulge in their sun-filled taste. She believes that “In the end, only three things matter: how much you loved, how gently you lived, and how gracefully you let go of things not meant for you.”