Debate has been raging for weeks now about whether we should be eating meat, whether it is good for us or whether becoming vegan might be better for the planet.
The amount of protein in different (generally 100g) portions of food. Source: https://www.bbc.com/food
Debate has been raging for weeks now about whether we should be eating meat, whether it is good for us or whether becoming vegan might be better for the planet. There is a lot of rather biased, hysterical and misleading information going the rounds. This article will, I hope, help to give you the information you require to make your own decision.
1. The need
We all need protein and the amino acids that they are composed of to sustain life. Protein, along with carbohydrates and fats are the three major nutrients in iur diet, often termed macro-nutrients. Unlike carbohydrates and fats, our bodies are not adept at storing reserves of protein. That means that if you ever go short on protein, the body may break down skeletal muscle in order to keep vital organs and body processes going. We need protein to build strength, make and renew cells, strengthen immunity and fight diseases like cancer.
2. Animal or vegetable?
The constituents of proteins, whether derived from an animal or vegetable sources, are the same. During digestion all protein is broken down into amino acids which the body re-builts into new strings of chemicals. These protein strands may for example, become DNA, help build bones, or might become a hormone like insulin. The thing that all body builders know is that protein is essential for building muscle. But while they are focused on building pecs, ‘ceps and quads the really crucial protein goes first into building and maintaining our organs. The heart is a muscle and composed of proteins very similar to a six-pack.
Animal and vegetable proteins can be equally beneficial, though are not always equally digestible, or available in the correct mix. Meat is not as good as eggs and milk which have been found to contain some of the most beneficial and easily digestible mixes of amino acids. All foods can be scored depending on their amino acid content and their digestibility. Here are some typical values:
Source: Protein Digestibility–Corrected Amino Acid Score. (Schaafsma, 2000)
Proteins with higher than 100% values can be used in combination with lower protein value foods. A classic example of this is the combination of milk and bread. The high lysine content of milk can compensate for the lower concentration in the wheat. Vegetarians can take advantage of this is formulating a healthy diet.
3. How much do we need?
The world health organisation has been gathering research on protein consumption since WWII. Their advice is that we need about 0.8g/day of pure protein for every kilo of body weight. Consult the info-graphic at the top of this article to understand how many grammes of pure protein in different foods.
It is best to eat protein at every meal. If you are still growing muscle and bone (under 25), sick, or over 50, many nutritionists now suggest that eating nearer 1g/kg/day may be beneficial. Some nations, like Norway and Australia recommend that protein be considered as a percentage of the diet, ranging from 10-20%. That boils down to an average protein requirement for a man or woman of normal weight of three good meals a day, each containing a minimum of 15-20g pure protein.
If you eat meat, this quantity is pretty easy to achieve. In fact, in countries like the USA, protein consumption is often far higher than this. Higher consumption is safe, though too much of any food can make us fat. An unbalanced diet is good for no-one.
However, it is far more difficult to achieve good levels of protein from plant foods. For example, 100g lean braising beef contains more than three times the quantity of protein compared to the same weight of cooked lentils (20g:6g). Vegetables like broccoli, mushrooms or avocado, though they contribute a little protein, should not be considered a main meal source. Half an avocado contains only 2g of protein.
Some people have an ethical objection to eating living things. But to say that red meat should be left uneaten, may be step too far. If you do decide to eat red meat remember that it isn’t the most efficeint, or lean source of protein. Eggs and milk offer the highest levels and chicken, fish, soy and legumes all offer a leaner meal. But red meat is one very good source of heme iron, which is easily absorbed. Eggs, chicken, fish and pulses also contain good quantities of readily available iron. Eating vegetable iron with vitamin C can improve the uptake of this non-heme iron, but we’re still not sure to what extent.
Anyone contemplating giving up all animal products all together should seriously consider the danger of a compromised nutrition. A vegan diet can not only reduce the protein we eat, but reduce our stocks of Iodine, Vitamin B12, Calcium, Iron and Vitamin D. It isn’t impossible, but it does require very careful menu planning, or a shedload of artificial supplements. Be very careful with the young, the elderly, the pregnant or the sick, who have less resilient to malnutrition. The vegan society recommends that vegans take a B12 supplement.
5. Processed protein
There is now little doubt that processed protein of any kind is bad for us. Recent studies have linked processed meat to cancer and cardiovascular disease. I would advise a very moderate intake of processed meats like sausages, bacon and jerky. These contain nitrates and nitrites (bio-active salts) that can interfere with our metabolism. Processed meats often have a higher fat and sugar content than unprocessed meat or leaner proteins. Careful scrutiny of the nutrition label is essential for processed foods of all kinds and processed meat products in particular – even those bearing an organic, low calorie or similarly ‘healthy’ label.
6. Lean protein
The high fat content in beef and pork make them less beneficial than pulses, soy, milk or fish. If you want to lose weight, restrict yourself to lean proteins, by which I mean chicken, fish, whole milk, soy and legumes. The protein in cheese, nuts and meat is high quality, but can add weight. On the other hand, the fats in full milk, while being flavoursome and satisfying, seem to react well in our digestion and not to cause the cardiac harm that other saturated fats are known for. In fact, several recent epidemiological studies show evidence that consumption of full fat milk and yoghurts reduce the risk of cardiovascular and heart disease (Dehghan et al., 2018).
7. Organic Protein
Protein is a very active substance. It is composed of highly reactive atoms like hydrogen, nitrogen and oxygen molecules strung together with carbon, in different configurations. The long strings are folded and twisted into complex forms. They are held together by electro-chemical bonds, by the strong attractions of minerals, like selenium, manganese, zinc or iron. Alternatively, the bonds may be electrostatic like the forces that cause hydrogen atoms to shoot about within protein structures, or to be powered by the weak and transient Van der Waals forces between atoms. The upshot of all this complexity is that under the scrutiny of an electron microscope proteins seem to dance and sway. They form portals, opening and closing to let substances into and out the cells; they form complex runs, like rails, along which other proteins progress like trains; they form claws that can capture and engulf viruses. Miraculously, within every cell in the body, proteins form and re-form again and again to make the perfectly beautiful double helix structure of DNA, creating a blueprint for cell division, regrowth and, of course, reproduction.
Hormones, pesticides and fertilizers, most of which are designed to interfere with the protein structure of microbes, weeds and pests can also interfere with human functions. The closer the food is to human structure ie mammalian meat, the more important this becomes.
Thus organic meat, where such contamination has been reduced to the bare minimum makes perfect sense. When you eat a highly dosed foodstuff you may be unwittingly ingesting highly active chemicals and additives than come along for the ride.
For example some pesticides are so chemically similar to nerve gas that they are stringently controlled in most western countries – but residues exist in everything we eat. Within proteins these contaminants can get a free ride, causing havoc. And because we are genetically so similar to other mammals there are dangers of ingesting artificial hormones from mammalian meat, as well as contracting diseases that can jump species like BSE.
If you live in a polluted city, where you are breathing in other bio-active chemicals, then eating organic may be even more important.
8. Sustainable protein – eating grass fed
Some meat production causes high levels of greenhouse gas emissions. In particular ruminants like cattle emit large quantities of methane, which is a very dangerous greenhouse gas, hundreds of times more potent than CO2. If the animal is fed on cereal that has been boosted with artificial fertilizers, then the emissions can be thirty times higher than the emissions from producing the same weight of vegetables or fruits (Rose, 2019). That is why we are all being advised to eat less meat and save the planet. But no reputable scientific evidence suggests that there is an immediate imperative for us to give up meat eating all together.
A sustainable diet is one that uses the least resources to deliver the most nutrition, in perpetuity. And while some systems can produce high yields in the short term, many farmers are now saying that it is organic farming that maintains good soil composition and can thus secure high yields and maximum nutrition in the long term.
Land which cannot be used for arable crops lends itself to grassland and grass-fed livestock farming. Some studies have shown that grass-fed livestock can actually contribute to reducing greenhouse emissions and improve the nutritonal quality of the meat.
The diagram below compares non-organic, non-grass fed emissions.
Imported meat will inevitably have clocked up a large number of food-miles, using energy to deliver it. Out of season products grown in a greenhouse may have required artificial lighting, heating and watering, all increasing the energy used to produce them and thus decreasing their sustainability. That is why GYO or buying in-season, direct from the farmer is recommended as the best of all possible worlds.
10. So what?
In deciding where you will draw your own lines, I would advise thinking about three things.
- First and foremost is the need to ensure that you and your family are eating a healthy diet. That means don’t stint on protein.
- Secondly, ensure that your diet contains crops that are safe for you and for the environment. I’d advice seeking the most local, freshest and least processed food you can afford. Go for good quality, lean protein.
- Thirdly, I would advise considering the entire food chain and production values in the food you buy and where you shop.
It is no good berating a friend for eating meat one day a week, if they walk to a local butcher, buy grass fed organic and use every scrap, while you take the Ranger Rover to buy an intensively farmed, imported, factory produced, meat substitute. Have a little understanding for your fellows along the way. The debate has become quite nasty, and that’s not good for any of us.
Look at food labels. They tell you a lot about what you are buying.
Baker, Katherine, (2018) Counting Calories? Count Your Carbon, Too ENVIRONMENTAL HEALTH, FOOD POLICY AND OBESITY Columbia Mailman School of Public Health Jun. 2018 https://www.mailman.columbia.edu/public-health-now/news/counting-calories-count-your-carbon-too
Go Grass-Fed! The Benefits of Buying Pasture-Raised Meats from Honest Weight
Links to the science:
British Nutrition Foundation (2016) Nutritional Requirements website. https://www.nutrition.org.uk/attachments/article/234/Nutrition%20Requirements_Revised%20Oct%202016.pdf Note that BDA recommend a slightly lower level of Protein than other international sources.
Cook and Reddy, (2001). Effect of ascorbic acid intake on nonheme-iron absorption from a complete diet. American Journal of Clinical Nutrition 2001;73:93–8. https://academic.oup.com/ajcn/article/73/1/93/4729737
Dehghan, Mente, Rangarajan et al., (2018) Association of dairy intake with cardiovascular disease and mortality in 21 countries from five continents (PURE): a prospective cohort study. The Lancet Volume 392, issue 10161, p2288-2297, November 24, 2018
Heller, Willits-Smith, Meyer et al., (2018) Greenhouse gas emissions and energy use associ-ated with production of individual self-selected U.S. diets. Environmental Research letters Online. 2018;13:044004.
Rose, Heller, & Roberto (2019) Position of the Society for Nutrition Education and Behavior(sic): The Importance of Including Environmental Sustainability in Dietary Guidance. Journal of Nutritional Education and Behavior 2019; 51:3,15.
Schaafsma, (2000) Protein Digestibility–Corrected Amino Acid Score
WHO (2007) Protein and amino acid requirements in human nutrition Report of a joint FAO/WHO/UNU expert consultation (WHO Technical Report Series 935) https://www.who.int/nutrition/publications/nutrientrequirements/WHO_TRS_935/en/