BENEFITS AND PITFALLS OF A VEGAN DIET
STEPHEN WALSH PHD

1) THE BENEFITS TO ANIMALS, PEOPLE AND THE ENVIRONMENT

Animals

All beings love life and fear pain, therefore their lives should be respected.
A person eating meat is responsible for a feeling being dying before its time, usually in fear and pain. If the animal has been raised on a farm, then in many cases it will have been raised in unnaturally confined and stressful conditions.
A person eating commercially produced eggs (including free range) is responsible for a lifetime of confinement in miserable conditions from which premature death is the only escape.

A person drinking milk is responsible for a lifetime of overwork and stress during which the mother cow will be made pregnant year after year only to see her calf torn away from her every time after just a few days. The unwanted male calves are often slaughtered immediately or killed for veal after about six months. After about a fifth of her natural lifespan, the worn out dairy cow will be slaughtered for meat.

People

Animal-borne infections

BSE raised the spectre of meat-eating leading to millions of people dying a horrible death as their brains were eaten away from within. So far only about a hundred people have died. The difference is a matter of luck.
As recently as two years ago, pasteurised milk was found to contain the paratuberculosis bacterium suspected of being a trigger for Crohn's disease in humans. Pasteurisation times were quietly increased and business as usual continued.
Modern animal farming means that new diseases spread ever more rapidly, as in the recent foot and mouth epidemic. Cases of food poisoning from known and easily killed infections remain common.

Saturated fat and cholesterol

Beef fat is about 40% saturated, with a polyunsaturate to saturate (P/S) ratio of about 0.10. Milk fat is over 60% saturated, with a P/S ratio of about 0.05. All animal products, especially eggs, contain cholesterol.
At dietary P/S ratios above 0.6 heart disease risk is about 40% lower. Cholesterol consumption increases heart disease risk by about 10 to 20%.
Low fat milk is not the solution: once the cow is milked, the fat is in the food supply and someone ends up eating or drinking it.
No plant food contains cholesterol and most have a P/S ratio around 1.

Fibre

Natural plant foods all contain fibre while animal foods do not.

Increased fibre consumption is linked with lower risk of heart disease, diabetes and obesity.

Antioxidants

Fruit and vegetables are the main source of antioxidants and are consistently associated with reduced risk of disease and death. At least 5, and preferably 10, servings a day spanning the rainbow of colour is recommended for maximum benefit.

Environment

Animals fed on pasture displace trees, which are vital to stabilising soil and abating global warming.
Animals fed on grains and beans require more land, water and energy to be used than if the plant food is used directly for humans.
Cattle and other ruminants are a major source of methane contributing to global warming.
Factory farming is a major source of pollution.

2) THE PITFALLS OF INAPPROPRIATE VEGAN DIETS

The five largest studies of vegetarian diets and health were pooled to permit an overall analysis, published in 1999, of the impact of diet on health. All dietary groups in the studies showed mortality rates about 40% below those of the general population and typically smoked less, exercised more, ate more fruit and vegetables and less meat than the general population. Differences between groups in the studies were more modest, but vegans did not come out best.

Heart disease

Regular meat eaters ~ 1.00
Occasional meat eaters ~ 0.8
Fish eaters ~ 0.66
Vegetarians ~ 0.66
Vegans ~ 0.74

Other non-cancer causes

Regular meat eaters ~ 1.00
Occasional meat eaters ~ 0.84
Fish eaters ~ 0.85
Vegetarians ~ 0.95
Vegans ~ 1.33

All causes

Regular meat eaters ~ 1.00
Occasional meat eaters ~ 0.84
Fish eaters ~ 0.82
Vegetarians ~ 0.84
Vegans ~ 1.00

One year extra life expectancy translates to a difference in mortality rate of about 0.09. The vegans studied matched the regular meat eaters but appeared to lag slightly behind intermediate groups. This was not a bad result for people choosing the vegan way of life for ethical reasons, but disappointing given the expected benefits of a vegan diet.
There are a number of likely reasons why the results for vegans were not better. The most important is almost certainly inadequate B12. A non-ideal balance between monounsaturated fats, omega-6 and omega-3 fats may also have contributed significantly, along with other factors such as low iodine, selenium, vitamin D and calcium intakes in some vegans.

B12

A 10% increase in homocysteine levels is associated with an 8% increase in mortality from all causes, so correcting elevated homocysteine could add four years to vegan life expectancy.

The solution:

Include at least 3 micrograms of B12 each day from fortified foods or supplements. B12 is not adequately provided otherwise in a modern hygienic plant-based diet.

Balancing fats (omega-3s and monounsaturates)

Omega-3s from fish oils are widely touted as reducing risk of heart disease despite obvious problems due to pollution and limited supply.

Less widely acknowledged is the fact that the most successful dietary intervention in heart attack survivors to date (the Lyon diet heart trial) used plant omega-3s and other plant foods and achieved a 70% reduction in mortality. This benefit is double that of the most successful drugs for reducing deaths from heart attacks (the statins) and two to three times greater than that found in trials using fish oils.

The Lyon trial diet replaced butter with rapeseed margarine and olive oil, increased consumption of fruit and vegetables and bread, and decreased consumption of red meat and processed meats. Saturated fat and omega-6 intake both dropped and intake of monounsaturated and omega-3 fats rose. Blood antioxidant levels also rose.
Vegan diets are usually even lower in saturated fat than this trial (5% of calories vs 8%) but much higher in omega-6 (10-12% vs 4%) and lower in omega-3s (0.4% vs 0.8%). To minimise risk of blood clots forming (a key element in stroke and most heart attacks) and allow the body to obtain all required omega-3s, a polyunsaturated fat intake of 4-7%, with about 20% of the polyunsaturates being omega-3s and 80% being omega-6s is ideal, along with saturated fat intake below 7%.

Fat intake need not be particularly low to meet these targets, so long as most of the fat is monounsaturated. Fats with less than 25% saturates and less than 25% polyunsaturates can be consumed quite freely, subject to maintaining a healthy weight. These include olive oil, hazelnuts, macadamias, cashews and almonds.
At the other extreme, highly saturated fats such as coconut and highly polyunsaturated fats such as sunflower seed oil should be consumed sparingly.
Small amounts of omega-3 rich fats are important. Flaxseed oil has an omega-3 content of about 50% of total fat, hempseed about 20% and walnuts and rapeseed oil about 10%. Because the omega-3 to omega-6 ratio in flaxseed is about 4:1, a small amount of flaxseed oil can meet omega-3 needs without contributing excessively to omega-6 intake or total polyunsaturated intake. One teaspoon of flaxseed oil or one tablespoon of ground flaxseed per day is sufficient to boost omega-3 intake to a desirable level. The next best source of omega-3s is rapeseed oil, which has a ratio of 1:2, followed by hempseed at 1:3 and walnuts at 1:4. An ounce (30 grams) of walnuts per day provides as much omega-3 as a teaspoon of flaxseed oil but much more omega-6, so walnuts can be the main source of omega-3s on a very low fat diet but will otherwise tend to promote excessive overall omega-6 intake. Soya products have an omega-3 to omega-6 ratio of 1:7 and are therefore more appropriately considered as an omega-6 than as an omega-3 source, despite a relatively high omega-3 content as a percentage of total fat. Most seeds, including sunflower, pumpkin, safflower, sesame and corn, and their oils, are overwhelmingly sources of omega-6 and should consumed moderately, if at all.

Rapeseed oil has a special place as it is high both in monounsaturates and in omega-3s, which was why it was chosen for the Lyon diet heart trial. It strongly contends with olive oil as the most healthful main oil, though olive oil and flaxseed are more readily available in unrefined form and together form the dream team of high fat plant foods.

Fat profiles of common fat-rich plant foods

Iodine, selenium, vitamin D and calcium

In the UK, dairy products are the main source of iodine as

- soil iodine levels are low
- iodine is added to cattle feed and used to treat udder infections
- iodised salt is not used

Two kelp tablets per week provide a safe and adequate boost to iodine intake. Inadequate iodine may impair thyroid function, potentially leading to low energy, elevated cholesterol and homocysteine, and impaired intelligence in children.

Selenium is also low in UK soil and an adequate intake can be conveniently assured by 100 grams of Brazil nuts per month (about one per day). Inadequate selenium may increase susceptibility to infections and cancer.

[Note: Kelp and Brazil nuts are highly concentrated sources of nutrients, so taking much more than the above amounts is not advisable.]

In the UK winter the body cannot make vitamin D from sunlight and it may be beneficial for bone health in older adults and young children to include about 10 micrograms of vitamin D2 per day.

Grains and cultivated fruits are poor to moderate sources of calcium compared with the plants eaten by wild primates and palaeolithic humans. Fortunately, there are readily available alternatives to compensate for this loss without any need to resort to drinking milk designed for a rapidly growing calf.

Adequate calcium and vitamin D is important for bone health and may also reduce risk of hypertension, obesity, heart disease and polycystic ovarian syndrome.

How do wild primate diets stand up?

Wild primates live in the tropics with plenty of iodine and selenium in the soil and plenty of sunshine for vitamin D. Their B12 levels are adequate, probably due to bacterial and insect contamination of food and water, which is absent in modern diets. Intake of saturates and polyunsaturates is less than 8% of calories each, with a P/S of about 1 and an omega-6 to omega-3 ratio of less than 2:1. Intakes of calcium and other minerals comfortably exceed current human recommendations.

Guidelines for a healthy plant-based diet

Eat a wide variety of plant foods with plenty of strongly coloured vegetables and fruits, including dark green leafy vegetables or broccoli. Aim for a total of at least a pound or 500 grams of fruit and vegetables per day.

Get at least three micrograms of B12 per day or 2000 micrograms per week from reliable sources (fortified foods or supplements).

Limit use of refined grains and hydrogenated fat.

Eat 1-2 ounces (30-60 grams) of nuts a day.

Include a good source of omega-3s each day (one teaspoon of flaxseed oil or a tablespoon of ground flaxseed or a tablespoon of hempseed oil or two tablespoons of rapeseed oil or an ounce of walnuts).

Make the main fat source monounsaturates (olive oil, rapeseed oil, almonds, cashews, hazels, macadamias) unless the diet is very low in fat.

Eat calcium rich foods such as spring greens (200 mg per 100 g), kale (150), broccoli (50), oranges (40), and fortified plant milks (120) or breads (400) or take a 400 mg calcium supplement. If sun exposure is limited, take 10 micrograms of vitamin D2 per day.

Include some legumes (beans, peas, soya) to boost protein intake, particularly if your calorie intake is low.

Include a Brazil nut a day to ensure good selenium intake and two kelp tablets a week or equivalent to ensure a good iodine intake. [Remember, these are concentrated sources - more is not better.]

Limit use of salt or use a low sodium alternative.