- What is a plant-based diet?
- Are vitamin B12 supplements necessary for those following a plant-based diet?
- Don’t we need dairy products for calcium, to build strong bones?
What is a plant-based diet?
A plant-based diet is one that consists entirely, or almost entirely, of foodstuffs derived from plants*. Vegan diets are plant-based, but may not always be healthy, as they are generally motivated by ethical rather than nutritional considerations. Vegetarian and omnivorous diets including very small amounts of animal products may also be considered plant-based, and may be healthy or unhealthy depending on the amount of processed and refined plant foods, salt, sugar and fat being consumed. Those interested in plant-based nutrition often refer to plant-based diets as whole-food plant-based, or low-fat plant-based, to distinguish them from unhealthy variants.
A healthy low-fat, whole-food, plant-based diet consists primarily of vegetables, fruits, whole grains and legumes, along with small amounts of nuts and seeds. These foods should generally be eaten in as close to their naturally occurring state as possible, with at least half ideally being eaten raw. Salt, refined sugars, hard fats and extracted oils (with the possible exception of omega 3 oils) should be minimised or excluded entirely. Children may require their food to be minimally processed (for example blended) to assist them in taking in sufficient calories.
*Also mushrooms (fungi), bacteria and yeasts.
Are vitamin B12 supplements necessary for those following a plant-based diet?
Yes, it is essential to take a vitamin B12 (cobalamin) supplement if you are not consuming any animal products all, and advisable if you are consuming only small amounts:
- B12 is a water-soluble vitamin found in most animal products (meat, fish, eggs and dairy), and fortified non-dairy milks, breakfast cereals and yeast extract. It is not found in plant foods.
- It is important for the formation of red blood cells (along with folate), and for the maintenance of a healthy nervous system. Low B12 intake has been associated with high levels of the amino acid homocysteine in the blood, which has been linked to increased rates of birth defects, depression, dementia and death from all causes. (1)
- Symptoms of deficiency include: numbness and tingling sensations, blurred vision, poor balance, memory problems and personality changes, delusions and paranoia. Babies may appear more lethargic and lose their appetite. Death or permanent neurological disability may result. (1)
- B12 is made by bacteria, fungi and algae, especially bacteria in the soil and water. Grazing herbivores have several stomachs containing B12-producing bacteria. It is thought that plant-eating primates such as gorillas obtain B12 from contamination of plant foods with bacteria, soil and insects. When fed a sanitised diet (for example, vegetables washed in chlorine), primates have been observed to develop B12 deficiency. (2)
- B12 is produced commercially for fortification and supplements by bacterial fermentation in large vats (2). There is therefore no essential difference between the B12 present in fortified foods and that available from supplements, apart from quantity (and cost). Taking a supplement ensures an adequate dose – relying on fortified foods means daily intake may be variable, and possibly less than ideal.
- The UK recommended daily amount (RDA) for adults (19-50 years) is 1.5 micrograms per day (2 micrograms for breast feeding mothers) (3). In the EU it is 1 microgram per day. In the US it is 2.4 micrograms (2.6 in pregnancy and 2.8 during lactation) (4).
- The US National Institutes for Health (4) also provide RDA’s for children:
0-6 months = 0.4 micrograms
7-12 months = 0.5 micrograms
1-3 years = 0.9 micrograms
4-8 years = 1.2 micrograms
9-13 years = 1.8 micrograms
14+ years = 2.4 micrograms
- The amount of B12 available from animal sources (its bioavailability) may be less than that of B12 from fortified foods or supplements. This is because in animal foods B12 is bound to protein, and certain stomach secretions are needed to break down these complexes. You also need something called intrinsic factor (also produced by the stomach) to absorb B12 from the diet.
- B12 deficiency is actually most commonly seen in adults (eating standard diets) over the age of 50, due to a decline in the body’s ability to absorb B12 from animal foods. People suffering with pernicious anaemia (a condition in which the body’s immune system attacks the stomach cells that produce intrinsic factor), or who have had their stomach surgically removed, are also unable to absorb B12 from food, and require lifelong treatment with B12 injections.
- Some commentators have suggested significantly higher doses for optimal health (for example, because homocysteine levels rise before clinical deficiency occurs), and not merely the avoidance of deficiency. The Vegan Society (1, 5) and the Vegetarian and Vegan Foundation suggest 3 micrograms daily from 2-3 servings of fortified foods (4 micrograms for breastfeeding mothers (6)), or 10 micrograms per day from a supplement (2). The difference is because absorption is better when B12 is taken in frequent, small amounts.
- Dr Caldwell B. Esselstyn favours 1000 micrograms daily (for adults – most of his patients are older).
- Deficiency leads to neurological damage, which can be severe, and there have been several case reports of young children becoming affected after being fed restrictive diets. Case reports rank very low in the hierarchy of evidence – the pyramid indicating the relative value of different types of scientific evidence.
- There is no evidence that a varied and appropriately supplemented plant-based diet puts children at risk. However no good prospective research has yet been formally conducted to assess this, or any other potential risks or benefits of plant-based diets in childhood, as far as I am aware.
- There is no evidence of damage being caused as a result of taking high doses of B12 supplements, but again, this is mainly due to a lack of research, rather than any well-designed study showing no effect. The Food Standards Agency (FSA) states that less than 2 milligrams per day is unlikely to cause any harm.
Many people are of the opinion that human beings should obtain all their nutrients from food. Certainly from a global population perspective there is merit in this view. Fortifying the food supply, rather than relying on individuals to take supplements, reduces the risk that vulnerable people will fall through the net. However, as individuals making conscious choices about food and diet in a Western setting (such as those who might be reading this website, for example), we have an unprecedented opportunity not afforded to our evolutionary or more recent ancestors.
The widespread availability of reliable B12 supplements (either as tablets/powders or as fortified foods) can only be a good thing, because it allows us to take advantage of all the heath benefits of a plant-based diet without worrying about deficiency. The alternatives are that we either obtain our B12 from foodstuffs also loaded with harmful fats, proteins, hormones and other toxins, or we eat caterpillar salad sprinkled with soil.
1. Plant Based Nutrition and Health. Stephen Walsh PhD. The Vegan Society 2003.
2. B12 and the Vegan Diet, Vegetarian and Vegan Foundation Factsheet: http://www.vegetarian.org.uk/factsheets/b12factsheet.pdf Accessed on 22nd February 2013.
3. Food Standards Agency Expert Group on Vitamins and Minerals 2003: http://www.food.gov.uk/multimedia/pdfs/evm_b12.pdf Accessed on 22nd February 2013.
4. National Institutes for Health (NIH) Dietary Supplement Factsheet – Vitamin B12: http://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/ Accessed on 22nd February 2013.
5. The Vegan Society, Nutrition: http://www.vegansociety.com/lifestyle/nutrition/ Accessed on 23rd February 2013.
6. Feeding Your Vegan Infant – With Confidence. Sandra Hood. The Vegan Society 2005.
Don’t we need dairy products for calcium, to build strong bones?
It’s hard to talk about calcium without talking about dairy products, although the two are not actually synonymous, as we in the West have been led to believe.
This is a big topic, and I want to try and keep it simple here. One of the first pieces of information that I came across on the subject, that stopped me in my tracks, made me do a double-take, made my head turn 360° on my shoulders, and made me question everything I had previously thought about the importance of dairy products in health, was this:
Countries that consume the highest amounts of calcium (mostly from dairy) also have the highest rates of hip fracture (1).
It is possible to plot a graph of hip fracture rates against national calcium consumption, and there is a positive correlation. This means that the more dairy we eat, the more likely we are to suffer a broken hip in old age as a result of osteoporosis.
If this is news to you, I’d like you to read the last three sentences again, and again, until you are sure you understand, because it goes so utterly against everything we have been, and continue to be, taught about the importance of dairy in our diets. If you remember nothing else of what I am about to say, just remember this one fact, and ponder it a bit when you are out and about, in the supermarket, at a restaurant, or wherever. Let it sink in.
So how do we begin to understand this observation, first published in 1986 by Harvard Professor Mark Hegsted? It can take a long time for scientific knowledge to enter public consciousness (about 30 years in the case of the connection between smoking and lung cancer – a lot of people died in that time), particularly if there are strong economic motivations to keep it within the covers of the peer-reviewed journals. Put another way, there are a lot of people with vested interests in our continuing to consume dairy. There is also a strong cultural bias: we like milk; it forms the basis of many of the foods we grew up on and associate with love and nurture; we have been consuming it for so long that we cannot imagine anything different. But this is a classic case of can’t see the wood for the trees. In fact, around 65% of the world’s adult population do not drink milk at all, and their bones seem to be just fine (2).
When we see something in science that doesn’t fit with what we currently believe to be true, we need to think again. Is the data correct? What might be the mechanism causing this?
The data does seem to be correct. One way of assessing this is to look at the problem from several different angles, to see if it all adds up. It is possible to plot hip fracture rates against the ratio of vegetable to animal protein in the diet in different countries. Those countries with the highest ratio (mostly plant foods, very little animal protein) have been shown to have almost no cases of hip fracture at all. In individual women too (over the age of 65), those consuming high amounts of animal protein compared to plant protein have been shown to have 3.7 times more fractures than, and to lose bone four times as fast as, those at the opposite end of the scale.
One proposed mechanism is that a high protein intake, particularly from animal sources, causes the blood to become more acidic. The healthy body maintains its pH (the level of acidity) within a very narrow range through a number of mechanisms, including buffering by calcium mobilised from the bones. This calcium is then excreted in the urine, and so is lost from the body completely. The bones become weakened, and high levels of calcium in the urine also contributes to increased formation of kidney stones.
So according to this theory, it isn’t the calcium itself in dairy products that is causing the problem, so much as the protein it comes packaged with. I’ll be talking about protein elsewhere, but for now suffice it to say that those populations who consume a lot of dairy produce tend to also consume a lot of meat, eggs and fish. Overall in the West we consume a very high proportion of our calories as protein (30-40%), and many are now saying that we need to be taking in much less (around 10% – the amount generally found in most plant foods) for optimal health. We do need a certain amount of protein for growth and tissue repair, but anything over that amount simply puts a strain on our bodies’ systems, resulting ultimately in disease.
Whole plant foods, as well as containing optimum amounts of healthy protein, do also contain calcium*, so dairy is not our only potential source (3). Those following a plant-based diet may consume less calcium in total, but they appear to absorb it more efficiently from the digestive tract. They also lose much less in their urine and use what they do take in to achieve better bone health overall.
Dietary calcium is of course not the only factor affecting bone development in childhood and strength in later life. Exercise is of vital importance, as bones that are used as they are intended, for weight-bearing, become much better able to carry out that job. Too much salt in the diet has also been suggested to be detrimental, as has caffeine.
In summary, it would appear that human beings are not designed to consume milk or milk products after weaning (and should ideally only consume human milk before then). Doing so results in weaker bones with a higher risk of fracture in later life.
[*Good plant sources of calcium include: vegetables (especially leafy greens), beans, figs, almonds, flax seeds, sesame seeds, oranges, tofu and fortified products.]
- The China Study. T. Colin Campbell and Thomas M. Campbell. BenBella Books 2006. p204-211.
- The Food Revolution: How Your Diet Can Help Save Your Life and Our World. John Robbins. Conari Press 2001. P97-112.
- Becoming Vegan: The Complete Guide to Adopting a Healthy Plant-Based Diet. Brenda Davis and Vesanto Melina. Book Publishing Company 2000. P89-102.