Tag Archives: Vitamin supplements

Calcium

You do not need to drink milk to get enough calcium. You will not make your bones stronger by drinking milk.

If you don’t believe these statements, don’t worry, you are not alone. Seventy years of marketing has convinced most health professionals that dairy foods, or a high-calcium substitute, are essential for human health. This is a rather narrow nutritional view when one considers that cow’s milk is only consumed by a minority of the world’s population, and for a relatively short period of human history. Most of the world’s population, including the majority of those of Asian or African descent, are lactose intolerant and suffer abdominal pain and diarrhoea if they drink milk.

While it is true that dairy foods are rich in calcium and that calcium is an essential nutrient for bone health, increased dairy consumption is not associated with stronger bones. In fact, a large Swedish study (Michaelsson et al 2014) found that higher milk consumption was associated with a higher rate of hip fractures (as well as a higher mortality rate). The higher prevalence of osteoporosis in countries that consume more dairy foods suggests that dairy products are not an effective preventative strategy.

You don’t need to reach for calcium fortified foods to get enough calcium on a whole foods plant-based diet

Like other minerals, calcium comes from the ground. Plants absorb it and animals in turn eat plants. Cows get their calcium from the grass. We can obtain all our calcium needs from whole plant foods, many of which have moderately high calcium levels. Some vegetables have a higher “nutrient density” for calcium than dairy foods (see Nutrient Density page). Interestingly, calcium is better absorbed from vegetables than milk, over 50% vs 32%. Many whole plant foods are rich in calcium – a cup of chopped kale, for example, provides as much absorbable calcium as a cup of milk.

Calcium content of food

Dairy (and ‘dairy alternatives’) has its own food group in the Australian Dietary Guidelines but this is no longer the case for the Canadian dietary guidelines. A liberal interpretation of ‘dairy alternatives’ might include beans, greens and other high calcium whole plant foods. A plant-based ‘milk’ with a similar calcium content to cow’s milk is not necessary. Indeed, it has been argued that a more appropriate comparator for plant ‘milks’ is human breast milk which has only a third of the calcium content of cow’s milk.

The recommended daily intake for calcium in Australia is extraordinarily high, up to 1300mg per day, a level which few people reach. It remains to be seen whether this will be revised in future guidelines given the evidence that high dietary calcium intakes are not protective against osteoporosis (Bolland et al 2015). The World Health Organization (2004) notes that calcium needs are increased by high intakes of animal protein and sodium. Dietary animal protein increases urinary loss of calcium and at very high protein intakes it can be difficult to absorb enough calcium to offset losses. WHO suggests a lower calcium requirement where animal protein intake is lower, and if sodium intakes were also lower as in developing countries then the calcium requirement would be even lower, e.g. 450mg (WHO 2004, p. 82).

A study of older Chinese men and women on a “plant-based diet” in the Journal of Bone and Mineral Research (Fang et al. 2016) suggested there was an optimal range for calcium intake, and that both very low and very high intakes were associated with higher fracture rates. It may surprise you to learn that this range of optimal intakes was 250-650mg/day for women and 275-780mg/day for men. In the discussion the authors suggest that policy makers rethink the dietary reference intakes for calcium and the policy of milk promotion in developing countries. These results provide evidence that older Chinese men and women eating a plant-based diet may require half as much calcium than their Western counterparts for fracture prevention – approximately 400mg per day. A typical whole foods plant based diet provides at least 500mg of calcium per day and more often 700-800g without having to reach for calcium fortified foods.

Calcium supplements are not effective in preventing osteoporosis and clinical trials have observed an increase in kidney stones and cardiovascular events. Australian doctors are now being urged to consider the risks and benefits before recommending calcium tablets. Osteoporosis is not caused by calcium deficiency and it is not prevented by calcium supplements. See Osteoporosis page. Getting enough calcium on a dairy-free diet of whole plant foods is a non-issue and there is no need to consume plant ‘milks’ for calcium.

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Page substantially revised 9 December 2019
Page last updated 30 December 2019
Resources updated 8 March 2024

Iodine

Iodine is necessary for the production of thyroid hormones. Severe iodine deficiency results in enlargement of the thyroid gland (goitre) and is of particular concern during pregnancy as it can adversely affect the growth and brain development of the foetus. Historically, Iodine deficiency affected people in regions with iodine deficient soils in the days when eating local was the norm. It was not thought to be an issue in Australia until researchers began measuring iodine levels and found that pregnant women often had levels that were considered mildly deficient. Iodine levels in children in the south east of Australia are lower than in Queensland and Western Australia due relatively low soil iodine levels in the south east. The median iodine intake in Australia is only about 100mcg which makes us mildly iodine deficient. The recommended intake is 150mcg for adults, 220mcg during pregnancy and 270mcg while breast feeding.

Several factors have further reduced national iodine status. The dairy industry stopped using iodine based disinfectant to clean milking equipment. The food industry failed to use iodised salt as processed food overtook salt added in the home as the main source of salt in the Australian diet. The problem is being addressed by legislation requiring bakers to use iodised salt but organic bread is exempt from this regulation and many people are avoiding bread because they are following gluten free, grain free or low-carb diets. We suspect that diets that are nutrient poor in general are a big part of the problem – many people obtain a lot of their calories from meat, dairy, sugar, oil and processed food and eat very few vegetables or other whole plant foods. 95% of Australians do not even get the recommended 5 serves of vegetables plus 2 pieces of fruit per day.

Although it is important to have an adequate iodine intake, particularly during pregnancy and breast feeding, more than 1000mcg per day can be toxic. There was an ‘outbreak’ of iodine poisoning in Australia several years ago when one soy company added too much of the iodine rich seaweed product, Kombu, to one of their soy milks. Many plants, including soy, cruciferous vegetables and flaxseed contain goitrogens, substances which inhibit the utilisation of dietary iodine. These goitrogens are not thought to be a problem at usual levels of intake in persons whose iodine intake is adequate.

We are confident that a whole foods plant based diet can provide adequate iodine in Australia. This style of eating eliminates nutrient-depleted foods such as vegetable oils and includes large volumes of a variety of whole plant foods. Furthermore these foods are sourced from many different regions including Queensland and WA where the soils are richer in iodine. Note there is a scarcity of Australian data on the iodine content of plant foods.The iodine content of land plants is dependent on the iodine content of the soil in the region in which they are grown so it varies across Australia. Be aware that if you use Australian nutrient tracking software many common plant foods have no measurement listed for iodine so it may make your iodine intake appear lower than it is.

We recommend if you are going to add salt to your meals that you use iodised salt rather than ‘gourmet’ salts (however, see our Salt FAQ for more information on why added salt should be minimised). Seaweed products are a rich source of iodine but be aware that Kombu (kelp) contains extreme levels of iodine while Hajiki contains toxic quantities of arsenic. Nori, wakame and dulse are recommended. You can add these to salads or soups a few times a week to boost your iodine intake.

Iodine content of sea vegetables:

  • Nori 15 mcg/g (40mcg per 2.5g sheet)
  • Wakame 220-280 mcg/g (dry weight)
  • Dulse 100 mcg/g (dry weight)
  • Kelp 2100-4300 mcg/g  (too much!)

Women who are breast feeding, pregnant or planning to become pregnant can have their iodine status checked with a urinary iodine measurement (which is not very accurate) or just take an iodine supplement of 150 mcg per day. Supplements are not necessary for women eating a whole food plant-based diet who have a consistently high intake of leafy green vegetables plus regular sea vegetable consumption.

Daily iodine intake:

  • 100 mcg   Average Australian iodine intake
  • 150 mcg   Recommended intake for adults
  • 220 mcg   Recommended intake during pregnancy
  • 270 mcg recommended intake during Breast feeding
  • 90 mcg   Recommended intake for children (1-8yr)
  • 1000 mcg recommended upper limit of intake


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Page created 6 April 2015
Page last updated 25 April 2021

Omega 3 Essential Fatty Acids

A whole foods, plant-based diet can provide all the essential fats we need. These are the omega-6 and omega-3 groups of polyunsaturated fatty acids. There is no dietary requirement for other polyunsaturated fats, monounsaturated fats or saturated fats other than as an energy source. Omega-6 fats (linoleic acid) are plentiful in our diet. It’s the omega-3 group that has become a nutrient of concern.

Essential fatty acid requirements

Human requirements for omega-6 and omega-3 fats are uncertain because deficiency states are rarely seen. Dietary requirements are given as an ‘adequate intake’ rather than a minimum requirement. Adequate intake is used when an RDI cannot be determined and is based on an average intake of an apparently healthy population. [see Nutrient Reference Values: Fats: Total Fats & Fatty Acids for Adequate Intake (AI) recommendations]

The ratio of omega-6 to omega-3 fats is more relevant than the absolute amount of each, and herein lies the problem. The modern food supply is overloaded with omega-6 fats and often low in omega-3 fats with ratios of 15-20:1. The optimal ratio of 6’s to 3’s is generally considered 4:1 or less. Many foods promoted as ‘good fats’ have an overabundance of omega 6’s. (See our FAQ What are good fats?).

Omega 6 : omega 3 ratios of common foods:

*Green leafy vegetables are low in fat therefore it takes a lot of them to have a meaningful effect on your omega 3 intake.

Fatty Acid Chemistry

Plants provide linoleic acid (omega-6) and alpha-linolenic acid (ALA)(omega-3). Our cells have enzymes that convert these to arachidonic acid (AA)(omega-6 fat), EPA (omega-3) and DHA (omega-3). (Cats are carnivores and lack this enzyme). Arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are substrates for cell membranes, and a large group of signalling molecules called eicosanoids that have powerful local effects in many different organs. Omega-6 fats are essential for inflammatory processes and blood clotting. Omega-3 fats are required in smaller amounts and are often considered anti-inflammatory, but this is an oversimplification.

Is there a dietary requirement for DHA?

The efficiency of the human enzyme that initiates the conversion of plant-based omega-3 (alpha-linolenic acid) into the long-chain forms (EPA, DHA) has been called into question. Only a few percent of plant-based ALA is converted to DHA. Estimates of the exact amount vary widely and are found to increase when requirements are greater, such as during pregnancy. An excessive dietary intake of omega-6 fats downregulates the conversion enzymes and impairs the production of DHA. Theoretically, flooding the body with excess omega-3 fats might also impair arachidonic acid production. We are confident that a plant-based diet with a reasonable omega-6 to omega-3 balance will allow the body to make just the right amount of AA, EPA and DHA to meet its needs.

No absolute requirement for DHA has been established. The controversy is over whether taking preformed DHA (from fish or microalgal supplements) leads to better health outcomes.

Measuring omega-3 in the food and the body

Dietary analysis is unreliable for measuring dietary intake of omega-3 because food composition tables do not have an omega-3 value for many foods, thus underestimating true intake.

Blood tests for omega-3 levels are popular and often offered by the same corporate groups that sell omega-3 supplements. Test results are presented as a numeric value and compared to a reference range and suggest an optimal level of the omega-3 index between 8-12%. As of December 2024, we have not found any scientific rationale for these suggested ‘optimal’ levels.

Risks and benefits of omega-3 supplementation

Heart disease: Several meta-analyses and reviews have failed to find a protective effect of omega-3 supplementation on cardiovascular disease (e.g. The Risk and Prevention Study Collaborative Group, 2013 ). Some studies have observed better health outcomes in people who eat fish. However, this is probably because of what fish replaces, e.g. Red meat and because fish intake is often an indicator of a healthy diet and lifestyle.

Omega-3 supplementation is associated with an increase in atrial fibrillation, a common heart arrhythmia that can lead to stroke (see Gencer et al 2021).

Brain health: Having failed to protect the heart, omega-3 supplements are now being promoted for brain health. The brain preferentially takes up omega-3 fats and concentrates them in cell membranes. In this regard, omega-3s are essential for brain health, but more may not be better. The issue of EPA/DHA supplementation is controversial among plant-based advocates. The research is mired in conflicts of interest, small changes of low clinical significance, and research subjects with poor-quality baseline diets.

Diabetes: There is an increased risk of diabetes in those who take fish oil supplements or eat fish.

Prostate cancer: Fish oil supplementation and fish intake is associated with an increase in prostate cancer risk. It’s possible that some of this risk may be attributable to the high levels of PCBs and other organic pollutants found in fish and fish oil supplements (see Sorongon-Legaspi et al 2013)

Premature birth: There is evidence that DHA supplements given to women with singleton pregnancies from 12 weeks reduce the risk of premature birth. The author wonders whether this effect is offsetting the high arachidonic acid intake of omnivores.

Bleeding disorder: Very high intakes of oily fish, such as the traditional Inuit diet, or excessive intake of supplements cause prolonged bleeding times due to impairment of blood clotting.

Osteoporosis: Some studies report that high blood DHA levels are associated with osteoporosis (see Li et al 2024). Others report healthier bones in subjects with a lower (more favourable) ratio of Omega-6 to Omega-3 in their blood. In the latter, the plant-based omega-3 (alpha-linolenic acid) was associated with a lower rate of bone loss (see Feehan et al 2022).

Take home points

  • Dietary omega-3 requirements are controversial among plant-based advocates.
  • Blood tests are not clinically useful because there is no evidence-based reference range.
  • Omega-3 brain research is mired by conflicts of interest and clinically insignificant results.
  • Humans can synthesize EPA and DHA (and arachidonic acid) in adequate amounts provided dietary essential fatty acids are in reasonable balance.
  • EPA and DHA supplements may be harmful, particularly in higher doses.
  • Dietary strategies can ensure that essential fatty acid needs are met.
  • A microalgael DHA supplement may be appropriate in some situations. A smaller dose may be a safer option.

Dietary strategies for adequate omega-3

  • Minimise intake of vegetable oils, particularly polyunsaturated oils such as sunflower oil, a common ingredient in plant milks and other processed foods.
  • Eat nuts, seeds and avocados in small quantities, and shift your diet towards the lower fat end of the whole plant macronutrient spectrum, tubers, whole grains and legumes.
  • Include some high omega-3 nuts/seeds with your meals, for example, flax or chia seed. Leafy green vegetables provide some omega-3 fats.
  • If you choose to eat higher quantities of nuts, seeds and avocados, as recommended by some plant-based advocates, include plenty of moderate to high omega-3 plants.
  • See our FAQ: What Are Good Fats?

 

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Page created 22 June 2013
Last updated 23 December 2024 (major revision)

Vitamins and Minerals

Specific vitamins, minerals and other nutrients:

Most vitamin and mineral supplements are of no benefit and some may be harmful. With few exceptions we recommend that you get your vitamins, minerals, fibre and other phytonutrients from minimally processed plant foods. The supplements that may be required are related to modern living conditions rather than any inherent deficiency of a plant based diet. Clean food and water and safe food handling, whilst preventing disease, may remove most of the bacteria-derived vitamin B12 from our food supply. Indoor living can deprive us of the UV rays that are required for vitamin D synthesis. Many people take supplements as an insurance policy against dietary inadequacy or to detoxify the effects of too many rich foods. Unfortunately, supplements neither emulate the benefits of nutrients from plants, nor detoxify the harmful effects of excess animal protein, fats and processed foods.

Whole food is complex (see ‘Whole’ by T Colin Campbell in resources below). Our understanding of it is very basic. We know which nutrients are absolutely essential for life and the approximate amounts required. We have identified only a small number of the thousands of other biologically active substances in plants (known as phytochemicals or phytonutrients). We know little of the interactions between these various nutrients and phytonutrients. Often a high intake of a particular nutrient from food is associated with a health benefit, such as less cancer, but when we give them as supplements rather than as whole foods the benefit may be absent or reversed, increasing cancer risk.

There are some medical conditions in which vitamin supplements can be used as a pharmaceutical. Several of the B group vitamins can assist in reducing high homocysteine levels and this has been shown to reduce the progression of the early stages of dementia (see VITACOG study). The dietary approach would be to remove the cause of the elevated homocysteine levels by reducing animal protein consumption. While on the topic of dementia, Dr Neal Barnard recommends a vitamin B12 supplement and advises against taking supplements that contain minerals such as iron, copper and zinc as high levels of these may damage the brain.

No particular food has exclusive ownership of any particular nutrient. You do not need dairy foods for calcium, red meat for iron or fish for omega 3 oils. You do not even need to know which foods are the “best” sources of any particular nutrient. You just need to eat enough calories of whole grains, legumes, vegetables and fruits to maintain a healthy weight. And if you wish to tweak your plant-based diet to include more omega-3s, iodine, resistant starch or any other nutrient or phytochemical then we suggest that you bypass the supplements and just find some whole plant foods rich in the particular phytonutrient and make them a regular part of your diet.

See video: Dr. John McDougall Medical Message: Vitamin Supplements

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Last updated 11 April 2015