Plant Based Nutrition Pt 2 - Addressing micronutrients deficiency
Achieving micronutrient adequacy is an important concern for all plant-based diet eaters. Poorly constructed diets might predispose individuals to deficiency which could have detrimental health and exercise performance implications (1-3). Attention should be paid to achieving adequate in vitamin B12, iron, calcium, zinc, iodine and vitamin D in order to optimise health.
The absence of animal and diary products increases the risk of developing Vitamin B12 (cobalamin) deficiency (4). Vitamin B12 is essential for our nervous system, homocysteine metabolism and DBA synthesis to function normally (5). Deficiency in vitamin B12 can lead to neurological symptoms such as megaloblastic anaemia and neuropathy (6). Moreover, long term vitamin B12 deficiency can lead to irreversible neurological damage (7).
Sources of vitamin B12 in a plant-based diet includes B12-fortified breakfast cereals, nutritional yeast and dietary supplements to ensure adequate intake of 2.4 μg ∙ day−1 for adults of both sexes (8), while some authors advised vegans to consume up to 6 μg ∙ day− 1 of supplemental B12 (9).
The main source of iron in the plant-based diet is found in the non-haem form, which is less bioavailable compared to haem iron found in animal products (10). This means that plant-based eaters needs to prioritise sufficiency in the bioavailability of plant-based iron (10,11). Also, it is important to note that there are dietary inhibitors such as polyphenols tannin that can be found in coffee, tea and cocoa reduces the amount of iron absorbed from the diet. While on the other hand, consuming iron rich food in conjunction with vitamin C enhances non-haem iron absorption (2, 11). The plant-based sources rich in iron are legumes, grains, nuts, seeds, fortified foods and green vegetables.
Iron-deficiency anaemia (insufficient iron consumption and decrease in red blood cells) results in symptoms such as fatigue, weakness, shortness of breath and reduced exercise tolerance (12). Iron-deficiency without anaemia results in reduction in endurance capacity, increased energy expenditure and impair adaptation to endurance exercise in females (13).
The recommended intake for adult males and females in plant-based diets are 14 mg ∙ day−1 and 33 mg ∙ day−1 (vs. the Recommended Daily Allowance’s 8 mg ∙ day−1 and 18 mg ∙ day−1). Supplements are recommended if adequacy cannot be achieved via diet. (97).
Zinc is involved in the metabolic processes that relate to DNA stabilisation and gene expression, which is important in cell growth, repair and protein metabolism. Similar to iron, zinc is also not readily absorbed (10). It is suggested that plant-based eaters might need to consume up to 50% more zinc than non-vegetarians owing to its poor bioavailability (11). It has been recommended that male vegans consume up to 16.5 mg ∙ day−1 of zinc (vs. the RDA of 11 mg ∙ day−1) and females up to 12 mg ∙ day−1 (vs. 8 mg ∙ day−1) (9). Common plant-based sources of zinc include beans, whole grains, nuts and seeds - foods that also contain phytate (10).
Calcium is necessary for blood clotting, nerve transmission, muscle stimulation, vitamin D metabolism and maintaining bone structure (15). It is recommended that the sufficient quantity of calcium intake is 1000 mg ∙ day−1 (15).
Plant-based sources of calcium such as beans, pulses and green vegetables containing low oxalate levels like broccoli, bok choy and kale. However, green vegetables such as spinach and arugula contains high oxalate, which impedes calcium absorption (16). Calcium-fortified foods are also widely available, such as calcium-fortified soy, nut milks and fruit juices provide readily absorbable forms of nutrient. If sufficient calcium levels cannot be achieved via diet, supplement might be a good alternative as well (7).
Iodine is essential for physical and mental growth and development, while also plays an important role in thyroid function and metabolism (11). However, do note that excessively high or low intakes of iodine can lead to thyroid dysfunction (17,18). The recommend DRI for iodine is set at 150 μg ∙ day−1 for adults (11) and appears to be well tolerated unless clinical susceptibilities to thyroid issues are present (19).
Vitamin D is essential for calcium absorption and bone health, which also plays an important role in many physiological processes (20). While vitamin D can be synthesise from exposure to sunlight, they can also be found in animal products and fortified foods (20).Vitamin D deficiency are usually caused by insufficient sun exposure (21) and negatively affects muscle strength and oxygen consumption. The Department of Health in UK recommended 10 μg ∙ day−1 (400 I.U) supplemented by individuals who do not achieve adequate sun exposure (22), suggesting that supplementation might protect against overuse injury via its role in calcium metabolism and skeletal muscle function.
Creatine has been well studied of its performance-enhancing effects to improve short term high-intensity exercise performance, muscle hypertrophy and maximal strength (23,24). Also, creatine might lead to increase in plasma volume, improve glycogen storage, improve ventilatory threshold and reduce oxygen consumption during sub-maximal exercise (24). Burke et al. (25) found that supplemental creatine attenuated low muscle creatine stores in vegetarians, who experienced greater improvements in Fat Free Mass, maximal strength and type II muscle fibre area compared to omnivores. Sufficient creatine dosage regime of 20 g ∙ day−1 for 3–7 days to load creatine followed by maintenance doses of 3–5 g ∙ day−1 are common (23). However, a smaller dose of 3–5 g ∙ day−1 taken over a 4-week period will achieve creatine saturation over the long term similarly (26).
In a nutshell, these are some vegan-friendly food sources that a plant-based individual can add into their daily consumption in order to achieve the necessary nutrients needed.
In general, a well strategised plant-based diet that is nourished with adequate micronutrients recommended can optimise health and performance in an individual satisfactorily. If you're interested to know more on how to personalise your nutrition and improve your health, do reach out to us here!
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