NFS302 Week 10: Vitamins and Minerals Part 1

Calcium: how lond do we have?

• 1-20 years of age is the period to build as strong bones as possible

  • 60-80% genetically determined

• Peak bone mass (PBM): achieved between age 20-30 and holds stable a bit

• We unequivocally start losing bone mass in our 30s

• Bones are like a bank, you put in deposits then try to maintain them

Calcium Requirements

• Children 9-18 years old:

  • RDA = 1300mg/day

• Adulthood:

  • AI drops to 1000mg/day

• After age 50 for females and age 70 for males:

  • Increases to 1200mg/day

• Pregnancy and lactation:

  • RDA = 1300mg/day (also growing bones for baby)

Dairy sources for calcium

• Milk, fluid, skim (250mL) = 316mg calcium

  • Alternative milk is fortified with same amount of calcium

• Cheeses = 250-450 mg/50g serving

  • Softer cheese → less calcium

• Yoghurt (175mL) = 250-300mg

• Animal products are likely the easiest way to get calcium

Non-Dairy Calcium Sources

• Cereals: 100-130mg Ca

• Nuts and seeds: 57-376mg Ca

• Vegetables and fruits: 50-266mg Ca

• Other: 120-350mg Ca

Calcium Factors

1. How well is that calcium absorbed by the body?

   • Vitamin D → helps with calcium absorption (milk)

   • Oxalates → hinder calcium absorption (veg)

   • Phytates → hinder calcium absorption (grains/legumes)

   • Caffeine, sodium, tannins and alcohol → limit calcium absorption

2. Is this food otherwise good for my health?

   • Tons of epidemiological evidence that nuts, fruits, and veg are great for overall health

   • Cheese not so much

BASICALLY, animal sources are great for absorption, while plant sources are great for health

Bone Health Experts of Canada

• Still must use critical thinking

• Drinking milk is good for calcium, as is drinking chocolate milk but you must still be aware of sugar and sodium levels

  • Don’t trade off calcium levels for health

• Lifting weights → also extremely important for preventing osteoporosis (stress causes body to lay on more bone)

Calcium Supplements and Bone Health

• Consistent evidence that use of calcium supplements reduces bone turnover by ~20% → associated with reduction in postmenopausal bone loss (reduced loss of bone mineral density/BMD)

  • Controversy in efficacy of calcium supplementation in reducing fractures

• These are both true

What causes fractures?

• BMD is predictive of fracture risk (reduced BMD → increased fracture risk)

• Getting to the RDA for calcium is important but everyone gets some amount through their regular diet

• Being physically fit is a LARGER predictor of fracture risk

Interventions for preventing falls and related injuries

• 108 RCTs; >23k subjects from 25 countries

• Evaluated the effects of any form of exercise as a single intervention on falls in people aged 60+ years

• Conclusion → the two most effective modalities of exercise:

  • Balance training

  • Resistance training

Fracture risk assessment

• Two tools for estimating 10 year risk major osteoporotic fracture:

  • CAROC

  • FRAX

• Factors these tools consider:

  • BMD, age, sex, BMI, rheumatoid arthritis, smoking and alcohol, prior fragility fracture, recent prolonged glucocorticoid use

Nuts and Falls

• Population-based observational study of <71k women, <60 years old in the USA

• Conclusion: strong and consistent inverse association between regular nut consumption and incident frailty

  • Not peanut butter though

Fracture data in Canada

• Latest data from the Public Health Agency of Canada’s Canadian Chronic Disease Surveillance (CCDSS)

• 150 hip fractures per 100k people aged 40+

• Double edged sword:

  • Women 2x more likely to fracture their hip than men

  • Men 1.6x more likely to die within a year of hip fracture compared to women

Negative Effects of Calcium Supplements

Study 1

• Eligibility criteria included:

  • Randomized, placebo controlled trials

  • >500mg calcium supplements per day

  • Subjects >40 years old

  • Duration > 1 year

  • > 100 subjects/study

• Pooled 15 trials totalling 20k people

• Conclusion:

  • Calcium supps (without VD) associated with a small increased risk of myocardial infarction

Study 2

• Tracked 23,890 people in Germany

• Average ~11 years of followup

• Conclusions:

  • Compared with lowest quartile, third quartile of the total calcium intake had a significantly reduced risk of a heart attack

  • However compared to non-users, calcium supplement users had a statistically significantly increased risk of heart attack

No Negative Side Effects of Supplements

• Community-based cohort study using 6236 subjects found no evidence that calcium supplementation use was associated with elevated risk of MI or CVD

• Individuals using a low dose (<500mg) had a lower risk of MI than individuals taking no supplement

Negative Consequences not seen with dietary calcium

• 110,792 healthy Japanese people followed for ~9 years

• Conclusions:

  • Dietary calcium intake from dairy products was associated with reduced mortality from stroke

  • No association with coronary heart disease or total CVD

Calcium “Goldilocks phenomenon”

• Maybe calcium has a relatively narrow range for optimal intake (“just right”, a sweet spot)

• DRI upper limits:

  • Adults > 50 = 2000mg/day

  • Adults 19-50 = 2500mg/day

• The ultimate decision should weigh the benefits (bone health) vs. the risks (CVD) and should be made by an RD

Acid-Ash hypothesis

• Acid yielding diets cause urinary calcium loss and accelerated skeletal calcium depletion

  • Bullshit

Theory has been discredited

• 55 studies met the inclusion criteria

• Several weaknesses were uncovered:

  • No intervention studies provided direct evidence of osteoporosis progression

  • Supporting prospective cohort studies weren’t controlled regarding important osteoporosis risk factors, including weight loss

  • No study revealed a biological mechanism functioning at physiological pH → not a single finding

NO evidence that an alkaline diet is protective of bone health

Anti-milk arguments

• Argument that milk is for babies - Arnold Schwarzenegger

• Animal cruelty - taking milk away from the calf?

• Naturalist fallacy used here

• CFG 2019 → removed “Milk products" group

Science says drinking milk will kill you

Study 1

• Cohort of 61,433 women and another cohort of 45,339 men in Sweden

• Followed for an average of 20.1 years

• Conclusion: “High milk intake was associated with higher mortality in one cohort of women and in another cohort of men”

  • Also greater fracture incidence in women

Study 2

• Cohort of 52,795 North American women, initially free of cancer, followed for ~8 years

• There were 1057 new cases of breast cancer during followup

• By drinking up to one cup of dairy milk/day, the associated risk went up to 50%

• No associations between soy and breast cancer

Should I drink chocolate milk?

• 9 endurance trained male cyclists

• Did an interval workout, recovered 4 hours then performed an endurance test

• 3 trials: chocolate milk, fluid replacement drink, or carbohydrate electrolyte drink

• Chocolate milk wins!

• Supported by the Dairy and Nutrition Council

Milk vs. Soy

• 8 regular exercisers

• Tested the effects of a soy vs. milk beverage post-leg workout; crossover design with >1 week washout period

• Significantly greater uptake of amino acids and greater rate of muscle protein synthesis in 3h after exercise with milk vs. soy protein ingestion

  • Milk protein → increased muscle protein synthesis

Science says drinking milk won’t kill you

• Followed a cohort of 136,384 individuals for ~9 years on average

• Asked about consumption of dairy (ie. milk yoghurt and cheese) using country-specific validated food frequency questionnaires

• Higher intake (>1 serving/day vs. no intake) of milk and yoghurt was associated with lower risk of mortality abd major CVD events

  • Not found in cheese

Final thoughts on drinking milk

Dairy products seem to be the:

• Easiest way to ingest vitamin D from food

• Best source of dietary calcium

• Best source in the Canadian diet for B vitamin riboflavin

• 9g of high quality protein per serving

• Hydration

• Nutritionally, milk is a cheap, convenient cocktail of very important nutrients

Vitamin D has been beneficially linked to:

• Bone health → helps with calcium absorption

• Breast cancer, colorectal cancer

• Risk of falls

• Immunity

• Muscle function

• Physical performance

• Blood pressure, diabetes, heart disease, arthritis, MS

How can vitamin D do so much?

• Thought to modulate expression of 1000+ genes

Vitamin or hormone?

• Vitamin D is actually a lipophilic pro-hormone

• Occurs 2 forms:

  • Cholecalciferol (vitamin D3) → active form

  • Ergocalciferol (vitamin D2)

• Must be conducted throughout the course of human history, most individuals never obtained any appreciable amounts of vitamin D through their diet

  • Fatty fish → best natural source

  • Mushrooms → vit D2

  • Milk → recently fortified with vitamin D

Reference for Vitamin D

• 75-250 nmol/L

• >50 meta-analyses of vitamin D supplementation and falls/fractures have been published

• Authors of this paper write: vitamin D supplementation alone doesn’t improve musculoskeletal outcomes

  • MUST exercise for improvement

How do we measure vitamin D status?

• serum-25-hydroxy vitamin D is the best biomarker

• What is the “optimal level”?

  • DRIs → <30nmol/L risk of deficiency

  • 50nmol/L is RDA

  • Canadian osteoporosis guidelines → 75 nmol/L

  • “Grassroots Health” → 100-150nmol/L

How much Vitamin D do we need?

• DRIs:

  • Most adults → 600 IU

  • Upper level intake → 4000 IU

• 2010 Canadian osteoporosis guidelines

  • Adults at low risk for deficiency = 400-1000 IU

  • Adults >50 at medium risk for deficiency = 800-1000 IUs

• Other organizations have guidelines too

  • Canadian Cancer Society (reduce time in sun), Endocrine Society

Vitamin D and Athletic Performance

• Possible mechanisms of improving athletic performance include muscle function, immunity, etc

• "Still gaps in the literature especially with regard to the extraskeletal effects of vitamin D in athletes

• Peak performance may occur when 25-hydroxy vitamin D is at least 50nmol/L

• Could also possibly protect against acute and chronic medical conditions

Background skin physiology

• Your largest organ, weighs about 9 lbs

• 2 Major layers:

1. Dermis → inner layer; provides most of skin’s toughness and thickness

   • Main cell type = fibroblasts

     • Contain collagen - accounts for ¾ of the dry weight of your skin

2. Epidermis → outer layer, only about 1 mm thick

   • Main cell type = keratinocytes

     • Also melanin in darker skin

Safe way to get a tan?

• Canadian Cancer Society → “no one is completely safe from the sun […] risk of skin cancer is greater today than it was 20 years ago and continues to increase”

• “Tanned skin is damaged skin”

• WHO upgraded UV-emitting devices from probable carcinogen to a known carcinogen

• “Don’t need to get a tan to get adequate amounts of viatmin D”

Tanning in the Sun

• Laying flat in the summertime sun at noon for 10-20 mins can lead to as much as 10,000 IUs of vitamin D - Dr. Vieth, UofT

The Sun & Human Evolution

• Solar radiation comes in a variety of wavelengths and energy levels

• UVR is broken into different categories as the wavelength get longer i.e. UVc, UVb, UVa

• Only UVa and small amount of UVb penetrate the atmosphere

• How much actually hits a part of Earth depends on latitude and topography

• Benefit → UVR in the UVb range stimulates production of vitamin D3 in the skin

• Problem → UVR is destrictive toward folate and DNA

• Equator → most UV rays received

  • Also associated with darker skin tone areas

  • Melanin is like a natural sunscreen

• At 35 deg latitude north/south, UVR become insufficient to make vitamin D

Vitamin D Status in Africans

• 367 adults from 5 different East African ethnical groups with traditional lifestyles; all living very near the equator; none using suncreen; stratified by levels of fish intake

• Average serum 25-hydroxy vitamin D was ~106nmoml/L

  • Significantly higher than any European population

• Authors concluded that sunlight was primary determinant, not fish intake

• Most humans had much higher levels of vitamin D status previously in history than now

Vitamin D status in Australians

• 11k+ people from all over Australia

• Average serum 25-hydroxy vitamin D = 63nmol/L

• Nearly 1/3 of the population was deficient (>50nmol/L)

• Prevalence of VDD significantly increased with:

  • Age, females, non-Europeans, obesity, higher education levels, physical inactivity

Vitamin D status in the USA

• 1181 Blacks and 904 Whites, living in the community

• Groups similar in age, sex, BMI, menopausal status

• Conclusion → Black people had significantly lower levels in serum 25-hydroxy vitamin D

• Also interesting that despite this, Blacks had greater BMD and reduced fracture risk

Vitamin D Status in Canada

• 2/3 of Canadians have okay vitamin D status when measured (>50nmol/L)

Vitamin D Status in Toronto

• 1384 ethnically diverse subjects (i.e. Caucasian, East Asian, South asian) aged 20-29 years

• South Asians had low status all year; ~50% were deficient (<30nmol/L)

Final thoughts on Vitamin D status

• VDD is common globally

  • Different estimates range from 40-75% of total population

  • An individual’s VD levels are influenced by: skin pigmentation, amount of sun exposure where they live, and many other factors

• Almost impossible to reach optimal VD level on diet alone

• Tactic of deliberately exposing your skin to the sun is highly questionable due to skin cancer risk

• Maybe vitamin D supplements are a good idea